Weed Control by Weeder Machine in Transplanted Rice Paddy Field for Mechanical Weed Control

This study was carried out to determine the effect of weed control by weeder machine and the number of treatments for mechanical weed control in paddy rice field. As the number of treatment of weeder machine were repeated, the efficacy of weed control was increased. It was 37.3~74.1% for using only one time, 71.5~81.6% for two times and 82.9~95.5% for three times, respectively. The reducing effect of labor hours was 95% for two times and 93% for three times compared to that of hand weeding. In determining the inputting time of the weeder machine after rice transplanting, as the inputting time was delayed, the effect of weed control was reduced and rice yield also decreased, suggesting the higher competition between rice and weeds as the inputting time was delayed. As the result, the most critical inputting time of the weeder machine which can gain more than 70% of weeds control and more than 5.0t ha-1 of rice yield was determined before 20 days after transplanting of rice at least.