Study On Soil Physical Properties And Soil Erosion Under Conservation Tillage

Basing on the research of conservation tillage experiment in the semi-areas of the Loess Plateau from 2000 to 2006, we set up field experiment plots under natural rainfall in sloping fields in 2007, selected liquorice, indigowoad root, lucerne and so on, collected soil sample, analyzed physical qualitys and observed the law of soil-loss in several kinds of typical conservation tillage measures, in order to find better planting mode for water and soil conservation in this area. The purpose of this study is to provide referenced data for doing water and soil conservation well in future in Loess Plateau area.This study is chiefly divided into two parts, the first study is conservation tillage of genuine traditional chinese drugs. Six treatments including conventional tillage of indigowoad root/liquorice intercropping(TIL) and spring wheat/liquorice intercropping (TWL), no-tillage with no stubble retention of indigowoad root/liquorice intercropping (NTIL) and spring wheat/liquorice intercropping(NTWL), no-tillage with stubble retention of indigowoad root/liquorice intercropping(NTSIL) and spring wheat/ liquorice intercropping(NTSWL). The second study is conservation tillage of strip intercropping of grain-grass-legume. Six treatments including conventional tillage of spring wheat/lucerne intercropping(TWL*), potato/lucerne intercropping(TPL) and cheick pea/lucerne intercropping(TCL), no-tillage with stubble retention of spring wheat/lucerne intercropping(NTSWL*), potato/lucerne intercropping(NTSPL) and cheick pea/lucerne intercropping (NTSCL). The results showed that:(1) Effects of conservation tillage on soil physical properties①The different of the tillage method had the different influence to the surface of soil bulk density. Compared with T, the treatment NTS can decrease the surface(0~5cm) of soil bulk density.②NTS can increase the soil pore size of surface soil(0~5cm) significantly.③Conservation tillage had great influence on soil compaction, NTS can reduce soil compaction remarkably. All treatments appeared a obvious fluctuation, increasing, decreasing, then increasing and decreasing. ④After dry sieving, soil aggregates at the size of 10mm to 5mm, 5mm to 3mm and 2mm to1mm had a little change. the aggregates contents of the size of 3mm to 2mm was the lowest, while after wet sieving, the percentage of aggregate disruption was very high, reached 92.34%.⑤NTS can increase the soil saturated hydraulic conductivity of surface soil(0~5cm ) significantly.(2) Effects of conservation tillage on soil erosion in sloping fields①Conservation tillage had significant effection to prevent soil erosion, the total amounts of runoff and soil loss of conservation tillage of genuine traditional chinese drugs of six treatments were TWL>NTWL>NTSWL>TIL>NTIL>NTSIL, the total of conservation tillage of strip intercropping of grain-grass-legume were TWL* >NTSWL*>TCL>NTSCL>TPL>NTSPL.②Sediment and yield runoff of Aug 8th 2007 were consistent with the annual, runoff and sediment yield mainly produced once or twice rainfall process in 2007, its sensitive period was August.③The total loss of organic matter, available N, available P, available K in the nutrients of sediment loss was maximum, but the total loss of whole N and whole P was minimum, and NTS had obvious function to reduce the loss of available K, available N, whole N and whole P, pH in the sediment had little change, with an average of 8.37.④The regression relation among runoff, sediment yield and rainfall were very notable.