Design, Development and Field Evaluation of Manual-Operated Applicators for Deep Placement of Fertilizer in Puddled Rice Fields

Abstract

Deep placement of urea increases nitrogen use efficiency, rice yields, and farm profitability compared to conventional broadcast urea. However, labor shortages for deep placement pose constraints for wider adoption. Therefore, two types of manual-operated applicators, an “injector-type” (non-continuous operation) and “push-type single row” (continuous operation), were designed during 2011–2015 to deep-place fertilizer briquettes in puddled rice fields. The design of the single-row applicator was improved from a double-row design developed earlier by the Bangladesh Agriculture Research Institute. In particular, the width of the furrow opener and skid was modified to ensure the precision placement of urea briquettes (UB) to 5–7-cm soil depth and coverage of the briquettes with soil. The single-row applicator has two cage wheels and one fertilizer hopper; the double-row applicator featured one cage wheel and two hoppers. This modification reduced the weight of the single-row applicator to 4.5 kg compared to the 10.0-kg double-row applicator. The injector-type applicator, which has four mechanisms—feeding, metering, delivery, and placement—weighs 1.5 kg. Field testing across different sites and seasons showed that the push-type applicator significantly reduced the labor requirement to 15–20 h/ha compared to the injector-type applicator or hand placement (28–50 h/ha). Applicators consistently placed UB at proper depth (5–7 cm) and spacing under most rice field conditions. Grain yields of applicator-placed UB were similar to hand-placed UB. There was no significant difference in grain yields between the two applicators when compared to yields achieved following hand placement.