The effect of conservation tillage on the structural characteristics of Fluvo-aquic soil

The effect of different conservation tillage measurement on structural characteristics of Fluvo-aquic soil were studied,and the variation law of soil structure under different ways of straw returning were searched. This study is based on long field experiments of Luancheng country of Hebei province Shijiazhuang city,six treatments of tillage systems were utilized:conventional tillage、tillage with straw returning、rotary tillage with straw returning,no tillage with mulch,no tillage with standing stubble and no tillage with crush returning,soil bulk density,soil organic carbon content,aggregate and organo-mineral complexes were measured. The results showed:the lowest soil bulk density value is no tillage with mulch; the MWD value of no tillage with mulch significantly higher than other treatments 30.4%～47.4% in dry sieving,while the MWD value of no tillage with standing stubble and no tillage with crush returning is higher than other treatments in wet sieving; the lowest disperse coefficient is no tillage with standing stubble,while the disperse coefficient of no tillage with crush returning is higher than other treatments 20.48%～330.93%; the original soil complex amount、original soil complex degree of tillage treatment is higher than no tillage 10.82%～21.62%,8.97%～20.97% respec-tively. The different ways of straw returning have a different influence on soil structure stability:no tillage with mulch can improve field soil structure; no tillage with standing stubble can advance the stability of microaggregate; no tillage with crush returning can increase the content of water stability macroaggregate through increasing soil organic carbon content.