Evaluation of Threshing Efficiency of a Locally Modified Rice Thresher in Niger State

This study evaluates the threshing efficiency and operational performance of a locally modified rice thresher under typical field conditions in Niger State, North Central Nigeria. Rice threshing is a critical post-harvest operation that significantly affects grain quality and losses, yet most smallholder rice farmers in Niger State rely on traditional hand-beating methods that are slow, physically demanding, and generate high grain breakage rates. This study modifies an existing axial-flow rice thresher design using locally sourced mild steel and available electric motor components to improve suitability for the grain size and moisture content range typical of Niger State rice varieties. Performance evaluation tests are conducted at three grain moisture content levels, 14, 18, and 22 percent wet basis, using Faro 44 and NERICA varieties grown in Bida and Lavun local government areas. Performance indices including threshing efficiency, cleaning efficiency, grain damage percentage, and throughput capacity are measured following standard ASABE procedures. Findings show that the modified thresher achieves threshing efficiencies of 96 to 98 percent across moisture content levels, with grain damage rates below 3 percent at 14 percent moisture content. Throughput capacity averages 280 kilograms of paddy per hour. The study concludes that the locally modified thresher represents a significant improvement over hand threshing methods for Niger State rice farmers. It recommends field-scale deployment trials and training of local fabricators in replication of the modified design.

Keywords: rice threshing, threshing efficiency, post-harvest, Niger State, grain quality.