Displays

Numerous studies worldwide have reported a dramatic increase in soil erosion rates following the development of agriculture. In Western Europe, food security issues led to an intensification of agricultural practices after World War II. A profound modification of the landscapes was operated that translated into an increase in hydrosedimentary connectivity and a decrease in soil cover in winter. Related on-site soil degradation and off site societal and environmental detrimental effects rapidly started to call for the implementation of conservation measures. Since 2000, the French water agencies, through the European water framework directives, started to fund the implementation of soft hydraulic conservation measures, such as vegetated filter strips or linear vegetation barriers. These measures have the advantage to be easily implemented and to be visible in the landscape without compromising the intensive agriculture production system. After twenty years of funding of soft hydraulic conservation measures, soil erosion is still an issue. Are these solutions just a plaster on a wooden leg or are they really effective? Recent efforts consisting in catchment scale monitoring programs and modelling exercise tend to show that soft hydraulic conservation measures may be usefull for local mitigation actions but may have a limited impact in terms of floods and muddy floods. On the basis of simulation exercises in contrasting environments we will discuss the advantages and limitations of such measures.

How to cite: Cerdan, O., Landemaine, V., Vandromme, R., and Grangeon, T.: Implementation of soft hydraulic conservation measures: are we done with soil erosion?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11744, https://doi.org/10.5194/egusphere-egu2020-11744, 2020.

Reseeding, using drought tolerant indigenous perennial grasses is a viable option for combating rangeland degradation, provision of livestock feed and improving livelihoods of pastoral communities. However, debates on whether monocultures or binary grass mixtures establishments are best suited for African rangelands managers, are still ongoing. Our opinion and contribution to this debate is informed by results obtained from a combination of an ecological field based and socioeconomic study in a typical semi-arid rangeland in Kenya. Perennial forage grasses indigenous to African rangelands Cenchrus ciliaris (African foxtail grass), Enteropogon macrostachyus (Bush rye grass) and Eragrostis superba (Maasai love grass) were established as monocultures and binary grass mixtures. Binary grass mixtures demonstrated significantly higher rehabilitation indices for plant frequency, basal cover and plant densities and soil hydrological properties (infiltration capacity, runoff and sediment production). However, pastoral communities showed preference to monoculture than binary mixtures. This was attributed to their role in livestock production. In conclusion, considering the ecological and socio-economic value of African rangelands to pastoral communities, the choice of either monoculture or binary grass mixture establishment will primarily be informed by the principle objective(s) of the rangeland manager.    

How to cite: Mganga, K., Nyariki, D., Bosma, L., Kioko, T., Kadenyi, N., and van Steenbergen, F.: Grasswise: monocultures or binary grass mixtures for African rangelands users?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13275, https://doi.org/10.5194/egusphere-egu2020-13275, 2020.

Biosolids are a source of nutrient-rich organic material that can be used to improve degraded or disturbed soils. However, public perception of the use of biosolids on land is both positive and negative and can change over time and be different in different regions of the world. Research on the land application of biosolids has increased in the past 20 years, but there is little consensus on how the environment responds to biosolids applications. Here, I (1) present public perception research on the use of biosolids in land application in British Columbia, Canada, (2) present a review of the literature on the effects of biosolids in land application with a particular focus on plant community development, and (3) provide recommendations for the use of biosolids in land application depending on potential differences in ecosystem reclamation goals. In the public perception research, many citizens see the value in the use of biosolids as a sustainable fertilizer, especially in mine reclamation, but some have expressed concerns about pathogens in biosolids and their effect on humans and animals. The literature review revealed that biosolids increase plant productivity but have no effect on plant diversity. The research suggests that climatic conditions and seeding are influential in altering ecosystem and community level responses to biosolids application.

How to cite: Fraser, L.: Why and when can biosolids be used as a soil amendment for ecosystem reclamation and rehabilitation?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2023, https://doi.org/10.5194/egusphere-egu2020-2023, 2020.

Soil salinization represents a wide-spread land degradation in the world, especially in arid regions. Current management involves excessive water consumption. As a pyrolyzed residue of biomass waste, biochar has the potential to combat salinization at limited water supply, the effect and mechanism, however, remain to be clarified. We monitored the movement of salts and water in the profile of irrigation-silt soil during watering and evaporation in both laboratory and the field in Kashgar oasis in Xinjiang, China, and found that biochar exacerbates salinization within a short period of time after its application due to its high content of salts, nevertheless, it strengthens salt leaching in irrigation while intensifies salt accumulation in the top soil at the expense below during evaporation, all as results of invigorated movement of salts. Removing the top 2 cm before sowing, therefore, rejuvenates the soil well. Adsorption of biochar retards migration of salts in cation forms, but the effect is trivial. Due to increase to soil water content, biochar promotes evaporation before soil cracking. This is reversed, however, once the cracking occurs, which is inevitable in irrigated farmland and increases evaporation by 77%. Biochar counteracts soil cracking by alleviating soil compaction, lowering water evaporation by 43% at 10% of biochar application rate. Our results indicated that agriculture application of biochar creates salt distribution conducive to desalting in a mechanical way. In conjunction with the effect of anti-fracturing and enhanced salt leaching, it lowers water demand substantially, providing a new solution to the agricultural sustainability at reduced water supply.

How to cite: Lee, X., Huang, Y., Yang, F., Xing, Y., Xu, L., Liu, Z., Wang, R., Holtzman, R., Kan, I., Li, Y., Zhang, L., Wu, W., Ma, Y., and Zhou, H.: Biochar manages salt-degraded land and conserves water: Effects and mechanism, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2159, https://doi.org/10.5194/egusphere-egu2020-2159, 2020.

Rare earth elements (REE) mines have an extremely high strategic value, especially, in national aerospace industry and military fields. The long-term open mining and extraction processing of REE in the weathered crust since 1970s have led to serious land degradation, e.g., vegetation degradation, soil loss, reduction of soil fertility, and especially, environmental pollution to subsoil and groundwater. Taking southern Jiangxi, where ion-type of REE mines are mainly located, as an instance, the total mining area is measured about 79 km² from 1291 mines, of which 56 km²  have been or are being managed with restoration measures identified by comparison between multitemporal very high resolution images available on Google Earth. Visual interpretation revealed that large-scale mining activities occurred after 2000 and restoration management was not intervened until 2010, in particular, 2013. As implemented by different enterprises or companies, post-mining restoration has a strong spatial variability in both management approaches and effectiveness from mine to mine. Up to today, no systematic monitoring and assessment have been conducted for this restoration intervention. It is, therefore, the objective of our study to evaluate the effectiveness of such restoration efforts using multitemporal October Landsat data with scene path/row number of 121/42-121/43 from 2000 to 2017. Eight managed and seven unmanaged typical mines were selected for a comparative analysis and restoration assessment.

After atmospheric correction using COST model, NDVI and GDVI (Generalized Difference Vegetation Index) that is more suitable for low vegetation, as proxy of vegetation vigor and biomass production, were derived from all satellites images. The mean NDVI and GDVI values of each selected mine were calculated. The results show that NDVI of the managed REE mines has been increasing from 0.32 to 0.67 and GDVI from 0.55 to 0.90 year by year since 2010, indicating a vegetation recovery, especially, for those with effective management. In contrast, in the unmanaged mines, NDVI values remain low ranging from 0.20 to 0.40, and GDVI from 0.22 to 0.60, implying that the damaged vegetation cover caused by open mining and pollution has low capacity to recover without human intervention, where continue serious water loss and soil erosion. We also noted in some managed areas that planted grasses have survived but trees died or are dying probably because of the residual pollution in subsoil. This means a holistic management should be implemented in both surface, subsoil and groundwater, and monitoring be conducted by remote sensing in combination with soil sampling. This will be our next task of research.

How to cite: Xie, L., Wu, W., Huang, X., Ou, P., Lin, Z., Song, Y., Wang, Z., Lang, T., Huangfu, W., Zhang, Y., Zhou, X., Fu, X., Li, J., Jiang, J., Zhang, M., Zhang, Z., Qin, Y., Peng, S., and Shao, C.: Restoration monitoring of rare earth element (REE) mines in southern Jiangxi, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8255, https://doi.org/10.5194/egusphere-egu2020-8255, 2020.

Soil carbon storage is crucial for global carbon budget and at the same time affect many key ecosystem functions. There are several studies showing that in initial soil substrates and or degraded soils with little overall soil organic matter content have high ability to sequester carbon. Mechanisms that cause this fast SOM sequestration are not completely elucidated but most likely arise from availability of vacant spaces where SOM can be bound by various mechanism and set of positive feedback loops which cause that increase in one SOM pool may increase rate of saturation in other pools. There are also some indication that major mechanisms how the SOM its stored in soil vary along soil development gradient. In Initial soils there may be high rate of SOM sequestration achieved under fast growing plants producing easily available litter, in this stage incorporation POC in mineral matrix, storing microbial neuromas and activity of earthworms play crucial role in SOM sequestration. While in latter stages of soil development, when soil is already close to saturation slow growing plants, producing slow decomposing litter result in higher carbon sequestration, ir seems to be that shift of microbial necromass to fungal rather than bacterial necromass, and difference in litter and microbial necromass decomposability may play important role in this stage. Implication of these finding for ecosystem restoration is discussed. 

How to cite: Frouz, J.: Do heavily degraded soil really sequester carbon faster? Can that be change for soil restoration?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18269, https://doi.org/10.5194/egusphere-egu2020-18269, 2020.

Massive biodiversity loss, alarming the scientific community, is a hot topic nowadays. On the other hand, mining sites, active or closed, represent almost 1 percent of Earths’ surface. Mine safety imposes physical protection and isolation of mines by high fences, signs and guards in active and sometimes even in closed mines. Human activity, other than extraction, is most often legally restricted in mines, and hence the human disturbance is low; even in active mines, extraction is mostly taking place in one relatively small part of the mine, at one time, while the fence protects the whole mining area. As such, even active mines might present shelters for biodiversity, especially outside the working hours (late afternoon and night) for animal species, or in areas that are not exploited at the moment for plant species.

However, active and closed mines are rarely regarded as an opportunity for biodiversity. They are rather commonly regarded as degradations that require intense fixing actions. Instead of constantly rehabilitating them, in order to make them less dangerous for local populations or making them functional for humans – by giving them back the function they had before mining (i.e. agriculture, forestry) or creating a new one like landfill or industrial zone in quarries or fishing, hiking or other leisure activities in gravel pits – should we keep them protected and look at them as potential biodiversity reservoirs, in nowadays landscapes, overpopulated and generally highly impacted by human activities?

Should we rehabilitate mining sites or let them be biodiversity sanctuaries, where nature will develop itself as is suits her? Should we humans constantly try to “improve” and “help” nature, or should we let it be?

Existing studies showed that spontaneous succession can lead to valuable high-diversity habitats, but the attention given to its effect in mining sites has not yet been extensive. We studied biodiversity in mining sties, and we present empirical evidence suggesting that mining sites where nature has been left to develop on its own should be regarded as opportunities for biodiversity.

We compared the influence of four different rehabilitation techniques - mineral base left to spontaneous succession, mineral base covered with topsoil, mineral base covered with topsoil and planted, and mineral base covered with topsoil, sown and planted - on biodiversity development in quarries and gravel pits, in order to determine the technique that favors the most biodiversity development. We conducted inventories of five taxonomic groups present on-site after application of those four different rehabilitation techniques. 29 flora plots and 18 fauna transects were thoroughly inventoried, several times, in sites in northeastern France. We recorded 186 species of plants, 14 individuals/2 species of reptiles, 479/11 of amphibians, 91/39 of butterflies and 325/27 of dragonflies. For all five taxonomic groups, natural succession had the most favorable impact, compared to other rehabilitation techniques.

Our results suggest a necessity for a perspective change in favor of regarding mining sites as opportunities for becoming biodiversity shelters.

How to cite: Pavlovic, V.: Mining sites: Landscape degradation or Opportunity for Biodiversity?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10901, https://doi.org/10.5194/egusphere-egu2020-10901, 2020.

Currently, we can see a rapid decline of agricultural land, especially for construction purposes. This negative trend is evident across Europe, the Czech Republic is the country with the fastest loss of land in the EU. One reason for the significant loss of agricultural land is building industrial zones is their utilisation of greenfield areas, and their occupying new areas of agricultural land, often the most the most fertile. The analysis deals with the occupied area (the area of a particular industrial zone), the percentage utilization of that industrial zone, the number of employees in the industrial zone, and the land quality expressed by means of the agricultural land protection class. The results of the analysis show the low usability of industrial zones, the large occupation of agricultural land, and the low benefits to the Czech state and Czech citizens. The results also show poor land use policy in relation to soil protection. This work is followed by the project Sustainable management of natural resources with emphasis on non-production and production ability of soil, the results of which will be included in legislation and binding for spatial planning.

Keywords: soil sealing, land take, land use changes, agricultural land management, land agriculture protection, brownfield

How to cite: Janku, J., Kozák, J., Macounová, K., Jacko, K., Marhoul, A. M., Vopravil, J., and Jehlička, J.: Land take and industrial zones, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8579, https://doi.org/10.5194/egusphere-egu2020-8579, 2020.

Rapid changes in land use due to intensifications of oil exploration and exploitation adversely affect the Eastern Mongolian steppe ecosystem. The expansion of supporting infrastructure and dirt road networks for oil production contribute to accelerate the human-induced land degradation process in the grasslands. So far, neither the extents of road networks nor the extent of surrounding grasslands affected by the oil industry are monitored which is generally labor consuming. This causes that no information on the changes in the area which is affected by those disturbance drivers is available. Therefore, the major aim of this study is to provide a cost-effective model to map the supporting infrastructure, sites and dirt roads of oil exploitation through classifying remotely sensed images using object-based classifications with Random Forest. By combining satellite data with different spatial and spectral resolutions (PlanetScope, RapidEye, and Landsat ETM+), the product delivers data since 2005. In the image classification, the variables of segmentation, spectral characteristics, and indices were extracted from all above mentioned imagery and used as predictors. Within this study examined the comparison analysis in order to quantify the uncertainty arising from the combination of data from different sensors in their spectral and spatial configurations. Besides that, this study analyzed the consequence of supporting infrastructure and dirt roads on surrounding ecosystems combining data from field vegetation surveys and drone imagery. Results show that overall accuracies of land use maps ranged 73%–93% mainly depending on satellites’ spatial resolution. Since 2005, the area of grassland disturbed by dirt roads and oil exploitation infrastructure increased by 88% with its highest expansion by 47% in the period 2005–2010. Consequently, the comparison of multiscale classification suggests that, although high spatial resolutions are clearly beneficial, all datasets were useful to delineate linear features such as roads. Furthermore, the results of this study provide an effective evaluation for the potential of Random Forest based model for extracting relatively narrow linear features such as roads from multiscale satellite images and map products that are possible to use for detailed land degradation assessments.

How to cite: Dashpurev, B., Bendix, J., and Lehnert, L.: Monitoring Oil Exploitation Infrastructure and Dirt Roads with Object-Based Image Analysis and Random Forest in the Eastern Mongolian Steppe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5465, https://doi.org/10.5194/egusphere-egu2020-5465, 2020.

Desertification, as one of the gravest ecological and environmental problems in the world, is affected both by climate change and human activities. As the consequences of global warming, the temperature in global arid and semi-arid areas is expected to increase by 1-3℃ by the end of this century. This change will significantly influence the spatial and temporal pattern of temperature, precipitation and wind speed in global arid and semi-arid areas, and in turn, ultimately impact the processing of desertification. Although current studies point out that future climate change tends to increase the risk of desertification. However, the future global or regional desertification risk under different climate change scenarios hasn’t been quantitively assessed. In this paper, we focused on this question by building a new model to evaluate this risk of desertification under an extreme climate change scenario, i.e. RCP8.5 (Representative Concentration Pathways, RCPs). We selected the northern agro-pastoral ecotone in China as the study area, where is highly sensitive to desertification. Firstly, the risk indicators of desertification were chosen in both natural and anthropic aspects, such as temperature, precipitation, wind speed, evaporation, and population. Secondly, the decision tree C5.0 algorithm of the machine learning technique was used to construct the quantitative evaluation model of land desertification risk based on the database of the 1:100,000 desertification map in China. Thirdly, with the support of the simulated meteorological data by General Circulation Models of HadGEM2-ES, the risk of desertification in the agro-pastoral ecotone in the north China under the RCP 8.5 scenario and SSP3 scenario (Shared Socioeconomic Pathways, SSPs) were predicted. The results show that the overall accuracy of the C5.0-based quantitative evaluation model for desertification risk is up to 83.32%, indicating that the C5.0 can better distinguish the risk of desertification according to the status of desertification impacting factors. Under the influence of future climate change, the agro-pastoral ecotone in northern China was estimated to be dominated by mild desertification risk, covering an area of more than 70%. Severe and moderate desertification risk is mainly distributed in the vicinity of Hulunbuir sandy land in the northeast of Inner Mongolia and the Horqin sandy land in the junction between Inner Mongolia, Jilin and Liaoning provinces. Compared with the datum period, the risk of desertification will decrease under the RCP8.5-SSP3 scenario. However, the desertification risk in Hulunbuir sandy land and that in the northwest of Jilin province will increase. The results of this study provide a scientific basis for developing more effective desertification control strategies to adapt to climate change in the agro-pastoral ecotone in north China. More importantly, it shows that the desertification risk can be predicted under the different climate change scenarios, which will help us to make a better understanding of the potential trend of desertification in the future, especially when the earth is getting warmer.

How to cite: Yue, Y. and Li, M.: Is the impact of climate change on desertification predictable?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6141, https://doi.org/10.5194/egusphere-egu2020-6141, 2020.

