Effect Of Straw-Incorporation On Some Physical Properties Of Paddy Soil

Straw incorporation in to the soil after harvesting may maintain the fertility of paddy soil, but ways of returning influence the manipulation of harvesting machines. The most Economic way is to mechanically 'bury' all the harvested straw under the ploughed layer straight away after the harvest, letting it be decomposed there. The objective of this study is to compare the effect of three ways of straw incorpration on some physical and chemical properties and the growing of rice.A randomized complete block design (RCBD) has been used under the field conditions to compare the effect of four treatments: 1) entire quantity of straw returned to the soil, but not cut into pieces (treatment A), 2) half quantity of straw returned, not cut into pieces as in treatment A (treatment B), 3) half quantity of straw cut into pieces returned (treatment C), 4) CK (treatment D) , without any straw returned to the filed. The results showed that straw returning had not significantly increased the content of organic matter except for the treatmentB. The treatments of straw-returning had a tendency to decrease the bulk density of soil in a no significant manner, thus increased the porosity of soil. One year after the experiment, the indoor aggregate analysis showed that the straw returning treatments, the treatments A, B andC, all increased the level of aggregation.In the laboratory, it has been found that the incorporation of straw into the soil increased the coefficient of saturated soil penetration, thus the macro-porosity of soil. The chemical analysis of the soil extracted solution has shown that the soluble salt in the soil is predominated by the divalent ions Ca2+ and Mg2+ which mean that the soil aggregates have been chemically stable during the field experiment.It has been concluded that the treatment of entire quantity of straw-incorporation in to the soil has not been significantly different from other ways of straw- incorporation and even the control treatment CK. That means straw- incorporation has not affected the soil aggregation significantly. In addition, plowing in the following years may further the incorporation of straw into the soil.Candidate: Yongjun Han Major: Agricultural Engineering Advisor: Prof. Enchen Jiang...