Efficiency of an Automatic Weed Suppression Robot in Organic Rice Farming: Increase of Management Work at Paddy Field and Reduction of Weeding Work

Abstract

Labor-saving weed control technology is essential for expanding organic rice farming. One such technology is an automatic weed suppression robot （referred to as AW） that moves freely in paddy water after transplanting rice seedlings and suppresses weed emergence because of suspended paddy water. Working hours of rice production process were investigated when AW was operated in organic rice paddy in Bando city, Ibaraki Prefecture, and compared to traditional weeding system with mechanical and manual weeding. The AW system reduced the total working hours by up to 30%. In particular, the working hours of mechanical and manual weeding were reduced by 87% and 79%, respectively. However, mechanical weeding was required in the paddy with many weeds, even when AW was operated. In AW system, the time spent plowing, harrowing, leveling, levee coating, and repairing levee increased because the stable operation of AW requires careful implementation of tasks to level the field and maintain water depth. Although the AW system increased the frequency of paddy patrols for water management, the total working hours remained unchanged due to a reduction in the working hours per patrol. The reduced hours per patrol were attributed to careful levee coating before and after transplanting.