Nitrous Oxide Emissions from Soil Incorporation of Crop Residues

Abstract

Field trials were undertaken on two experimental sites in Scotland, one on a sandy loam and the other a loamy sand. At the first site, N2O emissions were compared after incorporation of different varieties of Italian ryegrass (Lolium multiflorum), and different mixes of grass/clover varieties. At the second site comparisons of N2O emissions were made between five different crop residues - white clover (Trifolium repens), mustard, oats, trefoil (Trigonella coerula?) and forage peas. These emissions were related to measurements of soil available N, temperature and gravimetric soil moisture content. Short-lived fluxes of N2O occurred immediately after incorporation of residues at both sites. The greatest emissions, 23 g N2O-N ha-1 d-1, occurred after incorporation of the grass/clover trial, and were positively correlated with a rise in air temperature (r=0.5, P<0.01). Soil available N increased throughout the experiments, the greatest increases being at the second experimental site