[Influence of planting density and precipitation on N2O emission from a winter wheat field]

To investigate the impact of plant density on N2O emission from winter wheat field and the cause of seasonal variation in the emission, field experiment with four planting rates of 0, 90, 180 and 270 kg/ha was conducted at the Jiangning County near Nanjing during 1999-2000 winter wheat growing season. Data of the field measurements indicated that the N2O emission rates during the season from planting to overwintering were not influenced by the plant density, while the emission was positively correlated with the planting density during the season from turning green to maturity. The emissions from the field plots with planting rates of 0 and 90 kg/ha were not found to be significantly different. A further analysis suggested that the seasonal variation of N2O emission be mainly influenced by precipitation, which could be quantitatively described by an exponential function of a weighted average precipitation of 6-day period before measurement.