Browsing by Author "Maenhout, Peter"

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    Effectiveness of soil management strategies for mitigation of N2O emissions in European arable land: A meta-analysis
    (John Wiley & Sons Ltd, 2024) Valkama, Elena; Tzemi, Domna; Esparza-Robles, Ulises Ramon; Syp, Alina; O'Toole, Adam; Maenhout, Peter
    Soil management strategies involving the application of organic matter(OM) inputs (crop residues, green and livestock manure, slurry, digestate, compost and biochar) can increase soil carbon storage but simultaneously lead to an increase in non-CO2 greenhouse gas (GHG) emissions such asN2O. Although multiple meta-analyses have been conducted on the topic of OM input impacts on GHG, none has focused specifically on European arablesoils. This study plugs this gap and can assist policymakers in steering European agriculture in a more sustainable direction. The objective of thismeta-analysis was to quantify how OM inputs of different nature and quality, but also the application strategy, can mitigate soil N2O emissions in differentpedoclimatic conditions in Europe. We quantitatively synthesised the resultsof over 50 field experiments conducted in 15 European countries. Diverse arablecrops, mainly cereals, were cultivated in monoculture or in crop rotationson mineral soils. Cumulative N2O emissions were monitored during periods of30–1070 days in treatments, which received OM inputs, alone or in combination with mineral N fertiliser; and in controls fertilised with mineral N. Theoverall effect of OM inputs had a slight tendency to reduce N2O emissions by10% (n = 53). With the increasing carbon-to-nitrogen ratio of the OM inputs,this mitigation effect became more pronounced. In particular, compost andbiochar significantly reduced N2O emissions by 25% (n = 6) and 33% (n = 8)respectively. However, their effect strongly depended on pedoclimatic characteristics.Regarding the other types of OM inputs studied, a slight N2O emissionreduction can be achieved by their application alone, without mineralN fertiliser (by 16%, n = 17). In contrast, their co-application with mineral N fertiliser elevated emissions to some extent compared to the control (by 14%,n = 22). We conclude that amongst the seven OM inputs studied, the applicationof compost and biochar are the most promising soil management practices, clearly demonstrating N2O emission reduction compared to mineral N fertiliser. In contrast, other OM inputs had a small tendency to mitigate N2Oemissions only when applied without mineral N fertiliser.
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    Trade-offs and synergies of soil carbon sequestration: Addressing knowledge gaps related to soil management strategies
    (John Wiley & Sons Ltd, 2024) Maenhout, Peter; Di Bene, Claudia; Luz Cayuela, Maria; Diaz-Pines, Eugenio; Govednik, Anton; Keuper, Frida; Mavsar, Sara; Mihelic, Rok; O'Toole, Adam; Schwarzmann, Ana; Suhadolc, Marjetka; Syp, Alina; Valkama, Elena
    Soil organic carbon (SOC) sequestration in agricultural soils is an important tool for climate change mitigation within the EU soil strategy for 2030 and can be achieved via the adoption of soil management strategies (SMS). These strategies may induce synergistic effects by simultaneously reducing greenhouse gas (GHG) emissions and/or nitrogen (N) leaching. In contrast, other SMS may stimulate emissions of GHG such as nitrous oxide (N2O) or methane (CH4), offsetting the climate change mitigation gained via SOC sequestration. Despite the importance of understanding trade-offs and synergies for selecting sustainable SMS for European agriculture, knowledge on these effects remains limited. This review synthesizes existing knowledge, identifies knowledge gaps and provides research recommendations on trade-offs and synergies between SOC sequestration or SOC accrual, non-CO2 GHG emissions and N leaching related to selected SMS. We investigated 87 peer-reviewed articles that address SMS and categorized them under tillage management, cropping systems, water management and fertilization and organic matter (OM) inputs. SMS, such as conservation tillage, adapted crop rotations, adapted water management, OM inputs by cover crops (CC), organic amendments (OA) and biochar, contribute to increase SOC stocks and reduce N leaching. Adoption of leguminous CC or specific cropping systems and adapted water management tend to create tradeoffs by stimulating N2O emissions, while specific cropping systems or application of biochar can mitigate N2O emissions. The effect of crop residues on N2O emissions depends strongly on their C/N ratio. Organic agriculture and agroforestry clearly mitigate CH4 emissions but the impact of other SMS requires additional study. More experimental research is needed to study the impact of both the pedoclimatic conditions and the long-term dynamics of trade-offs and synergies. Researchers should simultaneously assess the impact of (multiple) agricultural SMS on SOC stocks, GHG emissions and N leaching. This review provides guidance to policymakers as well as a framework to design field experiments and model simulations, which can address knowledge gaps and non-intentional effects of applying agricultural SMS meant to increase SOC sequestration.