| In Loess area,block cloddy was universal existence in farmland surface.The physical and chemistry properties of block cloddy in plow layer were researched in this study.The results showed that the structure characteristics of block cloddy was with tight surface but loose inner,the bulk density of the crust can be high as 1.39～2.0 g/cm3, which was mainly affect by unreasonable tillage process.The tight surface can not be crushed by nature alternation of drying and wetting.Farming machinery to impact and rotary tillage were necessary when reduce them.Ca2+ can migration from block cloddy inner to surface during the environment evolution,which was deteriorated the block cloddy surface tight.It can verify the environment factor has great effect on the properties of block cloddy and disperse block cloddy after tillage is very important. |