Publications

Abstract. Agricultural soils, having been depleted of much of their native carbon stocks, have a significant CO 2 sink capacity. Global estimates of this sink capacity are in the order of 20‐30 Pg C over the next 50‐100 years. Management practices to build up soil C must increase the input of organic matter to soil and/or decrease soil organic matter decomposition rates. The most appropriate management practices to increase soil C vary regionally, dependent on both environmental and socioeconomic factors. In temperate regions, key strategies involve increasing cropping frequency and reducing bare fallow, increasing the use of perennial forages (including N‐fixing species) in crop rotations, retaining crop residues and reducing or eliminating tillage (i.e. no‐till). In North America and Europe, conversion of marginal arable land to permanent perennial vegetation, to protect fragile soils and landscapes and/or reduce agricultural surpluses, provides additional opportunities for C sequestration. In the tropics, increasing C inputs to soil through improving the fertility and productivity of cropland and pastures is essential. In extensive systems with vegetated fallow periods (e.g. shifting cultivation), planted fallows and cover crops can increase C levels over the cropping cycle. Use of no‐till, green manures and agroforestry are other beneficial practices. Overall, improving the productivity and sustainability of existing agricultural lands is crucial to help reduce the rate of new land clearing, from which large amounts of CO 2 from biomass and soil are emitted to the atmosphere. Some regional analyses of soil C sequestration and sequestration potential have been performed, mainly for temperate industrialized countries. More are needed, especially for the tropics, to capture region‐specific interactions between climate, soil and management resources that are lost in global level assessments. By itself, C sequestration in agricultural soils can make only modest contributions (e.g. 3‐6% of total fossil C emissions) to mitigating greenhouse gas emissions. However, effective mitigation policies will not be based on any single ‘magic bullet’ solutions, but rather on many modest reductions which are economically efficient and which confer additional benefits to society. In this context, soil C sequestration is a significant mitigation option. Additional advantages of pursuing strategies to increase soil C are the added benefits of improved soil quality for improving agricultural productivity and sustainability.

<p>The time for action on the Paris Agreement is upon us, requiring all signatory countries to have a robust reporting and accounting system that is transparent, accurate, complete, consistent and comparable (through the Enhanced Transparency Framework), with a periodical review of the collective achievement of the 2°C temperature goal (the Global Stocktake). The research community is therefore called to reinforce databases and methodologies to improve national greenhouse gas inventory estimates, especially for developing countries that are subject to new reporting obligations, but also to define a comparable scientific “benchmark" to assess the achievement of the Paris Agreement goal.</p><p>Despite the key role of science in the process, often research communities working on emission statistics have approached the problem of climate change through different angles and by using terminologies, metrics, rules and approaches (e.g. spatial and temporal scales) that do not always match with those used by the inventory communities. Within the VERIFY project (Horizon 2020, grant agreement No 776810) a networking between the two communities (research and inventory) has been established. The discussion between them highlighted the importance of a continue exchange to increase the mutual understanding of needs, terms, rules, procedures and guidelines in use, especially those adopted under the UNFCCC and Paris Agreement process.</p><p>The presentation will therefore guide the researchers through the monitoring, reporting and verification frameworks under the UNFCCC and Paris Agreement, identifying how and where science production can assist the inventory communities in improving greenhouse gasses estimations and verification systems. Land Use, Land-Use Change and Forestry is the most complicate sector to deal with because of intricacy of flux attribution (that can be both anthropogenic and non-anthropogenic) and methodological complexity, affected also by common misunderstandings in the use of terminologies and different definitions. </p><p>On the basis of the available literature and the outcomes of the work undertaken under VERIFY project, we provide an analysis on the possible critical issues and main misunderstanding that could arise, identifying options on how to solve them.</p>

China contributes the largest share of cropland’s greenhouse gas (GHG) emissions globally. Processed-based biogeochemical models are useful tools to simulate GHG emissions from cropping systems. However, model comparisons are necessary to provide information for the application of models under different climate, soil, and crop conditions. In this study, two widely-used models (DayCent and DNDC) were evaluated and compared under four main cropping systems in China. The field observations from nine experiments were used for model calibration and validation.  The DayCent and DNDC models simulated daily and seasonal CH4 emissions from early rice-late rice and rice-wheat cropping systems reasonably well (r2≥0.49 for daily simulation and nRMSE≤52.9% for seasonal simulation). Both models were able to satisfactorily predict seasonal N2O emissions from maize-wheat fields (0.6≤d≤0.8), but overestimated most daily N2O fluxes at fertilisation and irrigation events. Significantly positive relationships were found between simulated and observed cumulative N2O fluxes in spring maize growing season (0.61≤ r2≤0.85). The DNDC showed smaller differences in simulated and observed cumulative GHG emissions for spring maize and double rice, while DayCent showed better performance on estimating N2O and CH4 for maize-wheat and rice-wheat. This study shows that both models have strengths and weaknesses under a variety of cropping systems and growing regions, which are important to consider when choosing a model for a crop/region-specific simulation.

Soil health is a key concept in worldwide efforts to reverse soil degradation, but to be used as a tool to improve soils, it must be definable at a policy level and quantifiable in some way. Soil indicators can be used to define soil health and quantify the degree to which soils fulfil expected functions. Indicators are assessed using target and/or threshold values, which define achievable levels of the indicators or associated soil functions. However, defining robust targets and thresholds is not a trivial task, as they should account for differences in soil type, climate, land-use, management, and history, among other factors.We assessed (through theory and stakeholder feedback) four approaches to setting targets and thresholds: fixed values based on research, fixed proportions of natural reference values, values based on the existing range (e.g. lower quartile of the observed distribution), and targets based on relative change (e.g. a 20% increase of the indicator’s value). Three approaches (not including relative change) were then further explored using case study examples from Denmark, Italy, and France, which highlighted key strengths and weaknesses of each approach. Here, we present a selection of the assessment and case study results, as well as a framework, which facilitates both choosing the most appropriate target/threshold method for a given context, and using targets/thresholds to trigger follow-up actions to promote soil health.  

