Effects Of Straw Deep Application With Different Years On Physical Properties And Shearing Strength Of Soils

China is a country with high productivity of straw. Statistical results in 2006 showed that straw productivity overtakes 7.6×108t in China. As one of the major grain producing areas, Jilin province has 2.4×107t corn straw in 2010 and values about 15×108￥. However, such great amounts of resource has not been properly used, nearly 30% of straw was burnt after harvest in Northeast areas in China. Burning straw will causes problems like air pollutions, traffic safety, fire hazards and other social problems. On the other hand, Northeast areas in China are now facing a serious problem of soil degradation. Soil thickness, fertility, physical and chemical properties deteriorate gradually since reclaimed. Some of farmland has lost the agricultural productive capacity. This article mainly solve the problem of crop straw burning and black soil degeneration by crush ing the straw as fertilizer into the subsoil Layer(20~40 cm),and achieve the goal of upgrading the level of soil fertility, soil aeration and water storage capacity. In the past, it extensively studies concentrates on studying soil chemical property under the condition of straw mulching or applying the straw into the surface layer,however, the soil physical properties on the subsurface is seldom researched.The experiment studied the effect on hydro-physical properties after straw deep application(SDA)by testing growth of corn 、soil porosity、water capacity、aggregate、shear strength. The conclusion as below:1) Compared with the CK, The condition of corn growth and yield of SDA has significantly increased, NPK + O12 is the most significant.2) max moisture capacity、capillary capacity、field capacity、soil total porosity、non-capillary porosity、capillary porosity are significantly increased on the surface and subsurface layer after straw deep application for 3 years.3) It could increase the water infiltration capacity of the soil by SDA, especially the second year after SDA,it reached the peak,the water infiltration capacity of the other treatment of SDA almostly higher than CK4) It promote micro-aggregate(<0.25 mm)transfer into macro aggregate,and the peak value appeared at second year after SDA.5) Cohesive force of soil significantly firstly increases and then decreases the moisture content of soil increasing,the internal friction angle of soil decreases with the moisture content ofsoil increasing the moisture content of soil increasing,the results show SDA can effectively decrease cohesive force and internal friction angle of soil,and extent of reduction of cohesive force and internal friction angle after the straw deep application is the biggest at second year,the second is the first year of SDA,even though the cohesive force and internal friction angle increase at third year,but still lower than CK.