Increasing soil organic carbon (SOC) stocks in agricultural soils removes carbon dioxide from the atmosphere and contributes towards achieving carbon neutrality. For farmers, higher SOC levels have multiple benefits, including increased soil fertility and resilience against drought-related yield losses. However, increasing SOC levels requires agricultural management changes that are associated with costs. Private soil carbon certificates could compensate for these costs. In these schemes, farmers register their fields with commercial certificate providers who certify SOC increases. Certificates are then sold as voluntary emission offsets on the carbon market. In this paper, we assess the suitability of these certificates as an instrument for climate change mitigation. From a soils' perspective, we address processes of SOC enrichment, their potentials and limits, and options for cost-effective measurement and monitoring. From a farmers' perspective, we assess management options likely to increase SOC, and discuss their synergies and trade-offs with economic, environmental and social targets. From a governance perspective, we address requirements to guarantee additionality and permanence while preventing leakage effects. Furthermore, we address questions of legitimacy and accountability. While increasing SOC is a cornerstone for more sustainable cropping systems, private carbon certificates fall short of expectations for climate change mitigation as permanence of SOC sequestration cannot be guaranteed. Governance challenges include lack of long-term monitoring, problems to ensure additionality, problems to safeguard against leakage effects, and lack of long-term accountability if stored SOC is re-emitted. We conclude that soil-based private carbon certificates are unlikely to deliver the emission offset attributed to them and that their benefit for climate change mitigation is uncertain. Additional research is needed to develop standards for SOC change metrics and monitoring, and to better understand the impact of short term, non-permanent carbon removals on peaks in atmospheric greenhouse gas concentrations and on the probability of exceeding climatic tipping points.

Soil organic carbon (SOC) sequestration by improved agricultural practices is an acclaimed strategy to combat climate change. Nevertheless, the aim of increasing of SOC encounters limitations, e.g. with regards to permanence of carbon storage or leakage effects in food production. Agmforestry systems (AFS) are a promising land use option that is able to sequester substantial amounts of SOC while addressing these challenges. With a focus on temperate climate zones worldwide, available information on SOC in AFS was reviewed to determine their SOC sequestration potential and respective controlling factors. From a total of 61 observations, SOC sequestration rates in soils of AFS were derived for alley cropping systems (n = 25), hedgerows (n = 26) and silvopastoral systems (n = 10). The results showed that AFS have a potential for substantial SOC sequestration in temperate climates. SOC stocks were higher in the topsoil (0-20 cm) than in the control in more than 70% of the observations, and higher within the subsoil (20-40 cm) for 81% of all observations, albeit large variation in the data. The mean SOC sequestration rates were slightly higher at 0-20 cm (0.21 +/- 0.79 t ha(-1) yr(-1)) compared to 20-40 cm soil depth (0.15 +/- 0.26 t ha(-1) yr(-1)). Hedgerows revealed highest SOC sequestration rates in topsoils and subsoils (0.32 +/- 0.26 and 0.28 +/- 0.15 t ha(-1) yr(-1), respectively), followed by alley cropping systems (0.26 +/- 1.15 and 0.23 +/- 0.25 t ha(-1) yr(-1)) and silvopastoral systems showing a slight mean SOC loss (-0.17 +/- 0.50 and -0.03 +/- 0.26 t ha(-1) yr(-1)). Moreover, SOC sequestration rates tended to be higher for AFS with broadleaf tree species compared to coniferous species. We conclude that temperate AFS sequester significant amounts of SOC in topsoils and subsoils and represent one of the most promising agricultural measures for climate change mitigation and adaption.

Organic carbon sequestration is delineated from the different mechanisms underlying the storage of organic matter in mineral soils. The scene is set with definitions of the major terms within the complex of organic matter formation in soils, followed by describing the types of organic matter entering the soil and the major processes during turnover and the protective mechanisms leading to organic matter storage in soils. Detritusphere and rhizosphere are identified as soil compartments with high and specific organic matter input. From the process complex of OM degradation and binding, the potential of different soils for sequestering organic carbon is delineated and its limitations discussed with regard to the possibility of C saturation of mineral soils. In the light of these considerations, soil management options are deduced either by increasing organic carbon inputs to the soil by improved land use/management practices or by decreasing organic carbon outputs.

