Soil health is pivotal for maintaining environmental sustainability and plays a vital role in supporting diverse ecosystems, agricultural productivity, and overall human well-being. The interplay of climate change and anthropogenic (human-induced) activities can exert substantial influence on soil health, giving rise to a spectrum of challenges. In recent years, a growing body of scientific evidence indicates that climate change will adversely affect soil health. This impact manifests through the decline in soil organic matter, the degradation of soil structure, and an increased vulnerability to erosion and other forms of deterioration. Human activities, particularly pollution and widespread habitat degradation, further exacerbate these effects. Additionally, ongoing misuse of soil contributes to its continued degradation, resulting in adverse consequences such as diminished biodiversity, decreased agronomic productivity, reduced input efficiency, and heightened rural poverty.

Consequently, a paradigm shift is imperative, with a focus on adopting sustainable agricultural systems. This involves a need to restore soil health instead of contributing to its decline, actively mitigating and adapting to climate change rather than exacerbating it, promoting negative emission farming instead of being a source of greenhouse gases and transforming land into a significant carbon sink rather than a source. To deal effectively with the challenge of soil health in the context of climate and human-induced change, it is essential to adopt a global approach. This means integrating sustainable land management practices, formulating effective policies and encouraging global cooperation. These measures are essential to ensure the long-term health and productivity of our soils.

How to cite: Chabbi, A.: Unlocking the crucial interplay between soil health, climate change and global stewardship, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21813, https://doi.org/10.5194/egusphere-egu24-21813, 2024.

The sampling and analysis or visual examination of soil to assess its health status are widely practiced from plot to national scales. However, available data are often not made easily accessible and new data are not always shared with the wider public, creating a partial understanding of soil processes and health status across different geographies, as well as a misuse of resources.

To address these challenges, Varda has created an interactive digital soil platform, named SoilHive, which provides an overview of existing soil data across the globe, facilitates the identification of soil data gaps across regions, and supports soil data sharing and interoperability.

To facilitate the identification of functional soil data gaps, Varda created a visualization tool to enable users to identify the extent to which the data available in their selected regions of interest allow them to characterize key soil characteristics and functions, starting with soil health. To this end, Varda collaborated with a team at the Aberdeen University to define a minimum set of indicators and associated soil properties, covering diverse soil degradation processes and ecosystem services, to describe soil health at the local level with a focus on agricultural settings. SoilHive users will be able to select a region of interest and verify how many of those indicators are available to characterize soil health: the gap between the available data and the required data will be marked as the "Soil Health Data Gap" and described as the percentage of data over the total number of indicators.

This Soil Health Data Gap could facilitate the identification of those regions where data collection efforts should be intensified, informing the prioritization of actions aimed at bridging existing gaps while expanding the availability of soil data. Several proposed activities to address this gap include targeted soil mining activities to collect historical and non-digitized soil data, advocating for data-sharing collaborations among diverse stakeholders, and organizing brand-new soil sampling campaigns. Moreover, additional soil health definitions could be used to provide the user with different representations of soil health data gaps, in line with these definitions.

Closing the existing Soil Health Data Gaps bears significant importance, as it empowers us to deepen our comprehension of soil health dynamics. By expanding soil data transparency across all sectors and stakeholders, we would gain the ability to make well-informed decisions regarding optimal soil management practices, efficiently allocate resources, and strive to enhance soil health for the betterment of both present and future generations.

How to cite: Miglio, E., Albanito, F., Sala, S., and Smith, P.: Bridging the Soil Health Data Gap: informing prioritization of soil data collection efforts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13121, https://doi.org/10.5194/egusphere-egu24-13121, 2024.

Mining is crucial in driving economic development but entails extensive environmental damage, such as soil degradation and water and air pollution. Mining activity impacts the soil quality, often making it unable to support ecosystem function and structure and reducing its ecological resilience. Soil degradation reduces physical, chemical, and biological (PBC) soil properties. The current study aims to apply the soil quality index (SQI) to quantify soil restoration success in an open-pit phosphate mine in Israel’s hyper-arid environment. In this regard, we evaluated an ecological restoration practice that includes topsoil refilling compared to the adjacent undisturbed natural system. We used transformed and standardized scorings of 11 PBC soil properties that were further statistically integrated into overall SQI values. Our results revealed significant differences between the restoration practice areas and the nearby natural areas, with a higher soil quality value in the latter. It is proposed that the topsoil restoration method is mainly affected by soil biological indicators, such as soil organic matter, soil proteins, and polysaccharides related to biocrust development, and, to a lesser extent, by physical properties (primarily infiltration rate, followed by available water content). The former properties encourage the biocrust establishment, which is essential for soil surface stabilization. This, in turn, affects the water infiltration, nutrient availability, and erosion rates. The chemical indicators showed no significant differences between most sites for the overall soil quality. In conclusion, our results reflect a slow recovery of the SQI in the restored sites, demonstrating that achieving the quality of the natural areas requires a long-term recovery process. Moreover, the physio-biological indicators were more suitable for reliably estimating mining restoration practices in dryland areas. Our approach could have broader implications for evaluating the ecological restoration success in hyper-arid environments.

