Effects Of Organic Fertilizer Application On Winter Wheat Yield And Its Economic And Environmental Benefits In The Dry Land Of The Loess Plateau

Due to the drought of soil and insufficient precipitation in the Loess Plateau,the yield of wheat in dryland has encountered a bottleneck.Since the beginning of the last century,the application of chemical fertilizer has been increased,which has not significantly increased the yield of winter wheat and improved the water use efficiency of winter wheat.On the contrary,it has caused a series of environmental problems,such as groundwater eutrophication,Greenhouse Effect enhancement and so on.Application of organic and inorganic fertilizer can significantly improve soil quality and improve nutrient and water efficiency.Therefore,four kinds of organic fertilizer gradients were designed to analyze the effects of different amounts of organic fertilizer on winter wheat yield and water use efficiency in dryland farmland in loess plateau region,and to analyze and evaluate their economic and environmental benefits.In order to clarify the effect of organic fertilizer on yield,economic benefit and environmental benefit of winter wheat in dryland farmland under the current yield and economic level,so as to establish a combined application system of organic fertilizer suitable for local scientific development.The main results of the paper are as follows:1.After comparing the three-year data on average,the average yield was increased by12.8%,17.6%,17.9%and water use efficiency by 3.0%,7.0%and 6.1%,respectively,on the premise of applying different gradient organic fertilizer treatments and reducing the application amount of nitrogen fertilizer.At the same time,the application of organic fertilizer significantly increased the root distribution of winter wheat in the underground,increased the utilization of water and nutrients in the deep soil（60 cm～150 cm）,made up for the soil water deficit caused by local climate drought and insufficient rainfall,which was beneficial to the stable growth of winter wheat aboveground population and improved the environmental stress resistance of winter wheat.Under the current winter wheat yield level of dryland farmland on the Loess Plateau,the application of organic fertilizer can still improve the yield and water use efficiency of winter wheat in dryland farmland.Reducing the amount of nitrogen fertilizer and adding a certain amount of organic fertilizer in the process of agricultural production is a management model suitable for the development of dryland farmland in loess plateau area.2.By comparing and analyzing the data of three years,it can be seen that with the increase of the amount of organic fertilizer applied,the cost input in the early stage was also increased.Considering the input-output ratio of farmers,the economic benefit of applying a small amount of organic fertilizer（N150+M5t）for a long time will be higher.That is,the recommended amount of organic fertilizer for dryland farmland in loess plateau is about5 t/km².3.By comparing the data of the last two years,after the application of organic fertilizer,the dryland farmland ecosystem of the Loess Plateau showed the effect of carbon"sink",which reflected the net absorption of CO₂ and slowed down Greenhouse Effect.However,the comprehensive warming potential（GWP）was greatly affected by water,and there was no significant change among the treatments after the application of organic fertilizer.After the application of organic fertilizer,the wheat yield was increased,thus effectively reducing the greenhouse gas emission intensity（GHGI）of the farmland.The wheat produced per unit yield had little effect on the atmospheric ecological environment system after applying a certain amount of organic fertilizer to dryland farmland in loess plateau area..The results showed that the long-term application of a small amount of organic fertilizer in dryland farmland in loess plateau region could promote the yield increase of winter wheat and realize the unity of economic and environmental benefits of winter wheat.It can be used as a recommended crop management model for dryland farmland in loess plateau area.However,the specific relationship between organic fertilizer application and greenhouse gas emissions still needs to be further explored by long-term positioning test.