How scale affects N2O emissions in heterogeneous fields of a diversified agricultural landscape

Abstract

Abstract Nitrous oxide (N 2 O) emissions from agricultural soils vary due to factors such as soil organic matter, soil moisture, and crop type, leading to short-term variations and concentrated zones of high emissions, known as “hot moments” and “hotspots.” These peaks, occurring at various scales, contribute significantly to total N 2 O emissions. This is particularly relevant for sandy soils, where high porosity and low water-holding capacity promote gas diffusion and create moisture variability, leading to highly heterogeneous N 2 O emissions. We investigated N 2 O fluxes along a transect in six agriculturally used patches (0.52 ha) with varying texture, yield potential and crop rotation. We measured N 2 O fluxes bi-weekly over 2 years, using a non-flow-through non-steady-state (NFT-NSS) manual closed chamber system, covering different crops and weather conditions. Hot moments accounted for 6–71% of total crop N 2 O emissions and were mostly driven by soil physical properties. On a small scale, soil texture and environment determined spatial heterogeneity of N 2 O emissions being more pronounced for sandier soils. On patch level, N 2 O emissions differed more strongly than on microplot level and were mainly driven by crop-type and management. Our findings highlight the importance of accounting for intrinsic variability in soil texture, topography, and microclimate within patches. Additionally, broader differences across management-influenced patches must be considered to better understand the drivers of N 2 O emissions. This dual-scale approach emphasizes the need for high-resolution soil monitoring for mitigation strategies and to refine models. At the same time, it guides farmers toward soil-specific fertilization to reduce emissions and maintain yields in diverse agricultural landscapes.

Topics & Concepts