How to cite: Paz-Kagan, T., Karnieli, A., and Ziv, Y.: Quantifying Soil Quality in Dryland Regions as A Key Step in Phosphate Mining Restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4405, https://doi.org/10.5194/egusphere-egu24-4405, 2024.

The annual global production of plastics is currently nearly 400 million tons, leading to widespread concern regarding the quantity of degradation-resistant plastics entering terrestrial environments. Farmland soils are a major sink for microplastics (MPs, size <500 μm) owing to the wide use of plastic film mulching. Although the influence of MPs on soil parameters has been investigated, the response of microbiomes to soil microenvironments with contrasting limiting factors, particularly in flooded soil environments such as rice paddies, remains unknown. Using zymography and high-throughput sequencing, we conducted an experiment with polylactide (PLA) and polyvinyl chloride (PVC) MPs to compare the effects of biodegradable and conventional MPs on rice growth, exoenzyme kinetics, and microbial communities. Both conventional and biodegradable MPs significantly inhibited rice growth, possibly by affecting nutrition. Compared with the control soils, both PLA- and PVC-amended soils exhibited higher enzyme activity in the hotspots. The enzymatic resistance to MPs was higher in ‘coldpots’ with PVC addition compared to that in PLA and control treatments. 
Bacterial biomass increased but diversity declined in PLA-amended soils, possibly because PLA particles act as carbon input inhabited the population of bacteria. Our findings suggest that co-occurrence networks among bacteria were strengthened by the addition of both MPs, with an increase in microbial functionality resilience and enhanced competition with neighboring roots for nutrient mining. This competition for nutrients may 
adversely affect plant growth. 

How to cite: Razavi, B. S., Song, B., Shang, S., Cai, F. M., Liu, Z., Fang, J., Li, N., and Adams, J. M.: Microbial resistance in rhizosphere hotspots under biodegradable and non-degradable microplastic amendment: Community and functional sensitivity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13198, https://doi.org/10.5194/egusphere-egu24-13198, 2024.

The long-term transformation of organic matter in agroecosystems is modulated by soil properties and functional traits of plants and microorganisms, and is an indicator of soil quality. We studied how contrasting soil texture (loamy vs sandy) and two plant genotypes (a wild type, WT and a mutant deficient in root hairs, rth3) altered organic matter through microbial functioning in a field experiment after 5 years of maize monoculture. Our hypotheses were that (1) loamy rather than sandy soil will promote a larger OM storage; and (2) root-hairs, entailing a higher root-soil interface and water retention in the rhizosphere, boosting microbial processes and OM fluxes, will increase OM content not only in the rhizosphere but in the long-term, also in the bulk soil. To address these hypotheses, plots were filled with homogenized soil, being sandy soil a mix of 16.7 % loam with quartz sand, and the two maize genotypes. After 5 years of monoculture, soil was collected at the early maize growth stage of BBCH19, in the first 20 cm and the 20 to 40 cm depths. We determined stoichiometric ratios of total (TOC/TN) and labile (DOC/DON) fractions of soil organic matter, and microbial eco-physiological indexes related to OM transformation and sustainability, i.e. respiration-to-biomass ratio, qCO₂, and microbial-to-total organic C ratio, C_mic:C_org.  The 5- and 7-times larger C supply in loamy vs sandy soil, for WT and rth3, respectively was explained by 40% more efficient C metabolism, i.e. less C losses through respiration per biomass unit, by 90% lower specific labile C content (DOC:C_mic ratio) and by 60% faster microbial turnover (µ_max^-1) in the former. As the TN content was only 3.1 and 4.2 times larger in loamy than sandy soil for WT and rth3 respectively, the resulting C:N ratio was 1.7- times greater for loamy than sandy soil, indicating more unbalanced stoichiometry in the former for both genotypes. Remarkably, the C and N content increased 20 and 36 %, respectively, after 5 years of maize monoculture, in the plots under root hair-deficient mutant than under wild type maize resulting in significantly larger C storage at rth3-plots in loamy soil. This may be explained by the reported higher exudates production by rth3 under the field conditions. Soil depth up to 40 cm did not show big differences in the capacity for C storage, likely due to similar root density in both depths. Concluding, loamy soil showed a higher capacity of C storage through microbial turnover and sandy soil demonstrated larger C losses through DOC compounds and respiration after 5 years of maize monoculture. Finally, carbon availability was not the limiting factor in sandy soil for microbial growth, but rather other factors such as soil water holding capacity, or OM fluxes from rhizosphere to bulk soil.

