N2O emissions of low input cropping systems as affected by legume and cover crops use

摘要: Abstract Reducing environmental impacts of agriculture is a key issue for preserving water, soil and air quality. Among available options, the incorporation legumes allows to reduce synthetic N fertilizer use, use cover crops an efficient way decrease nitrate leaching recycle nutrients, while mechanical weeding together with crop rotation help limit pesticides. However, how these options affect N2O emissions remains uncertain. Here we studied four cropping systems which were designed as low input alternatives conventional wheat-sunflower in south-west France make aforementioned options. The used differ by input: 96 kg N ha−1 year−1 Low Input (LI) system 33 kg N ha−1 year−1 Very (VLI) incorporates grain legume rotation. For each two (LI VLI), both variation (+CC) without (−CC) studied. Daily fluxes measured almost continuously (at least 87% 3-year duration) using automatic chambers. Measurements water content, temperature, mineral nitrogen (N) content also carried out. Cumulative over whole range literature values all but they significantly higher VLI (1.12 kg N2O-N ha−1 year−1) than LI (0.78 kg N2O-N ha−1 year−1) on average +CC −CC. Patterns different between systems, taking place form short-lived peaks only after fertilization LI, occurred more frequently VLI. No difference −CC could be detected at scale (P = 0.47). Although increased few days destruction (P = 0.002), contribution such events cumulative remained negligible ( Because agronomical practices have limited effect emissions, their adoption can considered basis benefits address other important agronomic or issues.