HAL (Le Centre pour la Communication Scientifique Directe), Sep 3, 2017
International audienceIncreasing soil organic matter in cropped soils is a major challenge. Soil ... more International audienceIncreasing soil organic matter in cropped soils is a major challenge. Soil carbon in arable systems is mainly acquired through above and below-ground litter decomposition, with an efficiency depending both on litter chemical characteristics and on the composition and activity of the soil microbial communities; however, the interactions between these two factors remain poorly understood. To answer to this question, we selected fields from a same soil type which underwent different agricultural practices during 5 years. We tested whether the impacts of these practices on soil biotic characteristics will have legacy effects on litter-C microbial assimilation strategy. The study was conducted at the long-term experimental site SOERE ACBB, located in Northern France (49.873 N, 3.032 E), on a loamy soil (Orthic Luvisol, FAO classification) where six treatments varying by their tillage, N fertilization and crop residues management were set up in 2010 (Coudrain et al., 2016). We sampled in 2015 the 0-5 cm layer of the deep-tillage (CONV) and the reduced-tillage (RT) treatments. A laboratory incubation was performed during 29 days with, for each soil, three litter treatments, i.e. (i) no litter added (control), and uniformly (ii) 13C-labelled mature wheat (recalcitrant litter), and (iii) 13C-labelled flowering wheat residues (labile litter), mixed into the soil at the rate of 3 mg C g-1 dry soil. Dynamics of C-CO2 and 13C-CO2, microbial biomass C and 13C, and hydrolytic enzymatic activities were measured during the decomposition. Non amended RT soil (control) showed higher total C content, C-CO2 emitted, microbial biomass C and enzymatic activities than CONV soil. RT litter-amended treatments exhibited both higher carbon use efficiency (proportion of the litter-13C decomposed incorporated into 13C-microbial biomass) and enzymatic efficiency (amount of litter-13C mineralized per amount of enzymes produced), yet had lower or equivalent priming effects than CONV treatments. These results suggest legacy effect of agricultural practices such as reduced tillage on the microbial C assimilation strategy in soil. We observed also that differences between CONV and RT microbial activities and carbon use efficiency increased with the recalcitrance of the decomposing litter
Background and Aims: Agroecology practices can induce profound changes in soil inevitably influenc... more Background and Aims: Agroecology practices can induce profound changes in soil inevitably influencing soil biological properties and soil functioning. However, we still lack understanding of how soil biodiversity responds to agroecology practices and to what extent such practices, alone or combined, can be beneficial for soil functioning. Understanding soil biological activities under different agroecology practices is important for predicting carbon cycling in agroecosystems. Methods: By taking advantage of a long-term agricultural experimental research station in France, we monitored soil microbes, nematodes and soil respiration over three years in response to agroecology practices that varied in the rate of nitrogen (N) fertilization (low vs high), the tillage type (deep vs reduced), and the crop residue management (retain vs removal). Results: Shifting from conventional to agroecology practices had strong effects on microbial biomass, nematode community and soil respiration. Redu...
Depuis la publication du rapport du Millenium Ecosystem Assessment (2005), on observe une utilisa... more Depuis la publication du rapport du Millenium Ecosystem Assessment (2005), on observe une utilisation croissante de la notion de service ecosystemique (SE) par les chercheurs des sciences de la nature. Or cette notion, qui est generalement associee a une evaluation economique des services rendus a la nature par l’homme, renouvelle les relations entre science et politique. Elle reinterroge la nature des connaissances scientifiques, celles-ci devant contribuer plus directement a la definition des politiques de protection de l’environnement. Dans cet article, nous nous sommes plus particulierement interesses aux sols agricoles, pour etudier en quoi l’approche par service ecosystemique conduit a modifier la production scientifique sur cet objet. Pour ce faire, nous avons realise une etude bibliographique approfondie a l’aide du logiciel de lexicometrie Iramuteq. Nous avons analyse plusieurs corpus d’articles scientifiques de sciences du sol publies entre 1992 et 2012 et selectionnes sou...