How to cite: Martín Roldán, M., Vetterlein, D., Tarkka, M., and Blagodatskaya, E.: Stoichiometry of soil organic matter and microbial functional traits altered after 5 years of maize monoculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5424, https://doi.org/10.5194/egusphere-egu24-5424, 2024.

Mechanisms of nitrogen (N) acquisition in the rhizosphere often include microbial immobilization of mineral N and its further transformation into organic compounds. Therefore, visualization and quantification of organic N distribution and their correlation with N-related enzymatic hotspots helps to reveal the role of roots in plant-microbial interplay related to N cycling. In this study, time-lapse leucine aminopeptidase (LAP) zymography and amino-mapping were coupled to reveal amino-N distribution both in the soil and distinct root segments of Zea mays L. A strong overlap between amino-N content and LAP activity in seminal and lateral root tips, as well as seminal roots, highlighted the intricate interplay between plants and microorganisms in N acquisition. Remarkably, we also uncovered a significant decoupling of LAP activity from amino-N in lateral roots and bulk soil. The distinct patterns in different root parts provided a perspective on the major origins of enzyme production in the rhizosphere. Endogenous LAP production by roots and root-associated microbes in seminal roots and root tips contrasted with the reliance on exogenous rhizosphere microorganisms for enzyme activity in lateral roots. This finding not only advances our understanding of N acquisition but also opens up the new avenues for discussion on the ecological roles of different root segments in shaping the rhizosphere environment.

How to cite: Shen, G., Guber, A., Kravchenko, A., and Blagodatskaya, E.: Elucidation of the interplay between roots and microorganisms in the organic N transformation in the rhizosphere of maize, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3156, https://doi.org/10.5194/egusphere-egu24-3156, 2024.

Soil microbial communities are the main regulators of ecosystem services and are vital for carbon and nutrient cycling. Root exudates play a crucial role in shaping soil microbial assembly and hence, influencing biogeochemical processes that impact plant growth. Here, we hypothesized that continuous wheat cultivation would lead to lower glucose release, resulting in lower microbial growth, activity, and biomass. For the first time in situ glucose imaging was optimized for studying these interactions in the field - using installed root windows in the first (W1) and third (W3) wheat after break crop plots. Root and leaf samples were collected to determine the expression of sugar transporter genes using transcriptomics. Soil microbial respiration (characterized by Substrate Induced Growth Respiration (SIGR)) and enzyme kinetics (measured by fluorometric microplate assays of 4-methylumbelliferone (MUF) and 7-amino-4-methyl coumarin (AMC)) were measured in rhizosphere, root affected and bulk soil samples to assess C, N, and P acquisition.

W3 had the lowest proportion of hotspots for glucose release with 1.35 % of the total soil surface area, indicating a 17.7 % decline compared to W1. Also, we found that the expressions of functional orthologous genes of SWEET1a in wheat roots were significantly upregulated in W3 compared to W1. Furthermore, total microbial biomass dropped by 11.8 and 4.8 % in W3 in the rhizosphere and bulk soils compared to W1, respectively. The growing microbial biomass in the rhizosphere soil of W1 was about five times higher than W3. For β-glucosidase activity, soil samples from W1 had a higher maximum velocity of enzyme activity (V_max) compared to W3 samples, in all studied compartments (rhizosphere, root affected and bulk soil samples). Lower glucose release in W3 highlights the importance of root exudates in shaping rhizosphere interactions and microbial community dynamics in response to continuous wheat cultivation. Also, differences in SWEET gene expression in wheat roots and leaves, indicates shifts in nutrient uptake and resource allocation strategies. This decline in glucose release observed under W3 compared to W1 underscores the significance of root exudates in shaping rhizosphere interactions.