Abstract Topsoil samples from a long‐term fertilizer trial on a red earth rice paddy from Jiangxi Province, China, were used to investigate soil organic carbon (SOC) mineralization using aerobic incubation for 58 days at 20 °C and 25 °C. SOC mineralization rates varied between 0.62 and 0.76 mg C/g SOC/h at 20 °C, and between 0.65 and 0.97 mg C/g SOC/h at 25 °C. There was no significant correlation between the mineralization potential and SOC content in treated soil samples. However, a close correlation was found between total C mineralization and the carbon stability index. This suggests that the potential C release from the soil is controlled by C lability rather than by total SOC. The calculated Q 10 quotient was negatively correlated with dithionate‐citrate‐bicarbonate‐extracted Fe. It is suggested that the free Fe‐oxyhydrates that are prevalent in red earth paddy soils provide physico‐chemical protection and control biological decomposition rates under warming and these are modified in the long‐term fertilizer treatments. The enhancement of physico‐chemical protection of labile SOC by free Fe‐oxyhydrates is a potential mechanism for soil C stabilization under warming conditions. The interaction with fertilizers in the red earth‐derived paddies of South China deserves further study.

<p>The UNISECO project aims to provide recommendations on how the sustainability of agro-ecological farming systems (AEFS) in Europe can be promoted. In this deliverable D4.3, the results from a large-scale implementation of various agro-ecological approaches, from single practices such as undersowing in cereals to more systemic approaches, such as agroforestry, and to a full agro-ecological transformation of the agri-food system are presented. Based on the case-study results from WP3, various bundles of agro-ecological innovations have been identified in a multi-step stakeholder process. Suggested practices and approaches ranged from plot and farm-level to whole food-system level and a selection of those was then chosen for implementation in the two biophysical mass-flow models BioBaM_GHG_EU and SOLm. In BioBaM_GHG_EU, an option space of 432 options was built by combining several variants of a) more or less mixed-farming approaches integrating crop and livestock production; b) livestock diets (fully grass-based ruminant production); c) manure management (conventional, biogas digesters, etc.); d) hedges and undersowing on croplands; e) grassland use in a land sharing or land sparing variant with vegetation regrowth; d) reduced grassland use intensity in high nature value farmland. In SOLm, a detailed implementation of agroforestry systems was implemented, based on parameters from state-of-the-art literature, such as the different crops and trees varieties used and their respective shares per hectare agroforestry, the yield potential of agroforestry, and the performance regarding a number of environmental indicators (e.g. water use, NH3 emissions, C-sequestration). In all these scenarios and options, a number of environmental and socio-economic indicators was assessed, such as land use, GHG emissions, nutrient surplus, etc. or food supply and calorie and protein provision self-sufficiency.</p> <p>Key results show that many agroecological futures are possible in the EU without compromising food security and with improvements along a number of sustainability indicators if embedded within wider food-systems changes. Sustainable agro-ecological production cannot be addressed without addressing consumption. Key aspects of this are that a) the overall size of the food system is a strong determinant for the potential to increase agro-ecological farming practices and the current amount of livestock production needs to be reduced and redistributed in order to remain within current agricultural land endowment in the future; b) to play out the full potential of improvements, livestock production needs to be linked to cropland (monogastrics) and grassland (ruminants) potentials within the EU, and in combination with innovative livestock diets, is able to re-balance nutrient supply and demand at the sub-national scale; c) in such a contest, an increase in land under agro-ecological practices and a reduction of GHG emissions is possible within the EU in the year 2050 without compromising food security. A particularly large potential for climate change mitigation can be realized with agroforestry and the related carbon sequestration in woody biomass, which can compensate GHG emissions of future agriculture; d) agro-ecological practices such as undersowing cereals with leys and clover allows to reduce the utilization of synthetic nitrogen fertilizers and provide roughage for ruminant livestock and also reduces grazing intensities on grasslands; e) reducing grazing intensities on high natural value farmland is possible without the risk of shortages in grass supply for domestic ruminant livestock or strong ecological impacts. However, in all agroecological scenarios, adequate nutrient supply is a challenge that has to be addressed explicitly.</p> <p>The information compiled in this report illustrates the large option space that exists for sustainability improvements in the EU agriculture and food systems. It is aimed to help to inform and support the needed actions to implement the farm-to-fork strategy and the EU plans for maintaining biodiversity, as well as the Paris agreement. Policy makers can make use of the information provided in this deliverable to inform agricultural policy and decision making to align agricultural production and consumption in the EU with the broad sustainability goals while ensuring long-term food security. Regional policy makers and stakeholders with their detailed, specific knowledge base can gauge which innovations are best suited for a specific region and can then contextualize these agroecological innovations for the specific regions while still firmly linking them to the larger EU agri-food system policies.</p> <p>UNISECO is a European research project aiming to develop innovative approaches to enhance the understanding of socio-economic and policy drivers and barriers for further development and implementation of agro-ecological practices in EU farming systems. Learn more about the project: <a href="https://uniseco-project.eu/">https://uniseco-project.eu/</a></p> <p>This project has received funding from the European Union's H2020 research and innovation programme under grant agreement No 773901.</p> <p>This publication reflects only the authors' view and the European Commission is not responsible for any use that may be made of the information it contains.</p>