C-MIP: An international model inter-comparison simulating organic carbon dynamics in bare fallow ... more C-MIP: An international model inter-comparison simulating organic carbon dynamics in bare fallow soils. 6th International Symposium on Soil Organic Matter
The development of climate mitigation services partly depends on our ability to simulate, with co... more The development of climate mitigation services partly depends on our ability to simulate, with confidence, agricultural production and greenhouse gas (GHG) emissions so as to understand the effectiveness of the mitigation approach on both gas emissions and food production. The Soil C-N Group of the Global Research Alliance (GRA) on GHG has initiated an international model benchmarking and inter-comparison that will assess GHG balance and soil C sequestration of arable crops and grasslands as affected by agricultural practices. The inter-comparison arises from collaborations between GRA, AgMIP and four FACCE-JPI projects to lead to the largest exercise in this domain. An initial stock take has been conducted, resulting in the selection of datasets from five grasslands and five crop sites worldwide. A total of 28 models used in 11countries for the prediction of GHG emissions in crop and grassland systems are contributing, ranging from process-oriented models to simpler models. The stu...
A potential strategy for mitigating nitrous oxide (N2O) emissions from permanent grasslands is th... more A potential strategy for mitigating nitrous oxide (N2O) emissions from permanent grasslands is the partial substitution of fertilizer nitrogen (Nfert) with symbiotically fixed nitrogen (Nsymb) from legumes. The input of Nsymb reduces the energy costs of producing fertilizer and provides a supply of nitrogen (N) for plants that is more synchronous to plant demand than occasional fertilizer applications. Legumes have been promoted as a potential N2O mitigation strategy for grasslands, but evidence to support their efficacy is limited, partly due to the difficulty in conducting experiments across the large range of potential combinations of legume proportions and fertilizer N inputs. These experimental constraints can be overcome by biogeochemical models that can vary legume‐fertilizer combinations and subsequently aid the design of targeted experiments. Using two variants each of two biogeochemical models (APSIM and DayCent), we tested the N2O mitigation potential and productivity of ...
HAL (Le Centre pour la Communication Scientifique Directe), Sep 3, 2017
International audienceIncreasing soil organic matter in cropped soils is a major challenge. Soil ... more International audienceIncreasing soil organic matter in cropped soils is a major challenge. Soil carbon in arable systems is mainly acquired through above and below-ground litter decomposition, with an efficiency depending both on litter chemical characteristics and on the composition and activity of the soil microbial communities; however, the interactions between these two factors remain poorly understood. To answer to this question, we selected fields from a same soil type which underwent different agricultural practices during 5 years. We tested whether the impacts of these practices on soil biotic characteristics will have legacy effects on litter-C microbial assimilation strategy. The study was conducted at the long-term experimental site SOERE ACBB, located in Northern France (49.873 N, 3.032 E), on a loamy soil (Orthic Luvisol, FAO classification) where six treatments varying by their tillage, N fertilization and crop residues management were set up in 2010 (Coudrain et al., 2016). We sampled in 2015 the 0-5 cm layer of the deep-tillage (CONV) and the reduced-tillage (RT) treatments. A laboratory incubation was performed during 29 days with, for each soil, three litter treatments, i.e. (i) no litter added (control), and uniformly (ii) 13C-labelled mature wheat (recalcitrant litter), and (iii) 13C-labelled flowering wheat residues (labile litter), mixed into the soil at the rate of 3 mg C g-1 dry soil. Dynamics of C-CO2 and 13C-CO2, microbial biomass C and 13C, and hydrolytic enzymatic activities were measured during the decomposition. Non amended RT soil (control) showed higher total C content, C-CO2 emitted, microbial biomass C and enzymatic activities than CONV soil. RT litter-amended treatments exhibited both higher carbon use efficiency (proportion of the litter-13C decomposed incorporated into 13C-microbial biomass) and enzymatic efficiency (amount of litter-13C mineralized per amount of enzymes produced), yet had lower or equivalent priming effects than CONV treatments. These results suggest legacy effect of agricultural practices such as reduced tillage on the microbial C assimilation strategy in soil. We observed also that differences between CONV and RT microbial activities and carbon use efficiency increased with the recalcitrance of the decomposing litter
Background and Aims: Agroecology practices can induce profound changes in soil inevitably influenc... more Background and Aims: Agroecology practices can induce profound changes in soil inevitably influencing soil biological properties and soil functioning. However, we still lack understanding of how soil biodiversity responds to agroecology practices and to what extent such practices, alone or combined, can be beneficial for soil functioning. Understanding soil biological activities under different agroecology practices is important for predicting carbon cycling in agroecosystems. Methods: By taking advantage of a long-term agricultural experimental research station in France, we monitored soil microbes, nematodes and soil respiration over three years in response to agroecology practices that varied in the rate of nitrogen (N) fertilization (low vs high), the tillage type (deep vs reduced), and the crop residue management (retain vs removal). Results: Shifting from conventional to agroecology practices had strong effects on microbial biomass, nematode community and soil respiration. Redu...