Overall, the shift in glucose release is linked to altered root physiology and exudation processes, potentially reflecting the plant's strategy to create a less favorable environment for ambuscade and opportunistic pathogens. Hence, this study provides novel insights into the complex interactions between continuous wheat cultivation, root exudation, microbial dynamics, gene expression, and enzymatic activities.

How to cite: Rashtbari, M., Hosseini, S. S., Azimi, A. S., Schemmel, M., Zhou, Z., Han, L., Cai, D., and Razavi, B. S.: Glucose Release Controlled by Sugar Transporters in Wheat Plant Modulates Microbial Growth and Enzyme Activity Around the Root, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8602, https://doi.org/10.5194/egusphere-egu24-8602, 2024.

Soil is one of the most diverse and complex natural systems at global scale and is involved in several reactions of formation, development, and breakdown of chemicals, many of these depending on soil microorganisms.

According to the combination of soil forming factors, soil properties show a large horizontal and vertical variability, which can have a huge impact on soil microbial communities. However, relatively few investigations have been carried out to associate the changes in soil microbial community with the variations of soil properties across the genetic horizons and along depth.

In Italy, chestnut groves used to be key sources of products in mountain regions. Recent socio-economic changes have led to the progressive abandonment of this land use, producing degradation of the landscape and increased hydrogeologic risk. Now, programs for the restoration of this activity collide with outbreaks of illnesses such as ink disease, which is caused by Oomycetes present in the soil. In this framework, the physicochemical and biological features of soils play a crucial role in the distribution and assessment of the risk and severity of this disease.

The objective of this study was to correlate the diversity and eco-functionality of the microbial communities with soil properties and health indicators along depth and across a transect including chestnut trees with and without symptoms of ink disease.

The study area was a fruit chestnut grove located in the Apennine mountains south of Bologna, Italy. Soil profiles were opened along a transect ranging from a chestnut tree showing ink disease symptoms (INK1) to two subsequent chestnut trees with no visible symptoms (INK2 and INK3). In each profile, the horizons were described and sampled; to assess spatial variability, three minipits were opened around each profile, and their horizons were also described and sampled. Each horizon was also sampled in sterility. The samples were then analyzed for physicochemical and biological parameters, and total DNA was extracted to perform a taxonomic analysis.

Results showed that some physicochemical parameters, while presenting a trend with depth, also presented a trend with distance from the diseased tree: pH and base saturation decreased near this tree, while C:N and C:P increased, as well as water-extractable organic carbon. The taxonomic analysis showed that, while no substantial variation was detected in the bacterial composition of INK2 and INK3, INK1 showed a higher prevalence of phyla involved in the organic matter cycle (Acidobacteriota and Proteobacteria). Regarding the fungal population, in INK2 and INK3 the main trophic group was soil saprotrophs, while in INK1 the most frequent were short- and medium-distance ectomycorrhizae, which often indicate plant stress. Shannon index showed that bacterial diversity increased with depth while fungal diversity decreased. In both cases the profile near the diseased tree presented the least diversity. No difference was detected between the profiles in soil health indicators, such as organic matter content and microbial biomass and its activity, and these were not correlated with microbial diversity. These results suggest that taxonomic analysis of soil microorganisms could integrate traditional indicators in assessing soil and ecosystem health.

How to cite: Trenti, W., De Feudis, M., Falsone, G., Vittori Antisari, L., Puliga, F., Tabanelli, G., Zambonelli, A., and Gardini, F.: Soil health and microbial diversity in fruit chestnut groves affected by ink disease , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18278, https://doi.org/10.5194/egusphere-egu24-18278, 2024.

The role of soil health in regulating primary productivity at large scale across different land-use types remains poorly understood. This hinders our ability to predict the impact of soil degradation on essential ecosystem services such as food provision and climate regulation. To address this gap, we conducted a pan-European observational field study using data from 588 sites and 27 countries to investigate the link between soil health (a composite index based on soil properties, biodiversity, and plant disease control) and primary productivity across three major land-use types: woodlands, grasslands, and croplands. We found that soil health in woodlands was 31.4% higher than in grasslands, and 76.1% higher than in croplands. We further observed that soil health was positively linked to cropland and grassland productivity at the continental scale. Woodland productivity was linked to climate conditions rather than to soil health status. We observed that soil organic carbon and the richness of Acidobacteria, Firmicutes, and Proteobacteria had a positive effect on primary productivity. Among microbial functional groups, we found that nitrogen-fixing bacteria and mycorrhizal fungi positively related to primary productivity in croplands and grasslands, while plant pathogens showed a negative relationship. Together, our results point to the importance of soil biodiversity and soil health for maintaining primary productivity across contrasting land-use types.

