水稻连续免耕抛栽对土壤理化和生物学性状的影响

EFFECTS OF CONTINUOUS NO-TILLAGE AND CAST-TRANSPLANTING ON SOIL PHYSICAL,CHEMICAL AND BIOLOGICAL PROPERTIES

于2005～2007年在双季稻田以翻耕处理为对照，研究了水稻连续免耕抛栽对土壤理化和生物学性质的影响。结果表明，稻田免耕1年（2季），有利于土壤物理性状的改善，随着免耕时间（3年6季）的延长，土壤物理性质变差。但免耕2年后，采用紫云英和稻草还田能降低免耕稻田的土壤容重，提高总孔隙度和非毛管孔隙度。免耕有利于土壤养分在表层土壤富集。土壤中三大类微生物总量免耕处理小于翻耕处理，免耕土壤细菌的数量增加，而放线菌和真菌的数量减少。土壤中脲酶活性增加，而过氧化氢酶和过氧化物酶的活性均降低。脲酶、过氧化氢酶和多酚氧化酶的活性均与土壤有机质、全氮含量呈极显著相关，而过氧化物酶活性则与土壤全氮和速效钾含量呈极显著相关。该结果有水稻免耕抛秧栽培技术的推广应用的参考意义。

A three-year （2005 - 2007） experiment was conducted in paddy fields under a double rice cropping systern to study effects of continuous no-tillage and cast-transplanting on soil physical, chemical and biological properties. Results show that no-tillage treatment for one year （two crops）improved soil physical properties, but no-tillage treatment for three years （ six crops） , worsened soil physical properties. However, the effect of no-tillage treatment for two years varied. In the soil incorporated with milk vetch and rice straw, it decreased soil density of the cultivated horizon, but increased total porosity and non-capillary porosity therein, and helped nutrient enrichment in the surface soil layer. Soil analysis showed that the no-tillage field was less than the control, plowed field in total amount of three groups of soil microbes. However, in no-tillage field, the amount of soil bacteria increased, while that of soil actinomycosis and fungi re- duced, and urease activity in surface layer soil increased, while catalase and peroxidase activity reduced. Significantly positive correlations were observed of soil organic matter and total N with urease, catalase and polyphenol oxidase activity and, significantly positive correlations of soil total N and available K with peroxidase activity and. The findings provide a valuable reference for popularization and application of the technology of no-tillage and cast-transplantation of rice in the future.