Effects of Astragalus sinicus manure and fertilizer combined application on biological properties of soil in Anhui double cropping rice areas along the Yangtze River

【Objectives】 Astragalus sinicus-rice rotation systemhas been extended in rice production in order to prevent the ever growing areas of fallow fields. The effectsof incorporation of Astragalus sinicus combined with chemical fertilize of rice production and soil microbial properties were studied in order to provide a theoretical support for improving soil biochemical environment and soil quality, insuring high and steady yield of crops. 【Methods】 Based on the vetch-rice-rice experiment which was set by the Soil and Fertilizer Institute, Anhui Academy of Agricultural Sciences in 2008, microbial biomass C and N contents, soil enzymatic activities and correlation between biological characteristics of the soil and soil nutrients of paddy topsoil (0-20 cm) were analyzed. The soil productivity was evaluated with yield and agricultural traits of rice. The experiment included five treatments: no fertilizer (CK), 100% fertilizer, incorporatingAstragalu sinicus of 7500, 15000, 30000 kg/ha with 70% of normal amount of chemical fertilizers. 【Results】 1)Application of Astragalu sinicus can significantly improve grain yield of rice, increase the effective panicles and seed setting rate, especially in treatment application Astragalu sinicus 15000 kg/ha with 70% amounts o f chemical fertilizers, in which the highest yield of 7604.53 kg/ha was obtained, the effective panicles and seed setting rates are about 228.06% and 36.29% higher than those in CK and 100% fertilizer treatment. 2) Compared with the control, soil microbial biomass carbon(SMBC), soil microbial biomass nitrogen(SMBN), enzyme activities of soil acid phosphatase and urease are increased in chemical fertilizer treatments while the catalase activity decreased. Compared with the treatments of chemical fertilizer and CK, application of Astragalus sinicus combined with 70% chemical fertilizer significantly increased SMBC, SMBN, and soil enzyme activities. Which increased with the increasing amount of Astragalus sinicus application, and the treatment with 15000-30000 kg/ha of Astragalus sinicus returning with 70% amounts of chemical fertilizer had better comprehensive effects. During the whole growth period, the contents of soil microbial biomass C and N were increased by 21.03％-142.33％ and 19.97％-83.91％, and the activities of soil urease, acid phosphatase, catalase by 10.12％-100.33％,10.22%-43.23%,0.14%-7.28% after turnover of Astragalus sinicus , compared with CK. All the soil microbial biomass, activities of urease, and acid phosphatase had positive and significant relationship with soil organic matter, total N, alkalitic N (P0.05, P0.01), but the correlation between hydrogen peroxidase activityand soil nutrients content was not obvious. 【Conclusions】 Long-term application of Astragalus sinicus combined with chemical fertilizer can significantly increase the rice yield, soil microbial biomass and soil enzyme activity, improve paddy soil micro-ecological environment. Within the test area and on the condition of appropriate amount of fertilizer 70%, the incoporation of 15000-30000 kg/ha Astragalus sinicus is appropriate. This combination ratio of Astragalus sinicus and chemical fertilizer is conducive to improve soil productivity, and it is an effective way to improve crop yield and soil fertility in double-cropping paddy field areas along the Yangtze River in Anhui Province.