How to cite: Romero, F., Labouyrie, M., Orgiazzi, A., Ballabio, C., Panagos, P., Jones, A., Tedersoo, L., Bahram, M., Guerra, C., Eisenhauer, N., Tao, D., Delgado-Baquerizo, M., García-Palacios, P., and van der Heijden, M.: Soil health increases primary productivity across Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7955, https://doi.org/10.5194/egusphere-egu24-7955, 2024.

The land use changes and environmental pollution brought by urbanization are important aspects of global change. Cities provide a unique "natural laboratory" for people to understand the impact of human-nature composite ecosystems on global change and their response processes. Unlike natural soils, human activities during urbanization directly or indirectly affect the formation and development of soils. Generally, urban soils have a higher organic carbon content compared to agricultural soils and some natural soils, making them an important carbon reservoir in urban ecosystem carbon cycles. The urban-rural gradient method based on urbanization intensity provides a possibility for studying the response of Soil Organic Carbon (SOC) storage to urbanization on a global scale. Here, we define Urban Intensity (UI) as the proportion of impervious surface area within each 1x1 square kilometer (ranging from 0 to 100%). We first analyzed the trends of SOC storage along the UI gradient globally and in different climate zones, distinguishing the contributions of natural and socio-economic factors through multiple linear regression and residual quantification. The study found that as UI increases, SOC storage undergoes phased changes, with natural and socio-economic factors contributing differently in each urbanization stage and climate zone. For example, globally, when UI is low (UI ≤ 0.25) and high (0.75 < UI ≤ 1), SOC storage tends to decrease with increasing UI, while at medium intensity (0.25 < UI ≤ 0.75), SOC storage shows an increasing trend. Globally, changes in socio-economic factors (population, GDP) are the main drivers of SOC storage changes during urbanization. Particularly at low and medium urbanization intensities, socio-economic contributions reach 98% and 89%, respectively. However, as urbanization intensity increases, the driving role of natural factors becomes more apparent, contributing over 40% in areas of high urbanization intensity.

How to cite: Xu, F. and Li, S.: Trends and drivers of the soil organic carbon stocks along the urban-rural gradients globally, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4361, https://doi.org/10.5194/egusphere-egu24-4361, 2024.

At the heart of agro-ecosystems lie soils, essential components profoundly affected by intensive farming practices and global changes across various regions in Europe. This impact manifests as a loss of biodiversity, a decline in organic matter content, and heightened susceptibility to erosion. Recognizing these challenges, certain farmers are embracing innovative approaches to enhance soil quality, such as conservation farming and organic farming. These two systems differ significantly in their weed management practices, with conservation farming relying on synthetic herbicides and reduced tillage, while organic farming predominantly employs tillage.

To assess soil structural stability, we developed a new measurement protocol, the QuantiSlakeTest. This low-tech method operates on the principle of continuous quantitative measurement, evaluating the disintegration of a soil sample submerged in water. The resulting curves are normalized, and synthetic indicators, including relative weights at stabilization, time to reach maximum relative weight post-immersion, diverse slopes, and area under the curve, facilitate the comparison of various treatments.

Building on previous research demonstrating the relevance of this approach and the influence of tillage on soil structural stability (Vanwindekens & Hardy, 2023), our study employed the QuantiSlakeTest to highlight the annual evolution of soil structure stability over three years following the implementation of an organic cropping system trial in Gembloux (Wallonia, Belgium). Initiated in 2019, the trial involved converting a conventional 6 ha field to a seven-year rotation of organic farming. The three compared cropping systems differed in weed control, fertilization, and tillage practices. Soil samples were collected in early spring of 2020, 2021, and 2022 from various crops in the trial, including winter cereals, spring cereals, legumes, and maize, with cover crops or even uncovered after a winter ploughing.

Our main findings reveal a gradual differentiation of soil structural stability indicators during the first three years of cultivation. Cropping systems based on reduced tillage practices demonstrated a positive impact on soil structural stability, particularly in the third studied year (2022), while reference systems exhibited lower rates. These results confirm previous studies. We also detect a slight positive impact of legumes, cover crops, and/or crop associations, even in the two cropping systems with ploughing (2022). Further analyses, to be conducted over the seven years rotation will shed additional light on the dynamics of soil structural stability.

