Impact of mechanical harvesting on grain damage and storability of rice

Abstract

The trend toward mechanised rice harvesting in East Africa is accelerating, driven by labour shortages and government subsidy programmes. However, mechanical harvesting can crack, fissure, and bruise grain, reducing milling recovery and storage life. This research compared three harvesting methods—manual, mechanical at low speed (2.5 km/h), and mechanical at high speed (4.5 km/h)—for their effects on grain damage, milling quality, and storage weight loss over six months at the University of Nairobi’s Upper Kabete campus. High-speed mechanical harvesting produced 24.1% cracked grain versus 2.1% for manual, and storage losses after six months were 21.3% versus 5.6%. Reducing combine speed to 2.5 km/h cut grain damage to 5.8% and storage loss to 11.2%, offering a practical compromise between efficiency and grain quality.