| The world population is increasing rapidly,the food security problem is becoming increasingly prominent,and the ecological environment is destroyed,which are the major problems facing human beings at present.On the premise of ensuring the food security,reducing environmental pollution and improving the efficiency of resource utilization are conducive to the sustainable development of agricultural production.Low soil fertility and excessive fertilizer application coexist in the semi-humid and semi-arid winter wheat area on the Loess Plateau.In summer when rain and heat are concentrated in this area,there is a tradition of leisure.Can the purpose of improving soil fertility,reducing fertilizer use,and making full use of water,nutrients and light and heat resources be achieved by planting and pressing legumes green fertilizer in summer?Based on long-term trial in Changwu County,Shaanxi Province,the study of leisure during summer planting leguminous green manure(huai bean,soybean,mung bean and leisure,leisure for reference)and wheat growing season different n application(0,108,135,and 162 kg/hm~2)on winter wheat growth and yield,nutrient absorption and the influence of wheat field soil organic carbon and total nitrogen,aimed at further proven leguminous green manure reduce nitrogen fertilizer,improve wheat yield and soil fertility,the loess plateau area of farmland ecosystem green sustainable development.Main results are showed as listed:(1)Planting and turning over legume green fertilizer can provide nutrient resources to the soil.The biomass of green fertilizer returned to the field can reach 1083-3764 kg/hm~2.The biomass is related to the type of green fertilizer and the rainfall during the growth period.The nutrient return rate of green fertilizer was consistent with the biomass results,and the nitrogen return rate was up to 32.2-98.4 kg/hm~2.(2)During the 10 years(2008-2018)of the positioning test,in wet four years of green manure treatment could significantly increase wheat yield,in dry three years of green manure treatment resulted in wheat yield reduction,and there was no significant difference between three years of green manure treatment and leisure treatment.From 2016 to 2018,the planting of leguminous green fertilizer increased the number of ears and grains per ear of wheat,decreased the 1000-grain weight of wheat,and finally had no significant effect on the grain yield of wheat.Leguminous green fertilizer had no significant effect on nitrogen uptake of grain,stem and leaf and total nitrogen uptake of aboveground,but it had a tendency to increase the nitrogen harvest index of wheat.Nitrogen fertilizer application significantly increased wheat yield in both leisure and planting leguminous green manure,but there was no significant difference in wheat yield among the three treatments,indicating that there was great potential for nitrogen fertilizer application reduction in wheat in the North Weihe plateau.(3)Years of planting leguminous green fertilizer significantly increased the contents of organic carbon and total nitrogen in the soil 0-20 cm,and the contents of organic carbon and total nitrogen in the soil 20-40 cm long also showed an increasing trend,but had no significant influence on the contents of organic carbon and total nitrogen in the soil 40-60 cm long.Planting and turning over leguminous green fertilizer may have the potential to increase organic carbon and total nitrogen content in subsurface soil.(4)planting leguminous green manure can consume soil residual nitrogen after wheat harvest,and result in green manure turn green manure treatment before pressure 0 to 40 cm soil layer of soil nitrate-N content was significantly lower than follow treatment,but the green manure decomposing and turned down three weeks after the content of soil nitrate-N and leisure with no difference,in green manure treatment after wheat harvest of nitrate residue were significantly higher than leisure.The nitrogen input and output of green fertilizer treatment were significantly higher than that of leisure treatment,but there was no significant difference in the final result of nitrogen balance.In conclusion,planting and turning over leguminous green manure during summer leisure time in the Weibei dry tableland could significantly increase wheat yield and soil organic carbon and total nitrogen content of 0-20 cm in wet years.The application of n fertilizer can significantly increase wheat yield and soil total n content,and the area has the potential to reduce n application. |
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