To evaluate the effect of cropping system on N2O and CH4 emissions and to identify the key factors controlling the emissions,a field experiment was carried out in 2003 at Jiangsu Academy of Agricultural Sciences.

To investigate impact of environmental factors and crop- growing on CH4 and N2O emissions, a field experiment with different levels of organic matter application under conditions of normal irrigation and permanent flooding was performed at a county of Jiangning near Nanjing during 2000 rice- growing season.

5t/hm2) of organic matter (wheat straw) on CH4 and N2O emissions from rice field was studied under the conditions of conventional irrigation and permanent flooding inrice-growing season.

Two uplands of different reclamation years(since 1987 and 1993,respectively) were selected in our study to research the effect of cultivation years, precipitation,soil moisture and plant on N2O emission.

N2O emission was measured in rape growing season of a rice-rape rotation system in the Chengdu plain from November 2004 to May 2005.

The results showed,1) Nitrogen fertilizer application enhanced the N2O emission significantly.

The intact soil core-acetylene inhibition technique was used to study the effects of N-fertilizer application rates and types on the denitrification losses and N2O emissions in a calcareous purple soil-maize crop system in the upland area of central Sichuan Basin.