Summary
This ¹⁵N-tracing field study in central Spain examined nitrogen cycling and nitrous oxide emissions in an irrigated cover crop–maize rotation under semiarid conditions. The research demonstrates that cereal cover crops (barley) reduce N₂O emissions relative to legume cover crops (vetch) and improve subsequent maize fertiliser nitrogen recovery, whilst most N₂O originates from synthetic fertiliser rather than crop residues or endogenous soil sources. The findings suggest that strategic cover crop selection can enhance nitrogen use efficiency and mitigate fertiliser-derived greenhouse gas emissions in conservation agriculture systems.
UK applicability
The findings have limited direct applicability to rainfed UK arable systems, as the study was conducted under irrigation in semiarid Spain where nitrogen dynamics and microbial processes differ substantially. However, the results on cereal cover crop benefits for nitrogen use efficiency and N₂O mitigation may inform UK conservation agriculture practice, particularly in intensive irrigated systems or regions with summer moisture stress.
Key measures
Cumulative N₂O emissions (% difference between treatments); N₂O emission factors (% of applied N); ¹⁵N recovery in plant biomass and soil; plant uptake from labelled residues and labelled fertiliser; total N recovery
Outcomes reported
The study quantified nitrogen fate and nitrous oxide emissions from crop residues and synthetic fertiliser in an irrigated cover crop–maize rotation using ¹⁵N tracing. It measured cumulative N₂O emissions, N₂O emission factors by source, plant N recovery, and soil N retention across different cover crop treatments.
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