Effects of deficit irrigation and transplanting methods of irrigated rice on soil physical properties and rice yield.

摘要

This study evaluated how deficit irrigation and method of transplanting irrigated rice affected soil physical properties in the short term and rice yields under cultivation that did not involve wet levelling (puddling). Field experiments were conducted in 2009 and 2010 at Sakha Agric. Res. Sta., Egypt. Planting methods were as follows: traditional transplanting into flat flooded soil (M₁), transplanting into furrows (M₂) and into beds (M₃). The deficit irrigation treatments were as follows: irrigation every 6 days between transplanting and 2 weeks before harvesting, reference method (I₁), irrigation as in I₁ but with a continuous period of 12 days without irrigation (i.e. one irrigation event missed) at heading (I₂), irrigation as in I₁ but with an event missed at the beginning of tillering and at the start of head development (I₃) and irrigation as in I₁ but with 3 missed events, one each at the beginning of tillering, the start of the head development and panicle initiation (I₄). Results showed that relative to soil conditions before planting, both rice transplanting methods and deficit irrigation decreased soil bulk density, water holding pores percentage, fine capillary pores percentage and soil shear strength, whereas drainable porosity percentage increased. Soil cracked more under the reference treatment than under the other treatments. Rice transplanting into beds and maintaining irrigation every 6 days without any irrigation skip, treatment (I₁ x M₃), appeared appropriate for growing rice. This combination resulted in soil physical properties favourable for plant growth, producing the largest grain and straw yields of all the treatments.