Frédéric M. Vanwindekens and Brieuc F. Hardy (2023). The QuantiSlakeTest, measuring soil structural stability by dynamic weighing of undisturbed samples immersed in water, SOIL, 9, 573–591, https://doi.org/10.5194/soil-9-573-2023

How to cite: Vanwindekens, F., Hardy, B., Abras, M., Sail, S., and Huyghebaert, B.: Multi-year dynamics of soil structural stability under contrasting farming practices in a belgian organic field experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20583, https://doi.org/10.5194/egusphere-egu24-20583, 2024.

A significant portion of smallholder farming systems in Sub-Saharan Africa are marked by significant heterogeneity in both biophysical and socio-economic conditions. Resource access and the patterns of resource allocation at household level are often co-determined by wealth. We hypothesized that wealth plays a pivotal role in the effect of future-oriented farm management on soil organic carbon storage (SOC) and soil quality. To test this hypothesis, we conducted a study involving 42 households categorized in three wealth classes (high, medium, low) based on farm-household survey data from the Namibian Zambezi region. Soil samples were collected up to a depth of 1 m with a focus on soil organic carbon and nitrogen throughout the soil profile. Topsoils were additionally analyzed for texture, cation exchange capacity (CEC), pH, and available phosphorus; field size was measured. A follow-up survey wave captured information on crop species, yield, and soil management practices.

Results of the survey showed, that farmers of our study area typically burn their field regularly before the cultivation period. With rare exceptions no farmer fertilized their fields, neither with mineral fertilizer nor with manure. Results indicated that relatively wealthier farmers had larger fields, yet intriguingly, their yields per hectare were not higher than for farmers in lower wealth terciles. Notably, the Arenosols, which are widespread in the Zambezi region, had lower sand and higher clay and silt contents among the relatively wealthier farmers. Moreover, high wealth class showed significantly higher soil organic carbon and nitrogen concentrations in the topsoils compared to medium and low wealth classes along with CEC values. Though, no such a trend was observed for available phosphorous and pH. The elevated levels of soil organic carbon and nitrogen of relatively wealthy farmers persisted consistently up to a depth of 1 meter. These results indicate that the soils of farmers in the high wealth class have inherently better soil conditions. Contrary to our hypothesis, the wealthier farmers did not seem to invest more in land management in order to improve soil conditions. Instead, historically they seem to have been more inclined to settle on the more fertile soils in the Zambezi region of Namibia and benefit from larger fields and thus higher quality natural resources.

How to cite: Dr. Sandhage-Hofmann, A., Mira, F., Vanessa, A., Jan, B., Bisrat, G., and Wulf, A.: Unraveling the relationship between rural farm household wealth, carbon storage, and soil quality in Namibia's Zambezi Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10503, https://doi.org/10.5194/egusphere-egu24-10503, 2024.

Bush encroachment is a form of rangeland degradation. It is characterized by a shift from herbaceous to woody plant dominance, which has reduced indigenous plant and animal biodiversity and it’s a significant problem in southern African savannas, particularly in Botswana, Namibia and South Africa. Overgrazing by cattle on the one hand and the loss of a large part of large herbivores on the other hand, have been identified as main contributor to imbalance of this delicate ecosystem. The present study aimed to investigate bush encroachment effects on soil organic matter (SOM) in areas of low, medium, and high bush density in a farmed area of the Botswana’s savanna. Bush encroachment is expected to have significant effects on soil properties. It is assumed to decrease soil organic C concentration as well as contents of macro and micro nutrients. To investigate such possible impacts, a sampling was realized during the dry season in various plots with varying encroachment densities (Senegalia mellifera). The analysis included standard soil parameters, (pH, electrical conductivity, cation exchange capacity; elemental composition, and bulk density) the composition of the SOM was characterized by solid-state nuclear magnetic resonance spectroscopy. The preliminary results of these analysis revealed only small differences between sites with low, medium, and high levels of bush encroachment. This suggests that the impact of bush encroachment on savannah’s SOM is lower than expected and may not be directly related to bush density. Further research will compare the obtained data with data obtained during the wet season to obtain a better understanding of the SOM dynamics and the impact of encroachment on soil degradation.

Acknowledgement: The authors would like to express their gratitude to the European Commission for the financial support of this research within the European Framework Program for Research and Innovation Horizon 2020 (Grant No. 101036401).

