Weed management implications of introducing dry-seeding of rice in the Barind Tract of Bangladesh

Abstract

A single crop of transplanted rainfed rice each year provides a major component of livelihoods for farm families in the Barind Tract of Bangladesh. Variable rainfall, frequent drought during grain filling and limited irrigation constrain intensification of the cropping system in this region. Dry seeding allows earlier rice establishment, reduces the impact of late drought and allows timely planting of a subsequent chickpea crop to exploit residual soil moisture. Although the potential of this modified cropping system has been demonstrated in research trials, early season weed growth, which is suppressed by puddling and partially controlled by flooding in transplanted rice, remains a major constraint to farmer adoption. On-farm studies indicated that yield gap between production of transplanted rice under farmer management and the potential yield under weed free conditions in three villages in Rajshahi averaged from 0.29 to 0.47 t/ha, with 34% of farmers losing over 0.5 t/ha. Labour availability constrains timeliness of first weeding in this system. A range of weed management practices, including the integration of a pre-emergence herbicide with inter-row weeding with a hand-pushed weeder, resulted in similar yields of direct seeded rice to hand weeding. The use of these labour saving practices in relation to the potential adoption of dry seeding, maintaining rice yield and increasing the productivity of the cropping system is discussed