Yield and water requirement of Boro rice grown on a clay terrace soil of Bangladesh
A field experiment was carried out in a clay terrace soil to assess grain yield, water requirement, and weed control for Boro rice cultivation in Bangladesh to avoid wastage of water without hampering crop yield. Boro was grown in the dry to pre-monsoon seasons of 1992 and 1993 under different irrigation and weeding treatments with recommended applications of fertilizers. Limited irrigation, maintaining a moisture regime between field capacity and saturation, significantly reduced grain yield. However, irrigation leading to standing water showed no significant difference in grain yield, irrespective of the depth of water, and gave grain yields of 4.5-5.0 t ha -1 . No weeding also significantly reduced grain yield but only in one year. The water requirement for Boro was 620-700 mm from transplanting to harvest. Water use efficiency was highest for irrigation with minimum standing water between saturation and 1 cm, or for moisture regime between field capacity and saturation, depending on the intensity of rainfall during the growing season. A single weeding was sufficient for control. Deep standing water significantly retarded weed growth.