| A field experiment has been conducted by split-plot design with straw returning and no straw returning as the main factor,deep plough,rotational tillage and no tillage as the subplot,to explore the conservation tillage on winter wheat-summer maize field soil physical and chemical characteristics,water and nitrogen use efficiency,crop growth and development and yield in 2015-2017.The results showed that:Soil bulk density has been increased in deep soil than in surface soil,while soil water infiltration rate,soil total nitrogen content and soil organic carbon content has been devreased along with soil depth.Straw returning decreased soil bulk density for 0.02~0.04 g.cm-3.Straw returning significantly increased soil water infiltration rate and soil temperature when compared with no straw returning,but straw returning was not showed significant effect on soil nutrition content.NT obtained the highest soil bulk density,the lowest soil infiltration rate.The soil total nitrogen content was higher in RT and NT than in DT.Soil temperature showed a trend with initial decrease and increase in deep soil in RT and NT,while it was decreased with soil depth in DT.Straw returning significantly increased soil water content and profile soil water storage,decreased soil evaporation,thereby increased crop yield and water use efficiency compared with NS.Soil evaporation showed lower in NT and RT than in DT,annual water use efficiency and 0~40cm soil water storage showed higher in RT and NT than in DT.A negative correlation between 100~140cm soil water content and water table depth has been observed.DSSAT-wheat model performed well with different conservation tillage treatment in eastern Henan province.Winter wheat water use efficiency was higher in RT than in NT for 8.45% and 8.92% in 2015-2016 and 2016-2017 respectively,it was higher than DT for 5.24% in 2015-2016,and it was higher in S+RT than in NS+DT for 7.95% and 4.11% in 2015-2016 and 2016-2017 respectively.Summer maize water use efficiency was higher in RT and NT than in DT for 11.44% and 13.93% in 2016,it was higher in NT than in DT for 10.99% in 2017.Water use efficiency of S+RT was higher than NS+DT for 19.07% and 17.00%,and S+NT was higher than NS+DT for 19.59% and 34.01% in 2016 and 2017 respectively.Straw returning significantly increased winter wheat and summer maize plant height,LAI,SPAD,photosynthesis rate,aboveground biomass,plant N accumulation and summer maize yield,while it was not significantly increased winter wheat yield.Winter wheat and summer maize yield,plant N accumulation and N use has been significantly influenced by tillage treatment.Winter wheat yield of RT was higher than DT for 4.88% and 9.05% in 2015-2016 and 2016-2017 respectively,which was higher than NT for 3.64% in 2016-2017.The winter wheat yield of S+RT was higher than NS+DT for 8.68% and 16.98% in 2015-2016 and 2016-2017 respectively.Summer maize yield of RT was higher than DT for 7.82% and 3.99%,and summer maize yiled of NT was higher than DT for 7.26% and 6.72% in 2016 and 2017 respectively.S+RT increased summer maize yield for 12.94% and 9.85% in 2016 and 2017 when compared with NS+DT.The results indicated that straw returning with rotational tillage was an appropriate water and nitrogen saving crop cultivation practice in eastern Henan province. |
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