Determination of Crop and Machine Parameters Relevant to the Harvesting and Postharvest Handling of Acha

Abstract

Acha (Digitaria species) is a cereal crop produced predominantly in Nigeria. Harvesting acha is still being done by traditional methods. Existing regular combines cannot be applied to acha harvesting due to its unique grain characteristics. Appropriate harvesters suited to the characteristics of acha seed are not available. The aim of this study was to determine some crop and machine Parameters (CMPs) relevant to acha harvesting. Machine parameters were determined from the equation for effective material capacity given by ASABE (2015) and Hunt and Wilson (2016) while standard laboratory investigations were conducted to determine crop parameter (Angle of Repose, Particle Density, Particle Size, Coefficient of Uniformity and Fineness Modulus). Results obtained showed that operating speed (V) (1, 3, 5 km/h), knife speed (S) (300, 400, 500 rpm) and reel index (I) (1.0, 1.25, 1.5) were critical parameters in the design of an acha harvester. Angle of repose, particle density, particle size, coefficient of uniformity and fineness modulus of acha were found to be 32.5°, 0.584 g/cm3, 0.60 mm, 1.62 and 1.22 respectively. Not considering these parameters in the design of acha harvesting and handling machines results in heavy grain losses. It is therefore recommended that information from this work be adopted in the design of acha handling machines.