Air pollution caused by human activities contributes to the deglaciations of Arctic ice and highland areas, accelerates the process of climate change on the planet and leads to land degradation. Black carbon is the second largest artificial contributor to global warming and accelerates the deglaciations rates after carbon dioxide. Black carbon is formed as a result of incomplete combustion of fossil fuels, biomass, etc. Another important aspect of organic matter role is the presence of specific formations of combined biogenic-mineral materials on the surface of the glaciers – cryoconites. Cryoconites represent soil like bodies formed not on normal parent material, but on the surface of the ice. This type of accumulations appear in microdepressions, formed due to thawing of ice under accumulation of black carbon on the surface of ice. During the thawing, the cryoconite substances become located deeper in relation to initial surface and this result in additional accumulation of organic matter in microdepressions, they become wider and deeper. Spatial web of cryoconite became more developed and this result in degradation of the glacier surface. This cryoconite formation result in degradation of upper layers of ice and increases deglaciation rates.  The organic carbon of the cryoconite origin could be considered as specific form of natural organic matter stabilization and should be investigated on the molecular level. The advantage nuclear magnetic resonance spectroscopy method is the ability to quantify the content of groups of structural fragments and identify individual structural fragments in humic acid molecules. Studies on the organic compounds of HAs for the soils of the polar area by the ¹H-¹³C (HETCOR) NMR spectroscopy have not been carried out to current time. The advantage of this method is that, when analyzing the spectra of HAs, we can observe cross-peaks of H-C bonds, while for the ¹³C (CP/MAS) NMR spectroscopy we can only observe chemically bound carbon. The HETCOR method allows the study of single HAs fragments. Thus, the combination of the two methods ¹H-¹³C (HETCOR) and ¹³C (CP/MAS) NMR spectroscopy can reliably determine the molecular structure of HAs. In our research we investigate the cryoconitte on the Grønfjorden area in western Spitsbergen, Svalbard. Analysis of the molecular composition of HAs showed that the molecules of HAs formed on cryoconites are enriched with aromatic fragments and they contain in their composition a considerable number of aromatic fragments (41–43%) with a relatively small fraction of carbohydrate periphery, as evidenced by higher values of AR/AL (0.75 and 0.69). Higher aromaticity of HAs causes their high stability and the degree of hydrophobicity of HAs in these soils is also higher, which indicates the stabilization of HAs.

Acknowledgements: This work was partially supported by Russian Foundation for Basic Research, projects No: 19-54-18003, 19-54-18003 and 19-05-50107

How to cite: Abakumov, E. and Polyakov, V.: Molecular composition of black carbon in the cryoconite in Arctic by Two-Dimensional 1H-13C HETCOR and 13C CP/MAS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3920, https://doi.org/10.5194/egusphere-egu2020-3920, 2020.

Enhanced anthropogenic climate change (global warming) is already leading to significant changes in the properties, processes and dynamics of land surfaces of high latitude and high altitude areas. Rapid surface and subsurface warming, ice mass loss and ice margin retreat are now resulting in increased land surface instability. Evidence for this comes from increased sediment yield by mass movements on exposed slopes, and within river systems and along coasts. In turn, increased sediment yield results in geomorphic change in these areas. The concept of paraglacial response describes the nature of changes in sediment yield and land surface geomorphology during rapidly-warming deglacial periods. This concept is increasingly relevant in a global warming context to describe land surface changes in high latitude and high altitude areas. Hitherto, paraglacial land surface responses have not been considered as part of the wider topic of global land degradation, but increased slope sediment yield and changes in the sediment mass budgets of slopes, rivers and coasts have implications for the morphodynamics and geohazards of high latitude and high altitude areas, and are similar to land degradation processes found in other climatic and physical settings. This study highlights the similarities and differences in (i) processes, (ii) spatial and temporal scale of operation, (iii) geomorphic and sediment system responses, (iv) geomorphic and environmental hazards, both direct and indirect, and (v) societal or community impacts and responses. This comparison is undertaken between paraglacial relaxation in recently deglaciated terrain, and land degradation associated with desertification in Africa. Examples of deglaciating land surfaces in Spitsbergen and in mountain blocks worldwide are used to demonstrate the wide range of contemporary paraglacial (land degradation) processes affecting these high latitude and high altitude environments. It is notable that land degradation caused by paraglaciation in these areas pose significant challenges to the sustainability of communities and to environmental monitoring and management.

How to cite: Knight, J. and Strzelecki, M.: Land degradation in high latitude areas: the role of paraglacial land surface changes driven by global warming , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6435, https://doi.org/10.5194/egusphere-egu2020-6435, 2020.

A goal of Land Degradation Neutrality by the year 2030 was agreed by the Rio+20 conference in 2012, and subsequently included in the Sustainable Development Goals. It dilutes earlier goals of unrestricted control of desertification, for example, by proposing that the rate of land degradation should be reduced and the rate of restoration of degraded land increased so they offset each other by 2030. As with many environmental concepts that have emerged in recent decades, Land Degradation Neutrality was proposed in the political arena, and scientific study is only now starting to evolve. Yet distinct positions are already forming within the scientific community, for example, on the feasibility of monitoring land degradation neutrality in dry areas when there are no reliable estimates for the rate of desertification, and on what constitutes land restoration in dry areas. Land degradation neutrality is also yet to be put in the wider context of environmental degradation as a whole, e.g. how does it relate to the forest degradation component of the Reducing Emissions from Deforestation and Degradation (REDD+) mechanism of the UN Framework Convention on Climate Change, and to degradation of biodiversity which the Convention on Biological Diversity is seeking to reduce. This session will allow scientists working in the field of land degradation neutrality to share their perspectives in this emerging field.

How to cite: Grainger, A.: Is existing scientific knowledge sufficient to provide the basis for reliable monitoring of achieving land degradation neutrality?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22216, https://doi.org/10.5194/egusphere-egu2020-22216, 2020.

Globally, grazing systems have been consistently implicated in land degradation as reflected by changes in woody cover, soil degradation and losses of biodiversity. Pastoral systems can be a major contributor to global greenhouse gas (GHG) emission or a low-cost carbon sink for climate mitigation. In Australia, the $AUD 2.55 billion Emissions Reduction Fund (ERF) is the centre piece of climate policy and has resulted in >3.8 million ha of land use change. Traditional pastoral systems are now including management which increases carbon pools in vegetation (regeneration of native vegetation in rangelands) and soils (regenerative pasture management to increase the amount of soil biomass and limit soil disturbance). The scale of this land-use change is providing an unpredicted opportunity to deliver multiple ecosystem services, or core benefits (production of food and fibre, carbon sequestration and reduced loss of soil carbon). While there is increasing anecdotal evidence that regenerative agricultural practices results in increased farm profitability and greater wellbeing, there are key uncertainties around their potential to deliver multifunctional landscapes and contested views on the magnitude of these changes and opportunities. A major uncertainty revolves around climate impacts on carbon sequestration.

We provide two case studies which explicitly incorporate carbon sequestration and regenerative management practices and have the potential to deliver multiple environmental, economic and social benefits; (i) using a rangeland carbon farming example, we show how income from carbon sequestration in vegetation, re-directed to managing of grazing intensity, is leading to greater ecological and social resilience. Additional value of these carbon farming areas through ecological thinning and the use of woody residue for biochar production represents further mitigation potential as well as increased benefits in habitat for biodiversity (ii) using a temperate grazing system, implementing regenerative agricultural practices which reduce the amount of soil organic matter decline through minimal disturbance and pasture management may increase soil organic carbon. For each case study, Land Use Trade-Offs (LUTO) model, a high-resolution integrated environmental-economic model, is used to illustrate spatiotemporal dynamics of land-use options, quantify the magnitude of trade-offs adjusted for future climate impacts and assess farm-scale land use prioritisation and optimisation for multiple benefits. We identify land management practices that increase carbon sequestration (vegetation and soils) and realise opportunities for additional farm income are integrated with sustainable land management.

How to cite: Waters, C., Orgill, S., Ogilvy, S., and Simmons, A.: Demonstrating sustainable land management and delivering multiple environmental, economic and social benefits in Australian pastoral systems. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6192, https://doi.org/10.5194/egusphere-egu2020-6192, 2020.

Throughout the world, the arable agricultural lands are already fully utilized, and hence marginal land, including saline land, is being brought into consideration. Owing to its geographical and climatic characteristics, aggravated by impacts of climate change and anthropogenic pressures, Central Asian countries (CACs) are facing serious food and nutrition security challenges. Current agropastoral and farming-livestock systems have little experience in designing and implementing climate-smart land-use initiatives from so-called ‘marginal lands’.  As an instance, a land that is “marginal” for crop production may be well suited for grazing, bio-energy production, silvi-pastoral use. “Fragile” land may be sensitive to degradation under cultivation but may be sustainable used for agroforestry and afforestation practices. Nowadays there is not a world-known definition of the extent and characteristics of categories of marginal lands. Purposes of study: (1) investigate if land-use types have discrete, quantifiable vegetation characteristics; and (2) if these also have discrete soil characteristics.  Overall goal: in future, use the information to (1) characterize land use over the entire district and (2) better manage land to make more productive, increasing food and nutrition security of the local population.  Quantitative and qualitative assessment of vegetation condition of 6 land categories were performed using plant communities’ characteristics, species composition, canopy cover and biomass production along a salinity gradient. We rank the sites by their content of sodium ions in the salt surface crusts and the underlying soil horizons. The majority of lands of research target areas are strongly saline at the surface and with a vertical distribution of salinity typically down to a depth of 10 cm (with a maximum depth to 18 cm). This distribution of readily soluble salts is due to the proximity of saline groundwater.  With extreme arid climatic conditions, the toxic salts can be readily drawn upward toward the surface. Differences between sites are observed by the extent of salinization of the middle and lower soil horizons. The first land clusters are very high in salt content throughout the depth of the soil. The second group consists of lands in which salinity of the middle and lower soil horizons does not get above the mean (>0.3%).  There is quite low salinity (> 0.1%) immediately under the salt crust, (as estimated by the total amount of toxic salts). Investigated lands categories differed in plant functional types (glycophytes>euhalophytes>recretohalophytes). As soil salinity increased, the proportion of the perennial growth form increased from ~60% of species in sites with lower soil salinity to 100% in the natural solonchak with the greatest soil salinity. Remediation measures and multi-purpose use of marginal lands, such as saline lands; degraded pastures, abandoned farmer lands; wastelands surrounding water bodies and hydrothermal wells, field margins; tugay forest wetlands were recommended.

How to cite: Toderich, K., Shuyskaya, E., Lebedeva, M., Khujanazarov, T., and Yasui, H.: Phytoindicators of marginal saline lands: Potential for improving dryland management to increase agroecosystem resilience and productivity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7469, https://doi.org/10.5194/egusphere-egu2020-7469, 2020.

The trace element composition of stratified peat soils is interesting for the reconstruction of the geochemical background of atmospheric aerosol. The monitoring of trace element contents in peat deposits is often used for the identification of pollution around large industrial centers. The destabilization of the peatlands of the cryolithozone presents a global environmental hazard of the input of inorganic pollutants into the hydrologic network and their subsequent transport into the Arctic Ocean. Climate warming and permafrost degradation enhance the influence of deep peat layers on the trace element composition of groundwater and rivers. The purpose of the work is to assess the accumulation of trace elements in peat soils as a result of the aerogenic pollution of the territory and to identify their internal profile migration and accumulative characteristics. The peatlands investigated are in the far north taiga (Northeastern European Russia, 65°54′ N, 60° 26′ E), ecoton south tundra – forest-tundra (67°03′ N, 62° 56′ E) and ecoton north tundra – south tundra (68°02′ N, 62° 43′ E). The upper level of trace element accumulation was confined to the active (seasonally thawed) layer owing to airborne contamination over a long time span and related to the bioaccumulation of Hg, Cd, Pb, Cu, and other heavy metals (HMs) by plants and humus materials. The character of element accumulation and migration in the active layer is controlled by the stability of HM humates. Under high-acidity conditions, HMs are highly mobile and migrate to the lower boundary of the active layer, which is indicated by an increase in the fraction of water-soluble forms of a number of elements. Analysis with a scanning electron microscope revealed the presence of spherical and semispherical particles up to 1 μm in size containing Pb, Zn, Cr, and Ni in the upper peat levels, which indicates an anthropogenic source of their input owing to long-distance and local transport of air masses. The central level of element accumulation was confined to peat layers in the permafrost zone (60–120 cm), where enrichment in As and Cd relative to the mean contents in the Earth’s crust (and approximate permissible concentrations, APC, for soils) and accumulation of Fe, Al, S, and siderophile elements were observed. The source rocks of the peatlands are loams enriched in Cd, Zn, and As. The statistical analysis of relations of the contents of major and trace elements in the stratified peat horizons with the composition of peat-forming materials showed a significant contribution of the biogenic accumulation of elements. The reported study was funded by the RFBR No 18-05-60195 (No AAAA-A18-118062090029-0).

How to cite: Vasilevich, R.: Assessment of the trace element composition of peat soils from the European Arctic in a changing climate conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18613, https://doi.org/10.5194/egusphere-egu2020-18613, 2020.

Numerous methodologies are available so far measuring trends of land (LD) and ecosystem degradation (ED) with spatially explicit manner. Yet the delineation of spatial and temporal covariance between LD and ED remains challenging which limited the effectiveness of future conservation decision making for preventing risks of LD and ED simultaneously, especially in cold and drought areas because of high cost of restoration. Here, we produced the spatial networks for managing and restoring LD and ED based on the risk projection of LD and ED in Tibet plateau under human exploitation pressure and climate change. Firstly, we simulated 10 indicators for LD and ED separately by monthly interval from 2000 to 2015 to capture the current trends of LD and ED. Secondly, resilience, resistant, and risk exposure have been assessed to connect the vegetation traits, threaten factors and their reflections. Thirdly, by the exploration of relationship between LD and ED and their impact factors, we projected risks for both of them using 12 scenarios from different climate and land use change combinations identifying the key area of preventing LD and ED spatially. Finally, an effectiveness analysis has been processed ordering results under each scenarios leaded to the decline of nature capital for providing alternative strategies of regional land and ecosystem management. By our research, we found that LD and ED in Tibetan plateau have similar pattern of dynamic, while ED shows more significant correlation with climate change due to stronger intrinsic resilience in front of stressors. In opposites, once serious land degradation occurs, it is hardly being recovered by increasing of precipitation and temperature. Based on the relationship analysis, we modeled LE and ED risks under various potential scenarios suggesting that at least 100,000km2 area needed to human intervention for restoration. These suggested sites covered the worst 60% areas of both LD and ED producing 12.5 billion USD  dollars revenue from the maintenance of key regulating ecosystem services.

How to cite: Zhang, L.: Projection of land and ecosystem degradation for preventing risk of natural capital decline in Tibet plateau., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13459, https://doi.org/10.5194/egusphere-egu2020-13459, 2020.

The Qinghai-Tibetan Plateau (QTP) is the highest plateau on earth and has a large area of alpine swampy meadows. In the past few decades, overgrazing and climate change have caused severe desiccation and degradation of the alpine wetlands. The remote sensing technology has been used to assess the wetland shrinkage. However, changes in soil nutrients associated with the duration of alpine wetland degradation are poorly known. We took soil samples in three swampy meadows of the QTP, one terrain was relatively flat and the other two were with hummocks and hollows. Decadal gradients of degradation from nondegraded swampy meadows to degraded meadows were selected. The contents of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) were analyzed. The SOC, TN, and TP contents loss in degraded swampy meadows occurred mainly during the first decade. The soil nutrients loss was highly affected by the geomorphic characteristics of the wetland area. After degradation, the SOC, TN, and TP contents decreased at exponential rates on the flat terrain site. The top layer SOC, TN, and TP contents of the degraded about 30 years area were 24.76±0.91, 2.22±0.07 and 0.45±0.01 (mean ± SE) g kg^-1, respectively; and the SOC, TN, and TP contents decrease were 75%, 72% and 56% that of the nondegraded swampy meadows, respectively. On one hummock-hollow sites the top layer SOC, TN, and TP contents of the degraded for about 30 years area were 61.22±11.94, 4.09±0.73 and 0.44±0.05 (mean ± SE) g kg^-1, respectively; and the SOC, TN, and TP contents decrease were 45%, 52% and 46% that of the nondegraded swampy meadows, respectively. The soil nutrients decomposition rate of hummock-hollow sites was much lower than the flat terrain site. Large and tough hummocks in swampy meadow degradation sites can resist environment erosion and stabilize soil nutrients content at high levels.

How to cite: Li, H., Li, T., Sun, W., Zhang, W., Yu, L., Guo, B., Liu, J., and Zha, X.: Soil nutrients dynamics and the evolution of multi-decadal degradation in alpine wetlands of the Qinghai-Tibetan Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5235, https://doi.org/10.5194/egusphere-egu2020-5235, 2020.

Land degradation emerges when a critical component of productive land begins to diminish beyond a threshold. In tropical soils, organic matter may vary depending on the local climatic conditions and production of litter and organic materials and furthermore drastic changes in land use may be responsible for changes in organic matter which coincides with soil physical changes. In two research regions in mountainous (sub) humid conditions, organic matter was measured alongside surface and profile characteristics. In the Ethiopian Highlands, we measured organic matter, soil penetration resistance, soil texture, pH, and bulk density in three land use classifications (native forests, pasture lands, croplands).  In this region, soil in cropped regions and pasturelands had organic matter roughly below 4 %, had greater soil penetration resistance, lower pH (more acidic), and had greater bulk density. Soils in the native forests had organic matter roughly between the range of 4% to 12 % with lower soil penetration resistance, higher pH (less acidic) and lower bulk density.

The soils were investigated in the Andean region of the southwest of Colombia were analyzed for organic matter, hydraulic conductivity, soil texture, pH, and bulk density across two main land use classifications (native- and regenerated-forests and cultivated and pastureland). Soils in the cropped and pasturelands had organic matter around 4.8%, with low saturated hydraulic conductivity, greater fraction of fine particles, lower pH (more acidic), and greater bulk density. Soils in the native and regenerated forest cover had organic matter between 5 to 7%, with greater saturated hydraulic conductivity, lower fraction of fine particles, higher pH (less acidic), and a lower bulk density. While a universal optimal level of soil organic matter may not be applicable across various tropical regions, there are distinct changes that are consistent when organic matter falls below a regional threshold including increased compaction, acidity, and shifting of soil texture.  

How to cite: Guzman, C., Tebebu, T., Zimale, F., and Steenhuis, T.: What is the optimal level of soil organic matter in tropical climates to prevent soil degradation?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13538, https://doi.org/10.5194/egusphere-egu2020-13538, 2020.

