Development of Power Weeder for Weeding between Hills and Validation of its Feasibility in Organic Paddy Fields in the Cold District

Abstract

A kind of paddy power weeder was widely used by most of the organic rice cultivation in Japan for a better weeding effectiveness in addition to cultivation practices. Because increasing the paddy weeding effectiveness would benefit organic paddy farmers’ a vibration-agitation type of paddy weeder was developed and released to market by Company S and Company I in cooperation. This paddy weeder is characterized by its capacity to weed in space between plant stands by reciprocating vibration of weeding nail in addition to the conventional weeding between rows. As confirmed, it removed 96% and 84% of the weed plants (an average of 12,439 plants per square meter) by weeding three and two times, respectively. The rice grain yield increased as the weeding frequency increased, with a yield reaching 584kg/10a by three times of weeding, in comparison with the 375kg/10a in non-weeding control. It was confirmed that the damage to rice plants by weeding was within negligible range and the weeding speed was about 10a per hour. Moreover, the effect of the paddy weeder that combined the effect of puddlings and transplant timing was examined. Thus, the vibration-agitation type paddy weeder could work effectively in combination with other cultural practices such as multiple puddling and postponing transplanting to warm season to enhance weeds germination. As for the setting of the transplant time, it was thought that the time 20 days after the final puddling, when effective multiplication temperature reached 200 day-°C (effective temperature of 10°C ). was promising.