How to cite: García de Castro Barragán, J. M., Batisani, N., Pule-Meulenberg, F., Akanyang, L., de la Rosa Arranz, J. M., Reinoso Limones, M. R., and Knicker, H.: Relating bush encroachment density of savanna soils in the Kalahari district in Botswana to soil organic matter stocks and quality., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-588, https://doi.org/10.5194/egusphere-egu24-588, 2024.

Arbuscular mycorrhizal fungi (AMF) are indicators of soil health and are associated with various soil benefits, primarily linked to glomalin accumulation from hyphal turnover. However, the direct connection between glomalin-related soil protein (GRSP) and AMF has been questioned. In addition, conservation agriculture (CA) stands out as a pivotal plant production system that promotes agricultural sustainability and enhances soil quality.  In particular, the combination of minimal soil disturbance with residue retention has been linked with alterations in microbial biomass. The study aimed to explore the correlation between various fractions of GRSP and fatty acid fractions in the soil, along with examining the long-term impact of conservation agriculture practices on AMF biomass and GRSP content. Findings revealed a positive correlation between easily extractable (EE) GRSP and phospholipid fatty acid (PLFA) 16:1ω5, while no significant correlations were found for difficultly extractable (DE) or total GRSP fractions. These results highlight the complexity of GRSP dynamics and the need for further research on different fractions and their relation to AMF biomass. Additionally, the study demonstrated that mechanical soil management had a more significant impact on AMF hyphal biomass and EE-GRSP compared to residue management. Direct seeding, a reduced tillage approach, led to higher hyphal biomass and EE-GRSP, indicating AMF sensitivity to tillage intensity. This suggests that tillage practices exert a more substantial influence on AMF abundance and GRSP content than residue management.

How to cite: Thomopoulos, S., Elsgaard, L., Juhl Munkholm, L., and Ravnskov, S.: Evaluation of the relation between soil biomass of arbuscular mycorrhizal fungi and glomalin-related soil protein in conservation agriculture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8831, https://doi.org/10.5194/egusphere-egu24-8831, 2024.

Soil microbial community composition associated with novel rotation crops could contribute to increased yield to subsequent crops and an important factor influencing the composition of the rhizosphere microbiome. However, the effect of alternative dryland crops on soil microbial community composition is not clear in the northern Great Plains (NGP). The objective of this study therefore was to evaluate the effects of oilseed crops Ethiopian mustard (Brassica carinata A.) or camelina (Camelina sativa L.) or a 10-species forage/cover crop (CC) mix and fallow on soil microorganisms. A field study was conducted from 2014 to 2020 in the northern Great Plains, USA and was designed as a randomized complete block with three replications in a no-tillage system. Results showed that total bacterial proportion was significantly higher in camelina and fallow compared to CC and carinata. Total fungal proportion was significantly higher under CC mix compared to camelina and fallow. Fungal to bacterial ratio was significantly higher in CC and carinata compared to fallow. Fungi are often considered a good indicator of soil health while bacteria are crucial in soil functions. The changes in specific microbial communities due to crop-related alterations might play a key role in the yield of subsequent crop. Mechanisms responsible for these differences will be discussed.

How to cite: Dangi, S., Allen, B., Jabro, J., Rand, T., Campbell, J., and Calderon, R.: Effect of Alternative Dryland Crops on Soil Microbial Communities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14456, https://doi.org/10.5194/egusphere-egu24-14456, 2024.

Increased land use intensity, especially the transition from extensive to intensively managed agroecosystems, is frequently referred to as one of the primary causes of the decline in global biodiversity and is thought to be the primary force influencing soil biodiversity. For appropriate land management in the face of future land use change, it is essential to comprehend how soil biodiversity responds to various land use regimes. Still, there is a great deal of uncertainty regarding the consistent responses of various taxonomic groups to intensification of land use.

We systematically assessed and quantified through meta-analysis the effects of various forms of land use intensification on soil organisms in global agroecosystems (192 studies included, 3190 pairwise observations comparing intensified land use to undisturbed ecosystems across 59 countries) and analyzed the dependence of these effects on abiotic factors such as soil properties (organic matter, pH, nutrient and water availability, texture) and climatic zone.

We observed a substantial decline in springtails abundance (-34%) and species richness (-16%), while earthworms experience a positive abundance trend (+217%) but a reduction in species richness (-12%). Enchytraeids exhibit a negative impact on abundance (-32%) with no effect on species richness. Mites show a positive increase in abundance (+129%), but a significant reduction in species richness (-50%). Nematodes, on the other hand, experience a negative impact on abundance (-7%) with no effect on species richness.

