Nitrous oxide and carbon dioxide emission responses to litter incorporated in a grassland soil

While the Intergovernmental Panel on Climate Change (IPCC) guidelines include the possibility of N₂O emissions from crop residues, they do not include grazed pasture or supplementary feed litters. To quantify the relative greenhouse gas (GHG) emissions from pasture litter, ground shoots of clover (Trifolium repens L.), ryegrass (Lolium perenne L.) and maize (Zea mays L.) were incorporated into soil at 1.5, 1.0 and 0.6 g nitrogen (N) (~12.8 g carbon (C), on average) kg⁻¹ soil, respectively. A 42 d incubation at 20°C and either 86% (field capacity) or 54% water-filled pore space (WFPS) was performed. During the first 2 d, 92–95% of the N₂O was emitted. At 86% WFPS, N₂O emissions were 2–3% of the incorporated N with no litter species differences. At 54% WFPS, N₂O emissions were 1.7% > 0.7% = 0.5% of herbage N applied, for clover, ryegrass and maize, respectively (P