With rising population growth, there is a need for increased food production. With rising temperatures and more frequent droughts due to climate change, it becomes more challenging to keep up with this increased demand for food. Therefore, a change in land use and management is needed in which enhanced silicate weathering (ESW) can play an important role. Weathering of silicate rocks has been regulating the atmospheric CO2 concentrations for over decades, but with the rise in atmospheric CO2, the natural weathering is too slow. Grinding the silicate rocks into a fine powder and spread it over for example agricultural fields will increase the reactive surface area and hence, the amount of CO2 that is stored in soils. The application of silicate minerals to soils can enhance plant growth by multiple processes, for example by counteracting soil acidification and by the release of plant nutrients. In this way, ESW can be used on agricultural fields without competing for land like other carbon capture techniques (e.g. Bio-Energy with carbon capture and storage). This study investigates the use of olivine (a fast-weathering Mg-rich silicate mineral) as a fertilizer in agriculture using a full-factorial mesocosm experiment. Barley and wheat were grown under two different rain regimes (daily rain vs weekly rain) and with application of two different grain sizes of olivine (p₈₀ = 1020 µm and p₈₀ = 43.5 µm). Our results showed increased plant growth and biomass with olivine addition, albeit only for fine olivine. However, this was not translated in an increase in yield of wheat and barley. Besides changes in biomass, we found significant differences in plant nutrient concentrations. As expected, Mg concentration increased significantly. However, BSi and Ca concentrations decreased with fine olivine application. Nitrogen in grains was also increased in the fine olivine treatment. In contrast to fine olivine, coarse olivine addition had almost no influence on nutrients. Ca, Mg and Si concentrations in plant samples followed the same trend as in the soil pore water, in contrast to metal concentrations. Olivine addition increased Ni and Cr availability in the soil pore water, but the concentrations of these elements in plant tissue did not increase and were even below detection limit for the majority of samples. While the influence of olivine on metal concentrations in plant samples was not affected by rain treatment, the influence of olivine on nutrients in the plants and plant growth was. Fine olivine addition enhanced the plants resistance to drought as it reduced the decrease in biomass with weekly rain treatment compared to daily rain treatment. This positive effect of olivine addition can be due to the increased weathering rate in combination with enhancement of soil properties like increased soil water retention. In this way, the use of olivine as a fertilizer on agricultural fields can mitigate climate change while it can also contribute to the solution for increased food demand.

How to cite: Rijnders, J., Vicca, S., Struyf, E., Amann, T., Hartmann, J., Meire, P., Janssens, I., and Schoelynck, J.: The effects of olivine fertilization on growth and elemental composition of barley and wheat differ with olivine grain size and rain regimes., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15333, https://doi.org/10.5194/egusphere-egu23-15333, 2023.

Wildfires consist in an environmental problem with a global dimension, but also with future demands as fire prone regions will likely increase, driven by new climate constrains but also socioeconomic drivers. Similarly to other land degradation pressures, despite the large scale of its occurrence, wildfires impacts require assessment and mitigation actions at local scale. Therefore, there is an urgent need to identify local agent’s perspectives regarding wildfires impacts in the ecosystems, and incorporate their local knowledge into post-fire land management decision making. Can a local analysis contribute to political decision-making, streamlining and simplifying processes established at national level?

In an attempt to assess the local perception that technical forest managers have on soil erosion after wildfire, an investigation was conducted, having the central region of Portugal as case study. In this project, we assessed the relevance that technical forest managers give to post-fire soil erosion, by identifying the priority of their activities, established procedures, and their perception of present and future risk following wildfires. Thus, a survey was structured and provided to 108 entities (100 municipalities and 8 inter-municipal communities), being active for reply between 14 September and 14 October 2022. The survey was structured in three main sections: i) general characterization of the entity, ii) description of its global relationship with forest land management and actions after wildfire, and iii) identification of procedures and technical tools used for post-fire land management.

From the 108 requests, 78 answers were obtained, and 52 were considered valid for analysis. The results identified a general concern with soil erosion after wildfire. However, the focus of individual local concerns with wildfires impacts is mostly targeted to loss of biodiversity, the abandonment and degradation of affected areas, followed only then by the soil losses by erosion. Respondents also identified that they have implemented, or are aware of the implementation, of erosion mitigation measures in their actuation area, being these measures mainly represented by the construction of organic barriers and interventions in water bodies, for soil stabilization and overflow redirection. Technical tools are generally used for forest management planning, but not with the main intention to control soil erosion neither to promote its rehabilitation. Respondents also refer that an open source, and updated, technical tools on this scope would allow them to design an emergency strategy on time. This would also enable the support of the local decision-making process, and contribute to a standardized and streamlined response from diverse municipalities affected by the same wildfire.

