Nitrous Oxide Emissions from Soils with Different Vertical Soil Moisture Distribution Patterns

To reveal the impact of vertical non-uniform distribution of soil moisture on nitrous oxide (N2O) emissions, incubated experiments were conducted from April to August 2013 on silty clay and sandy loam with four watering regimes [surface watering (SW) and subsurface watering application to levels 12, 15, and 18 cm below soil surface (SUW12, SUW15, SUW18)]. Short-term pulse emissions of N2O from both soils during the drying process were observed. The soil water-filled pore space (WFPS) at 0-12 cm depths for peak N2O fluxes in SW and SUW soils fell within 34-66%, 22-72%, 25-35%, and 19-39% for silty clay and sandy loam, respectively. Our results also suggest that the N2O fluxes from soil of sily clay with higher N content are much higher than that from sandy loam, and N2O were more easily influenced by soil moisture in SW soils than in SUW soils. However, more research is needed to identify an ideal soil-wetting pattern and the way to realize the ideal soil-wetting pattern, especially on soil with plant growth and fertilization.