The Effect Of Straw And Astragalus Sinicus L.Cooperative Incorporation On Soil Fertility And Rice Yield

The"Rice(Oryza sutiva L.)-Astragalus sinicus L."rotation system plays an important role in increasing yield,enhancing nutrient efficiency and improving soil fertility in the rice field cropping system in southern China.In this study,by using a long-term experiment and pot experiment,the effects of rice straw co-incorporation with Chinese milk vetch returning to the field on the rice yields,the nutrient accumulation in plant and soil fertility was studied in the"Rice-Chinese milk vetch"rotation system.The main results are as follows:1)Compared with the control treatment(no straw returning and no Chinese sinica planting in winter),the rice yield increased by 1.93%～9.15%and 1.34%～12.48%under continuous straw returning alone and annual rotation under straw-Chinese milk vetch in-cooperative returning,respectively,and the yield increasing effect increased with the increase of year.At the same time,the continuous straw-Chinese milk vetch co-returning to the field was not only beneficial to the accumulation of nitrogen,phosphorus and potassium nutrients in early rice,but also had a certain after-effect on the accumulation of nutrients in late rice2)Compared with the soil nutrient content before the trial in 2015,after the late rice harvest in 2018,the soil organic matter,total nitrogen,available phosphorus and available potassium were reduced by 9.03%,11.11%,3.87%and 10.57%,respectively.The content of organic matter,total nitrogen,available phosphorus and available potassium in the soil under straw and Chinese milk vetch co-returning to the field treatment were increased by20.51%,25.00%,24.16%and 20.37%,respectively.The content of organic matter,total nitrogen and available phosphorus increased by 2.73%,7.14%and 14.20%compared to the straw returning to the field alone treatment respectively.3)In the rice-green manure planting system,both straw returning and nitrogen fertilizer application can significantly promote the yield and nutrient accumulation of fresh grass and have significant interaction.During the application of straw and nitrogen fertilizer,the yield of fresh grass increased by 14%～263%significantly.The highest yield of fresh grass was 272.85 g/pot treated with S2N3(straw returning to the field,nitrogen fertilizer 135 kg/hm~2)in all treatments Compared with N0(without nitrogen fertilizer),Application of nitrogen fertilizer significantly increased the accumulation of nitrogen,phosphorus and potassium of these N1(45 kg/hm~2),N2(90 kg/hm~2)and N3(135 kg/hm~2)by33.0%,61.6%and 115.1%respectively;Phosphorus accumulation increased by 33.5%,44.3%,70.2%;Potassium accumulation increased by 40.4%,65.6%and 102.0%respectively.At the same nitrogen level,compared to S0 processing,accumulation of nitrogen and potassium was S2N2(straw returning to the field all,nitrogen fertilizer 90kg/hm~2)treatment increased the most,25.0%,35.0%,Potassium accumulation was S2N1(straw returning to the field all,nitrogen fertilizer 45 kg/hm~2)treatment increased the most by 52.3%.All treatments were evaluated with S2N3(straw returning to the field all,nitrogen fertilizer 135 kg/hm~2)N,P,K nutrient accumulation is the highest.4)Cooperative incorporation of straw and Chinese milk vetch can significantly increase the content of soil available nutrients,and nitrogen application also positively promotes the accumulation of nitrogen,phosphorus,and potassium nutrients of Chinese milk vetch.The straw and Chinese milk vetch cooperative incorporation can make the practical goal of green manure"small manure,big manure"come true.The results of this study are based on pot experiments under controlled conditions and have certain reference value for field production,but they still need to be further studied by field experiments under different conditions.To sum up,the study shows that straw returning to the field combined with nitrogen fertilizer can significantly increase the fresh grass yield and nutrient accumulation of Chinese milk vetch,and the cooperative incorporation of straw and milk vetch in the rice growing season can make increasing and stabilizing rice production,while promoting nutrient absorption and improving soil fertility.Cooperative incorporation is an important way to effectively and comprehensively utilize organic fertilizer sources such as straw and Chinese milk vetch to achieve green and sustainable development of rice production.