According to the results obtained, two main strategies can be inferred in order to promote the local conservation of forest soils after an wildfire: i) local empowerment to act and contribute with technical support to private local forest owners and managers, and ii) the reinforce of the awareness-raising process, by adapting campaigns (information/language) to the different, affected and interested, stakeholders.

How to cite: R. Lopes, A., Valente, S., Keizer, J., and Vieira, D.: Local assessment of technical forestry awareness on soil erosion after wildfire – the case study of Central Portugal region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-277, https://doi.org/10.5194/egusphere-egu23-277, 2023.

A szén-elnyelő erdők és talajok előtérbe kerülnek a szénsemlegesség mielőbbi elérése érdekében. A folyamatosan növekvő kibocsátás felborítja a légkör egyensúlyát, és a folyamatok eltolódásával klímaváltozásban vagy időjárási szélsőségekben nyilvánul meg. Kutatásunk célja az erdei ökoszisztémákban különböző éghajlati és erdészeti viszonyok között tárolt szerves széntartalom felmérése volt. A talajelemzésre helyeztük a hangsúlyt, mert a talaj szén mennyisége közel azonos a föld feletti biomasszában tárolt szén mennyiségével. Mintegy 40 kijelölt erdőállományból vettünk mintát, hogy meghatározzuk az egyes erdőállományok talajában tárolt szerves szén mennyiségét. A talajmintákat 40 cm mélységű fúrással gyűjtöttük. A talajmintavétellel egyidejűleg a mintavételi pont közelében lévő egyes állományok élőfaállományát is felmértük. A 40 kijelölt erdőállományban eddig végzett vizsgálatok alapján a területek Cambisols, Luvisols és Arenosols talajosztályokba sorolhatók (WRB 2020). A talajminták pH-értéke többnyire savas (átlag = 5,9), az állaga vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek. 9) és a textúra vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek. 9) és a textúra vályogként határozható meg. A 0-40 cm-es termőtalajok talaj szervesanyag-tartalma (SOM) 1,45%, ami ~14 t széntartalmat jelent hektáronként. A környéken még mindig van elegendő csapadék a növényzethez zavartalanul; így a szénmérleg a térségben jelenleg stabil annak ellenére, hogy az alommennyiség csökkenése miatt a készletek már most is csökkennek.

Ez a cikk a TKP2021-NKTA-43 projekt keretében készült, amely a Magyar Innovációs és Technológiai Minisztérium (jogutód: Kulturális és Innovációs Minisztérium) a Nemzeti Kutatási, Fejlesztési és Innovációs Minisztérium támogatásával valósult meg. Alap, a TKP2021-NKTA támogatási konstrukció keretében finanszírozott. A Kulturális és Innovációs Minisztérium ÚNKP-22-3-I-SOE-99 Új Nemzeti Kiválósági Programja pedig a Nemzeti Kutatási, Fejlesztési és Innovációs Alapból támogatott.

How to cite: Végh, P., Balázs, P., Bidló, A., and Horváth, A.: Investigation of soil carbon sequestration and storage in Hungarian forest sites under different climatic conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14111, https://doi.org/10.5194/egusphere-egu23-14111, 2023.

Archaeological anthrosols constitute a heritage of long-term carbon storage and soil fertility. Their anthropogenic features are affected by the type and intensity of ancient human activities. Human activities can follow a gradation of disturbance intensity, with lower intensity related to a weak human pollution of natural soil, and stronger intensity related to anthropogenic materials inputs (e.g. refuse pits). Soil properties are indeed deeply modified by the addition of objects (e.g. bones, ceramic) and of organic matter with distinct chemical composition and biological stability (e.g. charcoal). The aim of the study was to establish a new analytical approach to distinguish intensities of human activities, based on organic matter characteristics. To this end, we studied intertropical soil profiles (0-120 cm) from Cameroon, Brazil and Bolivia, with spatial or temporal intensity variations of human activities. We used standard compositional parameters (hydrogen index, HI, and oxygen index, OI) and advanced thermal parameters (I-index and R-index) from Rock-Eval^® pyrolysis, as well as magnetic susceptibility, to characterize anthrosols.

