| This paper selects Xunxian County Yubei as the test point,the collection of the data required by DSSAT model,based on field experiment,the application of DSSAT model,design annual winter wheat summer maize test.First,the debugging of K8 wheat and maize varieties Jun Li Le 66 varieties of parameter by DSSAT,and with the simulation content,crop biomass and crop yield of farmland soil results of the fitting analysis.Analysis of two different cropping systems in northern Xunxian County area of farmland water,nitrogen and organic carbon in farmland day-to-day variation by using the validated model,and the influence between different periods of farmland water,carbon and nitrogen on Yield and crop growth.The results show that:The DSSAT model respectively.The correlation coefficients of yield of Winter Wheat in Xunxian County and the fitting error value: 0.96 and 1.12%,the quality of simulation of stem shoot(d)and correlation coefficient(R2)were 0.960 and 0.947,the variance of different soil moisture simulation(RSME)results were less than 0.1.Are ideal model;slightly underestimated the dry matter content of wheat under traditional tillage,and overestimate the soil water content in no tillage mode.The DSSAT correlation coefficient of Xunxian County summer maize yield and the error values were 0.91 and 3.2%,the D and R2 dry matter model shoots were 0.99 and 0.98,the variance of different soil moisture simulation were less than 0.1,the ideal simulation results;model underestimates the period of corn leaf area index.From the annual soil moisture and crop water use efficiency,crop evapotranspiration,crop yield index,straw mulching and no tillage on conventional tillage;from farmland evapotranspiration and soil evaporation,conventional tillage no tillage straw stalk >.The early stage of maize and wheat,soil water content increased the amount of conventional tillage > straw mulching and no tillage,mainly because the straw is not completely decomposed to absorb rainfall,increase the covering water content to reduce soil moisture.Straw returned to soil increased the content of organic carbon in the soil,and the decomposition rate of organic matter in maize and wheat was different,and the decomposition rate of organic matter was higher.The total amount of carbon in soil is due to the decomposition of soil organic carbon and withered matter decline;wheat season,soil organic carbon mineralization time mainly in the first 40 days of corn,organic carbon mineralization time from sowing until after harvest,and in maize season change is more obvious;in late wheat,because the rate of leaf the decomposition rate is higher than the withers soil organic carbon compounds wither,wither in soil organic carbon increased.The soil nitrate nitrogen in wheat and maize was about 40 days before,no tillage management after fertilization,soil nitrate nitrogen surface were significantly higher than those in conventional tillage;wheat straw returning to the mid and late management,nitrate content of 0-30 cm soil layer was lower than that of conventional tillage,maize,nitrogen the content of straw 0-100 cm soil nitrate was higher than that of conventional tillage;wheat from jointing to anthesis,maize from jointing stage to tasseling stage,is a crop of nitrogen absorption peak;straw returned to field,nitrogen assimilation of wheat in the late stage of maize is higher than that of conventional tillage;no tillage,nitrogen assimilation amount is lower than that of the traditional tillage,maize,nitrogen assimilation of no tillage was higher than that of traditional farming methods.In addition to wheat late,nitrate nitrogen and soil organic carbon in the soil of winter wheat and summer maize growth period has significant positive correlation,and the whole growth period of winter wheat and summer maize in the soil organic carbon and nitrate nitrogen and crop dry matter and nitrogen content have significant correlation the.This indicated that the carbon in the straw returned to soil increased the C/N in the soil,which promoted the absorption of nitrate in the soil. |
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