Depuis la publication du rapport du Millenium Ecosystem Assessment (2005), on observe une utilisa... more Depuis la publication du rapport du Millenium Ecosystem Assessment (2005), on observe une utilisation croissante de la notion de service ecosystemique (SE) par les chercheurs des sciences de la nature. Or cette notion, qui est generalement associee a une evaluation economique des services rendus a la nature par l’homme, renouvelle les relations entre science et politique. Elle reinterroge la nature des connaissances scientifiques, celles-ci devant contribuer plus directement a la definition des politiques de protection de l’environnement. Dans cet article, nous nous sommes plus particulierement interesses aux sols agricoles, pour etudier en quoi l’approche par service ecosystemique conduit a modifier la production scientifique sur cet objet. Pour ce faire, nous avons realise une etude bibliographique approfondie a l’aide du logiciel de lexicometrie Iramuteq. Nous avons analyse plusieurs corpus d’articles scientifiques de sciences du sol publies entre 1992 et 2012 et selectionnes sou...
C-MIP: An international model inter-comparison simulating organic carbon dynamics in bare fallow ... more C-MIP: An international model inter-comparison simulating organic carbon dynamics in bare fallow soils. 6th International Symposium on Soil Organic Matter
The development of climate mitigation services partly depends on our ability to simulate, with co... more The development of climate mitigation services partly depends on our ability to simulate, with confidence, agricultural production and greenhouse gas (GHG) emissions so as to understand the effectiveness of the mitigation approach on both gas emissions and food production. The Soil C-N Group of the Global Research Alliance (GRA) on GHG has initiated an international model benchmarking and inter-comparison that will assess GHG balance and soil C sequestration of arable crops and grasslands as affected by agricultural practices. The inter-comparison arises from collaborations between GRA, AgMIP and four FACCE-JPI projects to lead to the largest exercise in this domain. An initial stock take has been conducted, resulting in the selection of datasets from five grasslands and five crop sites worldwide. A total of 28 models used in 11countries for the prediction of GHG emissions in crop and grassland systems are contributing, ranging from process-oriented models to simpler models. The stu...
A potential strategy for mitigating nitrous oxide (N2O) emissions from permanent grasslands is th... more A potential strategy for mitigating nitrous oxide (N2O) emissions from permanent grasslands is the partial substitution of fertilizer nitrogen (Nfert) with symbiotically fixed nitrogen (Nsymb) from legumes. The input of Nsymb reduces the energy costs of producing fertilizer and provides a supply of nitrogen (N) for plants that is more synchronous to plant demand than occasional fertilizer applications. Legumes have been promoted as a potential N2O mitigation strategy for grasslands, but evidence to support their efficacy is limited, partly due to the difficulty in conducting experiments across the large range of potential combinations of legume proportions and fertilizer N inputs. These experimental constraints can be overcome by biogeochemical models that can vary legume‐fertilizer combinations and subsequently aid the design of targeted experiments. Using two variants each of two biogeochemical models (APSIM and DayCent), we tested the N2O mitigation potential and productivity of ...
Uploads
Papers by Sylvie Recous