Conservation agriculture (CA) has been promoted to reduce land degradation, improve the soil fertility, the soil structure and increase the level of soil organic carbon over time. It is expected to mitigate climate change and enhance the resistance of crops to the changing climate. Yet, its impacts on crop yields remains controversial. To gain further insight on the sustainability of CA, we mapped the probability of yield gain when switching from conventional tillage systems (CT) to CA worldwide. The range of yield changes were estimated with machine learning algorithms trained by 2828 paired yield observations on 8 crop species extracted from 323 publications. CA stands a more than 50% chance to outperform CT in dry and cool regions of the world, while it can lead to yield losses of up to 59% in warmer and wetter regions. Residue retention has the largest positive impact on CA productivity compared to other management practices. The promising and the risky regions for CA global implementation were identified. The productive performance of CA for different crops in future climate were also estimated and mapped globally, the results of different scenarios were compared and analyzed. Overall, with proper managements, CA appears as a sustainable agricultural practice for specific climatic regions and crop species.

How to cite: Su, Y., Gabrielle, B., Beillouin, D., and Makowski, D.: High probability of yield gain through conservation agriculture in dry and cool regions for major staple crops, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22040, https://doi.org/10.5194/egusphere-egu2020-22040, 2020.

The effects of plants on gravity erosion are still controversial, although vegetation has been widely used in soil and water conservation. In order to evaluate the influence of vegetation on gravity erosion, a series of laboratory experiments was performed on a 1.5-m-high loess-gully sidewall with a 70° slope, involving two types of shrubland (SL model) and bare land (BL model). The results revealed only an 8–20% decrease in total gravity erosion in the SL model compared to the corresponding BL model, which indicated that the impact of vegetation on gravity erosion is not significant. Compared with the BL model, the average landslide volume was 42% greater in the SL model, while the average avalanche and mudslide volumes in the SL model were 50% and 36% less, respectively. In addition, vegetation can change the type of gravity erosion and improve the degree of soil fragmentation. The amount of erosion after rain in the SL model was 33.17×10³ cm³ more than that in the BL model. Compared with the anchoring effect of vegetation, the change of soil water caused by vegetation on the slope has a greater effect on the gravity erosion under heavy rains. It is suggested that the shrub restoration measures can be used in the areas with frequent debris flow and hydraulic erosion, and structural measures may reduce the negative impact of plants on gravity erosion of the Loess Plateau.

How to cite: Gao,, H. and Xu, X.: How do shrubs impact the mass failures on the loess sidewall?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2041, https://doi.org/10.5194/egusphere-egu2020-2041, 2020.

Assessments of land degradation in arid and semi-arid regions frequently employ models calculating annual erosion rates from the size of sediment bodies, assuming grain-by-grain transport and constant processes of deposition. It is often attempted to connect historic sediment bodies to past land use and climate by correlations with demographic estimates and reconstructions of past precipitation averages. In addition, mass transport is often equalled with soil loss and fertility degradation, based on the idea that humus-rich topsoils store the greatest part of soil nutrients. However, such concepts are based on premises transferred from temperate regions, and their suitability for arid and semi-arid regions is questionable. For example, dryland soils usually contain very small amounts of organic matter, which means that their fertility is mostly a function of texture, and a limited loss of topsoil is rather irrelevant for agricultural productivity. Part of the sediments deposited in valleys come from soft, easily erodible rocks, which means that they reflect slope denudation and not soil erosion. As well, erosion-sedimentation processes do often not take place by continuous transport of single grains. This is illustrated with a valley fill in northern Jordan: sediments were deposited discontinuously, mainly by slumping and earth flows, and the largest parts of the fill accumulated in time frames of ~100 years during the two Little Ice Ages (6^th and 14^th century AD/CE). Due to a dominance of smectites, the clay-rich Red Mediterranean Soils in the vicinity shrink and form cracks during the dry period. Because of the cracks and underlying limestone karst, they can swallow strong rains without erosion risk. However, when water-saturated, soils expand and may move in slump flows. Soil-covered geoarchaeological features like a buried ancient cemetery illustrate that such viscous flows created new land surfaces, sealing cavities but not filling them. This suggests a major role of rare but intense rainfall events in erosion-deposition processes. Analogies with modern rainfalls, including record levels of precipitation during the winter 1991/1992, indicate that levels of soil moisture triggering similar slump flows have not been reached during times of modern rainfall monitoring. That ancient land use played a minor role for erosion is supported by intense surveys of archaeological material on fields surrounding the valley, which indicate that the periods of most intensive land use coincided with very limited sediment deposition. Concepts of land degradation in semi-arid and arid regions should be reconsidered, respecting the more irregular environmental setting, the specific soil properties, and traditional land use systems which evolved in constant adaptation to this environment. Rare but extreme rainfall events as potential main drivers of land degradation should be considered more: they are difficult to control or mitigate, but may increase due to climate change.

How to cite: Lucke, B.: Questioning models of land degradation in arid and semi-arid regions: a re-assessment based on evidence from northern Jordan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9275, https://doi.org/10.5194/egusphere-egu2020-9275, 2020.

Soil water holding capacity is an important soil property which influences soil and water conservation as well as land degradation and development. Some studies indicated that field capacity (FC) was increased as soil organic matter (SOM) is improved, but the positive effect of SOM on FC was still contradictory. No consistent reports were found for the SOM potential that could be increased. Whether FC could be improved due to increase in SOM by organic amendment is not well established. It is still unknown whether or not there is benefit of improving SOM for enhancing FC; what is the threshold level of SOM for increasing FC, and how much SOM can be boosted. The field study and literature review were conducted to answer all those questions. Soil samples were taken at four sties manured and not manured in the Southern United States, then SOM and FC were measured. The soils amended with poultry litter had higher SOM (3.2%) and FC (35.38%), while the soils without amendment of poultry litter had lower SOM (1.7%) and FC (30.33%), a positive effect of SOM on FC was observed. For different soils with various clay content, a strong positive relationship was observed for soils with clay content less than 15% (R²= 0.7). We found that FC started increasing as SOM was increased over 2%, it is the threshold level of SOM for improving FC. Previous research also reported that there was no positive effect on FC for cultivated soils with a mean SOM of 1.2% in Greece. Another study found that the increase in water content is significant for sandy soils with 0 to 20% clay content. Our results revealed a pronounced effect for silt loam soils with 1 to 28% clay as SOM was larger than 2%. The SOM ranged from 0.9 to 5.42 %, with a mean value of 2.60 % for the 167 soil samples we measured. We found the highest level of SOM that amendment of poultry litter can increase was not greater than 6.0 %. We suggest SOM should be increased over 2% for improving FC, there is large room for SOM improvement in subtropical humid regions.

How to cite: Feng, G., Li, X., and Reginelli, D.: How high can we go: defining and breaching the threshold for soil organic matter to improve soil water holding capacity?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9678, https://doi.org/10.5194/egusphere-egu2020-9678, 2020.

In the highlands of Tigray both crop yield and soil erosion are important concerns. At the same time the impact of climate change is felt in the form of delayed and more erratic rains. Different adaptation strategies are proposed to increase resilience. The successful implementation of most of these strategies, like for example, agroforestry, conservation tillage and water harvesting, heavily relies on improved infiltration and the amount of water stored in the root zone. In this presentation the water storage in the root zone is discussed in relation to crop productivity and hydrological performance of the local (agricultural) land use system. For this purpose measurements of (gravimetric) soil moisture content, taken at different depths in the root zone and at regular time intervals during four growing seasons in the period 2010-2013, were considered. In total 43 sites were involved, which were measured for one up to three years. In addition to soil moisture content, at selected sites also bulk density, saturation, field capacity and wilting point were determined. On the basis of the data collected, site-specific changes in soil moisture budgets were analyzed and trends observed were related to crop productivity and hydrological parameters (like rainfall and evapotranspiration). First outcomes pointed to a relatively rapid increase of soil moisture stock at the start of the growing season, followed by a more or less stable level, and ending at crop maturation with a very rapid decrease. Typical figures for gravimetric moisture content at the stable level were between 25 and 30 %. Soil depth was in most cases shallow (around 40 cm) and likely limiting moisture storage capacity. Assuming that at the start of the stable phase rainfall still is exceeding evapotranspiration, this then will point to a relatively high risk for run off at this stage. Stock change of soil moisture as such appears a relevant and low cost indicator to assess hydrological performance of land use systems in terms of infiltration capacity and soil moisture availability. In line with that, analysis of stock change of soil moisture might provide relevant clues for designing and optimizing effective land management strategies that successfully deal with erosion hazard and result in a more resilient and sustainable production of food crops.

How to cite: Kraaijvanger, R.: Stock change of soil moisture under crop cultivation: A relevant and low cost indicator to assess hydrological performance of agricultural land use systems in Tigray, northern Ethiopia., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7750, https://doi.org/10.5194/egusphere-egu2020-7750, 2020.

General knowledge based on the good agricultural soils in temperate climates is that no-till and conservation-till practices increase infiltration of the rainwater and decrease runoff and erosion.  Experiments in the semi-humid Ethiopian highlands do not often show the same benefits and in many cases no-till actually increases runoff above conventional and deep tillage. In contrast, for conservation-tillage with mulch at the surface, more of the water infiltrates and enhances plant growth

Reduced tillage systems increase infiltration through soil fauna that form soil macropores through which rainwater flows to the subsoil bypassing the soil matrix with limited conductivity. Most degraded soils (at least in the Ethiopian highlands) have a hardpan at shallow depths restricting downward movement of water. Runoff on conventionally tilled soils is caused by saturation excess when the perched water table in the plowed soil layer reaches the surface.  Thus, the amount of runoff is determined by the water free pore space in the surface layer.  Since this pore space is less under no-till, no-till has greater amounts of runoff than conventional till. 

Under mulch tillage, organic matter is introduced at the surface and soil fauna becomes well-developed which will improve the soil structure and porosity of the soil.  This structure will be maintained because the mulch decreases the sediment concentration in the water and the pores will remain open. Under conventional tillage sediment concentrations are high and any pores formed will be filled up with sediment. Our expectation is that since organic matter under mixed farming is used to feed the cattle, widespread implementation of no-till and conservation tillage will be limited to areas with high value crops in which farmers can afford using organic matter as a mulch.

How to cite: Steenhuis, T., Hussein, M., muche, H., Belay, S., Gessess, A., Guzman, C., Schmitter, P., Reyes, M., and Tilahun, S.: Will no-till be the new panacea for degraded tropical landscapes?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12254, https://doi.org/10.5194/egusphere-egu2020-12254, 2020.

Fifty years of sustainable no-tillage agriculture in the semi-arid Canadian Prairies 

Agriculture collapsed in the Canadian Prairies during the multi-year drought of 1926-1934. Two changes to local agriculture practice became critical in the recovery of top-soil and agricultural yield. One was abandonment of summer fallow, the other was adoption of no-tillage techniques pioneered in this region. We have obtained soil samples from commercial fields in cereal production (up to one century), from long-term experimental field-plots at research stations, from undisturbed prairies, and from secondary grasslands converted from agriculture. The data provides a chronosequence of fields about 40 years in continuous no-tillage, to contrast against fields in traditional tillage, against secondary grasslands, and undisturbed native prairie. For all samples, we measured free-living nitrogen fixation capacity (15N) in the laboratory, aggregate size distribution, microbial nitrogen fixing community (nif gene), and both bacteria (16S DNA) and eukaryote (18S DNA) diversity. We reconstructed eukaryote community structure and food web structure for the fields. Our results indicate that despite decades of continuous no-tillage, free-living nitrogen fixing capacity remains far below undisturbed prairies, but improved from ploughed fields. Soil aggregate size distribution remains lower in continuous no-tillage, but grasslands contain more larger-sized aggregates enabling more nitrogen fixation. Biodiversity indices follow a pattern of reduced diversity with increased disturbance from agriculture. Biodiversity improves with years into no-tillage or abandonment to secondary grasslands. Overall, we had anticipated a greater recovery of biodiversity, food web complexity, and of free-living nitrogen fixation in decades old continuous no-tillage fields, compared to continuous tillage. Nonetheless, the region of Canadian prairies in no-tillage has been resilient to cyclical droughts, and has accumulated soil organic carbon since adoption of no-tillage. The results are significant because about 95% of the area in cereal crops (~10 million Ha) is in no-tillage, and significant soil organic matter has accumulated in the agroecosystem to contribute to carbon storage to mitigate climate change. 

How to cite: Adl, S., Kumar, M., and Paupescu, L.: Fifty years of sustainable no-tillage agriculture in the semi-arid Canadian Prairies , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12589, https://doi.org/10.5194/egusphere-egu2020-12589, 2020.

Cities in the humid- and seasonal-humid tropics depend on small watersheds for their water supplies.  Under normal conditions with ample rainfall, water supplies are reliable.   However, water shortages can occur during extended dry periods.  The literature contains contradictory findings regarding the effectiveness of different land management strategies aimed at enhanced delivery of hydrologic ecosystem services during periods of significant rainfall deficit, so-called “green infrastructure”.  Recent research results from field and modeling studies in the Panama Canal Watershed indicated that land-cover dependent flow paths play an important role in partitioning throughfall into subsurface stormflow and groundwater recharge.  Land management practices considered included continuous and rotational grazing, silvipastoral treatments, and different ages of secondary succession including old regrowth forest.  The effectiveness of land management was found to depend on both land use practice and annual rainfall as determined by orography in steep regions.   These dependencies at least partially explain some of the discrepancies in the literature.

How to cite: Ogden, F. L.: On the Effectiveness of Land Management Decisions in Restoration of Hydrologic Ecosystem Services in Humid and Seasonal-Tropical Catchments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20329, https://doi.org/10.5194/egusphere-egu2020-20329, 2020.

Since 1970s, an increasing attention has been paid to land degradation worldwide (FAO, 1971; Zhou et al., 2017). Generally speaking, the connotation of land degradation commonly refers to the destroy of ecological balance, and the decline of soil quality and environmental capacity  (regeneration, and carrying capacity), and could be categorized as soil erosion, land desertification, soil salinization-alkalization, land impoverishment, land contamination, land destruction  according to their reasons (water/wind erosion, deforestation / overgrazing, unreasonable irrigation, inadequate fertilizer, pollution, mineral resources exploitation) (Liu, 1995; Zhou & Huang, 2001). The various related theories have been developed to evaluate the land degradation, such as global assessment of human-induced soil degradation (GLASOD), the assessment of the status of human-induced soil degradation in South and Southeast Asia (ASSOD), and the theory put forward by the Moscow State University and Russia Academy of Science (RUSSIA) (Sun et al., 2001). For each type of land degradation, it has various indicators and varied in different countries and regions (Morales & Zuleta, 2019).

Human activities are recognized as the major reason of land degradation, and countermeasures for effective prevention and treatment of land degradation are developed accordingly, including the formulation of laws and policies (Liu, 1995; Sun et al., 2001). Soil-environmental criteria are multi-objective functions with the range of values based on scientific research on relationships between soil pollutant concentrations and ecological risk or human health effects (Zhou et al., 2007). Compared with soil-environmental standards, they do not consider economic or technological factors and are not mandatory, but are the data foundations and scientific bases for development of soil-environmental standards (Zhou et al, 2017; Teng & Zhou, 2018). Currently, many countries and regions have developed various soil-environmental quality standards to meet the demand for soil management, such as screening levels, and intervention values. Generally, the methodological and deriving researches of soil-environmental criteria were far from adequacy for the development and revision of their standards, and further to serve the prevention and treatment of  land degradation.

References

Food and Agriculture Organization of the United Nations (FAO) (1971). Land Degradation. Soils Bulletin 13, Rome, 1091, 1-10.

Liu, H. (1995). Types and characteristics of land degradation and countermeasures in China. Resources Science, 4, 26-32.

Morales, N. S., & Zuleta, G. A. (2019). Comparison of different land degradation indicators: Do the world regions really matter? Land Degradation & Development, 1-13.

Sun, H., Zhang, T. L., & Wang, X. X. (2001). Land Degradation and its evaluating methodology. Agro-environmental Protection, 20(4), 283-285.

Teng, Y., & Zhou, Q. X. (2018). Conversion relationships between environmental quality criteria of water/air and soil. Science China-Earth Sciences, 61(12), 1781-1791.

Zhou, Q. X., & Huang, G. H. (2001). Environmental Biogeochemistry & Global Environmental Changes. Beijing, China: Science Press.

Zhou, Q. X., Luo, Y., & Zhu, L. Y. (2007). Scientific research on environmental benchmark values and revision of national environmental standards in China. Journal of Agro-Environment Science, 26(1), 1-5.

Zhou, Q. X., Teng, Y., & Liu, Y. (2017). A study on soil-environmental quality criteria and standards of arsenic. Applied Geochemistry, 77, 158-166.

How to cite: Teng, Y. and Zhou, Q.: The Action of Soil-environmental Criteria in Prevention and Treatment of Land Degradation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9742, https://doi.org/10.5194/egusphere-egu2020-9742, 2020.

Grazing largely affects vegetation dynamic of grassland communities. An intensified grazing will likely lead to grassland degradation. Therefore, to restore degraded grasslands, grazing exclusion by fence might be very helpful. However, the direction and the strength of grazing management effects on vegetation characteristics and plant diversity are currently disputable. In addition, vegetation cover and species richness are often independently examined under different grazing regimes in typical studies. Diversity-cover relationship is not adequately detected in degraded grasslands.

In this study, I aim at understanding effects of grazing exclusion on vegetation characteristics, plant diversity and their relationship. For this, I performed a fencing experiment in three grassland types, namely meadow (since 2009), mountain steppe (since 2013) and dry steppe (since 2013) in Mongolia. Each of three grasslands was set by two treatments: grazing exclusion and freely grazing. Vegetation characteristics were mirrored by vegetation cover and height. Plant diversity was evaluated by indices of species richness, Shannon-Wiener diversity and Pielou evenness.

The empirical results show that grazing exclusion by fence generally increases vegetation height regardless of grassland types. On the other hand, the changing direction of vegetation cover caused by grazing exclusion is not consistent in three grasslands. Fencing decreases species richness and Shannon diversity. While Pielou evenness responds slightly to changes in grazing regimes. Greater species richness benefits an increment of vegetation cover independent of grazing treatments and grassland types.