We developed an integrated model of soil processes – the Bodium – that enables us to predict possible changes in soil functions under varying agricultural management and climatic change. The model combines current knowledge on soil processes by integrating state-of-the-art modules on plant growth, root development, soil carbon and matter turnover with new concepts with respect to soil hydrology and soil structure dynamics. The model domain is at profile scale, with 1D nodes of variable thickness and weight. It is tested with long-term field experiments to ensure a consistent output of the combined modules. The model is site-specific and works with different soil types and climates (weather scenarios). The output can be interpreted towards a broad spectrum of soil functions. Plant production and nutrient balances can be determined directly. The same is possible for water dynamics, with potential surface runoff (as infiltration surplus), storage and percolation together with travel time and groundwater recharge. In addition, nitrate losses are calculated, and the travel time distribution can help with the evaluation of pesticide percolation risk. To evaluate the habitat for biological activity, the activity is calculated in terms of carbon turnover, and the state variables carbon availability, water, air and temperature for the are accessible. Also, for macrofauna the earthworm activity is included. The comparison of scenario runs can be evaluated quantitatively in terms of potential developments of soil functions. The model is work in progress. Further modules that will be implemented are pH dynamics, more explicit microbial activity, and a more complete set of effects of agricultural management on soil structure are integrated.

Soils on riverine floodplains in temperate climate may be characterized by a mollic epipedon, i.e. by dark colour, enhanced content of soil organic matter (SOM), high 'base' saturation and developed structure in the topsoil. We studied 124 soil samples from ten central/east European countries to investigate whether SOM in mollic horizons has similar chemical features. We determined carbon contents with a thermal-gradient method to differentiate SOM with varying thermal stability, and carbonates. We characterized SOM by diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy. According to the World Reference Base for Soil Resources, 102 of the samples fulfilled all criteria of a mollic horizon. Mollie features were not restricted to the uppermost horizon but also detected in buried former surface horizons. Soil colour was mostly the criterion to exclude non-mollic samples. Mollie and adjacent non-mollic horizons contained thermostable SOM, indicating SOM stabilized by interaction with minerals or as black carbon (BC), to very similar extent, up to 20.4% of total soil organic carbon (SOC). However, the correlation between the contents of thermostable SOC and total SOC, the SOC:N ratios of the thermostable fraction, and the smaller extent of metal complexation of carboxyl groups, pointed to a larger contribution of BC to SOM of mollic samples than to SOM in non-mollic samples. Thus, like in mollic horizons in Chernozems and Phaeozems not affected by fluviatile dynamics, SOM in mollic horizons of floodplain soils seemed to consist of SOM affected by natural or anthropogenic fires, constituting a common chemical feature of SOM. Thus, BC may contribute to soil colour and SOM stability in mollic horizons of floodplain soils. However, apart from BC contribution, SOM in mollic horizons of floodplain soils may have further pathways of formation and development, as SOM may be inherited from deposited material or form/transform by degradative or constructive processes.

While the change of soil functions under different management is important in the evaluation of long term strategies in agriculture, they are often difficult to be quantified. The obstacles are measurement problems on one hand, and on the other hand predictions for new management strategies and changing climate scenarios require estimates for yet unknown conditions. Comprehensive modeling of soil processes provides a road to both: Soil properties and processes that are per se difficult to measure can be included in a model to derive suitable indicators for soil unions. In this way, also, predicitons in the future for different climate scenarios and management strategies are possible. In this presentation we give definitions for a limited set of indicators to quantify the most important soil functions in terms of both the current soil state and the soils’ potential to fulfill these functions. This includes the production of biomass, storage of carbon, storage and filtering of ground water, nutrient cycling, and habitat for biodiversity. The quantitative evaluation of soil functions byel based indicators and their dynamics facilitates further socio-economic assessment and the development tools for governance.

The increasing demand for food and bio-energy gives need to optimize soil productivity, while securing other soil functions such as nutrient cycling and buffer capacity, carbon storage, biological activity, and water filter and storage. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soil with those functions, as well as the feedbacks between these functions. We developed a systemic soil model to simulate the impact of different management options and changing climate on the named soil functions by integrating them within a simplified system. The model operates on a 1d soil profile consisting of dynamic nodes, which may represent the different soil horizons, and integrates different processes including dynamic water distribution, soil organic matter turnover, crop growth, nitrogen cycling, and root growth. We present the main features of our model by simulating crop growth under various climatic scenarios on different soil types including management strategies affecting the soil structure. We show the relevance of soil structure for the main soil functions and discuss different model outcome variables as possible measures for these functions. Further, we discuss ongoing model extensions, especially regarding the integration of biological processes, and possible applications.

