Physical and engineering properties of urea briquettes relevant to design of ICAR-NRRI urea briquette applicator

Abstract

Fertilizer deep placement has been proven effective in increasing fertilizer use efficiency in wetland rice production, but because of problems associated with fertilizer granules properties, machines developed to place them gave inconsistent results. Despite the wide range of metering mechanisms used, metering variation is still inherent in the machines developed because of the varying physical and engineering properties of the fertilizer material. Keeping this in view current study was carried out to determine the physical and engineering properties of urea briquettes relevant to design of the mechanical applicator. Physical and engineering properties viz. size, shape, urea briquette weight, bulk density, angle of repose and coefficient of friction of urea briquettes of UB1 (3g) and UB2 (2g) were evaluated in laboratory. Size and shape of metering cup were designed on the basis of maximum size of briquettes. Both roundness and sphericity of briquettes affected singulation. Free flow of urea briquettes in the briquette hopper was influenced by angle of repose and coefficient of static friction of urea briquette. Length, breadth and thickness of the urea briquettes UB1 and UB2 were 18.84±0.2.8 mm, 18.39±0.33mm, 13.76±0.28 mm and 16.49±0.18 mm, 16.22±0.19 mm and 11.18±0.17 mm, respectively. Mean diameter was greater for UB1 (16.83±0.22 mm) in comparison to that of UB2 (14.41±0.15 mm). Roundness of UB1 (3g) and UB2 (2g) were 0.82±0.01% and 0.78±0.11%, respectively, while sphericity of these briquettes in the natural rest position were 0.89±0.01 and 0.85±0.01%, respectively. Mean briquette weight was greater for UB1 (2.81±0.11 g) than that of UB2 (1.78±0.07 g). Angle of repose for mild steel surface was 31.64±0.13° and 31.67±0.28° for urea briquettes UB1 and UB2 respectively. The design values of the metering cup viz. cup diameter and depth were selected based on the dimensions of urea briquettes.