紫云英和稻草还田免耕抛栽对水稻产量和土壤肥力的影响

【研究目的】研究紫云英和稻草还田免耕抛栽对水稻产量和土壤肥力的影响，为南方稻区免耕抛秧栽培技术的推广应用提供参考。【方法】2007-2008年在连续两年双季稻免耕抛栽定位试验的基础上，以翻耕抛栽处理为对照，探讨紫云英和稻草还田免耕抛栽对土壤物理性状、养分、土壤酶活性、土壤微生物和水稻产量的影响。【结果】连续免耕两年以后，免耕水稻产量低于翻耕处理，施用有机肥能够提高水稻单位面积的有效穗数和每穗粒数，从而提高水稻产量；随着稻田免耕时间的延长，土壤物理性状变差，紫云英和稻草还田可以降低土壤容重，改善土壤孔隙性；免耕稻田的土壤养分在表层土壤富集，紫云英和稻草还田对提高翻耕处理土壤养分的效果更明显；脲酶，过氧化氢酶、多酚氧化酶、过氧化物酶的活性均与土壤全氮含量呈极显著相关；土壤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，施用有机肥后三大类微生物数量均有所增加。【结论】紫云英和稻草还田可以提高水稻产量，降低土壤容重，改善土壤孔隙性，缓解长期免耕导致的土壤板结,有利于土壤养分含量和土壤酶活性的提高，改善微生物的生存环境。

Effects of no-tillage and cast-transplanting with milk vetch and straw incorporation on rice yield and soil fertility

his study was aimed to analyze the no-tillage and cast-transplanting with milk vetch and straw incorporation on the changes of rice yield and soil fertility and the findings provide a valuable reference for popularization and application of the technology of no-tillage and cast-transplantation of rice in the south china paddy rice. A two-year （2007-2008） experiment was conducted in paddy fields under a double rice cropping system to probe effects of no-tillage and cast-transplanting with milk vetch and straw incorporation on soil physical properties,soil nutrient,soil enzymes activity,soil microbe and rice yield. The no-tillage treatment of two years decreased rice yield. Application of organic manure increased the effective panicle and spikelet per panicle,and improved the rice yield; as the time of no-tillage prolonged,worsened soil physical properties. Application of organic manure reduced soil density and improved soil porosity; the no-tillage treatment helped nutrient enrichment in the surface soil layer. Application of organic manure increased soil nutrient,particularly conventional tillage; Significant positive correlations were observed of total N with urease,catalase,polyphenol oxidase and peroxidase activity; 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 reduced. Application of organic manure increased the number of soil microbes. Application of organic manure improved the rice yield. At the same time,it reduced soil density and improved soil porosity,and alleviated the soil compaction caused by long-term no-tillage. It also increased soil nutrient content and soil enzyme activity and improved the environment for the survival of micro-organisms.