Effects of Astragalus sinicus ploughed at maturity stage on rice yield and soil properties of paddy field.

【Objective】 The effects of Astragalus sinicus ploughed at maturity stage as green manure on paddy soil properties were studied to provide references for advancing the production of green manure and sustainable development of field.【Method】 A three-year field positioning experiment was carried out.In the first year,five different levels(0,2.81,5.61,8.42,11.23 t/ha) of Astragalus sinicus ploughed at maturity stage were designed.And in the next two years,the amounts of Astragalus sinicus at maturity stage ploughed were based on the natural growth amounts of Astragalus sinicus at maturity stage of the year in each plot field.The yields of Astragalus sinicus at maturity stage were estimated and ploughed directly before rice transplanting.Rice yield,soil nutrients,biological properties and water-stable aggregates of paddy fields were measured as well.【Result】 The effective panicles and rice yields increased significantly after ploughing Astragalus sinicus at maturity stage.Meanwhile,the organic acid content in paddy field increased and the activities of soil phosphatases,invertase and catalase were higher.The soil dissolved organic carbon also increased with the increasing application of green manure.However,excess amount of green manure inhibited the soil microbial biomass carbon content.The macro aggregates and micro aggregates richened closer to middle aggregates.【Conclusion】 As green manure,the use of Astragalus sinicus at maturity stage could improve soil physicochemical and biological properties,boost soil fertility and increase rice yield significantly.But the ploughing amount of Astragalus sinicus at maturity stage before rice transplanting should be less than 8.42 t/ha(dry weight).