Results demonstrated the potential of Rock-Eval^® pyrolysis parameters to identify human activities changes. First, the deviation of I-index (delta-I) between our samples and a reference value from natural sites informed about the intensity of human impacts, allowing for the distinction between artificial infilling of refuse pits and soil profiles with no or few human impacts. Second, positive HI:OI correlation established the importance of charcoal as main organic C source. The magnetic susceptibility informed about the presence of burnt soils in a Brazilian and one of the Bolivian sites. The combination of all these parameters, when represented with soil depth, allowed for the estimation of temporal changes in Brazilian and Bolivian sites. The topsoils were similar for all sites, relative to a low intensity of human activities or to the resumption of natural pedogenesis, thereby alleviating the effects of ancient human activities on organic matter characteristics. In contrast, the subsoils exhibited higher intensities of ancient human activities, with even higher values of intensities in Bolivian sites, thereby evidencing the long-term conservation of their effects on organic matter characteristics.

To conclude, anthropogenic activities may durably affect organic matter characteristics in tropical sites, even after several centuries. Beyond being of interest for archaeological research, this new approach raises questions about the long-term consequences of our current human activities.

How to cite: Aubertin, M.-L., Malou, O. P., Arroyo-Kalin, M., Lombardo, U., Chevallier, T., Oliva, P., Delarue, F., Thiesson, J., Quenea, K., Sebag, D., and de Saulieu, G.: New approach to evaluate the intensity of ancient human activities, based on organic matter characteristics using Rock-Eval® thermal analysis., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3504, https://doi.org/10.5194/egusphere-egu23-3504, 2023.

Mediterranean mountains have been affected by an intense process of cropland abandonment since the middle of the last century, as a result of the rural exodus. This has led to the activation of natural revegetation processes in marginal areas that have not been managed. Literature has recorded different soil responses to secondary succession depending on factors such as climate, altitude, soil depth and type, but still very little is known about the influence of soil pH. Thus, the main objective of this work is to identify how soil quality and carbon sequestration are affected by secondary succession after abandonment for two types of soil lithologies (acidic and alkaline). For this purpose, the Leza Valley (La Rioja, Spain) was selected as the representative study area. Soil samples were collected for each lithology, at different depths (0-40 cm), for 5 stages of succession (cropland (CRL); shrubland (SH); bushland (BS); young forest (YF); and old forest (OF)), and their physicochemical properties were analysed in the laboratory. Data analysis was carried out and these are the most relevant results: i) there are significant differences between acidic and alkaline organic carbon stocks; ii) the alkaline soils increase their SOC stock with the advance of succession, and significant differences were observed between the first stages of abandonment and BS, YF and OF; iii) while in the acidic soils no significant differences were observed, and the highest values were recorded in YF; iv) these results may be the combination of interactions between pH, soil properties and plant and microbiological communities that establish in these areas. Our work has shown the relevance of considering the lithology of our soils in order to determine which post-abandonment management practices may be the most appropriate for our study area. Therefore, it is necessary that policies and management strategies include this type of analysis to achieve the best results of soil carbon sequestration.

Acknowledgement: This research project was supported by the MANMOUNT (PID2019-105983RB-100/AEI/ 10.13039/501100011033) project funded by the MICINN-FEDER. Melani Cortijos-López is working with an FPI contract (PRE2020-094509) from the Spanish Ministry of Economy and Competitiveness associated to the MANMOUNT project

Keywords: abandoned croplands, natural revegetation, carbon sequestration, soil pH, Iberian System (Spain)

How to cite: Cortijos-López, M., Sánchez-Navarrete, P., Lasanta, T., and Nadal-Romero, E.: How acidic or alkaline soils affect SOC stock in a post-abandonment secondary succession process: a case study in th Mediterranean mid-mountains., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1570, https://doi.org/10.5194/egusphere-egu23-1570, 2023.

Soils constitute a carbon reservoir that can help to mitigate climate change, or conversely accelerate greenhouse gas emissions if not managed properly. Soils are heterogenous and dynamic systems, which physico-chemical properties impact their current soil organic carbon (SOC) stocks and their capacity to store more carbon. Land-use planning aiming to preserve and increase SOC stocks should therefore be aware of the spatial repartition of various soil types and of the SOC dynamics therein.

