淹水时间对土壤粘闭的影响

本文研究了植稻前淹水时间长短对土壤物理性质和粘闭作用的影响。结果表明,淹水可以显著地降低土壤强度,但土壤抗穿透力并不随淹水时间的延长而进一步明显下降;延长淹水时间,可以促进土壤粉粒和粘粒的分散,但土壤粘闭胼形成的有效粘闭层厚度以及粘闭后表层土壤强度的降低、主要受所使用的粘闭机具的影响,而与淹水时间的长短无关。因此,过分地延长淹水时间的措施,在生产实践上的意义并不大。

EFFECT OF SUBMERGENCE TIME ON PUDDLING

In most of the tropical Asia, wetland preparation by puddling is the usual method of preparing rice field for planting. For evaluating the effect of prolonged submergence on puddling, comparative experiment by using clayey paddy soil has been earried out in International Rice Research Institute. Results showed that submergence gave significantly lower soil resistance for all three water treatments than that before water treating, but no significant difference in soil resistance was observed among submergence treatments. It was found that prolonged submergence could achieve higher contents of water dispersible silt and clay before and after puddling, but the lowering of soil strength and the forming of effective puddling layer were affected by puddling implements in the experiment rather than by submergence time. It implied that prolonged submergence might be not so practical for increasing puddling effectiveness.