Simulation Of Maize Yield , Soil Water Content And Nutrient Content Under No Tillage And Conventional Tillage Managements In Northwest Shanxi

Different tillage managements can impact the soil water-heat and nutrient process.Unreasonable tillage management can cause the crop yield reduction,soil and water resources loss and environmental pollution issues.Therefore,researching the effects of tillage managements on crop growth and yields,soil water and nutrient dynamics,which can provide theoretical foundation for developing the best management,practice,improving the crop yields and soil situations,maintaining the healthy environment.In this study,Conventional tillage?CT?and No-tillage with straw mulching?NTS?treatments were carried out during 2014-2016.The field experiments data and Crop System Module?CSM?in Decision Support System for Agrotechonlogy Transfer?DSSAT?model were both used to evaluate the effects of CT and NTS managements on maize yield,crop growth,soil water and nutrients.The main results as follows:?1?The results showed that the measured maize yield under CT is higher than that under NTS treatment.The maize variety parameters were obtained through trial and error method,DSSAT CSM-CERES-Maize model were successfully calibrated by using the measured maize grain yield and leaf area index?LAI?data of CT treatment.Excellent agreement between the simulated and measured maize grain yield(n RMSE = 0.02 %,E =-0.67 kg·hm^-2,d = 1.00),good simulated LAI were also achieved compared with the measured data for CT treatment.The model was successfully validated under NTS treatment with the statistics of n RMSE,E and d equal to 0.79 %,-34 kg·hm^-2 and 1.00 respectively.The agreements between the simulated and measured LAI were lowed under NTS than those of under CT treatment during 2014-2016.Results above showed that the model can be using to well simulate maize grain yield and growth in northwestern Shanxi.?2?The soil water content decreased with the soil depth increasing for both CT and NTS treatments.The simulations of average soil water content were higher than the measurements under both CT and NTS treatments for all soil layer depths,and the average error E ranged from 0 to 0.04 cm³·cm^-3,but no statistical difference between the simulated and measured values were found,especially for the 80-100 cm soil layer depths,better simulations agreement were achieved with the measurements for NTS treatment.The water use efficiency?WUE?was highest in 2015,reaching 43.5 % under CT treatment,while 24.8 % under NTS treatment,indicating that WUE was mainly affected by tillage managements.The water use efficiencies of NTS decreased by 10.5 %,18.7 %,and 10.0 %,respectively compared with CT.?3?The soil mineral nitrogen content increased obviously after the fertilizer was applied in 2015-2016,but returned to a stable state in a short time.The simulation values were lower than the measured values for both tillage managements.The agreements between the simulated and measured soil mineral nitrogen contents in 2015 were better than those of 2016 for CT treatment,especially for 20-60 cm soil layer depth.For the NTS treatment,better agreements between the simulated and measured values for all soil layer depths in 2015 were achieved than those of 2016.The model simulated results showed that no significant differences between the two treatments for both the litter organic carbon storage and soil total organic carbon content during 2014-2016.The litter organic carbon storage and the soil total organic carbon content showed the same varied trend as the "M" type during 2014-2016.It indicated that the No tillage with straw mulching did not increase the soil organic carbon content in a short period of time.?4?The correlation between soil moisture content,nutrient and corn yield were analyzed.Results showed that the aboveground dry matter accumulation was significantly correlated with crop transpiration and soil nitrogen mineralization at the emergence stage,the correlation coefficients were 0.784 and 0.322,respectively.The main factors affecting the maize growth during the jointing stage were crop transpiration and soil nitrogen mineralization.There was a significant positive correlation between the aboveground dry matter accumulation with soil moisture,aboveground dry matter accumulation and accumulated nitrogen mineralization,and a significant negative correlation with soil organic carbon content during the tasseling period.There was a significant negative correlation between crop transpiration and soil moisture content,cumulative nitrogen mineralization and soil organic carbon content were found as well during the tasseling period.During the harvest period,the aboveground dry matter accumulation was significantly negatively correlated with crop transpiration.However a significant positive correlation were found between the aboveground dry matter accumulation with soil water content,cumulative nitrogen mineralization,soil organic carbon content and maize yield.The traditional tillage method is more suitable for the northwestern Shanxi region in a shorter period of time.The protective tillage has little effect on the physical and chemical properties of the soil in a short period of time.The model can simulate corn yield very well in northwestern Shanxi,the soil moisture simulation effect is better,the simulated value is higher than the measured value,the simulation effect on soil nutrient is poor.The results of model application showed that the water use efficiency of maize was the highest in dry years,and the water use efficiency under traditional tillage was higher than that of conservation tillage.