Effects of nitrogen fertiliser and wheat straw application on CH4 and N2O emissions from a paddy rice field.

摘要

A 3-year field experiment was conducted to study the effects of nitrogen fertilizer and straw application on CH< sub>4 and N< sub>2O emissions from a paddy rice field in China from 2003 to 2005. Three rates of nitrogen fertilizer (0, 200, and 270 kg N/ha) and 2 levels of wheat straw (0 and 3.75x103 kg/ha) were adopted in this experiment. The effect of nitrogen fertilizer application on CH< sub>4 emission seemed to be affected by application rate. Nitrogen fertilizer decreased CH< sub>4 emission relative to the control when applied at a rate of 200 kg N/ha, but the effect lessened if the application rate was further increased to a rate of 270 kg N/ha. The depressive effect of nitrogen fertilizer application on CH< sub>4 emissions from rice fields became more pronounced when wheat straw was also incorporated with fertilizer, compared with nitrogen fertilizer application alone. Straw incorporation significantly enhanced CH< sub>4 emission by 3-11 times (P<0.05). Nitrogen fertilizer application increased N< sub>2O emission by 5-6 times when applied at a rate of 200 kg N/ha and by 10-14 times when applied at a rate of 270 kg N/ha. On average, straw incorporation tended to decrease N< sub>2O emission by approximately 30% significant (P>0.05). More than 50% of seasonal total amount of N< sub>2O was emitted within 11 days after fertilizer application at panicle initiation. The global warming potential caused by both CH< sub>4 and N< sub>2O emissions was affected by nitrogen fertilizer application rate and significantly stimulated by wheat straw incorporation. The global warming potential was lowest when nitrogen fertilizer was applied at a rate of 200 kg N/ha.