| Now in rice production,the blind pursuit of high yield,high volume or excessive use of chemical fertilizer,not only to improve rice yields,but lead to unnecessary increase of investment,brought such as rice quality is not high and the farmland nitrogen utilization rate is low,a series of problems of environmental pollution etc.Therefore,ensure that the yield of rice is not reduced on the premise of improving the utilization rate of nitrogen fertilizer and make full use of nitrogen fertilizer,it is an attention and research topic in the process of current cultivation of rice.As a main winter green manure in China's southern rice region,Chinese milk vetch has a strong ability of nitrogen fixation and high nitrogen utilization efficiency,the decomposition of plant body was helpful to improve soil nitrogen content,so it is better than common vetch,bean green manure crops for aftercrop yield under the condition of equal nitrogen,As the organic fertilizer,it can effectively supply the soil available nitrogen,reduce the usage of nitrogenous fertilizer,rich and balance soil nutrients,improve soil physical properties,increase crop yield,balance and adjust crop absorption of nitrogen and phosphorus,potassium and trace elements,improve the quality of agricultural products,so it plays an important role on the maintenance of soil nitrogen cycle in the ecological farmland system of southern China.As the representative of green manure,planning Chinese milk vetch in the area of winter fallow land,it has a great significance for the protection of national food security,improve the quality of the environment and agricultural sustainable development.The rescarch on September of 2014 to November 2016,carried out the experiment in Jiangxi Agricultural University Science and Technology Park experimental field and Yujiang county agricultural experiment field respectively.The results of the study are as follows:(1)Compared with the conventional nitrogen,after returnning Chinese milk vetch,reduce 20%nitrogen fertilizer of rice tillering increased by 11.92%,the number of panicles increased 1.92%,rice yield increased by 5.62%,reduce 40%nitrogen after nitrogen can not achieve the purpose of increasing production,but can maintain the single nitrogen of rice yield.The single application of Chinese milk vetch or reduce 60%nitrogen fertilizer can significantly reduce rice yield.(2)At the early stage of Astragalus sinicus straw decomposition,nitrogen is one of the key factors affecting nutrient release,the appropriate amount of nitrogen fertilizer can promote Chinese milk vetch decomposition and nitrogen release;Astragalus sinicus straw and nitrogen fertilizer could significantly increase soil available nitrogen,total nitrogen,mineral nitrogen content,improving soil nitrogen pool of active ingredients and soil nitrogen supplying capacity milk vetch;nitrogen release rate,rice at booting stage rice nitrogen uptake and soil total nitrogen and available nitrogen are correlated significantly.(3)Compared with the fallow treatment,Chinese milk vetch nitrogen fertilizer per panicle of rice increased by an average of 1 8.86%;milk vetch mulching and nitrogen under the nitrogen yield of rice increased by an average of 23.04%,with conventional nitrogen treatment was the highest,with an average increase of 25.52%,followed by nitrogen optimization of nitrogen treatment,with an average increase of 23.81%,two those were significantly higher than that of fallow and conventional treatment;nitrogen and nitrogen optimization compared with two treatments,the high amount of nitrogen treatments on rice yield decreased,a decline of 4.13%?6.25%.Rice brown rice rate,milled rice rate to optimize nitrogen treatment was the highest,and other than the roughness,an increase of 0.85%?1.59%,milled rice rate,an increase of 1.30%?4.15%,significantly higher than that of winter fallow treatment and single application of Chinese milk vetch Astragalus treatment;Compared with the fallow treatment,winter vetch under each treatment rice amylose content was declined,a decline of 0.56%?2.26%,and the single application of Chinese milk vetch treatment compared with Chinese milk vetch and nitrogen rice amylose content also declined,a decline of 0.29%?1.71%.(4)The 2 year test results show that,compared with the winter fallow treatment,early rice dry weight of Chinese milk vetch treatment increased 15.57%?36.21%,the late rice for 14.41%?24.89%,nitrogen absorption increased about 60.24%?93.04%,compared with the single application of Chinese milk vetch,early rice dry weight of Chinese rice milk vetch with nitrogen fertilizer increased 20.14%?28.35%,late rice increased 14.7%?18.07%;average nitrogen uptake increased 40.73%?69.53%;Nitrogen recovery efficiency,agronomic efficiency and nitrogen partial productivity of optimization nitrogen were the highest,increased by 43.18%,64.55%,56.14%than conventional nitrogen respectively,is suitable rice mode about Chinese milk vetch application in Jiangxi province.