Ergonomic Comparison of Modified Hoe and Chisel Weeders for Enhanced Operator Comfort in Weeding

Manual weeding remains a labor-intensive and ergonomically demanding agricultural task, especially in smallholder farming systems. This study evaluated and compared the ergonomic performance of modified hoe and chisel weeders, incorporating adjustable handle angles (45–65°), lightweight mild steel frames (4.5 kg), and optimized cutter blades (175 mm length), to address gaps in existing designs. Field experiments at SHUATS, Prayagraj, involved four male operators aged 20–35 years, measuring anthropometric, physiological (heart rate, OCR, EER), and postural (BPDS) parameters. The chisel weeder demonstrated significantly lower physiological strain than the hoe weeder, with mean heart rate (90–134 vs. 91–135 b/min; p < 0.05), oxygen consumption rate (0.346–0.847 vs. 0.357–0.859 l/min), and energy expenditure rate (6.5–17.6 vs. 7.4–17.91 kJ/min). Postural discomfort (BPDS) was 28% lower for the chisel weeder (20–45 vs. 23–52), particularly in younger operators (20–23 years: BPDS 20 vs. 23). These findings underscore the importance of ergonomic modifications in manually operated weeders to enhance operator comfort, reduce fatigue, and minimize the risk of musculoskeletal disorders. The study provides design recommendations for further improving manual weeder ergonomics in small-scale agriculture.