This study fills the knowledge gap of grazing management effects on vegetation characteristics and plant diversity in Mongolian rangelands. The results clearly demonstrate that grazing exclusion by fence is not an efficient way to restore degraded grasslands. This will also allow to project the impact of changes in land use on ecosystem functioning.

How to cite: Guo, T.: The role of grazing exclusion by fence in regulating vegetation characteristics and plant diversity in Mongolian rangelands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2131, https://doi.org/10.5194/egusphere-egu2020-2131, 2020.

A Dzud is a climate event in the Mongolian that causes serious environmental and economic damage. Although a natural phenomenon, its effects can be exacerbated by human activities such as livestock overgrazing and inadequate fodder, resulting in mass deaths of the livestock in the spring following a severe winter. This article is based on the analysis of various Dzud events (2000, 2001, 2002, and 2010) and their specific effect on the vegetation condition by analyzing Normalized Difference Vegetation Index NDVI in the Gobi regions of Mongolia. Our evaluation methods utilize the seasonal aridity index, time series of MODIS NDVI and data from livestock statistics. Heavy snowfall is one of the limiting factors for animal productivity and socioeconomic development in Mongolia. Based on the findings, steppe areas have the highest degree of vulnerability of climate, with the potential decline of growth grassland being stronger for humid areas. When there are high snowy winters, there is a 10 to a 20-day earlier peak of NDVI values as well as an increase in vegetation growth. Additionally, grazing pressure (caused by high livestock loss) played a minor role in plant growth. We found that during the dry winter conditions of a black Dzud, low soil moisture, and high evapotranspiration, the vegetation growth phase begins later due to water deficiency, leading to a lower peak in growth. During the year 2009/2010, a white Dzud occurred in the presence of a thick snow layer, which acted as a water reservoir. The effect of livestock loss and the reduction of grazing pressure played a minor part in vegetation recovery after different types of Dzud events in Mongolia.

How to cite: Vova, O., Kappas, M., Fassnacht, S. R., and Renchin, T.: The impact of "Dzud" on vegetation condition in Gobi regions of Mongolia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20046, https://doi.org/10.5194/egusphere-egu2020-20046, 2020.

      Land degradation is an important ecological and environmental problem facing the world. “Land Degradation Neutrality” is one of the core indicators in the United Nations Sustainable Development Goals for 2030. However, achieving this is a serious challenge in Mongolia where land degradation continues. The increasingly serious land degradation in Mongolia has had a direct impact on the ecology of the entire Mongolian plateau and adjacent regions. Land degradation and restoration in this region fluctuate spatially and temporally because of the impacts of global climate change and human activity.

      We obtained land cover data for Mongolia for 1990, 2000, 2010, and 2015 with a resolution of 30 m using the object-oriented remote sensing image interpretation method.Land cover types include forest, real steppe, meadow steppe, desert steppe, cropland, built area, water, sand, and barren land. Based on a spatial analysis module in a geographic information system, the multi-period land cover data were superimposed and calculated. We defined the land degradation cover types and restoration cover types in the processing. Thus, a serials of high-resolution distribution maps of land degradation and restoration for fixed monitoring time intervals were obtained for first time.

      We analyzed trends in land degradation and restoration and estimated the typical areas of each in Mongolia. We specifically analyzed the process of land cover change in these areas, comprehensively considered natural factors and human activities driving this change. Finally, we proposed targeted strategies to control the land degradation and promote land restoration in different regions in Mongolia.

How to cite: Wang, J., Wei, H., Yao, J., Shao, Y., Liang, X., Chonokhuu, S., Ochir, A., and Davaasuren, D.: Analysis of spatiotemporal patterns and driving forces for land degradation and restoration in Mongolia from 1990 to 2015, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2363, https://doi.org/10.5194/egusphere-egu2020-2363, 2020.

How to cite: Vacula, S., Niacsu, L., Secu, C., and Vasiliniuc, I.: Land degradation by soil erosion and sedimentation within Sarata catchment, Republic of Moldova, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10249, https://doi.org/10.5194/egusphere-egu2020-10249, 2020.

Land degradation by soil erosion, gullying, landslides and reservoir sedimentation is a major environmental threat in the Barlad Plateau of Romania. This paper reviews both land degradation and the development of soil conservation measures in a representative 32,908 ha catchment. Previous studies focused on larger regional areas and provided insufficient detailed information about land degradation and land improvements. Results estimated the mean value of soil loses at 22.7 t ha-1 y-1 based mostly on the USLE. Gully erosion is very limited in extent (covering 3% of the catchment area), but has considerable impacts in terms of sediment production and triggering or reactivating landslides. The 1:5,000 scale landslide distribution map shows that 56% of Racova Catchment is covered by landslides, in any shape or age. Most of them are shallow seated and inactive landslides. Traditional agriculture in the Barlad Plateau focused on ‘up-and-down slope’ farming on small plots. Soil conservation measures were actively undertaken over a 20-year period (1970-1989). However, more recent legislation (No. 18/1991 Agricultural Real Estate Act) includes two provisions that discourage maintaining and extending soil conservation practises. Hence, the former contour farming system has been abandoned in favour of the traditional, degradational farming methods. The mean annual sedimentation rate in reservoirs is moderate at 2.7 cm y-1 in the upper Racova Catchment and almost double that rate in Puscasi Reservoir at the catchment outlet. Consequently, land degradation remains a serious problem in the study area and effective soil conservation is urgently needed.

How to cite: Niacsu, L., Ionita, I., Samoila, C., Grigoras, G., and Belebea-Apostu, A.-M.: Land degradation and soil conservation in the Barlad Plateau, Romania: a case study from Racova catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2311, https://doi.org/10.5194/egusphere-egu2020-2311, 2020.

Soil cracking is an important feature of degraded terrestrial ecosystems, which cuts the closed and intact land, alters microtopography and also influences the dynamics of soil nutrients, water and heat, then further affect species distributions. Despite their importance, the patterns and causes of cracks related to overgrazing on alpine rangeland have rarely been reported previously, and the effects of cracks on soil properties and plant distributions are poorly understood. Therefore, we used a comprehensive cross-scale approach to investigate the distribution of crack-soil areas at the eastern Tibetan plateau (217 survey sites), then selected the grazing-induced parameter that was closely related to the cracks at a small scale, and quantified the effects of microtopography (raised areas and healed cracks) induced by cracking on the soil properties, and community composition at crack-mosaic patch from 2013-2018, then to evaluate the further roles of soil cracking on alpine rangelands. The results showed that cracks only formed in the alpine meadow after overstocking. The increased soil compaction under overgrazing was closely related to soil cracking. On crack patch scale, the healed cracks facilitated nutrient and water enrichment due to the increasing surface roughness, then improved the plant communities. To some extent, healed crack mosaics are good for the conservation of water and nutrients. We provide key and easy-to-measure indicators to prevent overgrazing and cracking: a residual biomass greater than 65 g/m² and a height greater than 6 cm, and the soil compaction should be lower than 1044.26 ± 188.88 kPa. We should pay more attention to crack phenomena to prevent severe degradation. Overgrazed alpine meadows should be treated in the early phase of cracking and it may be able to return to optimum conditions in healthy rangelands. Otherwise, soil cracking becomes the most critical turning point in the process of alpine rangeland severe degradation.

How to cite: Niu, Y., Zhu, H., Yang, S., Zhou, J., Chu, B., Ma, S., Hua, R., Wang, T., and Hua, L.: Soil cracking induced by overgrazing triggers the severe degradation or initiates the natural recovery of overgrazed alpine meadows on the Tibetan plateau?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3845, https://doi.org/10.5194/egusphere-egu2020-3845, 2020.

Abstract: Globally, the loss of forest is of great concern as forest plays many key roles in the earth system, for example, it contributes to biogeochemical cycles and rural livelihoods. Forest could provide ecosystem services such as soil retention and flood regulation and is especially critical in mountain environments. Deforestation in such regions further results in carbon emission and biodiversity loss and may reduce agricultural productivity and increase the poverty rate. In China, recognition of these problems has prompted a series of ecological construction programs, including “Returning Farmland to Forest” (RFF), which advocates stopping farming on sloping land that is prone to soil erosion and promotes afforestation and recovery of forest vegetation and was initially implemented in 1999. The program has been widely applied in Guizhou Province, a typical fragile karst mountain area of southwest China. There is, however, a lack of knowledge of the effectiveness of the RFF policy, and the relative roles played by possible factors that lead to forest change. Here we analyze the pattern and process of forest change in the karst mountain regions of Guizhou province between 1980 and 2018 and evaluate how RFF and other driving forces contribute to these changes. Based on a temporal sequence of satellite images, we develop a Markov model to examine the forest change, and found that most of the forests grow on the slopes of 15-25°, the forest cover has increased by 1,410 km² between 1980 and 2019, and 36% of cropland in Guizhou province has been converted to forest since 1980. Out of nine municipalities in the province, the most significant increases in forest cover occurs in Qiandongnan, which accounts for 20% (583 km²) of the increased area. we also found that the RFF program has had a marked positive impact on forest cover and has also improved hydrothermal conditions in the region. However, population, GDP, and traffic accessibility have a negative impact on forest cover. Climate factors appear to have the least impact on forest change during the period of 1980 to 2018. The findings offer useful information for resource managers to engage in forest protection, deforestation prevention, and ecological restoration in regions with similar conditions.    

KEYWORDS: forest; restoration; RFF; GDP; karst areas

How to cite: Guo, X., Chen, R., Li, Q., Meadows, M. E., and Pan, Z.: Forest recovery and its driving forces in karst areas of southwest China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10192, https://doi.org/10.5194/egusphere-egu2020-10192, 2020.

How to cite: Feng, S., Wang, H., Liu, H., Zhu, C., and Li, S.: Forestland change and soil erosion in karst watershed under the Grain to Green Project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4456, https://doi.org/10.5194/egusphere-egu2020-4456, 2020.

The Geo-Hazards Triggered of Serial Reclamation Land of Extreme Precipitation in Typical Regions of the Loess Plateau
Gao Zhe¹,Zhang Genguang ^1*,Gao Jian'en^1,2,3,Li Xingyao¹,Han Jianqiao^2,3,Kang Youcai³,Guo Zihao³,Long Shaobo²,Dou Shaohui²,Zhang Yuanyuan³
1. College of Water Resources and Architectural Engineering, Northwest A&F University, 712100, Yangling, Shaanxi, China;
2. Institute of Soil and Water Conservation, Northwest A&F University, 712100, Yangling, Shaanxi, China;
3. Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, 712100, Yangling, Shaanxi, China;

The “Gully Land Consolidation Project”(GLCP) was widely carried out all over the world, such as Spain, the United States and China. It was a new attempt to solve the shortage of regional land resources. Aiming at the problem that the influence of extreme rainstorms on the “Gully Land Consolidation Project”(GLCP) on the Loess Plateau.By using the method of actual measurement and analysis of categorical data, the erosion disaster in July 26 2017 was investigated in Niu Xue Gully of Wuding River Watershed in Zizhou County of the Central part of the Loess Plateau. The results showed : 

(1) The Niu Xue Gully Small Watershed in Zizhou County (109°55'25"E, 37°39'46"N), which was located in the central part of the Loess Plateau and belonged to the northern Shaanxi Loess Hilly-Gully region. The Niu Xuegou catchment covered an area of 0.48 km² and the average altitude of the region in about 1000-1200 meters, land consolidation in the basin about 38 mu（25333.3m²）since 2014.

(2) This storm was characterized by "long duration and large precipitation", the accumulated rainfall was 147.9 mm, the average rainfall intensity was 13.45 mm/h, the maximum rainfall intensity was close to 5 mm/min, the maximum flood peak discharge was 44.64 m³/s, the flood duration was about 11 hours, and the flood recurrence period was more than once in a hundred years.

(3) The storm caused nearly a thousand geological hazards at the channel of the basin. The main types of disasters were as follows, gravity erosion types, such as landslides, landslides, and mudflows, account for 14.85% of the conventional geological hazards; secondary disasters of water erosion types, such as trench erosion and dam erosion, occurring at different locations on the slope, accounted for 51.05% and composite new-derived land destruction and dam break disasters account for nearly 10% .

(4) The damage of cascade land preparation was closely related to the average flood discharge, embankment height and ecological vegetation cover in the watershed.
The investigation provided technical support for the consolidation of the Chinese implementation of the "Cropland to Forest (Grass)" results on the Loess Plateau, and also provided theoretical support for the safe implementation of the “Gully Land Consolidation Project”(GLCP) around the world.

Keywords: The loess plateau; Extreme rainstorm;The “Gully Land Consolidation Project”(GLCP)

Funding:(National Key R&D Program of China: 2017YFC0504703)；(National Natural Science Foundation of China,41877078,41371276,51879227);(Research and Development and Integrated demonstration of key Technologies in soil and Water Conservation Engineering,A315021615)

How to cite: Gao, Z.: The Geo-Hazards Triggered of Serial Reclamation Land of Extreme Precipitation in Typical Regions of the Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16059, https://doi.org/10.5194/egusphere-egu2020-16059, 2020.

Due to their great economic benefits, there are many apple orchards on the Loess Plateau and aggressive expansion is planned. However, little is known about their ecological impact in relation to the deep soil water, soil organic carbon and soil particle aggregation. An accurate evaluation of the ecological impact of apple orchards is crucial to ensure the establishment of sustainable ecosystems on the Loess Plateau. We, therefore, measured the soil water content variation in deep layers (WCAD) (200-800 cm), soil organic carbon (SOC) content and density (0-800 cm) and, soil aggregate stability (0-40 cm) in apple (Malus pumila) orchards and ecological plantations of black locust (Robinia pesudoacacia) and korshinsk peashrub (Caragana korshinskii). The results suggested that (1) the soil water in deep soil was generally lower under apple orchards (13.29%), black locust (12.4%) and korshinsk peashrub (13.46%) than under arable land (18.35%), both in the semiarid and semihumid regions. This finding implied that apple orchard, black locust and korshinsk peashrub plantations caused intense reductions in soil moisture compared with the arable land, leading to severe soil desiccation. (2) Apple orchards (1.85 to 5.49 g kg^-1) had significantly (p <0.05) lower SOC density than ecological plantations (2.15 to 8.95 g kg^-1), especially in 0-100 cm soil layer, in both semiarid and semihumid regions. This result suggests that apple orchards have no profitless for SOC sequestration over the long-term because their clean cultivation management increase the risk of SOC loss by soil erosion. (3) In semiarid and semihumid regions, soil aggregate stability (the mean weight diameter, MWD) in apple orchards (0.26-0.63 mm) was significantly (p <0.05) lower than under black locust (0.63-2.97 mm) and korshinsk peashrub (0.72-2.13 mm) plantations in 0-40 cm layers, and even lower than in arable land in the 0-20 cm layer in most regions, which means that apple orchards have low anti-erodibility. Our results suggest that continued expansion of apple orchards and ecological plantations both consumed much deep soil water, but the ecological effect (e.g., SOC sequestration, soil and water conservation) brought by apple orchard is much lower than that of ecological plantations. In the interest of sustainable development in the region, apple cultivation should be undertaken with caution, especially in semiarid regions.

How to cite: Yang, M., Wang, S., Zhao, X., and Gao, X.: Ecological impacts of apple orchards on China's Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5349, https://doi.org/10.5194/egusphere-egu2020-5349, 2020.

Evaluation of the influences of the Beijing–Tianjin Sand Source Control Project on soil wind erosion and ecosystem services is imperative for mastering the benefits and drawbacks of the program, as well as for distinguishing more reasonable estimations to evaluate regional sustainable development. Within the Beijing–Tianjin Sand Source Region, we quantified the spatiotemporal patterns of land use/cover changes (LUCCs), soil wind erosion modulus (SWEM), and essential ecosystem services throughout 2000–2015 by utilizing field investigations, remotely sensed data, meteorological data, and modeling. The influences of ecological projects on wind erosion and ecosystem services has been subsequently assessed by using those modifications brought on via the LUCCs (e.g., conversion from cropland to grassland/woodland) during the ecological construction. The results indicated that the SWEM showed a decline and ecosystem services which included carbon storage, water retention, and air quality regulation exhibited growth driven by using both local climate exchanges and human activities such as ecological projects. Excluding the effects of climate factors, the LUCCs stemming from ecological projects caused a total SWEM decrease of 3.77 million tons during 2000–2015, of which approximately 70% was prompted by the way of the transition from desert to sparse grassland. The sub-regions of desert grassland in Bayannur, Ordos Sandy Land, and Otindag Sandy Land were hot spots for wind erosion declines and ecosystem service enhancements induced by the ecological projects. We recommend that endeavors be coordinated toward the scientific management of the degraded lands and distribution of the local populace, as well as the implementation of diverse measures in the expected hotter and drier future.

How to cite: Zhao, Y. and Chi, W.: Ecological and environmental consequences of ecological projects in the Beijing–Tianjin Sand Source Region, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12375, https://doi.org/10.5194/egusphere-egu2020-12375, 2020.

Abstract：Saline soil has a serious negative effect on crop growth in the world, subsurface organic fertilizationcombined with plastic film mulching (OMP) is one of the effective measures to solve this issue, which could alleviate salt stress, increase nutrient content and microflora diversity, then furtherly improve crop productivity. However, its impact on soil structure especially soil pore structure has not well documented, so a three-year experiment was conducted to analysis effect of OMP on aggregate distribution and stability, aggregate organic carbon distribution and pore size distribution, during 2015-2017 in Wuyuan Country, Inner Mongolia, China. Four treatments were set in the experiment, including plowing without plastic mulching (CK), plowing plus plastic mulching (PM), subsurface (10–30 cm) treatment with organic manure (OM), and OM plus plastic mulching (OMP). The results showed that in condition of no mulching OM significantly increased the 0.25-2mm aggregates content (18.09%) in 10-30cm soil layer, and significantly increased the organic carbon content of > 2mm (30.79-158.76%) and 0.25-2mm aggregates (161.27-290.94%) in each soil layer compared with CK.In condition of mulching, only OMP can significantly increase the average weight diameter (21.58% for 0-10 cm and 55.95% for 10-30 cm) and the organic carbon content (2.44-94.35% for 0-10 cm and 23.23-215.29% for 10-30 cm) of soil aggregates compared with CK.  Under the condition of subsurface organic fertilization (OM, OMP), the dominant particle size of each soil layer changed from < 0.053 mm aggregate to 0.25-2 mm aggregate, which increased the content of large aggregate and water stability.Compared with OM, the average weight diameter of soil aggregates in 0-10cm and 10-30cm soil layers of OMP increased by 21.58% and 14.36% respectively, but the content of organic carbon in each particle size aggregate in 0-10cm and 10-30cm soil of OMP decreased by 4.24-24.89% and 19.35-40.26% respectively. Furtherly, the large porosity (greater than 30 μm) of 10-30cm and 30-40cm soil layers of OMP increased by 10.52% and 0.71% than that of CK, and the porosity of each equivalent pore size range also increased significantly. Therefore, combination of subsurface organic fertilization and film mulching could effectively optimize soil physical structure by increasing the stability of soil aggregates, maintaining higher organic carbon content, enhancing soil respiration and improving soil pore structure.