An increase of soil organic carbon (SOC) stocks in agricultural soils does not only have positive effects on soil quality and soil resilience but may also contribute to climate change mitigation. The '4 per 1000' (4p1000) initiative launched at the 2015 United Nations Climate Change Conference in Paris aims at increasing global SOC stocks in 0-40 cm depth by annually 4 parts per thousand in order to compensate the increase of anthropogenic CO2 emissions. In this study we analysed the feasibility of this target for agricultural soils in Bavaria, Southeast Germany. Assuming a total organic carbon (OC) amount of 276 Tg currently stored in the upper 40 cm of agricultural soils in Bavaria (cropland and grassland), the 4p1000 goal corresponds to an annual carbon (C) sequestration of 1.1 Tg. Based on a site-specific analysis of present soil management, we developed spatially explicit C sequestration scenarios including five promising management practices (cover cropping, improved crop rotation, organic farming, agroforestry and conversion of arable land to grassland). The results revealed that the 4p1000 target is not feasible for Bavaria. The total potential of the five practices to sequester C resulted in increases in 0.3 to 0.4 Tg OC per year corresponding to around l parts per thousand of the present SOC stocks. Expansion of cover crops and agroforestry were identified as most promising options to increase SOC in agricultural soils. Although only around 1.5% of Bavaria's yearly GHG emissions would be compensated, this represents an essential contribution to climate change mitigation. Besides the need to develop new incentive systems (particularly for agroforestry), implementation of networks including farms and/or field trials that demonstrate improved soil management practices would be required to inform farmers and other stakeholders about the benefits of such practices. To maintain a resilient agriculture that withstands more extreme weather conditions in the future, healthy soils are needed. We therefore conclude that expected positive effects of a SOC stock increase on nutrient and water storage, soil erosion, biodiversity and food security are crucial for climate change adaptation.

Agricultural soils are highly important organic carbon (OC) reservoirs in Central Europe. Their OC stocks are crucial for a wide range of ecosystem services such as food security or climate regulation through atmospheric CO2 storage. There is increasing evidence that the controlling factors of OC stocks may differ between topsoil and subsoil, but distinct knowledge about the factors at a regional scale for temperate soils is scarce. In order to identify the controlling factors of OC storage in agricultural soils we implemented a random forest model on a data set of 692 soil profiles located in Bavaria, Southeast Germany. We differentiated between topsoil (0-30 cm profile depth) and subsoil (30-100 cm) and predicted OC stocks (kg OC m(-2)) using 13 predictor variables including soil type, topographical factors, climatic factors and information on land use. The explained variance of the topsoil random forest was higher than that of the subsoil (51 and 23%, respectively). The fact that major proportions of the variance in the modelling of subsoil OC remained unexplained, revealed high uncertainties that persist about subsoil OC storage. OC storage of both, topsoils and subsoils, was to a large extend determined by four factors: land use history, soil type, major landform and topographic wetness index (TWI). Climatic factors as well as clay content had surprisingly low impact on the model. Topsoil OC was mainly controlled by the legacy of the land use resulting in highest stocks under permanent grassland use. In contrast, soil type and topographical factors, i.e. major landform and TWI, largely determined subsoil OC stocks. The topography indicates the lateral transport of OC due to soil erosion and its subsequent deposition in low lying landform positions. There, high soil moisture as indicated by the TWI, hampers the decomposition of the OC. Human activities such as tillage amplify the lateral OC transport and therefore the amount of buried OC. As a result of these processes, highest subsoil stocks were found in alluvial, colluvial and groundwater affected soils. The findings demonstrate the close link between the generic soil type, topography, land use and OC stocks. We further conclude that the legacy of human activities affect both, topsoil and subsoil OC storage.

The distribution of soil organic carbon (OC) in the landscape shows high variability between landform positions. Soils in depositional sites are characterized by a highly diverse vertical structure and can contain significant amounts of OC over the whole soil profile. However, anthropogenic modifications of the landscape such as land use and artificial drainage can significantly alter the OC balance in a catchment. Here, we analyse the spatial distribution of OC stocks along an agriculturally used catena in a catchment, tributary to the Danube River in the Bavarian Forest in Southern Germany. The combination of geomorphic aspects with highly detailed soil data based on 16 soil profiles along a catena allowed us to closely examine the relationship between soil OC and the factors of landform position, soil inherent properties and grassland vs. cropland land use. We determined bulk density, total carbon (TC) and inorganic carbon (IC) for each soil horizon in order to quantify OC stocks and picture the vertical OC distribution in the soils. Pedogenic oxides were analysed as an indicator for the redox conditions as well as the soil development. Furthermore, we analysed the clay fraction as well as poorly crystalline iron oxides (Feox) as potential binding agents for OC. The persistence of OC in the landform positions could be designated by the proportion of C-14 content of the bulk soil OC. Our data revealed that the amount of OC stored in the topsoil is mostly determined by land use, but subsoil OC stocks highly depend on landform position. Most OC of this catena is stored in the floodplain featuring particularly high amounts of OC in their subsoils. Radiocarbon signatures of the floodplain OC indicated a young C-14 age compared to the footslope subsoils. We assume that these high OC stocks were due to 1.) formerly high input of OC-rich sediments, 2.) preservation of this OC from decomposition due to high water saturation and 3.) current land use (grassland). Dropping of the ground water table due to artificial drainage measures left detectable footprints within a few decades in the depth distribution of pedogenic iron oxides and indicated currently dominant oxic conditions within the uppermost 100 cm of the floodplain soils. We suspect that under these conditions the OC stocks are now vulnerable to OC losses. Even though we found no correlation between Feox and OC, it can be assumed that the interplay between Feox and OC will play a key role for the stabilization of the floodplain OC in the future. Today most floodplains in Central Europe are not in their natural state, but drained and under agricultural land use. Therefore this work points to the necessity of monitoring the OC pools in these landform positions and to consider quick responses when it comes to changes in the hydrologic regime and/or land-use system.

