| The Loess Plateau region of Longzhong is an important food production base in northwest C hina and one of the most serious areas of soil erosion in the world,Low precipitation,strong evaporation,unequal season distribution,and long-term artificially unreasonable farming all contribute to the fact that spring wheat production in the region has been low and unstable.In order to improve the local crop yield,improve the utilization of limited rainfall resources,reduce the loss of water and soil resources,and improve the ecological environment,this study was based on field trial data of spring wheat yield and soil moisture content under different farming practices in 2016 and 2017 of the Dry Farm Comprehensive Experiment Station of Gansu Agricultural University in Anjiapo Village of Anding District,Dingxi C ity,Gansu Province,C hina,the DSSAT-Wheat model parameters were tested and verified,and the applicability of the model in the LOESS plateau region was evaluated.The yield and soil water content of spring wheat under traditional tillage(T),traditional tillage + straw mulching(TS),no-tillage(NT)and no-tillage + straw mulching(NTS)in 2017 were simulated by using the verified model.The soil water use efficiency and yield of spring wheat from 1987 to 2016 under four different tillage measures were simulated and analyzed,the results showed that:1.The relative error between the measured values and the simulated values of the main growth period of spring wheat in the Loess Plateau of Gansu Province is within 5%.The normalized mean square root error(n RMSE)of the yield simulation is within the range of 8.89%-10.98%,the MRE value is within the range of 8.51%-9.90%,and the n RMSE value of the soil water content in the whole soil section is 10.39%,and the value of the soil water content in the whole soil section is 5%.In the range of 10.39%-14.91%,the accuracy of model simulation is high,the measured values are in good agreement with the simulated values,and the simulation results are very good.That is,the simulated DSSAT crop growth simulation model has good applicability to the growth and development of spring wheat in the Loess Plateau of Gansu Province.2.The dynamic changes of soil water content in different growth periods of spring wheat under four kinds of tillage measures in 2017 were analyzed.The results showed that the soil moisture content under the four farming measures of 0-20 cm layer was NTS>T>TS>NT.The soil water content in the 20-40 cm layer was NTS>TS>T>NT.NTS could significantly increase the soil moisture content of 0-40 cm soil layer in spring wheat in semi-arid area.3.The DSSAT model was used to comprehensively analyze the changes of 30 years soil moisture content in the 0-40 cm layer.The long-term effects of four different farming practices on the soil moisture of spring wheat farm were simulated.The results showed that under the same year type,NTS soil water use efficiency and stability were higher than the other three farming practices.The order of soil water use efficiency for spring wheat was: NTS> TS> N T>T,indicating that straw coverage significantly increased crop water use effic iency and reduced surface evaporation to maintain the stability of soil moisture.The vertical variation of soil moisture in the four cropping practices was similar(NTS>TS>NT>T)regardless of whether the dry season or the abundance year,and the vertical variation of the soil moisture content gradually decreased from top to bottom and showed obvious.4.Using the DSSAT model to analyze the stability of spring wheat yield and yield under three different precipitation years in 30 years,the study found that the annual average yield of spring wheat under the three precipitation types is: NTS> TS> NT>T,indicates that the yield of no-tillage+straw-covered spring wheat is higher than that of the other three tillage measures in any precipitation type,and the stability of NTS is higher than the other three types of tillage measures. |
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