Key words：Saline alkali soil; organic fertilizer; soil aggregate; soil pore structure; micro CT

How to cite: Zhang, H., Pang, H., Lu, C., Wang, J., Wang, G., Chang, F., and Li, Y.: Combination of subsurface organic fertilization and film mulching could effectively optimize soil structure in saline alkali soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21144, https://doi.org/10.5194/egusphere-egu2020-21144, 2020.

Artemisia halodendron Turcz. ex Besser occurs following the appearance of a pioneer species, Agriophyllum squarrosum (L.) Moq., and the former “killed” and replaced the latter during the naturally vegetation succession in sandy dune regions in China. A previous study revealed that the foliage litter of A. halodendron had strong negative allelopathic effects on germination of the soil seed bank and on the seedling growth. It is unclear whether an allelopathic effect of A. halodendron litters positively or negatively affects the seed germination, leading to a progressively replacement of the plant species in sandy dune regions.

We, therefore, carried out a seed germination experiment to determine the allelopathic effects of three litter types of A. halodendron (roots, foliage, and stems) on seed germination of six plant species that progressively occur along a successional gradient in the semi-arid grasslands of northeastern China.

In line with our expectation, we found that the early-successional species rather than the late-successional species were negatively affected by the allelopathic effects of A. halodendron, and that the allelopathic effects on seed germination increase with increasing concentration of litter extracts, irrespective of litter types.

Our study evidenced the negative allelopathic effects of A. halodendron on the species replacement and on the community composition during dune stabilization. Further studies are needed to better understand the successional process and thus to promote the vegetation restoration, as A. halodendron itself disappeared also during the process.

How to cite: Du, Z., Luo, Y., Yan, Z., Zhao, X., Li, Y., Yang, Y., and Li, M.-H.: Artemisia halodendron litters have strong negative allelopathic effects on earlier successional plants during vegetation restoration in a semi-arid sandy dune region in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6041, https://doi.org/10.5194/egusphere-egu2020-6041, 2020.

Agriculture is a drive for land reclamation. Reclaiming coastal saline soils is increasingly undertaken as water and heat resources are normally plentiful in coastal land. However, growth of both crops and soil microorganisms is limited due to high cation content and osmotic stress, making saline soils unproductive when converted to arable land. For crops, great efforts have to be made to screen salt-tolerant species suitable for land reclamation. For soil microorganisms in saline soils, will the same separation and domestication of salt-tolerant species be necessary to improve microbial activity as done with crops?

To improve such understandings, we studied coastal saline soils covering non-, mild-, and severe-salinity. Their bacterial diversities were characterized by high throughput sequencing, and microbial metabolic activities analyzed with substrate-induced heat release curves. Abundant and diverse bacterial communities were detected in the severe-salinity soils. While we did not observe soil salinity significantly affected the microbial richness, it did shift soil bacterial community composition. However, the severe-salinity soil was not dominant with salt-tolerant microbial species. With thermodynamic analysis, we discovered glucose amendment efficiently promoted microbial metabolic activity regardless of their community composition. Severe salinity did not inhibit potential metabolic activity of soil microbial community. A further 2-month incubation experiment supported that microbial metabolic kinetics of the severe-salinity soil amended with maize straw recovered and moved toward to the non-salinity soil.

Therefore, our study supported that salt-tolerant species are not indispensable in land reclamation. An addition of labile organic amendments can help to rapidly multiply microbial growth and recover soil microbial functions.

How to cite: Chen, R., Zhang, J., and Feng, Y.: Can reclaimed land be converted to arable land? –Positive: Evidences of soil microbial activity from a laboratory experiment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6499, https://doi.org/10.5194/egusphere-egu2020-6499, 2020.

Mudflats are valuable land resources located in the interaction zone between land and sea and are found in many parts of the world. The newly reclaimed mudflats are high in salinity and low in fertility as indicated by poor soil structure, extremely low organic matter content, low nutrient level and lack of microbial diversity, which is not suitable for cultivation. The keys to mudflat reclamation to arable lands are (1) to reduce salinity and (2) to increase the soil organic matter content and thus soil fertility. The former determines whether the reclaimed mudflat can be used for crop production and the latter determines whether the crop production is sustainable. On the basis of salt reduction measures, adding exogenous organic matter to drive the formation of soil aggregates in mudflat saline-alkali soil is a prerequisite for inhibiting the return of salt, improving fertility and promoting the transformation of mudflat reclaimed soil into arable soil. Research on the formation of clustered soil aggregates during the evolution of mudflat soil into arable soil should focus on the regulatory, formation, and stability mechanism of different exogenous organic matter. In addition, exploration of the effects of the special properties of mudflat soil, e.g., high salinity, high pH, and low microbial diversity, on the formation and stability of soil aggregates is necessary. The regularity and regulation of soil structure and fertility evolution of the mudflat driven by exogenous organic matter were clarified. Research on soil aggregate formation not only enrich the basic theory of soil quality evolution of mudflat, but also have practical guiding significance for the maturation of mudflat soil.

How to cite: Bai, Y., Gu, C., and Shan, Y.: The Formation Mechanism Of Mudflat Soil Aggregates Driven By Exogenous Organic Matters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12309, https://doi.org/10.5194/egusphere-egu2020-12309, 2020.

Land reclaim can be converted to arable land in China. Land reclamation is the process of reclamation and restoration to arable land on the basis of the original abandoned independent land. It mainly includes: land for coal mines, quarries, brick kilns, warehouses, other enterprises and institutions, and abandoned rural construction land. As of 2015, China's construction activities and natural disasters have damaged about 10 million hm² of land, with an annual increase of about 270,000 hm². China's land reclamation rate is about 45%, of which about 50% of the land reclaimed is arable land. China has a large number of land reclamation practices and has very rich experience. First, we carried out land adaptability evaluation in the reclamation area .we selected the currently land for coal mines, quarries, brick kilns, warehouses, and other enterprises and institutions from natural, economic, and social aspects to evaluate its suitability, comprehensively calculated the consolidation potential, and calculated the area that could be reclaimed as arable land. Second, we carried out arable land construction in the reclamation area. Through land consolidation methods such as land leveling, farmland irrigation and drainage construction, shelterbelt network layout, and farmland road construction, rural residential areas that can be reclaimed as arable land, which will be sorted higher productivity arable land with a centralized patch, good irrigation and drainage , and complete farmland roads. Third, according to the soil conditions of the reclamation area, we carry out soil fertilization. We plowed the soil, applyed organic manure and soil biochar, improved soil water retention and porosity, enhanced soil fertility, improved arable land quality, and increased land production potential. Finally, after the land is reclaimed as arable land, we will monitor the soil conditions and ecological environment of the newly reclaimed arable land on a regular basis through the establishment of a regulatory agency. As same time, while we tried to meeting the fertility of the newly reclaimed arable land, we moinitor the ecological environment of the newly reclaimed land, ensuring sustainable use of arable land. Through the land reclamation, the per capita arable land area in the country have be increased by 0.08 mu. the annual grain yield per mu is calculated at 400kg, which increased 40 billion kg of grain each year. what’s more, farmers have increased the area of ​​arable land, increased their family income, and let themselves live better. By land be reclaimed to arable land, Chinese government has effectively protected 1.2 billion hm² of Red line of arable land and ensured national food security. At same time, farmers' income was increased by increasing of crop area, and intensive land conservation has been achieved, which has solved our country to a certain extent.

How to cite: Kong, X. and Wen, L.: The practice of reclaimed land be converted to arable land in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9067, https://doi.org/10.5194/egusphere-egu2020-9067, 2020.

Xinjiang is located in the northwest of China and in the hinterland of Eurasia. The area is dominated by basins and deserts, with less rainfall and large evaporation. Therefore, most of the agricultural cultivation in this area is developed in piedmont oases. 
 Shihezi City is located in the middle of Xinjiang and has a typical continental climate. We have carried out long-term follow-up observation on two cultivated lands near Shihezi. Plots 147 # and 148 # were originally used for planting cotton, but due to the shortage of irrigation and the serious problem of soil salinization, cotton plants in these two plots were eventually abandoned. In 2008, local farmers began to use drip irrigation system to replant wheat on fallow land 147 # and 148 #. The outcome shows some achievements have been made. In 2008, the amount of irrigation on 147 # and 148 # was 360mm-405mm, and the yield was 7676kg/hm²-8879kg/hm². 
 We believe that there are three main reasons for successful farming on reclaimed land: 
(1) The reclaimed land was leveled to reduce the difference in land height and improve the uniformity of irrigation. 
(2) Compared with previous flooding irrigation, the drip irrigation system can better save water and reduces soil salinization; 
(3) The application of water-soluble chemical fertilizer has changed the traditional fertilization method in the past and improved the efficiency of using fertilizer. 
After ten years of reclamation and cultivation, what has attracted our attention is that there are also problems in plots 147 # and 148 #: 
(1) White pollution: In order to reduce soil evaporation brought by local heat, farmers generally use plastic mulching to cover the soil. According to the field observation and our related research, the problem of plastic film residue in the soil is very serious. At present, the density of plastic film residue increases around 16.37 kg/hm² per year. 
(2) Excessive application of chemical fertilizer causes potential soil pollution: Compared with traditional flood irrigation, the amount of fertilizer applied after the drip irrigation system is reduced, but the amount of chemical fertilizer used is still very large, which causes potential soil pollution. 
(3) The problem of soil salinization always exists: the drip irrigation system can effectively reduce the salt on the surface of the soil during the growth cycle of crops, but the salt deep in the soil always accumulates and cannot be effectively excreted. 
In view of the above problems, the more effective solutions at present are: 
(1) Degradable plastic film: The new plastic film can degrade itself and reduce accumulation in soil. 
(2) New plastic film recycling machine: improve the recovery rate of plastic film. 
(3) Optimizing irrigation and fertilization scheme: Through field experiments, find out the most reasonable irrigation and fertilization scheme. 
(3) Salinization control: Different methods such as using an underground pipe to discharge salt and applying soil conditioners are adopted to control the salinization of land, but different saline-alkali land control measures have their own advantages and disadvantages, therefore, further analysis is needed in practice. 

How to cite: Wang, T., Wang, Z., and Zhang, J.: Experience and Problems in Planting Winter Wheat in Reclaimed Wasteland in An Oasis Area in Xinjiang, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10270, https://doi.org/10.5194/egusphere-egu2020-10270, 2020.

Whether the hot and humid subtropical plateau region could leads to land degradation in the form of weathering and gully erosion. In this study, chemical weathering, gully erosion and cohesiveness are investigated together to bring out a new comprehensive idea with a view to understand their controlling factors. This study aimed to address potential land degradation in the extended part of Chotanagpur plateau region. The layers of controlling factors of gully erosion were developed and prioritized considering advanced decision tree, decision tree and random forest algorithms in the R software and the results of these methods were also validated using receiver operating characteristic (ROC) curves. Degree of chemical weathering and cohesiveness were measured through the chemical, physical and spectroscopic analysis of the randomly collected 412 soil samples. Apart from this, the climatic elements like temperature and rainfall were considered for estimating the chemical weathering. The results of the gully erosion models have superb accuracy, i.e. ROC values were 0.970, 0.960 and 0.955 respectively. Therefore, advanced decision tree model has been integrated with the results of degree of chemical weathering and cohesiveness in GIS platform end eventually the land degradation map has been developed. The land degradation map shown that 15% of the study area is highly affected by land degradation whereas 18% area is moderately affected by land degradation and rest of the 67% area is less affected by land degradation. This study provides essential information to the policy makers in order to taking decision for minimizing and controlling the land degradation. This innovative comprehensive approach is significant to assess degradation of existing land to a large scale.

Keywords: Land degradation; weathering; cohesiveness; gully erosion; spectroscopic analysis

How to cite: Chandra Pal, S. and Chakrabortty, R.: Responses of chemical weathering and gully erosion causing land degradation in the extended part of Chotanagpur plateau in India, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6607, https://doi.org/10.5194/egusphere-egu2020-6607, 2020.

The importance of grasslands for the sustenance of global biodiversity is paramount. Grassland ecosystems support rich and unique diversity at all trophic levels, are remarkably productive, and resilient to environmental changes. Grasslands in the Indian subcontinent are among the most threatened due to habitat loss, sparking renewed interest in the ecology of the different grasslands found here. We studied land cover dynamics of woodland-grassland mixtures that are part of the Terai ecosystems located at the base of the Himalayan mountain ranges. The vegetation in this region is known to be extremely dynamic even within short time scales, but the patterns and processes associated with this dynamism are not well understood. We analyzed the landcover changes at eight protected wildlife conservation areas from the region (four from India and four from Nepal) that occurred over the last three decades. We used the random forest classifier and an ensemble-based classification technique to carry out supervised classification of the land cover, which was dominated by vegetation. Landsat data, verified with a set of ground measurements and Google earth imagery, were used to generate the landcover types. Using the time series of land cover data, we quantified the observed transitions over decadal timescales. We then used Linear Discriminant functions and Bayesian spatial models to determine the relative importance of environmental variables influencing land cover transitions. We found that the area occupied by grasslands have reduced across all the protected areas we studied. In the last 30 years, the overall natural grassland area decreased by 24 percent, while the agricultural area doubled. The woodland cover increased by 28 percent as a result of ecological succession. Distance from human settlements was found to be the most crucial factor affecting the transitions, followed by topography and distance to water bodies. The grasslands are being widely transformed or degraded to early successional woodland and farmlands, and show increased alien plant invasions. Human encroachment and an increase in human activities have a major influence on these transitions. The impact of these changes on biodiversity and ecosystem function needs to be studied and the urgent attention of managers to stop further degradation is needed.

How to cite: Banerjee, S., Das, D., and John, R.: Recent degradation and transformation of grasslands in the Terai ecosystems of the Indian subcontinent, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6295, https://doi.org/10.5194/egusphere-egu2020-6295, 2020.

In the period of globalization, India a subtropical region, presently facing the acute problem of land degradation and it has severe impact on earth ecosystem as well as economy in defectively. Where India is a most populated agricultural based country, need a large volume of food grain production to control starvation condition with balancing between the need of the population and production yield. Though the conversion of fallow and forest cover area to agricultural land is increasing day by day but due to the people’s daily needs and rapid growth of settlement is capturing productive land and ultimately amount of agricultural land remains in static. Thus, such consequent processes are declining soil fertility and land degradation have been witnessed in different forms of erosion as like sheet, rills, gullies, ravines etc. with the passage of time non tillage farming practices are accreting by replacing the tillage farming for maximizing the rate of production which causes the large scale soil erosion and make a source of sedimentation. The government and local stakeholders are already taken some initiatives for reduction of land degradation by some support practices with considering both structural and non-structural measures. The structural measures especially the engineering construction (check dam, percolation tank etc.) are installed or constructed without considering eco-centric approach.

The current research work has focused the light to evaluate the positive and negative impact of support practices on land resources. This study is mainly conducted on the basis of empirical field observation in different parts of the India. For reducing the rate of soil erosion, the plantation programme has been initiated and still going on as an accepted scheme. This valuable programme has been committed through the plantation of traditional vegetation and external species (Acacia auriculiformis, Eucalyptus globulus). The introduction of external species which are not only changing the properties of soil but also demolishing the soil fertility and soil moisture to cause land degradation. The local administrations are providing this type of external species for plantation programme without making the consciousness about the heath of environment.

Key Words: subtropical region; conversion of fallow; land degradation; structural measures; plantation programme

How to cite: Chakrabortty, R. and Chandra Pal, S.: Role of support practices for minimizing the vulnerability of land degradation in sub-tropical India: positive and negative impacts on land resources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6638, https://doi.org/10.5194/egusphere-egu2020-6638, 2020.

The main objective of this research is to build a simulation model of land use change and coverage (LULC) of the Capucuy River Basin (Ecuadorian Amazon Region) by the year 2026 through the use of official historical cartographic information to estimate changes in LULC and carbon stock. First, it was quantified and defined the most representative anthropic drivers that have been affected LULC in the basin and modeled with historical LULC cartography from the years 1990 to 2016 with the help of DYNAMIC EGO program. Second, forest biomass was determined using an indirect method where 3 forest plots were established to obtain dasometric parameters and estimated the carbon stock of each different type of forest of the basin. Finally, agricultural carbon stock was determined with surveys and secondary data through the use of DNDC program. The results obtained show that the simulation of the maps of 2008 - 2016 allows us to obtain a simulated map of 2026 with an error of less than 5%, presenting the most significant error in the anthropic area with a 3.18% difference. It is expected that by 2026 the forest, the body of water, agricultural land and the anthropic zone occupy 56.83 %, 2.14 %, 40.09 % y 1.34 % of the total area of the Capucuy River Basin, respectively. Also, this model allowed to estimate the carbon stock reduction and its impact on climate change.

How to cite: Salazar, J., Campos, C., Chamorro, P., and Fernández De Arroyabe, P.: Multitemporal analysis of change of soil use and vegetable coverage for the development of a probabilistic prospective model and estimation of carbon stock in the capucuy river basin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20162, https://doi.org/10.5194/egusphere-egu2020-20162, 2020.

