Simulation And Application Of Different Tillage Practice On Soil Water Storage In Dryland Wheat During Fallow Period Based On The APSIM Model

At present,dryland crop is mainly developed in the East of the loess plateau of China.Due to the shortage of water resources in this area agriculture depend on natural precipitation.Insufficient precipitation and strong soil evaporation lead to contradiction between the supply and demand of the farmland water in this area.Faced with this problem,crop production assessments were needed to increase crop yields by adopting appropriate tillage practice during fallow period.Dryland wheat was the main crop in dryland.Studying the water storage mechanism of different tillage practice and the effect of soil moisture changes on wheat yield were of great significance for achieving high yield and high efficiency in dryland agriculture.This study collected the wheat production data under different tillage practice from July 2009 to June 2014(five cropping season)in the Wenxi County,Shanxi Provinces.The APSIM-Wheat model was calibrated and validated by using the data of growth period,biomass,yield,leaf area index,and soil water storage of winter wheat“Yunhan 20410” under the normal farming method(CK),the subsoiling method(SS),the deep plowing method(DP)during fallow period to achieve localization of the model.Then the model was used to simulate the changes in wheat yield and soil moisture in the study area in the past 30 years,and we analyzed the effects of different tillage practices on the changes in soil water and wheat yield in wheat field under different precipitation year types.The test results are as follows:(1)Through calibrating and verifying the APSIM-Wheat model,the model can well simulate the growth and development of winter wheat and soil water storage of wheat field under different tillage practice.By the calibration and validation of the model,it can better simulate the growth and development of wheat and soil moisture in wheat fields,and then simulate the winter wheat yield and soil water of wheat field in the study area in the past 30 years.(2)During the process of calibrating the soil model of the APSIM-Wheat,we found that soil water evaporation and surface runoff can be reduced by subsoiling and deep plowing method during the fallow period to achieve water storage and conservation in the production of dryland wheat.(3)We did the simulation of wheat yield,soil water storage efficiency,water consumption of the growth period and water use efficiency of wheat under three tillage practices with different precipitation patterns during the growing period and fallow period.The results showed that the wheat yields were significantly increased by 23%,26% and 34% by the deep plowing methods in normal year,wet year and dry year,respectively,moreover the deep plowing method had the smallest coefficients of variation.Regardless of the tillage practice,the wheat yield in wet year was the highest and the coefficient of variation was small.The soil water storage efficiency of the deep plowing methods in fallow period was 25% and 10% more than that of the farming methods and subsoiling method in wet year,respectively.The soil water storage efficiency of the deep plowing method during fallow period was 49% and 44% more than that of the normal farming method and subsoiling method in dry year respectively.Regardless of the tillage practice,the soil water storage efficiency during fallow period was the lowest and the coefficient of the variation was the largest in dry year.The water consumption during the growing period was no significant difference between different tillage practice in different precipitation patterns.When the tillage practice was not considered,the water consumption during the growing period in different precipitation patterns had significant differences,with the highest in wet year,the lowest but the largest coefficient of variation in dry year.Water use efficiency of the deep plowing methods were significantly increased by 20%,11% and 21% during the growing period in normal year,wet year and dry year,respectively.(4)We analyzed the simulation results of wheat yield,soil water storage efficiency,water consumption of the growth period and water use efficiency of wheat under three tillage practice with different precipitation patterns during fallow period.The results revealed that the wheat yields of the deep plowing method were significantly increased by 36%,25% and 31% in normal year,wet year and dry year,respectively moreover the deep plowing method had the smallest coefficient of variation.The soil water storage efficiency of the deep plowing method was 29% more than that of the normal farming method during fallow period.In wet year,the soil water storage efficiency of the deep plowing method was 25% and 10% more than that of the farming method and the subsoiling method during fallow period respectively.In dry year,the soil water storage efficiency of the deep plowing method was 35% and 23% more than that of the normal farming method and subsoiling method during fallow period,respectively.The water consumption of the deep plowing method during the growing period was 17% and 10% more than that of the farming method and the subsoiling method in normal year,respectively.In wet year,the water consumption of the deep plowing method during the growing period was 11% more than that of the normal farming method.In dry year,the water consumption of the growing period was no significant difference between the different tillage practice.Water use efficiency of the deep plowing method during the growing period were significantly increased by 20%,13% and 22% in normal year,wet year and dry year,respectively.In conclusion,no matter during the growing period with fallow period or only during fallow period,the deep plowing method improved the soil water storage efficiency during fallow period and water use efficiency of the growing period in normal year,wet year and dry year,thus the wheat yield of the deep plowing method was more than that of the normal farming method or the subsoiling method.The deep plowing method has the best effect of improving soil water storage,soil moisture retention and crop yield increase,which is a suitable farming practice during fallow period for dryland wheat field in the south of Shanxi province.