Floodplain soils are important reservoirs of organic carbon (OC) in the terrestrial carbon cycle. Few rivers and floodplains in the world and particularly in central Europe are in a natural state. They are regulated, stabilised from erosion behind artificial levees, drained and used for agriculture. Fluvisols store high amounts of OC from the topsoil to the subsoil, but little is known about the soil organic matter (SOM) quality and its vulnerability to decomposition. In this study, two regulated floodplains originating from different parent materials under grassland use in Southern Germany (Alpine Foreland and the Bavarian Forest) were sampled and analysed for the quantity and quality of inherent SOM in the topsoil and two subsoil levels. We characterised bulk soil (pH, texture, inorganic carbon and total nitrogen) and applied a combined density and size fractionation scheme to obtain six fractions. The chemical composition of the fractions was further determined using solid-state 13C NMR spectroscopy (SOM composition), as well as X-ray diffraction (clay mineralogy) and N2-BET (specific surface area (SSA)). Contributions of light fractions and especially of occluded particulate organic matter (oPOMfine) to the total OC were remarkably high in the subsoils. Organo-mineral associations (OMFfine) highly contributed to total OC at both sites but only in the topsoils. The highest OC concentrations of OMFfine were found in calcareous parent material, which shows that polyvalent cations promote OC storage. However, the inter-site as well as intra-site heterogeneity of oPOMfine and OMFfine OC contribution was highly variable. In the Bavarian Forest, oPOMfine was enriched in lipids in the subsoil. This was most probably due to a limited supply of oxygen in the aggregates through fluctuating groundwater levels that retarded decomposition and selectively preserved aliphatic compounds. In the Alpine Foreland, soil biota had mixed fresh SOM into the subsoil. There, oPOMfine contained all the functional C-groups, particularly carbohydrates. A changing global climate jeopardises OC reservoirs in floodplains, due to increased flooding and associated river bank erosion. Such disturbances not only cause losses of productive land but also release OC stored in light fractions that could be oxidised to CO2, depending on its chemical composition, thus adding to global warming.

Background: In flat-rate reimbursement systems, the hospital's own costs should not exceed its revenues. In a cohort of primary breast cancer (pBC) patients, costs and reimbursement for febrile neutropenia (FN) were compared to verify cost coverage. Methods: A prospective, observational study in pBC patients receiving adjuvant anthracycline +/- taxane-based chemotherapy calculated the costs per in-patient FN episode. The correlating revenues were retrospectively analyzed from diagnosis-related group (DRG) invoices. The actual costs of the therapies were compared to the individual DRG revenues, and the results are presented from the provider's perspective. Results: In 50 patients, n = 11 patients were treated for FN as in-patients. The hospital's overall treatment costs were (sic) 18,288, on average ((empty set)) (sic) 1663 per case (range (sic) 1139-2344); the overall DRG revenues were (sic) 23,593,(empty set)(sic) 2145 per case (range (sic) 1266-2660). In n = 8 cases, the DRGs were cost covering, and in n = 3 cases, a loss was observed, but overall resulting in a gain of(empty set)(sic) 482 per case and thus being cost covering for the provider. Inadequate DRG coding (n = 4/11; 36.4%) resulted in a preventable loss of(empty set)(sic) 1069/case. Conclusions: The costs of FN treatment vary substantially and DRG reimbursements do not necessarily reflect the provider's costs. Surprisingly, the in-patient treatment of FN here is overall more than cost covering if adequately coded. The main reasons are asymmetrical costs for this FN low-risk pBC group. These results emphasize the importance of correct medical coding to avoid potential losses.