The Integrated Crop-Livestock-Forest Systems (CLF) have been able to capture and store the carbon (C) in the form of Soil Organic Matter (SOM), in different regions in Brazil, thereby contributing to mitigate agricultural greenhouse gases emission. This is an eligible practice in Low Carbon Emission Agriculture Plan in Brazil, and currently has around 15 million hectares under use, a very positive and important trend in soil land use in Brazil. SOM is considered a relevant indicator of soil quality due to its direct relationship with biological, chemical, and physical properties, allowing it to evaluate the impacts of agricultural management. Laser-based spectroscopies as Laser-Induced Fluorescence Spectroscopy (LIFS) and Laser-Induced Breakdown Spectroscopy (LIBS) have become promising tools in the evaluation of the SOM in agricultural soils. LIBS can measure soil C, and LIFS can infer about the chemical structure of SOM, mainly aromaticity. The standard protocol for measuring soil C changes involves soil sampling at the field and chemical sample preparation for laboratory analysis. Although this procedure produces precise results, it takes time, generates chemical residues, and the costs restrict its routine for large scale use in agricultural projects. Thus, there is a need to develop clean (green chemistry), rapid, precise, and cost-efficient methods for measuring soil C changes in the field. Also, information about the chemical structure of SOM usually is done through spectroscopic techniques, such as ¹³C NMR, EPR, and fluorescence of humic acid, which are not applied for large scale measurement and mapping. LIFS can be applied in whole soil and can be used to evaluate the aromaticity of SOM, and consequently, its chemical stability.  The objectives of this study were to evaluatethe soil C stock and SOM Stability of some Brazilian soils under different integrated systems, such as,Crop-Livestock-Forest (CLF), Crop-Livestock (CL) and Livestock-Forest(LF). The results showed the combination of soil carbon accumulation, and an increase of SOM aromaticity for CLF, which can be promising for sustainable intensification in agriculture.

Keywords: Sustainable Intensification; Soil Organic Matter; Carbon stock; Laser-Induced Fluorescence Spectroscopy; Integrated Crop-Livestock-Forest Systems

How to cite: Tadini, A. M., Xavier, A. A. P., Martin-Neto, L., Milori, D. M. B. P., and Bernardi, A. C. D. C.: Integrated Crop-Livestock-Forest Systems: Soil Carbon Sequestration and Organic Matter stabilization as detected by laser-based spectroscopies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11899, https://doi.org/10.5194/egusphere-egu2020-11899, 2020.

Lowland soils represent 4 to 6% of the earth's surface, covering an area of 7 to 9 million km². Most of these areas can be used for flooded rice cultivation, as a paddy field. These soils commonly have low fertility due to the traditional flooded rice cultivation systems, which are based on intensive soil tillage and rice monocropping. On the other hand, soil conservation management systems, such as no-tillage and integrated crop-livestock systems (ICLS) may increase the soil fertility and consequently improve rice yield. In lowlands, these practices are contributing to sustainable soil management. Therefore, our study aimed to evaluate soil fertility properties by measuring soil organic matter (SOM) and soil available phosphorus (P) and potassium (K) contents, five years after the adoption of different paddy-farming systems in an Albaqualf soil. The long-term ICLS experiment is located in Cristal county, Rio Grande do Sul State, in Southern Brazil. The systems consisted of two ICLS under no-tillage (NT), in comparison to the traditional system (S1) of flooded rice cultivation under soil disturbance, rice monocropping, and winter fallow. The ICLS systems were based in: rice cultivation in summer season and pasture (annual ryegrass) with cattle grazing in winter season (S2), and crop rotation (rice and soybean) in summer season and livestock production in winter season (S3). In 2013, at the beginning of the experiment, and after five years (2018), soil samples were collected in the 0–10 and 10–20 cm layers, and then the SOM, and available P and K contents were analyzed. Regarding the rice yield, S2 and S3 always had higher rice yields than S1. The S2 and S3 showed increases in yields of 8.9 and 16.4% in relation to S1, with average yields of 11.3 and 12.1 Mg ha^-1, respectively. In addition to S3 having the highest rice yields, it also had high soybean yields for lowland environment in the period evaluated, with an average of 3.8 Mg ha^-1. After five years, S2 and S3 increased SOM contents by 27% and 50%, respectively, in the 0–20 cm soil layer. Similar behavior was verified in available P, with decrease of 4.6 mg dm^-3 in S1 and increase of 16.0 mg dm^-3 in the S3 compared to the initial evaluation. The available K content was higher in S3 (79.3 mg dm^-3), followed by S2 (68.1 mg dm^-3) and S1 (59.5 mg dm^-3) on average of two years evaluated, in the 0–10 cm soil layer. Therefore, the results shows that NT adoption, combined with crop rotation and ICLS, improve soil fertility attributes, which results in high rice yields over time, reaching the sustainable intensification of lowlands.

How to cite: Denardin, L. G. D. O., Martins, A. P., Tiecher, T., Carvalho, P. C. D. F., Chabbi, A., and Anghinoni, I.: No-till and integrated crop-livestock system ensure high rice yield through soil fertility improvement of Brazilian lowlands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11778, https://doi.org/10.5194/egusphere-egu2020-11778, 2020.

The Nigerian Guinea Savannah is the largest agro-ecological belt, encompassing about 49% of Nigeria, and is one of the most diverse, fragile and threatened ecosystems in the country.  Land degradation in the zone is a serious challenge driven by deforestation, agriculture and other livelihood needs. Yet the link between land degradation and unsustainable human influence is widely acknowledged but spatially under explored. The study thus examined the spatial relation of human influence with land degradation in order to inform better land use management. We updated the Human Influence Index by combining the following spatial layers, namely: (1) distance to a major city; (2) land use/land cover; (3) human population density; (4) distance to major roads; (5) distance to railways; and (6) navigable waterways. We then overlaid the Human Influence Index with MODIS-derived land degradation status in order to explain the level of human influence on land degradation. In total, 38% of the Nigerian Guinea Savannah land area are becoming more degraded, while 14% and 48% of the remaining area show either improvement or no change, respectively. However, spatial proximity of human activities was observed to influence land degradation, but with more degradation occurring in areas of low population density. This shows that the spatial pattern of Human Influence Index data cannot completely explain land degradation in the zone. We thus present a more holistic approach to identifying human influence on land degradation in the Nigerian Guinea Savannah.  

How to cite: Adenle, A. A. and Ifejika Speranza, C.: Drivers of Degradation: Linking Large-scale Degradation to Human Influence in the Nigerian Guinea Savannah, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20664, https://doi.org/10.5194/egusphere-egu2020-20664, 2020.

                                                                        ABSTRACT

Maintenance of Soil Organic Matter (SOM) has been recognized as a strategy that could reduce soil degradation, improve soil organic carbon (SOC) pool thereby reducing atmospheric concentration of carbon iv oxide (CO₂) so as to ameliorate the effect of carbon and other greenhouse gases on the environment. Soil fertility depletion in the humid tropics is a serious problem emanating from erosion and leaching due to intense rainfall. Decrease in soil fertility and productivity is believed to be due to depletion in SOM. This study aims at determining the relative contributions (RC) of the various aggregated soil carbon (C_WSA) (which is a function of available organic matter in the soil) to Soil organic carbon pool. Soil samples were collected from an area of land (0.1125ha) planted to sole cowpea, sole maize and maize-cowpea intercrop in No till (NT) and conventionally tilled (CT) plots amended with poultry droppings (PD), pig waste (PW), cassava peels (CP) at 20t/ha each and a control in a split-split plot in Randomized Complete Block Design with three replicates. Cropping system was assigned to the main plots, tillage system was assigned to split plot while organic amendments and control was assigned to the split-split plot measuring 7.5m². The same treatment was maintained for two planting seasons (2012 and 2013), with the residual taken in 2013. Soil samples were collected at 0-30cm at the end of each planting season and SOC of the whole soil and the aggregated  soil carbon (2mm, 2-1mm,1-0.5mm 0.5-0.25mm and < 0.25mm) were determined using Walkley  and Black method as described by Nelson and Sommers (1982). Data collected were subjected to Analysis of Variance (ANOVA) using Genstat release 7.22D. The result revealed that there is a trend of aggregate size fractions 1-0.25mm contributing more carbon to the SOC than aggregate size fractions >2-1mm irrespective of the cropping system, tillage method or organic amendments applied. The highest relative contribution of aggregated soil carbon to the SOC pool shifted from the micro-aggregates (<0.25mm) to the macro-aggregates (1.0-0.25mm) for as long as the organic amendments lasted but gradually returned to the micro-aggregates when the amendments were withdrawn. It is therefore recommended that organic amendments be use to improve the soil aggregation which goes a long way in improving soil carbon pool thereby ameliorating the effect of carbon and other green house gases on the environment.

Key Words: Soil Organic carbon pool, Soil Aggregated carbon, Relative Contribution, Macro and Micro Aggregates

How to cite: Onunwa, A. O., Uzoh, I. M., Okolo, C. C., Igwe, C. A., and Nwite, J.: Relative Contribution of aggregated soil Carbon to soil organic carbon pool in an Ultisol, SouthEastern Nigeria, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6761, https://doi.org/10.5194/egusphere-egu2020-6761, 2020.

South Africa is greatly affected by land degradation, partly due to the high variability of its climatic conditions, the strong population growth and resulting economic demands. Thus reaching a number of SDGs, like achieving food security (#2), access to clean water (#6), and the sustainable use of terrestrial (#15) and marine (#14) resources represents a clear challenge under the present global change pressures. Land degradation has been linked in South Africa to the terms veld degradation and soil degradation and has been addressed by numerous measures. But there is still uncertainty on the extent of human induced land degradation as compared to periodic climate induced land surface property changes.

In cooperation with South African institutions and stakeholders (ARC-ISCW, SAEON, SANParks, SANSA, Stellenbosch University and University of the Free State, Equispectives Research and Consulting Services, Nuwejaars Wetlands SMA), the overarching goal of SALDi is to implement novel, adaptive, and sustainable tools for assessing land degradation in multi-use landscapes in South Africa. Building upon the state of the art in land degradation assessments, the project aims to advance current methodologies for multi-use landscapes by innovatively incorporating inter-annual and seasonal variability in a spatially explicit approach. SALDi takes advantage of the emerging availability of high spatio-temporal resolution Earth observation data (e.g. Copernicus Sentinels, DLR TanDEM-X, NASA/USGS Landsat program), growing sources of in-situ data and advancements in modelling approaches. Particularly, SALDi aims to:

1. i) develop an automated system for high temporal frequency (bi-weekly) and spatial resolution (10 to 30 m) change detection monitoring of ecosystem service dynamics,
2. ii) develop, adapt and apply a Regional Earth System Model (RESM) to South Africa and investigate the feedbacks between land surface properties and the regional climate,

iii)    advance current soil degradation process assessment tools for soil erosion, as this process represents an intrinsic limiting factor for biomass production and other regulating, supporting and provisioning ecosystem services, like providing clean water.

The aim of this presentation is to introduce this new cooperative research project to the EGU Community and to seek new opportunities for collaboration.

How to cite: Baade, J. and Kaiser, A. and the team of SALDi: South African Land Degradation Monitor (SALDI) – A German – South African SPACES collaboration to advance land degradation assessments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21870, https://doi.org/10.5194/egusphere-egu2020-21870, 2020.

Despite huge efforts in soil and water conservations such as terraces, little or no evidence of economic efficiency and physical effectiveness is known. Thus, this study aimed to identify whether these investments are economically and technically viable and profitable for smallholder farmers. The economic surplus approach which is rooted in the Double-in-Difference approach was used to assess the economic performance of bench terraces (BT) on potato yields based on two sub-sample populations randomly selected from two datasets collected in two different periods (2004 and 2009) in the Congo-Nile divide (highlands) namely in Nyamagabe District. In terms of physical effectiveness of bench terraces, we compared traditional slope farming practice, referred to as non-protected plots (NP) against bench terraces (BT) in terms of runoff, soil and nutrient losses in the Beburuka highlands (Burera District) using Wischmeier-type bounded erosion plots (22.2x5 m) at 43% slope gradient.

Our findings suggest improved land productivity associated with investment in bench terraces. Potato yields increase for the period 2004 to 2009 is about 60% on bench terraces compared to the change of 40% without BT. However, the change in yield cannot solely be attributed to the fact that a given household has terraced land (or not) but also other multiple variables determinants of the economic performance of household specific characteristics. On the other hand of physical effectiveness of bench terraces, results revealed that bench (BT) terraces effectively control erosion, once they are well established, managed and regularly maintained by land owners. Terraces effectively reduced runoff and soil and nutrient losses with more than 85 and 98%, respectively. Both assessments thus confirmed the huge potential of bench terraces to reduce soil erosion effects and improve land productivity when established within an integrated approach, paying attention to correct installation and fertility-supporting agronomic practices. Bench terracing proved to be most effective but with slow economic efficiency in Rwanda which influences its adoption.

How to cite: Rutebuka, J., R. Bizoza, A., M. Kagabo, D., Vermeir, P., and Verdoodt, A.: Economic efficiency and physical effectiveness of erosion control systems towards their adoption in the Highlands of Rwanda , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20700, https://doi.org/10.5194/egusphere-egu2020-20700, 2020.

Changes in land use/cover are among the most important anthropogenic transformation on the physical environment affecting proper functioning of the earth system. Hitherto, land characterization has often been studied using archived satellite data products to understandd trends in space and time. However, due to future uncertainties in land use change in developing countries and the associated impacts on the physical environment, there is need to model these changes at a local scale. A modelling framework to simulate empirically quantified relations between land use and its driving factors was used in the Sio-Malaba-Malakisi catchment between Kenya and Uganda. Changes for the catchment were simulated for a period of 30 years (2017 – 2047) using model parameters that define location characteristics, spatial policies, area restrictions, land use demand and conversion elasticity settings. Elevation, slope, population density, soil organic carbon, soil CEC and precipitation were potential factors selected to evaluate the suitability of devoting a grid cell to a land use type using a stepwise regression model. The scenarios evaluated include first growth, slow growth and an urbanization scenario. The high ROC value in all statistical tests (>0.72) indicated that the spatial distribution of some land use types in the basin could be explained by the selected driving variables. In a fast growth scenario (under policy restriction), areas under open soil and shrubland would be converted to cropland when demand for cash crop goes up in the region. Areas under open trees and marshland outside protected zones, would be converted to agricultural land while barren land with rock outcrops would remain largely unchanged over the period. In a slow growth scenario, expansion of the area under cropland would follow historical trend at 1.25% growth per annum. Marshland areas unsuitable for agricultural expansion are projected to remain the same. In an urbanization scenario, built-up areas would increase steadily at >1% per annum especially in areas earmarked for infrastructural development. In all the scenarios explored, topography, precipitation, soil characteristics and population density were identified as the key drivers of land use change. Results of this study would enhance the understanding of the complexities in projecting future land cover changes and provide baseline data for supporting ongoing soil and land management programs in a data scarce area.

Key words: Land use change; CLUE-S model; Scenario analysis; Sio-Malaba-Malakisi catchment; Transboundary basin

How to cite: Chasia, S., Olang, L., Sitoki, L., and Hernnergger, M.: Modelling land use/cover change scenarios in a transboundary catchment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9385, https://doi.org/10.5194/egusphere-egu2020-9385, 2020.

Understanding the geographical distribution of soils is indispensable for policy and decision makers to achieve the goal of increasing agricultural production and reduce poverty, particularly in the Global South. The soilscapes of the Giba catchment (900-3300 m a.s.l.; 5133 km²) in northern Ethiopia were studied, in support of sustainable soil use and land management. Based on their morphologic, physical and chemical properties, 141 soil profile pits and 1381 additional augered profiles were classified according to the World Reference Base for soil resources. The dominant soil units are Leptosols (19% coverage), Vertic Cambisols (14%), Regosols and Cambisols (10%), Skeletic and Leptic Cambisols and Regosols (9%), Rendzic Leptosols (7%), Calcaric and Calcic Vertisols (6%), Chromic Luvisols (6%) and Chromic and Pellic Vertisols (5%). The soilscapes are best explained by the topography and parent material that are the major factors determining the geomorphic processes in the area. Besides these two factors, land cover that is strongly impacted by human activities, may not be overlooked. Except for the Vertisols and patchy Phaeozems that are stable since the Mid-Holocene, all other soil units in the study area are the result of profile truncation on the one hand, and colluviation more downslope on the other hand. In addition, due to three millennia of soil tillage, lynchets have been formed at many places along the slope, and rock fragments concentrated on the surface, leading to armouring that locally prevents deeper erosion. Our soil suitability study shows that currently, after thousands of years of agricultural land use and concomitant land degradation, a new dynamic equilibrium has come into existence in the soilscape, in which ca. 65% of the catchment remains suitable  for agricultural production.

How to cite: Nyssen, J., Tielens, S., Teka, K., Haile, M., Zenebe, A., Munro, R. N., Poesen, J., Dondeyne, S., Frankl, A., Deckers, S., and Tsegay, A.: Historical land degradation strongly influences soil geography – a case in Ethiopia’s mountains, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3315, https://doi.org/10.5194/egusphere-egu2020-3315, 2020.

Ancient land management is inherited and at the base of the current landscapes and must be known to facilitate a sustainable land development for the future. Understanding past land-use systems is helpful for evaluating the current and future state of both biological and physical environments, and for disentangling the role of people in shaping current landscapes. Many different perspectives are involved in reconstructing the cultural impact on the environment. Palynology has great potentiality for environmental and palaeoethnobotanical purposes, with the study of high-resolution sequences formed under natural and anthropic (cultural) forces. Pollen data are fruitfully used to reconstruct land transformations in a diachronic palaeoecological perspective. For example, palynological records from central Mediterranean archaeological sites showed evidence of land uses and evolution of agrarian systems from Neolithic to Bronze Age, allowing a comparative view of the long-term changes in the land footprint of ancient Mediterranean societies. In this study we report on the level of detail on land management provided by palynological research from archaeological sites of Greek Basilicata (south Italy) and Roman Tuscany (central Italy). The local land use types and different management strategies inferred from palynology provide an important contribution to the knowledge of land development and implications for a sustainable soil management in these regions.

