Effects of long-term fertilization on mollisoil enzyme activities and microbial respiration

The long-term field experiment was carried out to evaluate soil enzyme activities and soil respiration with the different fertilizer treatments in farmland soil at the Key Observation Station of the Harbin Black Soil Ecology,Ministry of Agriculture,Heilongjiang Province,China.The results showed that the soil enzyme activities(catalase,invertase and urease) had significant difference among fertilization treatments regardless of sampling time.The urease and invertase activities of organic and inorganic fertilizers treatment were stronger than that of the single application of chemical fertilizers,organic fertilizers and inorganic fertilizer treatments.However,fertilizing had a negative effect on the catalase activity.At the same treatments,the activities of soil catalase,invertase and urease at 0~20 cm soil layer were higher than 20~40 cm.In addition,fertilizing had some negative effects on the fungal and bacterial respiration.