Research On Growth Simulation Of Winter Wheat-summer Maize Rotation System And Optimization Of The Irrigation And Fertilization System In The Guanzhong Plain

The Guanzhong Plain area is an important grain production area in China,and the technical requirements for the sustainable development of grain in this area are urgent.Water and nitrogen fertilizers are two key factors in agricultural production.In order to achieve a stable water- fertilizer-saving,irrigation fertilization technology application and demonstration in this area.In this study,the Wugong area of Baojixia irrigation area in Guanzhong Plain was taken as the study area.With the winter wheat and summer maize planted in this area as the research object,the DSSAT model(DSSAT-CERES-Wheat;DSSAT-CERES-Maize)was used to study and analyze the winter wheat and summer maize of the optimal sowing date,the key requirement water and fertility period in the growing season,and at the same time,the amount of nitrogen applied to water-saving joint fertilizers for winter wheat and summer maize under the typical precipitation year(wet year,general year,and drought year)was investigated.The amount of nitrogen applied in irrigation during the production practice in the study area was used to estimate the maximum potential for water and fertilizer saving in the area.The main results of this study were shown as follows:(1)From October 2015 to October 2017,in the Wugong region of Guanzhong Plain,experiments were conducted to investigate the effects of different levels of nitrogen fertilization on the growth and yield of winter wheat and summer maize.Studies have shown that a reasonable increase in the amount of nitrogen applied to irrigation can increase the yield of winter wheat and summer corn.Final yield,plant height,leaf area index,aboveground biomass,and growth period.(2)Based on the measured data,the DSSAT model was established and calibrated to lay the foundation for the later simulation test.The comparative analysis of the relative errors between the measured values and the simulated values of the final yield of winter wheat and summer maize shows that the established DSSAT model and the corresponding genetic parameters have higher credibility.(3)For the winter wheat and summer maize rotation system in the plain area of Guanzhong River,Shaanxi,the best time for winter wheat and summer maize planting was October and mid-June respectively;the best combination of time for irrigation and fertilization of winter wheat and summer maize in the plain area of Weihe River valley in Shaanxi was WGJ(Wintering,returning greening and jointing)and JH(joining and heading)are based on actual production conditions in the study area of the study area and can be selected on an as-needed basis.(4)Using precipitation data from the period of 1961 to 2015 and the past 55 years in this area,wavelet analysis,climatic bias rate,and R/S analysis method were used to analyze the characteristics of precipitation in the area.Research shows that 11,6 and 18 a are the three major cycles of the annual precipitation time series respectively.In the region,the precipitation rate of annual,the precipitation rate of winter wheat season and summer maize season was-1.734,-8.775,8.074 mm/10 a,and the coefficient of variation was 0.3,0.4,and 0.2 respectively;the seasonal precipitation of summer maize in this area accounted for the annual precipitation.The proportion is large,with a maximum of 79.97%.According to the calibrated DSSAT model,a preliminary simulation was conducted to estimate the amount of nitrogen applied to water- fertilizer-saving of the amount water-nitrogen that is suitable for the typical winter wheat and summer maize production in the study area.And preliminary estimates of the largest potential of water-fertilizers-saving in the region,shows that the potential for water-fertilizes-rsaving is very large.It should be pointed out that although this study was based on field experiments and crop model simulations,have obtained suitable for winter wheat and summer maize rotation system of the best sowing date can be used in Guanzhong Plain,the optimal dates for fertigation and the amount of water-fertilizer-saving for water nitrogen applied.Limited by time,condition and individual ability,there are still some deficiencies: There are many factors affecting the growth period of summer wheat and summer maize;Simulation studies have not considered the impact of pests,freezing damages and farming methods,so that the crop simulation yield is greater;The small differences among crop cultivars,the considerations for crop rotation are preliminary,the amount of nitrogen applied has little effect on the simulated yield.It is hoped that in-depth studies on these aspects can be conducted in the future.