How to cite: Mercuri, A. M. and Florenzano, A.: Palynology as a tool for the knowledge on the millennial human impact and land management in the central Mediterranean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10224, https://doi.org/10.5194/egusphere-egu2020-10224, 2020.

Do conservation practices contribute to the sustainability of soils in row crop agriculture?

Martin A. Locke

In row crop agriculture in the United States, so called conservation practices such as reduced tillage and cover crops are promoted as a means to improve the condition of soil (i.e., soil health, soil quality, soil sustainability).  In a series of studies conducted in the alluvial plain of the Mississippi River, various conservation practices were implemented, and several parameters were measured to determine how these practices influenced soil conditions.  Conservation management practices in corn or cotton production systems included reduced tillage, cover crops, and a government sponsored called Conservation Reserve Program, or CRP, where land is removed from agricultural production and replanted with native species as a fallow or buffer area.  Synthesized conclusions from the reduced tillage and cover crop studies showed that: (a) Cover crop and reduced tillage resulted in modest increases in soil organic carbon and nitrogen; (b) Soil biological activity was enhanced by cover crops (e.g., enzymes, mycorrhizae); (c) Runoff losses of solids was reduced with no-tillage and cover crop; (d) The phosphorus and nitrogen associated with runoff solids were reduced with cover crop and no-tillage; (e) Soluble phosphorus and nitrogen in runoff was variable; at times higher with cover crop and no-tillage; (f) cotton and corn grain production in cover crop and reduced tillage systems did not differ from that of conventional systems.  Three years after implementing CRP, microbial biomass, enzyme activities (phosphatase, glucosidase, and N-acetylglucosaminidase), and soil carbon and nitrogen in the surface of CRP soils were higher than in adjacent row crop soils.  Loss of some nutrients in runoff from the CRP was lower than that of row crop areas.  These two studies indicate that conservation practices can improve some environmental parameters related to soil sustainability.  Economics needs to be evaluated to determine the sustainability of maintaining these systems.

How to cite: Locke, M.: Do conservation practices contribute to the sustainability of soils in row crop agriculture?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22043, https://doi.org/10.5194/egusphere-egu2020-22043, 2020.

Identifying the relationship between earthworm activity and soil organic carbon is vital for both planning and performing farming operations. Numerous studies have emphasized that earthworms affect soil organic carbon greatly. However, the extent of this effect is still somewhat vague, and very little is known, not to mention the role of earthworm excrement. The objective for this study is to determine the effect of earthworm excrement on soil organic carbon following different tillage practices based on physical structure stability parameters. Both no tillage (NT) and ridge tillage (RT) led to significant total pore surface area, permeability, fluid conductivity, water resistance index and tensile strength increment than moldboard plow (MP) (p<0.05), whereas water repellency significant decrement (p<0.05). Similar to soil organic carbon, NT and RT significantly increase organic carbon in earthworm excrement than MP (p<0.05). A significant positive correlation (p<0.05) was found between organic carbon in earthworm excrement and total pore surface area, water repellency, tensile strength, respectively. This finding demonstrates that conservation tillage increase organic carbon in earthworm excrement through physical structure stability namely aggregation effect of earthworm excrement on soil water movement and gas diffusion, potentially important for the soil organic carbon increment.

How to cite: Chen, X., Liang, A., Wu, D., Jia, S., and Zhang, Y.: Conservation tillage positively influences soil organic carbon through earthworm excrement physical structure stability in a Chinese Mollisoil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3973, https://doi.org/10.5194/egusphere-egu2020-3973, 2020.

The interaction between plants and arbuscular mycorrhizal fungi in the rhizosphere plays a vital role in driving vegetation recovery and restoration of soil nutrients. However, how this interaction affects vegetation succession and how soil nutrient recovery is driven by vegetation restoration and rhizosphere processes are still largely unknown. In this study, a well‐documented grassland restoration chronosequence on the Loess Plateau, China (fields at 0, 7, 12, 17, 22, and 32 years after farmland abandonment and a natural grassland reference) was selected. The species richness and diversity reached maximum values between 17 and 22 years after farmland abandonment, whereas the plant total above and belowground biomasses simultaneously peaked at 22 years and then remained stable. In the dominant plant rhizosphere and bulk soil concentrations of total glomalin‐related soil protein (including both old and recently produced fungal proteins) substantially increased from 3.58 to 4.87 g kg^-1 and from 2.67 to 3.86 g kg^-1, respectively, between 12 and 32 years after farmland abandonment. The concentrations of soil organic carbon (SOC) and total nitrogen (TN) in the plant rhizosphere and bulk soil significantly increased between 17 and 32 years and reached the levels of the natural grassland. The aboveground plant biomass, soil SOC, and TN concentrations were positively correlated with the glomalin‐related soil protein (GRSP) concentration (p < 0.05). Our study suggested that interactions among plant‐mycorrhizae association, plant diversity, and biomass promote GRSP and nutrient accumulation in the plant rhizosphere and bulk soil, and GRSP largely contributes to SOC stabilization and the accumulation of SOC and TN.

How to cite: Liu, H., Xue, S., and Liu, G.: Plant‐mycorrhizae association affects plant diversity, biomass, and soil nutrients along temporal gradients of natural restoration after farmland abandonment in the Loess Plateau, China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4265, https://doi.org/10.5194/egusphere-egu2020-4265, 2020.

Soil erosion, contributing to land degradation, was identified as an essential driving factor for the evolution of Earth’s critical zone. Although runoff plots along the slope and weirs on river valleys are often used to monitor short-term soil and water loss, it is usually difficult to evaluate the long-term soil loss rates across spatial scales. The ¹³⁷Cs tracer can effectively measure the long-term soil erosion rates but its capability to quantify regional soil erosion characteristics and the driving mechanisms remains a big challenge. To deal with this gap, we integrated and synthesized 61 peer-reviewed articles of soil erosion research by using ¹³⁷Cs tracer methods in the Loess Plateau of China to reveal the regional variability of soil erosion and the effects of land uses on (a) reference ¹³⁷Cs inventory, (b) ¹³⁷Cs soil profile distribution and (c) ¹³⁷Cs-derived total measured erosion rate. The results showed that reference ¹³⁷Cs inventory range from 900 to 1750 Bq/m² with a mean value of 1351 Bq/m². The reference ¹³⁷Cs inventory decreased significantly with the increase of latitude and longitude (p<0.001), while it didn’t change obviously with the mean annual precipitation and temperature. The assumption of ¹³⁷Cs tracing method was supported by ¹³⁷Cs soil profile distribution under tillage and un-disturbed land. Tillage land was considered to have uniform distribution in soil profile and a similar exponential distribution of ¹³⁷Cs content can be found in terrace and no-tillage land. Furthermore, ¹³⁷Cs loss percent had a significant positive relationship with soil erosion rate (p<0.001). Average long-term soil erosion rate of cropland was more than 15000 t/(km²·a) and significantly higher than no-tillage land (5462.52 t/(km²·a) including that of grassland (3890.86 t/(km²·a)), forest (>6000 t/(km²·a)), and terrace (<5000 t/(km²·a)) (p<0.001). The average long-term soil erosion rate of cropland presented high spatial variability and loess hill and gully region had significantly higher average long-term soil erosion rate on cropland due to the coupling effects between heavy rainfall and steep slope. Appropriate reference sites and soil erosion conversion models were important factors for accurately quantifying the long-term soil erosion while the variation of climate, land uses, and geomorphic types had significant impacts on the spatial distribution of erosion rates. Our study can facilitate the understanding of the ¹³⁷Cs tracing method for long-term soil erosion rate and its spatial pattern, which can be supportive for soil and water conservation planning and relevant policy-making.

How to cite: Hu, J., Lü, Y., Fu, B., Comber, A. J., Wu, L., and Harris, P.: Spatial variability of 137Cs-drived total soil erosion rate and its driving factors at regional scale: a meta-analysis in China’s Loess Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4561, https://doi.org/10.5194/egusphere-egu2020-4561, 2020.

Understanding the interactions among different soil microbial species and how they responded to reclamation is essential to ecological restoration and the land development. In this study, we investigated the bacterial distribution in different reclamation sites and constructed molecular ecological networks to reveal the interactions among soil bacterial communities along the reclamation timeline. The relationship between the microbial network module and environmental factors were also analyzed. Bacterial community diversity and composition changed dramatically along the reclamation timeline. PCA and NMDS analysis showed the microbial distribution patterns varied along the reclamation years. Additionally, based on the network profile, phyla Acidobacteria, Planctomycetes and Proteobacteria were distinguished as the key microbial populations in most reclamation sites. Moreover, different network structures were significantly correlated with different soil properties, such as pH value, soil organic matter, soil dehydrogenase and urease activity, which implied that microbial network interactions might influence the soil ecological functions. The variation of the network complexity along the reclamation years revealed that the microbial development and the persistent agricultural utilization promoted the land development of the reclaimed soil in disturbed mining area. Overall, our findings could provide some information of how microorganisms changed along the increasing reclamation time, and how they responded to reclamation activity by regulating their interactions in different ecosystems.

How to cite: Chen, F. and Ma, J.: Explicating potential soil development of reclaimed farmlands using the molecular ecological network analysis in mining disturbed area, East China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6475, https://doi.org/10.5194/egusphere-egu2020-6475, 2020.

Soil structure plays important roles in land degradation, soil fertility, and agricultural productivity and thus has great ecological importance. Soil aggregation is a crucial soil function for maintaining soil porosity and enhancing the stability of soil structure to prevent soil erosion. Biochar was reported to be a binding agent for organic matter in aggregate formation and thus alleviate aggregates degradation. Therefore, this study attempts to a) investigate the impact of the biochar on soybean plant growth, plant nutrients content and soil chemical properties; b) analyze the effect of maize cob biochar (CB) and wood biochar (WB) on soil aggregate structure in vulnerable dry land area.

Field trial was performed on two sandy soil fields (at MLZ and BDG village) and one loamy clay soil field (at RQ village) which located in Ningxia, China. Two treatments (20 t ha^-1 of CB and WB application) and control were repeated 7 times. In this study, we analyzed biomass, grain yield, and nutrients content of soybean plant while soil nutrients were observed as well. Nine soil aggregate size classes (ASCs) were obtained (>10, 10-7, 7-5, 5-3, 3-2, 2-1, 1-0.5, 0.5-0.25 and <0.25 mm) through dry sieving to analyze soil structure. In addition, soil dry mean weight diameter (dMWD), dry geometric mean diameter (dGMD), and structure coefficient (Ks) were measured to estimate the aggregate stability, erodible fraction, and agronomically valuable fraction. After that, redundancy analysis and ridge regression analysis were applied for further data processing.

Our results indicated a) biomass and grain yield: both CB and WB significantly increased shoot biomass in loamy clay soil by 48.7% and 45.0%, respectively. In the two sandy soils, biochar indicated no significant enhancement on the plant growth and grain yield. Even though, the mean value of grain yield increased by 29.7% and 35.1% with the CB and WB application in the MLZ field, respectively. CB application also increased the mean value of grain yield by 34.2% in the BDG field. Although the data shows insignificant difference with high standard errors due to field heterogeneity, the mean values can still give insights into agricultural field practices; b) soil aggregate structure: soil type exerted stronger influence on soil aggregation and plant growth rather than biochar. The sandy field in MLZ showed high soil loss potential by wind erosion referring to a low value of dGMD, and the loamy clay field showed the highest dMWD, dGMD and Ks values for an ideal aggregate structure for crop growth. Findings indicate that biochar had no significant influence on aggregate structure in both sandy and loamy clay soils; c) soil nutrients: CB can significantly increase soil total carbon content in RQ and BDG fields. Soil potassium content can be enhanced by CB application in loamy clay soil.

How to cite: Ma, H., Li, Q., and Bellingrath-Kimura, S. D.: Impact of maize cob and wood-derived biochar on soybean plant growth and soil aggregate structure in dry land, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13007, https://doi.org/10.5194/egusphere-egu2020-13007, 2020.

Abstract

Cowpea, a food and nutrition security crop is being threatened by decline in soil fertility especially in small holder farmstead. The natural arbuscular mycorrhizal fungi in the soil could improve its ability to acquire and retain nutrients thereby leading to higher yield. This irrigated field research was conducted to determine the effect of biochar rates and cropping systems on selected soil chemical properties, soil microbial biomass carbon (SMBC), nitrogen (SMBN), phosphorus (SMBP), and vesicular-arbuscular mycorrhizal (VAM) spore count and mycorrhizal fungi colonization (AMF) of cowpea. Experimental design was 3 x 3 factorial in randomized complete block design (RCBD). Factor A was three cropping systems; sole cowpea, intercropping and intra-cropping, while factor B was three biochar rates; control (biochar at 0 t ha^-1 (B₀)), biochar at 2.5 t ha^-1 (B₁) and biochar at 5 t ha^-1 (B₂). These were replicated in three blocks to constitute 27 plots. The entire plot was cleared, ploughed and demarcated into beds with hoes and diggers. Cowpea sole or inter- or intra- cropped with maize were planted in a spacing distance of 25cm by 75cm, with intercropped cowpea being in-between the interrow spacing (75 cm), while the intracropped cowpeas was planted between the intrarow spacing (25 cm). Biochar soil amendment were applied two weeks after planting by making a groove in-between the rows in the soil and covering them with soil. The result showed that biochar soil amendment and interaction of biochar with cropping system significantly (p<0.05) affected SMBN, SMBC, total  VAM spore count and AMF colonization by cowpea, whereas cropping system significantly affected only total VAM spore count and AMF colonization by cowpea. B₂ amended soil had the highest SMBC content (0.028 mg kg^-1) while the least was from control plot (0.021 mg kg ^-1), SMBN was highest in B₁ amended soil (0.004 mg kg^-1), followed by control plot (0.002 mg kg^-1). Control had higher AMF and total VAM spore count while biochar amended soil had higher soil microbial properties. Considering the cropping systems, inter and intra-cropping had higher microbial biomass and total VAM spore count than sole cowpea whereas sole cowpea had higher AMF infection of cowpea than the intercropped cowpea. Biochar at 5 tha^-1 had the highest available P. Generally, this study showed superiority of the interaction of biochar with cropping systems over sole cropping in the improvement of soil properties in degraded soils of North-West province of South Africa.

Key words: Cropping systems; Chromic Luvisol; Microbial properties; Soil fertility; Soil amendment

How to cite: Uzoh, I. M., Okolo, C. C., Onunwa, A. O., and Babalola, O. O.: Soil P, Arbuscular mycorrhizal spore count and root colonization of cowpea in biochar amended soils under maize/cowpea cropping systems , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12936, https://doi.org/10.5194/egusphere-egu2020-12936, 2020.

In soils clay loss by leaching and surface runoff is one of the initial steps increasing the risk of erosion. Here we set out to determine the effect of fine-sized biochar amendment on colloidal dynamics of soil clay, with the aim of answering whether biochar addition enhances or curbs soil erosion. Fine-sized biochar samples were prepared from fern Dicranopteris linearis’s biomass under non-biochar-oriented pyrolysis (open heating) and biochar-oriented pyrolysis (N₂-supported heating) over a temperature range from 400 to 900°C. The clay fraction (< 2 µm) separated from a clay-rich soil in a hilly area of the Red River basin containing relatively high amounts of kaolinite was tested for its dispersion properties under the presence of the prepared biochars. Surface charge of biochar-soil clay mixtures was determined by polyelectrolyte titration using a particle charge detector, while corresponding colloidal properties of the mixtures were examined by the test tube method. Both, the soil clay fraction and biochar samples showed strongly negative surface charge and their surface charge was variable depending on pH. In a pH range from 3 to 10 and at an electrolyte background of 0.01 M NaCl, surface charge of the clay fraction decreased from -1.68 to -44.75 mmol_c Kg^-1, while the biochars surface charge varied from -0.6 to -48.8 mmol_c Kg^-1. Soil clays were more strongly dispersed in the presence of biochars by increasing electrostatic repulsive forces. The biochar preparation method had a crucial role for surface charge properties of biochars and in consequence colloidal dynamics of biochar-clay mixtures. The N₂-supported pyrolysis at lower temperatures does not increase charge density but creates a more porous structure, thereby increasing the total negative net charges. As a result, the N₂-supported biochars favor clay dispersion more effectively, while the open-pyrolysis biochars showed lesser effects. Our results indicate that fine-sized biochar amendments generally enhance the risk of clay loss, however, such techniques for creating low-charged biochars can help to decrease clay dispersibility when applying biochar for soil.

How to cite: T. Mai, N., T. T. Pham, N., T. Q. Nguyen, A., T. N. Nguyen, A., M. Nguyen, A., T. H. Bach, N., L. Do, C., T. Nguyen, T., H. Nguyen, N., Dultz, S., and N. Nguyen, M.: Colloidal dynamics of soil clay under the effect of fine-sized biochars: Implication for biochar amendment towards preventing clay loss and soil erosion, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6481, https://doi.org/10.5194/egusphere-egu2020-6481, 2020.

The aim of this study was to evaluate the effects of long-term application of exogenous organic matter on soil organic matter and water storage. Addition of organic matter is of importance in sandy soils that are in general poor in organic matter, acidic, conducive to drought and used in agricultural production throughout the world. In this study the sandy podzol (63-74% sand) was amended with chicken manure or waste spent mushroom substrate through more than 20 years. Soil organic matter content, water retention curves, acidity and structural stability were determined at three depths in the top 60 cm in organic amended and control plots. Enrichment of the soil with chicken manure and spent mushroom substrate caused increase in soil organic matter content in the top 0-20 cm from 1.34 to 3.50% and from 0.86 to 4.71%, respectively. Corresponding increases in field water capacity were from 13.6 to 31.8 m³ m⁻³ and from 17.7 to 27.2 m³ m⁻³. Both amendments improved soil structure, reaction and nutrient status. In general, these positive effects were greater in chicken manure than spent mushroom substrate amended soil and less pronounced at depths 20-40 cm and 40-60 cm compared to upper soil. Increase in the field water capacity and water storage capacity made the soils amended with  organic matter more drought resistant. Our findings provide valuable insights the spent mushroom substrate left after growing the mushrooms and chicken manure are environmentally friendly and economical viable soil management practices to increase soil quality and crop productivity.

