Effects of water regimes on nitrous oxide emission from soils

Abstract

Water regime is one of the key factors affecting nitrous oxide (N 2O) emissions from soils. To gain insights into how irrigation activities on paddy soils in southeastern China affect the dynamic process of N 2O emissions, soil column experiments were conducted with three irrigation regimes, namely, flooding, intermittent and natural drying. Natural drying had the most contribution to N 2O emissions. Soil cracking stimulated the greater emissions of N 2O whereas flooding irrigation regime had the least contribution. There was a highly significant positive correlation between the N 2O emissions and the concentrations of dissolved N 2O in surficial water. Under flooding irrigation regime, 80% of the variability in the N 2O emissions ( F1) could be explained by dissolved N 2O in surface water (Ds1), dissolved N 2O in leachate ( D1) and pH (pH1) as shown here: F1 = 0.220Ds1 − 0.12 D1 − 21.75pH1 + 157.64; R 2 = 0.804, p = 0.032. Moreover, pH had a significant correlation with dissolved N 2O in leachates under intermittent irrigation regime. It is indicative that natural drying should not be practiced as much as possible while cultivating rice in order to avoid massive N 2O emissions into the atmosphere. However, future studies should investigate potential emission of other greenhouse gases to recommend a particular irrigation regime.