Focusing specifically on earthworms, we observed varying effects depending on the specific forms of intensification employed. Positive impacts on earthworm abundance are observed with agroforestry (+60%), cover crops, low input cropping (+113%), managed grasslands (+52%), vegetable gardens (+52%), and pastures (+218%). Conversely, negative effects are noted in arable cropland (-24%), orchards (-35%), specialty crops (-61%), crop livestock integration (-13%), and managed forests (-95%). Furthermore, the analysis reveals that the intensification effects on earthworm abundance vary across different climatic zones, with significant impacts observed in zones A and C. Higher intensification effects are noted in areas with greater mean annual precipitation, higher soil pH, finer soil textures (clayey, loamy, and silty), and increased organic matter content.

This comprehensive exploration sheds light on the intricate dynamics between land-use intensification and soil fauna, providing valuable insights for sustainable land management practices tailored to different ecological contexts.

How to cite: Betancur Corredor, B., Zaitsev, A., and Russell, D.: Understanding the Complexity: A Meta-Analysis of the Impact of Land Use Intensification on Soil Fauna in Global Agroecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15886, https://doi.org/10.5194/egusphere-egu24-15886, 2024.

Sludge is an increasingly growing concern in Lebanon given the absence of proper treatment and disposal methods. As a solution, this two-years study proposes the valorization of sludge as an organic amendment on soil cultivated with rainfed wheat (Triticum icaversea) and itsimpact on soil properties, microbial activity, wheat yield and grain quality. Baseline characterization of sewage sludge collected from secondary treatment plant (SS) and tertiary treatment plant (TS) in Bekaa, Lebanon, showed that both sludge types can be classified as suitable for restricted agricultural use (Class B), which cannot be used on soils to grow fruits or vegetables that are eaten raw as per the Lebanese guidelines for sludge use. Post-harvest analysis of the amended soils revealed a significant enhancement in organic matter (OM), organic carbon (OC), soil moisture, wheat yield and grain quality in both seasons SS and TS amended soils compared to the control. All the tested heavy metals were much lower than the allowable limits for agricultural soils, except for zinc (Zn).  Wheat biomass and grain quality assessment revealed a significant increase of 30% in grain yield in both treated soils (SS: 74 g/m², TS: 81 g/m²) compared to the control (46 g/m²). Notably, TS treatment exhibited the highest protein content (14.5%) and ash (1.9%) in the first season, while both SS and TS treatments showed a significant increase in grain moisture in the second season. Soil microbial analysis were not consistent in the two seasons, but showed a potential risk of total coliforms contamination with SS application in the second season. This research provides valuable insights into the positive effects of sewage sludge application on soil fertility, microbial communities, and wheat grain quality. The findings emphasize the potential benefits of sewage sludge in sustainable agriculture, underscored by numerical improvements in various parameters. Although promising soil quality improvement and yield increase were observed in this study, further research is still needed to assess the potential soil microbial contamination and heavy metal accumulation over the long term.

How to cite: Abou Jaoude, L., H. Mohtar, R., Kamaleddine, F., Dbaibo, R., Bou Said, R., Keniar, I., and F. Yanni, S.: Using Treated Wastewater Sludge to Improve Soil and Growth characteristics of Rain-fed Wheat under Semi-Arid Conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22474, https://doi.org/10.5194/egusphere-egu24-22474, 2024.

[1] Atreya, M.; Desousa, S.; Kauzya, J.; Williams, E.; Hayes, A.; Dikshit, K.; Nielson, J.; Palmgren, A.; Khorchidian, S.; Liu, S.; Gopalakrishnan, A.; Bihar, E.; Bruns, C. J.; Bardgett, R.; Quinton, J. N.; Davies, J.; Neff, J. C.; Whiting, G. L. A Transient Printed Soil Decomposition Sensor Based on a Biopolymer Composite Conductor. Adv. Sci. 2022, 2205785, 1–10. https://doi.org/10.1002/advs.202205785.

How to cite: Atreya, M., Sharpe, T., Liu, S., Killick, R., Gong, M., Verhaalen, K., Gopalakrishnan, A., Smock, N., Sarralde, I., Bean, M., Davies, J., Quinton, J., Bardgett, R., Neff, J., Thomas, E., and Whiting, G.: Novel Soil Decomposition Sensor: Field Studies and Design Improvements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21191, https://doi.org/10.5194/egusphere-egu24-21191, 2024.