NITRIFICATION,DENITRIFICATION OF GREENHOUSE VEGETABLE SOIL IN THE SUBURB OF SHANGHAI

Soil gross nitrification rates and denitrification rates were determined using the barometric process separation(BaPS)technique in greenhouse vegetable soils in Shanghai Suburb,and the factor analysis were used to evaluate factors affecting soil nitrification and denitrification process.The results showed that there were significant differences in soil gross nitrification rates and denitrification rates among all greenhouse vegetable soils(One-way Anova,p0.01).Soil gross nitrification rates ranged from 177.58 to 457.26 Nug/kg·h,soil denitrification rates ranged from 231.51 to 415 Nug/kg·h.Soil gross nitrification rates were positively related to soil nitrate content(p0.05) and negatively related to soil bulk density(p0.05).Soil gross denitrification rates were positively related to soil moisture(p0.05),and to soil organic matter,nitrate(p0.01).Soil moisture,soil organic matter,nitrate and soil bulk density were the important factors to affect soil nitrification and denitrification process,and these four indices indicated more than 80 percent information of all measured soil indices.Soil gross nitrification and denitrification contribution to the emission of soil N2O were 47.5%,52.5%,respectively.Both soil gross nitrification and denitrification were responsible for the nitrogen loss from greenhouse vegetable soils.