This project aims to map the effect of soil typology on the spatial and vertical repartition of soil carbon stocks, additional storage potential and storage dynamics at a regional scale to improve guidance of SOC storage strategies. The study site is a 320 km² temperate rural region in NE France. Eight dominant soil types are defined, notably Calcaric cambisols in the agricultural valleys, deep silty and acidic soils in the forested plateaus, shallow rocky calcaric soils on the hillslopes, and deep clay-rich hydromorphic soils in the alluvial valleys.  

Based on logarithmic fits of soil carbon data extracted from 197 full-depth soil profiles, mean soil organic carbon stocks are obtained as a function of depth for each represented soil type and land cover. The additional storage potential corresponds to the difference between the current stock and the maximum stock, as estimated by the fit of the upper 25% of the soil carbon content data.  Finally, a depth-dependent SOC dynamic model using multilayer soil modules is used to simulate SOC stock evolution. Results are mapped by combining the spatial information given by a pedological map and a map of land covers.

Median soil carbon stocks over the full soil profile range from 78 to 333 tC ha^-1, of which 59 to 148 tC ha^-1 are in the topsoil (0-30 cm). The lower stocks are found in the shallow, rocky cultivated soils, and the highest stocks in the gleysols under grasslands. The additional storage potential varies from 19 tC ha^-1 for shallow, rocky forest soils to 197 tC ha^-1 for cultivated gleysols. SOC build-up is heterogenous and depends on the mean residence time of carbon in the represented soil types.

Maps of carbon stocks show the areas to preserve to avoid C losses, and maps of additional storage capacity for different time horizons show areas in which to implement carbon storage practices. Going forward, the association of carbon stock mapping and modelling should allow us to estimate at which depths and over which timescales.

How to cite: Derrien, D., Chirol, C., Saint-André, L., and Séré, G.: Mapping spatial and vertical repartitions of soil carbon stocks, additional storage potential and storage dynamics at the regional scale, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11518, https://doi.org/10.5194/egusphere-egu23-11518, 2023.

The main hurdle in instrumentalizing agricultural soils to sequester atmospheric carbon is a development of methods to measure soil carbon stocks on farm level which are robust, scalable and widely applicable. Specifically, it is necessary that socio-economic barriers related to cost, usability and accessibility are overcome. We present the Wageningen Soil Carbon Stock pRotocol (SoilCASTOR), a method for soil carbon stock assessment using satellite data, direct soil measurements via mobile soil sensors and machine learning which can help overcome these socio-economic hurdles. The method has a low cost per hectare and uses plug-and play tools (soil scanner), which lower the threshold users need to overcome. The method has been tested and applied for multiple farms in Europe and the United states on agricultural fields with variable crop rotations, soil types and management history. Results show that the estimates are precise, repeatable and that the approach is rapidly scalable. Carbon stocks in the top 30 cm range between 1.8-6.1 kg C/hectare and resolution is up to 10x 10 meters. The precision of farm C stocks is below 5% enabling detection of SOC changes desired for the 4 per 1000 initiative. The assessment can be done robustly with as few as 0.5 samples (or 2-3 minutes) per hectare over a range of scales, for farms varying from 20 to 200 hectares.These findings can enable the structural and widespread implementation of carbon farming. This approach has recently been awareded the Bayer Grants4Tech innovation prize.

How to cite: Verweij, S., van Doort, M., Fuijta, Y., van der Voort, T., and Ros, G.: Enabling carbon farming: a robust, affordable and scalable approach leveraging remote and proximal sensing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13552, https://doi.org/10.5194/egusphere-egu23-13552, 2023.