 Acknowledgements

The work was partially funded by the HORIZON 2020, European Commission, Programme: H2020-SFS-4-2014: Soil quality and function, project No. 635750, Interactive Soil Quality Assessment in Europe and China for Agricultural Productivity and Environmental Resilience (iSQAPER, 2015–2020).

How to cite: Lipiec, J., Usowicz, B., Klopotek, J., Turski, M., and Frac, M.: Effects of long term application of chicken manure and spent mushroom substrate on organic matter and storage of water in sandy soils , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7490, https://doi.org/10.5194/egusphere-egu2020-7490, 2020.

Bioflocculants produced by microorganisms have advantages in removing heavy metals because of their environmental friendliness and biodegradability. In this study, the bioflocculant from a soil bacteria was investigated for its application in chromium (Ⅵ) and arsenic (Ⅲ) removal. The bioflocculant-producing strain was indentified as Pseudomonas fluorescens. It showed maximum flocculating activity of 2579.94 U/mL and yield of 4.84 g/L under optimal condition. With a fed‑batch fermentation strategy, bioflocculant production was further enhanced by 32.6%. The bioflocculant was as extracellular polymer substance composed of 76.67% polysaccharides and 15.8% protein with a molecular weight of 117 kDa. It showed excellent capacities in heavy metal removal, 80.13 and 45.93 mg/g for chromium(Ⅵ) and arsenic (Ⅲ), respectively. The bioflocculant outperformed conventional adsorption materials and could represent a promising biotechnology for the remediation of environmental problems.

How to cite: He, N.: A novel bioflocculant for chromium (Ⅵ) and arsenic (Ⅲ) removal: Extracellular polymeric substance (EPS) of Pseudomonas fluorescens, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7964, https://doi.org/10.5194/egusphere-egu2020-7964, 2020.

Greater Shanghai, one of China’s top megacities, is susceptible to extreme heat events during the summer. This study investigated the spatiotemporal dynamics of land development intensity and its influence on summertime extreme surface urban heat island (SUHI) effect in Greater Shanghai, during 1990 and 2017. Driven by the robust economic development and population growth, the formation of Greater Shanghai has dramatically changed from a traditionally compact city to an explosively urbanizing region in 1990–2017. The results revealed an overall increase in regional LDI of Greater Shanghai in the loss of cropland and water bodies. Simultaneously, the intensified SUHI effect was measured by the increasing relative SUHI intensity (from 1.81℃ in 1990 to 3.16℃ in 2017) and magnitude (from 306.80 km² in 1990 to 1570.56 km² in 2017). The urban-rural gradient analysis based on centric buffers and the representative transects further revealed the spatiotemporal heterogeneity of LDI and its linkage with the evolutionary pattern of the SUHI effect. As indicated, the areal extent of downtown Shanghai within the 0–15 km buffer increased by 201.70 km² in 1990–2017. However, its stably decreasing trends in LDI and associated SUHI effect were observed across the study period. In contrast, the urban periphery and exurban area, which attracted huge investment to develop the infrastructure required for population resettlement and the industrial restructure, experienced a dramatic increase in 1660.57km² of newly developed land. Concurrently, the remarkably increases in LDI and associated SUHI effect the urban periphery and exurban area were notable. Finally, focusing on the overall alarming situation of the summertime SUHI effect in Greater Shanghai, policy implications, and practical suggestions towards sustainable land development and UHI mitigation were discussed.   

How to cite: Zhang, H. and Dai, X.: Spatiotemporal dynamics of land development intensity and summertime extreme surface urban heat island effect in Greater Shanghai (1990-2017), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21923, https://doi.org/10.5194/egusphere-egu2020-21923, 2020.

Soil sealing is considered one of the most dangerous land degradation processes on global, European and national scales. Numerous policies aiming to mitigate this soil threat testify the importance of the phenomenon, which however is continuously growing, or at least does not shows signs of abating. Here we would show a spatial decision support system (S-DSS) – based on a Geospatial Cyberinfrastructure – with the aim of applying it as an operational instrument aiming towards soil sealing mitigation. The system developed within the framework of the LANDSUPPORT EU project (www.landsupport.eu) started on May 2018 has the ambition to impact on those who take decision over soil sealing issues.  It currently represents an evolution of a previous S-DSS tool named Soil sealing and landscape planning, still operational and described in a scientific publication (https://doi.org/10.1002/ldr.2802). The system, focusing on mitigating such crucial land degradation, allows the users - freely and via the Web – to produce ‘what-if’ land planning scenarios thanks to the ‘on-the-fly’ modelling engines. Therefore, integrated geospatial quantitative data and procedures may be directly and freely used by planners. The system is continuously evolving and is thought to function on the fly from local (administrative limits) to the European scale, addressing among others the issues of rural fragmentation, loss of soil ecosystem services, estimates of soil sealing evolution over time, etc. The tool is being developed with the help of end users and indirectly explores a change of paradigm where soil science and landscape/urban planning work together to provide operational instruments that may be adopted by local communities in addressing soil sealing issues with a proactive approach.

How to cite: Manna, P., Basile, A., Bonfante, A., D'Antonio, A., De Michele, C., Iamarino, M., Langella, G., Mileti, F. A., Munafò, M., and Terribile, F.: A web based Geospatial Decision Support System to quantify the impact of soil sealing on soil functions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11621, https://doi.org/10.5194/egusphere-egu2020-11621, 2020.

An increased rate of shallow lakes overgrowth is a commonly observed process in the European lowlands. The transition period from the lake to the peatland state is the most productive phase in the whole evolutionary history of a lake. In this study, we analyze the influence of environmental changes in the Lake Rakutowskie wetlands complex (central Poland) and water level fluctuations on soil cover modifications in the immediate vicinity of the lake.  Multidisciplinary research was conducted in a transect consisting of eight soil profiles. The transformation of soil cover was reconstructed on the basis of detailed studies of soil characteristics, water level fluctuations, radiocarbon dating, etc. Significant acceleration of the lake decline rate is associated not only with natural processes but predominantly with anthropic pressure. The obtained C¹⁴dates indicate a very rapid disappearance of the lake. Taking into account the causative factors, the lake will most likely disappear in the next hundreds of years. The contemporary surface of Lake Rakutowskie is several times smaller than in the past, and this is an effect of the influence of natural and anthropogenic factors. Former fibric materials have been transformed into sapric and hemic ones as an effect of soil exsiccation. The next (and last) step in the degradation of organic soils is muck formation. Along with the progressive dehydration and mineralization of organic soils, its physical and chemical properties have deteriorated, which is visible e.g. in soil structure and elemental content, especially TOC and TN. With the disappearance of the lake, larger adjacent areas are subjected to gradual degradation, leading directly to plant cover changes and irreparable landscape modifications.

How to cite: Słowiński, M., Kruczkowska, B., Jonczak, J., Słowińska, S., Bartczak, A., Kramkowski, M., Uzarowicz, Ł., and Tyszkowski, S.: Soil cover development in the coastal zones of disappearing lakes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13169, https://doi.org/10.5194/egusphere-egu2020-13169, 2020.

High resolution remote sensing images plays a critical role in detection and monitoring of land degradation and development. Monitoring the soil parameters represents great importance for sustainable development and agriculture, as well as smart food production. The space segment component of the Copernicus programme (e.g., Sentinel-1, Sentinel-2 etc.) enables continuously monitoring of Earth’s surface at 10-m spatial resolution. New technologies, development, and minimization of sensors led to the development of micro-satellites (e.g., PlanetScope). These satellites allow us to monitor the Earth's surface daily in 3-m spatial resolution. The developed algorithm for soil moisture mapping is based on the fusion of Sentinel-2 and PlanetScope images. This allows a soil moisture mapping in high spatial resolution. Soil moisture was estimated based on the Leaf Area Index (LAI) and Enhanced Vegetation Index (EVI) using modified water cloud model. Ground-truth data were collected from 15 stations of the International Soil Moisture Network across the globe and used for mapping and validation of soil moisture. The developed algorithm provides a new knowledge that can be widely applied in various research for the detection and monitoring of land degradation and development.

How to cite: Gašparović, M. and Kumar Singh, S.: Fusion of Sentinel and PlanetScope images for high resolution soil moisture mapping: Algorithm and preliminary validation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8324, https://doi.org/10.5194/egusphere-egu2020-8324, 2020.

Grassland degradation is a global ecological problem, and grassland on the Qinghai-Tibetan Plateau (QTP) is suffering serious and continuous degradation. Due to the vulnerability of grassland ecosystem on the QTP and its sensitivity to global climate change, alpine grassland degradation needs more attention. In this study, we extracted 7 visible vegetation indices by using an unmanned aerial vehicle (UAV) with visible light sensors. We used random forest model and stepwise multiple regression establishing the relationship between visible vegetation indices and filed degradation index to assess alpine meadow degradation. The result showed that ExG (Excess Green Index) was effective in the simulation with an R² value of 0.53. The degradation distributions of 50 field sites were obtained at 10cm spatial resolution. This study with visible vegetation indices by UAV provides an effective approach for monitoring grassland degradation at low altitude. The high resolution contributes to more refined grassland management.

How to cite: Han, W., Su, X., and Liu, G.: Assessment of grassland degradation in alpine meadow using visible vegetation indices by UAV on Qinghai-Tibetan Plateau, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12415, https://doi.org/10.5194/egusphere-egu2020-12415, 2020.

Land degradation (LD) is a complex process affected by both anthropogenic and natural driving variables, and monitoring LD progression in areas under human‐induced stresses has become an essential task. In this study, we developed an approach for evaluating and mapping potential LD risks associated with human-induced and biophysical driving variables. We employed machine learning algorithms (Support Vector Machine (SVM), Multivariate Adaptive Regression Splines (MARS), Generalized Linear Model (GLM), and Dragonfly Algorithm (DA)) for LD risk mapping based on topographic (n=7), human-induced (n=5) and geo-environmental (n=6) variables and field measurements of degradation. The performance of different algorithms was assessed using receiver operating characteristic (ROC), Kappa index, and Taylor diagram. An urbanized watershed, Pole-doab in central Iran, was selected as the case study. The performance data indicated that DA (an novel optimized algorithm) was most accurate in LD risk mapping. In LD zone maps produced using SVM, GLM, MARS, and DA, 19.16%, 19.29%, 21.76%, and 22.40%, respectively, of total area in the Pole-doab watershed had a very high degradation risk. In all cases, the LD risk maps indicated that land in the southern part of the Pole-doab watershed is most exposed to degradation of different types.

How to cite: Torabi Haghighi, A., Darabi, H., Karimidastenaei, Z., Davudirad, A. A., Rouzbeh, S., Sajedi Hosseini, F., and Klöve, B.: Land degradation risk mapping using novel machine learning algorithms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12710, https://doi.org/10.5194/egusphere-egu2020-12710, 2020.

Pedotransfer functions to mapping total and adsorbed phosphate using Vis-NIR (DRS)

José Marques Júnior ^a, Romário Pimenta Gomes ^a, Luis Fernando Vieira da Silva ^a, João de Deus Ferreira e Silva ^a & Laércio Santos Silva ^a

Department of Soils and Fertilizers, Research Group CSME - Soil Characterization for Specific Management, State University of São Paulo (UNESP), Via de Acesso Prof. Paulo Donato Castellane s/n, 14883-292 Jaboticabal, São Paulo, Brazil

Soil oxides-Fe can be an excellent predictor of spatial variability of total and adsorbed P, contributing to rapid mapping, low cost and differentiation of minimum areas of phosphate fertilizer management. In the Western Paulista Plateau (Brazil) were collected 300 soil samples representing the lithological (sandstone and basalt) and geomorphic variability (less, moderately and highly dissected), at a depth of 0.0 – 0.2 m. The total (P_total) and adsorbed phosphorus (P_ads) determined by conventional methods and hematite and goethite by X-ray diffraction (XRD). By partial least squares regression (PLS) and chemometric calibration, internal validation and external calibration, the Ptotal and Pads were estimated by diffuse reflectance spectroscopy (Vis-NIR-DRS), using hematite (Hm) and goethite (Gt) as a predictor. Then, the spatial pattern was obtained by geostatitic analysis. Phosphorus ware influenced by geology and dissection of the landscape and is a covariate of Hm and Gt, important indicators of environments with high or low P adsorption and content potential. Partial least squares (PLS) regression analysis of the spectral data demonstrated the influence of iron oxides on P_total and P_ads, whereby Hm affects the former and Gt the latter. The lower maximum phosphorus adsorption capacity indicates the scarcity of P minerals and Fe oxides from sandstone sediments, with severe risk of phosphate loss and environmental damage. Significant correlation between P_total and Hm and P_ads and Gt in Vis-NIR-DRS indicates the potential of this study in mapping large areas based on iron oxides, which can be used to develop soil P inventories as well as monitor and estimate the future impacts of land use, considering the complex relations between soil and landscape.

Keywords: Diffuse reflectance spectroscopy, goethite, hematite, geostatistics.

How to cite: Marques Júnior, J., Gomes, R. P., da Silva, L. F. V., Silva, J. D. D. F., and Silva, L. S.: Pedotransfer functions to mapping total and adsorbed phosphate using Vis-NIR (DRS) , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22055, https://doi.org/10.5194/egusphere-egu2020-22055, 2020.

This study aims to establish future vegetation changes in the east and central of northern China (ECNC), an ecologically sensitive region in the transition zonal from humid monsoonal to arid continental climate. The region has experienced significant greening in the past several decades. However, few studies exist on how vegetation will change with future climate change, and great uncertainties exist due to complex, and often spatially non-stationary, relationships between vegetation and climate. In this study, we first used historical NDVI and climate data to model this spatially variable relationship with Geographically Weighted Logit Regression. We found that temperature and precipitation could explain, on average, 43% of NDVI variance, and they could be used to model NDVI fairly well. We then establish future climate change using the output of 11 CMIP6 models for the medium (SSP245) and high (SSP585) emission scenarios for the mid-century (2041-2070) and late-century (2071-2100). The results show that for this region, both temperature and precipitation will increase under both scenarios. By late-century under SSP585, precipitation is projected to increase by 25.12% and temperature is projected to increase 5.87^oC in ECNC. Finally, we used future climate conditions as input for the regression models to project future vegetation (indicated by NDVI). We found that NDVI will increase under climate change. By mid-century, the average NDVI in ECNC will increase by 0.024 and 0.021 under SSP245 and SSP585. By late-century, it will increase by 0.016 and 0.006 under SSP245 and SSP585 respectively. Although NDVI is projected to increase, the magnitude of increase is likely to diminish with higher emission scenarios, possibly due to the benefit of precipitation increase being gradually encroached by the detrimental effects of temperature increase. Moreover, despite the overall NDVI increase, the area likely to suffer vegetation degradation will also expands, particularly in the western part of ECNC. With higher emissions and later into the century, region with low NDVI is likely to shift and/or expand north-forward. Our results could provide important information on possible vegetation changes, which could help to develop effective management strategies to ensure ecological and economic sustainability in the future.

How to cite: Yuan, W., Wu, S., and Hou, S.: Projecting future vegetation change for northeast China using CMIP6, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9639, https://doi.org/10.5194/egusphere-egu2020-9639, 2020.

The top metre of the soil is one of the largest terrestrial carbon reservoirs. More than 50% of the soil carbon is stored as soil organic matter (SOM). Several papers report about the SOM losses due to tillage and land-use change. On the other hand, a huge amount of papers focus on the environmental potential of various min-till, no-till and other techniques for regenerative agriculture. The change of the fertilization regime also has an influence on SOM so it also can influence the humus status of the soils. This presentation focuses on the effects of different kinds of fertilization and abandonment of arable lands on the quantity and quality of the SOM.
The present study is based on Martonvásár Experimental Station (Hungary) which was established in 1958. The research focused on maize monoculture with the following treatments: (a) no fertilization, (b) NPK, (c) NPK with manure addition. The soil of the plots is Chernozem. Two controls were selected: (a) a natural Grassland and a secondary grassland. The secondary grassland was an arable land until 1990. Five repetitions of soil samples were taken from each plot and times. Soils were fractionated to silt and clay associated OM (s+c), aggregate associated OM (S+A), dissolved organic matter (DOM) and particulate organic matter (POM) according to Zimmermann’s method (4). Quality parameters of the DOM were studied by CN analyser, UV-Vis spectrometer, spectrofluorometer, zetasizer and size exclusion chromatograph. Solid SOM fractions were studied by CHNS analyser, ATR-FTIR and DRIFT FTIR. The V3-V4 regions of the 16S rRNA gene obtained from the soil samples were sequenced on the Illuma platform for the description of microbial diversity.
Twenty years were enough to restore the natural SOM content of the soils (land-use change from arable land to grassland). Labile fractions of the SOM were higher in case of secondary than the primary grasslands. We have found differences in weight ratios of SOM fractions between fertilization regimes, as well. The proportion of microbial contribution to SOM were higher in the arable soils than the grasslands based on the C:N ratios of the SOM. However, the predominance of phyla Proteobacteria, Acidobacteria, Bacteriodetes, Actinobacteria and Verrucomicrobia in all studied soils, microbial diversity is generally higher in the grasslands than in the arable plots. The DOM of different fertilization regimes and land uses have shown the most characteristic differences. The difference between arable plots (with various fertilization regimes) and grasslands can be characterized by humic substances (HS) with higher condensation degree and molecular mass. The application of manure has result same proportion of peptide-like components and HS with lower molecular as the DOM of grassland soils.
The microbial diversity of abandoned arable land remained similar to that of the arable lands over twenty years. The major part of the growth of SOM occurred in the labile fractions. The change of the fertilization regime also has limited potential to grow a total mass of SOM.
Support of the GINOP 2.3.2-15-2016-00056 and National Research, Development and Innovation Office under contracts K123953 are gratefully acknowledged.

How to cite: Szalai, Z., Noémi, U., Vancsik, A., Hallabi, A., Jakab, G., Filep, T., Borsodi, A., Megyes, M., Kiraly, C., Szabó, L., Árendás, T., and Márialigeti, K.: The impact of fertilization regime and land use change on the SOM after 60 years of maize cropping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19887, https://doi.org/10.5194/egusphere-egu2020-19887, 2020.