Effects of no-tillage and rice-seedling throwing with rice straw returning to paddy soil on profile morphological characteristics
稻草还田免耕抛秧对水稻土剖面形态特征的影响

The effect of no-tillage with rice-seedling throwing on profile morphology was investigated by comparison of conventional tillage and no-tillage lasted two and seven years. The results showed that conventional tillage with rice-seedling throwing did not significantly affect morphology, but no-tillage with rice-seedling throwing formed new morphology of sub-plough-layer. The upper layers in no-tillage treatments became looser, more acidic and blacker compared with conventional tillage. The rice roots were concentrated in the surface layer and the location of fissures was raised in the plough layers in the no-tillage treatments. The plough layer solum constitutions of no-tillage without rice straw returning to paddy soils was Aa1- Aa2- Aa3, while that of no-tillage with rice straw returning to paddy soils was O-Aa1- Aa2- Aa3. The no-tillage with rice straw returning to paddy soil reduced soil density and had more iron-humus mottling, blacker and looser plough layers, but the no-tillage without rice straw returning to paddy soils tended to have solid sub-layer and thinner upper layer. Thus the profile formed by no-tillage with rice straw returning to paddy soils is the best to coordinate soil fertility.