Temporal dynamics of ammonia and nitrous oxide emissions following green crop residue recycling in soils

Abstract

Abstract The recycling of green crop residues is promoted for enhancing soil organic carbon sequestration and health, but can also stimulate emissions of nitrous oxide (N₂O) and ammonia (NH₃). Soil tillage can lead to different residue distributions which affect contact with decomposers and local gas and solute diffusion. This study aims to quantify N₂O, NH₃, and carbon dioxide emissions from N-rich red clover residue subjected to three different distributions in the soil—surface, layered, and mixed—across three contrasting agricultural soils. The incubations were performed under laboratory conditions for 50 days at 15 °C, with a water-filled pore space of 60%. Gas fluxes as well as soil ammonium and nitrate contents were measured. Results showed that N₂O emissions were strongly influenced by soil type and residue placement, with sandy loam producing the highest cumulative fluxes, particularly in the mixed (17.4 kg N ha⁻ 1 ) and layered (11.5 kg N ha⁻ 1 ) treatments. NH₃ volatilization occurred almost exclusively from surface residues, peaking at 10.2 kg N ha⁻ 1 in sandy loam soil. Emission for N 2 O were significantly higher than previously reported for residues. These findings highlight that both residue placement and soil properties critically determine gaseous emission patterns.