稻草还田免耕抛秧对水稻土剖面形态特征的影响

为探讨免耕抛秧栽培对土壤剖面形态特征的影响,分别对连续2年和7年结合稻草还田的常耕和免耕试验的土壤剖面进行了研究。结果表明,常耕对土壤剖面形态特征影响不明显。免耕改变了耕作层亚层的剖面形态特征,且表层土壤疏松和pH值变小;水稻根系向土壤表层集中和裂隙出现部位增高。普通免耕形成的耕作层构型是Aa1-Aa2-Aa3,疏松表层较薄、亚表层有变坚实的趋势。稻草还田免耕形成的耕作层构型是O-Aa1-Aa2-Aa3,鳝血斑的数量增加、土壤颜色加深、疏松和体积质量降低。以稻草还田免耕抛秧形成的土壤剖面协调土壤肥力效果最好。

Effects of no-tillage and rice-seedling throwing with rice straw returning to paddy soil on profile morphological characteristics

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.