Effect Of Covational And No-tillage On Soil Water Use Efficiency Under Different Mulching Method In Dryland Area

With the northwest Loess Plateau as an interesting study area, the paper was based on the experimental study on conservation tillage on spring wheat. The experiments were conducted at Dingxi County, a typical semi-arid area of the Loess Plateau. The paper was designed to explore the soil water content ,soil water storage, regular of soil water consumption and water use efficiency in diffirent of spring wheat.The result showed as follows:(1) The upper limit of the effective soil water is DUL,the lower limit is CLL,and the middle area is PAWC. CLL get over the abuse of DUL,its curve is increasing with soil layer adds.The area of curve underside is invalid on crop,which can't be used.So it can reflect the ability and condition of soil water use.(2)The content of soil water storage of the both treatment T and NT in fallow period is the highest.The treatment TS take on the strong ability of water supply while the TP has good ability of water retainment.Under no-tillage with different mulching, the treatment NTS take on the strong ability of water supply while the NTP has good ability of water retainment.(3)The change of soil water under conventional tillage with different mulching in the fallow showed that water content in the upper layer of soil was the highest under the treatment of TS,that was lower under the treatment of TP.But water content under the treatment of T was the highest bellow upper-layer. The change of soil water under no-tillage with different mulching in the fallow showed that water content was the higest under the treatment of NTS both in the upper and in the middle layer,in the deeper layer that was the higest under the treatment of NT.Water retainment had good ability under mulching more than that under no-mulching in the whole stage of wheat growth,no-tillage was good more than conventional tillage,the ability of water supply was the highest under the treatment of NTS in the stage of much needing water for wheat while NTP had good ability of water retainment.(4)The yeild of T was the higest under different mulching with both conventional tillage and no-tillage,it was 1816.05kg/hm2 ;WUE was that NTS (7.93 kg.hm-2mm-1) >T (7.33 kg.hm-2mm-1) >TS (6.37 kg.hm-2mm-1) >NT(5.66 kg.hm-2mm-1) >TP (5.42 kg.hm-2mm-1) >NTP (5.10 kg.hm-2mm-1) . Compared all mulching with no mulching ,the yeild of wheatunder the treatment of NTS was 34.27% higher than that under the treatment of NT;as compared to T,the yeild of TS reduced 9.83%, the yeild of TP reduced 20.40%,The yeild of NTP was 12.48% lower than that of NT.