Effects Of Organic Materials And Deep Tillage On Topsoil Biological Properties In Paddy Field

To investigate the effects of organic materials and tillage depth on soil nutrients,enzyme activities and microbial community structure,we examined topsoil properties in paddy fields in Jinqu basin of Zhejiang Province,and a field experiment was conducted at two experimental stations in Lanxi and Wucheng.（1）The investigation on topsoil properties in paddy fields in Jinqu basin of Zhejiang Province showed:the contents of soil available phosphorus,available potassium and organic matter,soil urease activity,microbial PLFA and soil microbial diversity indices in the high yield paddy field were higher than those in the low yield paddy field.（2）The tillage depth and straw incorporation experiment consisted of four treatments:shallow tillage（tillage depth 10-12cm）without straw（LS₀）,shallow tillage with straw incorporation（LS₁）,deep tillage（tillage depth 18-20cm）without straw（DS₀）and deep tillage with straw incorporation（DS₁）.The results showed:1)The contents of soil available phosphorus was highest in DS₁ at Lanxi,while the content of soil available phosphorus was highest in LS₁ at Wucheng.2)Straw incorporation improved the activities of soil beta glucosidase,acid phosphatase and urease,while deep tillage increased soil beta glucosidase activity.In addition,straw incorporation increased the contents of soil fungal PLFA,gram negative bacteria PLFA and total PLFA.（3）The organic material experiment consisted of four fertilizer treatments:no fertilizer（CK）,chemical fertilizer（H）,rape straw manure in combination with chemical fertilizer（T）,and pig manure in combination with chemical fertilizer（Y）.The results showed:1)Y and T increased the content of soil available potassium at Lanxi.The contents of soil alkaline hydrolyzable nitrogen and available phosphorus were highest in Y at Wucheng.2)Y and T decreased the activities of soil aryl sulfate esterase and dehydrogenase.Y increased the activity of soil urease;T increased the activity of soil beta glucosidase,the contents of soil fungal PLFA,gram negative bacteria PLFA and total PLFA.（4）The correlation analysis of soil physical,chemical and biological properties revealed that soil alkaline hydrolyzable nitrogen,available phosphorus and organic matter were significantly positively correlated with the activities of soil aryl sulfate esterase,beta glucosidase,dehydrogenase and fungal PLFA in the tillage depth and straw incorporation experiment.Soil alkaline hydrolyzable nitrogen,available potassium and organic matter were significant positive correlation with the activities of soil arylsulfatase,beta glucosidase,catalase,and dehydrogenase,the amounts of bacteria PLFA,fungi PLFA,gram positive bacteria PLFA and gram negative bacteria PLFA and total PLFA in the organic material experiment.