(5)The soil proportion of Chinese milk vetch treatment average declined 2.54%,and the proportion soil of Chinese milk vetch with fertilizer treatment declined 2.81%;after planing Chinese milk vetch,the total soil porosity increased by 2.20%?7.00%,compared with 2015 late rice,late rice in 2016the soil total porosity of all treatment were increased of 1.78%?7.89%;The particle size of 5mm was the highest in the conventional nitrogen treatment,compared with the fallow treatment increased by 9.02%,3 particle size aggregates of 2?5 mm,1?2 mm and the number of 0.5?2 mm of Chinese milk vetch with nitrogen were higher than that in winter,the number of 1?2mm of medium size aggregates than in winter fallow treatment high 1.81%?2.61%;Compared with the 2015 rice fallow treatment,soil organic matter of winter fallow treatment decreased by 2.74%,single application of Chinese milk vetch treatment decreased by 1.34%,Chinese milk vetch of optimization nitrogen,conventional nitrogen,high nitrogen were increased by 7.47%,11.28%,12.69%respectively;Compared with the winter fallow treatment and single application of milk vetch treatment,optimized nitrogen treatment soil alkali hydrolyzable nitrogen improved 20.87%and 14.88%respectively;Winter milk vetch could significantly improve soil nitrogen,available phosphorus,available potassium content,but after planting rice,soil available phosphorus and potassium will be reduced.(6)Compared with fallow and no nitrogen application,the single application of Chinese milk vetch could significantly increase soil total organic carbon and labile organic carbon content,under the single application of milk vetch treatment,soil total organic carbon content increased by 13.72%,active organic carbon content increased by 21.55%.The change of soil labile organic carbon was more sensitive to soil organic carbon,which could indicate the change of soil quality.Compared with the fallow treatment,Chinese milk vetch increased soil microbial biomass carbon content,the average increase-was 69.95%,microbial quotient increased 15.64%?79.54%,carbon pool index increasedby 1.45%?13.56%,compared with the single application of Chinese milk vetch,soil microbial biomass carbon and nitrogen fertilizer treatment of Chinese milk vetch increased by 82.76%on average,microbial quotient increased 36.60%?55.19%,but microbial quotient declined of 1.97%?13.61%.(7)N2O emission of high nitrogen application is the highest,compared with the fallow treatment,increased by 69.90%,compared with the single application of Chinese milkvetch,increased by 38.89%;Compared with the increase of winter fallow treatment,total CH4 emissions of Chinese milk vetch treatments increased by 26.04%?111.12%,CO2 emissions increased by 45.84%-83.88%,compared with the single application of Chinese milk vetch,Chinese milk vetch with nitrogen CH4 emissions increased 44.75%?67.51%,CO2 emissions increased by 12.91%?26.08%;From the comprehensive emission greenhouse effect of N2O and CH4,global warming potential of fallow treatment is lowest,global warming potential of N2O and CH4 increased gradually with the increase of nitrogen and high nitrogen treatments under greenhouse gas emissions intensity is highest,69.77%higher than fallow treatment,compared with the single application of Chinese milk vetch treatment 11.83%,compared with the conventional nitrogen,optimization of nitrogen fertilization had no significant effecton rice yield,but can reduce the total emissions of CO2 and CHa,is conducive to energy saving and emission reduction in paddy field.(8)Compared with the fallow treatment,under treatment of single Chinese milk vetch,agricultural products total output increased 7.56%?20.83%,gas regulation functioan increased 21.64%?37.61%,soil conservation value increased 4.27%?13.86%,total value of ecosystem services increase in 14.23%?38.65%,the effect is more bentter especially Chinese milk vetch cooperation with fertilizer,under the optimization nitrogen,the total value of agricultural product supply,ratio of output to input,gas regulation value,functional value,conservation of water and soil conservation value were the highest;in the total value of ecosystem services in paddy field,the supply of agricultural products occupies the dominant position,proportion is 39.16%?46.43%,the functional value of gas regulation value,proportion is 36.39%?39.05%,soil nutrient accumulation function value,soil conservation value,conservation of water and soil the function value of the proportion were smaller,proportion is 16.90%?22.37%. |
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