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Poster De Conférence Année : 2021

Soil macroaggregates: the hotspots determining emission or mitigation of greenhouse gases according to the management system adopted

Résumé

No-tillage (NT) associated to legume cover crops have been considered as efficient tool to offset greenhouse gases (GHG) in subtropical soils. Under these systems, however, the soil dynamics of nitrous oxide (N2O) and methane (CH4), powerful GHG, is not fully understood in microscale. To understand the GHG dynamics in microscale, our objective was evaluating emission of N2O and CH4 in three soil aggregates classes in a subtropical Acrisol under conventional tillage (CT) and NT combined to oat/maize (O/M) or oat+vetch/maize+cowpea (OV/MC). We have incubated large macroaggregates (> 2mm), small macroaggregates (2-0.25 mm) and microaggregates (<0.25 mm) under 40% (aerobic environment) and 70% (anaerobic envoronment) of water content for six months. In large macroaggregates of NT under 40% of water content, N2O emission was three times greater in OV/MC than O/M, reaching 0.78 mg N2O-N kg–1. On the other hand, great CH4-C influx (-19 mg kg–1) in NT OV/MC have a compensation effect under 40% of water content. Considering net cumulative emission by kg of C in aggregates (NCECagg), large and small macroaggregates of NT and legume cover crops reduced that emission by 40% compared to CT without legume under 40% of water content. However, all treatments became C sources to atmosphere under 70% of water content, with a NCECagg of large and small macroaggregates increasing from -68.40 under 40% to 3685.75 under 70%, on average. NT was able to reduce NCECagg by 39% compared to CT in large and small macroaggregates of OV/MC, on average, under 70% of water content. Management systems did not impact GHG emission of microaggregates. By containing labile organic forms, soil macroaggregates are considered the hotspot of soil greenhouse gases determining then the processes of emission/mitigation in the soil. Although favor N2O emission, NT and legume cover crop lead to offset GHG emission by promoting CH4 influx and C accumulation in soil macroaggregates.

Domaines

Science des sols
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Dates et versions

hal-04293328 , version 1 (18-11-2023)

Identifiants

  • HAL Id : hal-04293328 , version 1

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Murilo Veloso, Coline Deveautour, Cimélio Bayer. Soil macroaggregates: the hotspots determining emission or mitigation of greenhouse gases according to the management system adopted. EuroSoil 2021, Aug 2021, Geneva, Switzerland. ⟨hal-04293328⟩
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