Cropland soils show large potential to sequester carbon to achieve climate neutrality. Changes in management can affect an increase of carbon sequestration or reducing carbon losses in form of emissions or leaching. However, the impact of management changes on the sequestration and other processes needs to be quantified to provide advice to farmers. Experiments to analyse impacts of management changes are costly and labour intensive. Additionally, these experiments take time and cover only a small range of environmental conditions. Therefore, modelling is widely used to over-come these limitations. Model results allow the estimation of all relevant fluxes for the overall greenhouse gas emission balance or, depending on the model, for some parts. This is a fast and efficient method to quantify soil organic carbon (SOC) changes due to modifications in agricultural management. Even though, models proved their quality of simulating SOC changes, there are some restrictions in the use of models for actual advice based on model results. In the here presented study, three key points will be analysed: First, the additional impacts beside the SOC changes. Carbon sequestration can be offset by emission of other greenhouse gases or management changes affect yield, which needs to be included in the analysis. While these two variables are well covered by usual model approaches, other aspects like food quality are more difficult to include. Second, how does the complexity of the model affect the result. The simple assumption that more complex models are potentially more accurate, but also require more input data is in most cases realistic (this is a generic assumption which is not always true). More input data and more complexity are also associated with potentially increased uncertainty. Third, who is running the model. While research-based advice using more complex models might be potentially more accurate, models used by farmers might be more specific and direct in providing key information. Additionally, the impact of the increased data demand and required data can affect an increased error. These points are analysed on examples and case studies. This includes an analysis beyond the carbon sequestration and how to include these aspects in the analysis. Further, results of a tool developed for stakeholders/farmers is compared with results of a biogeochemical model for selected sites. Finally, an analysis of the limitations of the models due to data demand and data availability. The analysis of wheat yields shows mainly positive impacts on the SOC change, but mainly reduced yield. The comparison of the two models indicates the impracticability of the more complex option, as the data demand is not orientated on the data availability. The decision based on model results requires a careful use of models and a good understanding of the results.

How to cite: Kuhnert, M.: Using modelling and tools for advice on improved agricultural management to achieve climate neutrality in croplands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14833, https://doi.org/10.5194/egusphere-egu23-14833, 2023.

Climate change and agricultural intensification are placing enormous pressure on soil to provide essential services, from water storage and nutrient provision to carbon sequestration. Indeed, storing carbon in agricultural systems is proposed as an effective climate mitigation approach. Yet, storing carbon comes often at a cost in terms of water consumed—water used either to increase productivity and carbon inputs to soil, or to create conditions in the soil that promote carbon storage. These linkages are perhaps most evident in rice paddy systems.

Rice – a staple food for 3 billion people – consumes more water than any other crop, leading to unsustainable water withdrawals. However, this large water consumption allows paddy soils to store more carbon than under other land uses, because flooding of the fields keeps soils saturated and inhibits organic matter decomposition. Therefore, changing water saving approaches such as alternate wetting and drying has the potential to reduce carbon storage and alter the provision of other ecosystem services. But how much can soil organic carbon change across land uses and when water management is altered?

In this contribution, we discuss the mechanisms of carbon storage in paddy fields, using data from a meta-analysis of soil carbon budgets in tropical rice paddies and from a detailed investigation of carbon storage along a gradient of a land use and soil age in a temperate rice system. The meta-analysis shows that, as expected, reducing the time of flooding decreases soil organic carbon, but also results in a net decrease of greenhouse gas emissions. The more detailed study shows that in temperate conditions with relative short flooding time, rice paddies can store as much organic carbon as forest sites, despite the higher carbon inputs of forests compared to rice systems. This higher carbon storage is achieved thanks to decreased soil respiration in anaerobic conditions and increased mineral associations of organic carbon. These results show that water management strongly affects soil carbon storage, and that trade-offs emerge between sustainable water use and long-term provision of soil-related ecosystem services.

How to cite: Schwarz, E., Johansson, A., Lerda, C., Livsey, J., Scaini, A., Said-Pullicino, D., and Manzoni, S.: Trading water for carbon in agricultural systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8708, https://doi.org/10.5194/egusphere-egu23-8708, 2023.

Soils are often underestimated and overlooked in reviewing national economic structures. Soils and groundwater are the essential basics for food production. Beyond securing nourishment, quantity and quality of soils are pivotal factors in farming, forestry and further land use. The potential of soils governs the availability and variety of its products for national food security and trading. In most industrial European countries, farming has only a share of about 1% of the national gross domestic product but secures vital needs. In the Sub-Saharan region, the same share varies between 16% and 20%, largely depending on regional weather, water availabilty and soil quality. The largest threats are climate change and depletion of soils. Whereas European countries aim for steadily increasing sustainability, countries in Southern Africa are often struggling between short term profits, preservation of soils and necessary climate adaptions. The study sheds some light on the different roles of soils in European and Southern African economies, their inter-dependencies, the necessity to map quantities and qualities of soils for managemant measures and growing needs with a still fastly rising population in Southern-Africa. 

How to cite: Meyer, U.: Soils and Economy - Snapshots on Europe and Southern Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6715, https://doi.org/10.5194/egusphere-egu23-6715, 2023.