Effects Of Tillage And Straw Application Modes On The Improvement Of Topsoil Quality In The TuMoChuan Plain Irrigated Area

There were some problem in soil that organic matter content of cultivated soil gradually reduced,layer soil was shallow,plough layer was thickness,water and nutrient retention of the top-soil was poor,and sustainable production ability reduced in Inner Mongolia.Therefore,the objective of the study was to explore the effect of different tillage and straw application modes on soil quality,and to elucidate the improvement mechanism,through measuring and analyzing of soil physical and chemical properties of different treatments.The results will provide theoretical support for the local government to adopt suitable straw application measures to improve and protect the soil quality of cultivated land.The research results show below:(1)Rapid available phosphorus is the most important index of soil quality evaluation in the irrigation area of TuMoChuan plain.There were markedly difference in soil evaluation indexes among treatments,the overall performance was deep plough(DP)0.70>deep spinning with straw returning(SCR)0.63>no-tillage with straw mulching(NTR)0.56>deep spining(SC)0.55>no-tillage(NT)0.52>shallow rotary tillage(RT)0.46>deep scarification with straw returnning(SSR)0.44>deep plough with straw turnover(DPR)0.40>deep scarification(SS)0.34.Compare with RT,DP soil quality improved 52.17%.(2)SS and DP had significantly reduced soil bulk density and increased soil porosity,especially during silking stage.Soil bulk density of both were respectively 8.55%and 16.3%lower than that of RT at 15-30cm layer,and the soil porosity increased by 14.16%and 27.00%compared with the control.There was a similar trend to the coupled straw mulching mode.SC,SS,DP,NT and the corresponding straw application modes can significantly improve soil moisture content in 0-100cm depth at the big mouth stage of maize,which showed NTR>SCR>DPR>SSR>DPR>DP>NT>SC>SS>RT.Compared with RT,NTR significantly improved moisture content of 0-20cm?20-40cm?40-60cm?60-80cm and 80-100cm by 75.67%,86.68%,65.03%,74.65%,18.57%,respectively.SS and DP could effectively reduce compactness of the soil layer,the SS and DP treatments during silking stage were respectively 25.83%,35.47%lower than the RT treatments.DP could effectively reduce the proportion of soil solids and increase the proportion of liquid,so that the soil three-phase could be closer to the ideal ratio(2:1:1)than other tillage treatments.NTR and SCR also had the function of coordinating the soil ratio.(3)Different tillage methods and straw returning patterns have obvious effects on soil nutrient content.The content of organic matter in SSR,DPR,SS,NT and DP treatment was 37.35%,33.18%,32.82%,22.14%and 4.37%higher than that in control RT,respectively.The alkali-hydrolyzed nitrogen content of SC,SS,DP,NT and their related straw returning treatments increased compared with the control RT,NT and NTR increased most significantly,165.16%and 103.10%respectively.The content of available potassium in all tillage treatments except NT treatment was higher than that in RT treatment,and the effect of straw returning on accumulation of available potassium was obvious.Compared with RT,the content of available phosphorus in SC,NT,NTR,SCR and DP treatment increased significantly by 95.39%,48.42%,54.73%,41.38%and 44.21%,respectively.(4)The significant improvement of fertilizer retention capacity for SS and SSR,the actual cation exchange capacity of them increased by 112.9%and 74.93%,respectively,compared with that of RT.