Optimization of Operational Parameters to Minimize Cutting Energy during Kenaf Harvesting

This study evaluated the cutting and specific cutting energy of different kenaf varieties at different maturity stages during mechanical harvesting, while evaluating an improved kenaf harvester. The effects of operation parameters (related to the crop's biological properties; crop varieties "Cuba 108,” "Ifeken 400,” and "Ifeken Di 400"; and crop maturity: 10 to 16 weeks after planting) on the machine performance were optimized in a 3 × 4 factorial experiment using randomized response surface methodology (optimal custom design) to optimize the energy consumption. The results showed that the cutting energy required for harvesting kenaf increased from 1.8 to 3.3 joules as the crop matured from 10 to 16 weeks after planting (WAP). Among the tested crop varieties, "Ifeken 400" consistently required the highest cutting energy, followed by "Cuba 108", while "Ifeken Di 400" required the least energy. The specific cutting energy increased from 5000 to 11661 J.m⁻² as the crop matured, indicating differences in energy demand among the kenaf cultivars. These findings imply that the physical and mechanical properties of kenaf directly affect its stiffness. The stiffness factor of the crop is determined by crop maturity (weeks after planting) and crop variety. Therefore, the proper estimation of these operational parameters is vital for increasing the energy efficiency during the harvesting of kenaf.