Effect Of Long-term Different Fertilization Treatments On Soil Hydraulic Properties,Winter Wheat Yields And Farmland Water Balance

Soil hydraulic properties determine the ability of soil to retain water and conduct water,which in turn affects the processes of soil water movement and crop production,and is a key factor in maintaining sustainable agricultural development.Rational fertilization is of great significance to improve water use efficiency and grain yield and to take effective control measures according to local conditions.From the 36-year long-term fertilization experiments conducted at Changwu Agri-ecosystem station in the Loess Plateau,four different fertilization treatments were chosenanalyzed,including no fertilization(CK),chemical fertilization with nitrogen and phosphorus(NP),manure fertilization(M),and comprehensive fertilization with nitrogen,phosphorus and manure(NPM).The differences among soil hydraulic properties,winter wheat yield,and farmland water balance were analyzed between different fertilization treatments.The main conclusions were as follows:(1)NPM and M significantly increased organic matter content in the soil surface layer(0-20 cm)compared with CK,and NPM had better effect;long-term single application of NP increased soil bulk density and reduced soil porosity of the surface layer(0-20 cm);all fertilization treatments effectively improved water holding,among which,the NPM and M significantly increased the field capacity and available water holding in the 0-20 cm soil layer,and saturated hydraulic conductivity of 0-30 cm soil layer.Different fertilization treatments had no significant effect on the physical properties of 30-40 cm soil layer.(2)All fertilization treatments increased the yield of winter wheat,and NPM increased the yield most significantly.M has the highest yield rate,and the gap between the NP and the NPM gradually narrowed.While increasing yield,it also increases interannual yield variations.There was no significant difference in the effect of the long-term climate trend on the yield of winter wheat among four fertilization treatments.Among the meteorological factors that have a significant impact on yield,the precipitation during the growth period,the average relative humidity and the annual production precipitation,and the average relative humidity are positively correlated with the winter wheat yield.Hours are negatively correlated,and together they explain the response of yield to interannual meteorological variability.(3)Based on the data of soil particle size distribution,saturated water content,field capacity and wilting point,three different types of empirical models were used to calculate the saturated hydraulic conductivity for three typical soils in the Loess Plateau(Lou soil,Helu soil and Huangmian soil),and it was found that the Kozeny-Carman model was suitable for the sandy loam soil of the Loess Plateau,and the Van Genuchten model Suitable for Loess Plateau loamy clay and clay loam.(4)The optimized Hydrus-1D model can simulate water balance elements of winter wheat farmland in loess plateau well.The simulation results showed that the water revenue and expenditure of winter wheat farmland under each fertilization treatment in the past 35 years had basically maintained a dynamic balance.The trend of evapotranspiration,infiltration and soil water content were basically the same as precipitation.Among them,evapotranspiration was the main form of farmland water consumption.NP,M and NPM increased farmland evapotranspiration,reduced deep seepage,and effectively improved the water use efficiency of winter wheat at the same time,which also led to a decrease in soil water storage.