Fertilizer Deep Placement Increases Rice Production: Evidence from Farmers' Fields in Southern Bangladesh

Efficient use of fertilizer is needed to meet the increasing food demand, minimize negative environmental impacts, and maximize farmers' profits. Fertilizer deep placement (FDP) could be one of the best management techniques to achieve these multiple benefits. Experiments were conducted in 115 farmers' fields spread over 35 upazilas across eight districts over nine contiguous rice (Oryza sativa L.) growing seasons during 2009 to 2012 in southern Bangladesh to compare the effects of deep placement of urea briquettes (UB) and nitrogen-phosphorus-potassium briquettes (NPK), with farmers' broadcast prilled urea (PU) on rice yield and net economic return. Deep placement of either UB or NPK significantly increased grain yields and net economic return across all the rice-growing seasons and years compared to PU. Across the years, average yield increase in UB and NPK over PU was higher during the Aus and Aman (wet) seasons (21-31%) than in the Boro (dry) season (11-17%). In addition to increase in grain yield, deep placement of UB and NPK saved urea by 33 and 44%, respectively, during the Aus-Aman seasons, and by 35 and 28% during the Boro season. The deep placement of one 2.4 g NPK (similar to 44 kg N ha(-1)) for the Aus-Aman season and two NPK (87 kg N ha(-1)) for the Boro season would be more profitable for southern Bangladesh. The FDP also provides the greatest benefits under rainfed wet season conditions where farmers have little control of water management and timing of N application.