INVESTIGATING THE EFFECT OF BLADE CUTTING ANGLES OF A MANUAL HOE ON OPERATOR’S HEART RATE DURING WEEDING OPERATIONS

Abstract

The present findings focus on the assessment of manual hoe blade cutting angles on operator heart rate during weeding operation. Three hoe blades were developed with different blade cutting blade angles (65^o, 75^o, and 85^o) using AutoCAD software and analyzed by 3D modeling. Heart rate (bpm) was measured using a polar heart rate monitor and recorded at rest, during the entire period of work and recovery thereafter for a period of 5 mins. Soil bulk density and moisture content (db) were determined using a standard method from literature. Randomized Complete Block Design (RCBD) was employed to evaluate the effect of hoe blade cutting angle,
soil moisture content, soil bulk density and the operator’s height on the heart rate of the operator during weeding operations. Three levels of cutting angles (65^o, 75^o and 85^o), bulk density (1.2, 1.3 and 1.5 g/cm³), moisture content (13, 15 and 18 %) and two different operator’s heights (1.56 and 1.65 m) making a 3 x 3 x 3 x 2 factorial experiment design and analyzed using ANOVA and Tukey’s Studentized Test mean comparison. Results obtained show that mean heart rate increases with an increase in soil moisture content, soil bulk density and operator’s height respectively, but decreases with hoe blade cutting angle. The optimum heart rate of 84.24, 80.35, 72.01 and 74.61 bpm were obtained at 85^o blade cutting angle, 15% soil moisture, 1.2 kg/m³ bulk density and 1.56m operator’s height respectively. It was, however, recommended that a study on manual hoe be carried out to ascertain its effects on the weeding
index, performance index and cost of operation.