免耕不同秸秆覆盖量对土壤酶活性及土壤有机碳含量的影响OACSTPCD

No-tillage with stover mulching can influence soil microbial biomass and activity,and increase soil organic matter,which is one of the core conservation tillage practices to improve the comprehensive ecological efficiency of the soil.To investigate the changes and regulatory mechanisms of soil microbial enzyme activities under no-tillage with different amounts of stover mulching,field experiment was conducted at the conservation tillage research and development station of Institute of Applied Ecology,Chinese Academy of Sciences.Using conventional tillage(tilling+no stover mulching,CT)as a control,we assessed soil enzyme activities,microbial biomass and organic carbon contents across different soil layers(0-5,5-10,10-20 cm)under no-tillage with no(no-tillage+no stover mulching,NT0),low(no-tillage+1/3 stover mulching,NT1/3),medium(no-tillage+2/3 stover mulching,NT2/3),and high(no-tillage+full stover mulching,NT3/3)stover mulching.The results indicated that compared with CT,no-tillage with stover mulching predominantly influenced the enzyme activities in the topsoil 0-5 cm,such as Cellobiohy-drolase(CB),β-N-acetylglucosaminidase(NAG)and Peroxidase(PER).The activity of CB under no-tillage with low(NT1/3)and high(NT3/3)stover mulching was significantly higher than that of CT by 1.24-fold and 1.53-fold.The activities of NAG under all no-tillage treatments were significantly higher than that of the CT by 78.1%to 124%,and there was an ascending trend in NAG activity from low to high stover mulching levels(NT1/3<NT2/3<NT3/3).The NT1/3 significantly increased PER activity by 1.50-fold compared with CT,and PER activity exhibited a declining trend with varying stover mulching amounts(NT1/3>NT2/3>NT3/3).No-tillage with stover mulching had a minimal impact on the enzymatic activity of 5-10 cm and 10-20 cm soil layers.It was also found that soil enzyme activities were influenced by both physical and chemical factors including soil organic carbon(SOC),total nitrogen(TN),dissolved organic carbon(DOC),dissolved organic nitrogen(DON),ammonium nitrogen(NH4+-N),nitrate nitrogen(NO3--N),pH,and water content,and were also substantially affected by microbial biomass and composition.NT3/3 increased total enzyme activity by 60.5%,SOC content by 35.6%,and microbial entropy by 21.6%compared with CT.Notably,there were significant and positive correlations between total enzyme activities,SOC,and microbial entropy.These findings suggest that promoting microbial enzyme activities is conducive to enhanced SOC accumulation.In conclusion,no-tillage with a high amount of stover mulching(NT3/3)provides a more suitable and favorable microbial available carbon source for soil microbial activity increase,which promotes SOC sequestration.