Effects of an Automatic Weed Suppression Robot for Paddy Fields on Weed Suppression and Paddy Rice Yield

In organic paddy-rice cultivation, weed control is important for preventing the reduction of rice yield but is a labor-intensive task. Therefore, easier and more stable weed-control technology is required. In this study, an automatic weed suppression robot for paddy fields ("weed suppression robot") powered by solar energy and GPS-navigated, was tested in 36 organic paddy rice fields for two years. The weed suppression robot reduced the number of mechanical weeding operations by an average of 58%. The average estimated weed dry-matter weight at the panicle formation stage was 16.6 g m-2 and the weeds were controlled enough to prevent the reduction of rice yield. The weed suppression robot tended to be more effective on annual weeds than on perennial weeds. This robot was considered to have little effect against perennial weeds, which have a long emergence period, because it could be used for only about three weeks after transplanting paddy rice. Therefore, additional physical control such as mechanical weeding would be necessary for further control of perennial weeds. The average yield was 424 g m-2, a 10% increase compared to practical organic cultivation. These results suggest that the weed suppression robot is an effective new weeding tool for reducing weeding labor while ensuring yield in organic paddy rice cultivation.