Simulation of Tef Seed Broadcasting

A. D. Zewdu

Abstract


In this investigation broadcast seeding of tef seed was considered. In order to predict particle trajectory on and off disc, after developing a mathematical relationship, simulation of particle movement on and off disc of a spinning disc was undertaken. The terminal velocity and coefficient of drag force of tef seed were determined experimentally in laboratory. Projected distance of particle thrown off the disk was calculated by varying different particle property (such as moisture content, coefficient of friction, TGM and particle density) and machine parameters (such as cone angle and angular velocity). The projected distance of a particle increased with increase in moisture content of seed, spreader revolution per minute and inclination of disc with the horizontal. The increase in moisture content was associated with increase in coefficient of friction, which do have effect on-the disc particle motion. The increase in moisture content has influence also on thousand grain mass, particle size, sphericity, particle density and coefficient of drag force which affected off-disc particle trajectory. This investigation showed the possibility of using a spinning disc spreader in order to broadcast tef seed, which could replace broadcasting of tef seed by hand manually. Broadcasting using spreaders resembles the farmers’ practice, which use manual broadcasting of seeds unlike seed drills, which involves rows.

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