Study On The Temporal Variability And Control Mode Of Soil Water And Nitrogen About Grain Field In Yellow River Irrigation Areas

At present,the agriculture development is faced withirrigation water use efficiency low,available water reduce continuously,non-point source pollution serious,land degradation intensify in Yellow River irrigation area.Scientific and efficient use of the Yellow River water resources, increase efficiency of nitrogen are the inevitable choice of construction of ecological water-saving irrigation area.Against these existing problems,promote the development of water-saving ecological agriculture,The paper adopt field investigation,monitor, experiment and numerical simulation method,study on the ecological environment effects of Yellow River water and well water ,water changes and evapotranspiration ,space variation of water and nitrogen in surface irrigation fertilization .this research play an important role in improving the surface fertilization system design,management,evaluation,and selecting reasonable scientific regulation model of soil water and nitrogen.The main conclusions are as follows:The change of Yellow River water's temperature is great,a concentration of nitrogen is high, powder is the main portion of suspended particles,which are beneficial to the improvement of soil particle composition and yield of wheat.The water content of field soil is mainly between 0.1 and 0.30 of winter wheat and summer maize in the years of 2015 and 2016.The deeper the depth,the smaller the change in time of water content,the same depth varies has consistency over time,and all have different levels of deep leakage at four times irrigation.Along the direction of border lengthwise,the variability of evapotranspiration at six observation point is large,but the change in time have consistency.The average daily evapotranspiration is 0.75-5.69mm,total evapotranspiration is 350.17mm,and crop coefficient is 1.05 after regeneration of winter wheat.The average daily evapotranspiration is 1.02-6.25mm,total evapotranspiration is 340.459mm,and crop coefficient is 1.20 after shooting period of summer maize.The long border's irrigation time and acceptance water time multiples than the shorter , the shorter More saving water, more uniform. Organic nitrogen to total nitrogen in water by 71% to 89%, nitrogen mainly exists in the form of organic nitrogen. Under the influence of flow velocity, it is obvious of the washing in the border's front and the accumulation in the back of nitrogen in scattering, and the coefficient of correlation of concentrations of total nitrogen,Organic nitrogen ,ammonium and nitrate along the border lengthwise in surface water and distance are greater than 0.8, which is high correlation .The fertigation of the spatial and temporal variability is less than the broadcast .Which can improve the uniformity of nitrogen in surface water.Soil quality moisture content decrease continuously of short border along the soil profile after irrigation,The uniformity of water content is 97-98%,The depth of the supply is 70cm approximately.The cumulative amount of water content Along the direction of border lengthwise in short border is 100m>75m>50m>0m>25m>125m>150m.The change of soil quality moisture content along the soil profile after irrigation in long border is seldom.and the uniformity of water content is 97-98%,have deep leakage.Under the concentration of nitrate nitrogen is relatively high before irrigation, leaching losses at surface layer is serious after irrigation,and the depth is 40cm.The concentration at surface layer is fertigation under short border>broadcast under short border>fertigation under long border>broadcast under long border. In the long border,the transfer depth of nitrate nitrogen is greater than the shorter.Broadcast has the characteristics of a lower nitrogen nitrogen concentration in the border's front and a higher concentration in the back. Fertigation can improve the uniformity of nitrogen in soil.In the years of 2015 and 2016 ,it is better that two irrigation quotas after regeneration of winter wheat are 50m3/mu,and,two irrigation quotas after squaring period of summer maize are 55m3/mu.On the basis of field test parameters,it is calculated of length of border check is 179.17m...