Water use during the puddling period in a large-sized paddy field area

Effective water delivery during the puddling period in an area with limited water resources was investigated based on the results of water use observation in a large sized paddy field area in Sisui, Kumamoto. The water requirement in the area during the puddling period was estimated by superimposing planned patterns of water requirement during the puddling period which were modified in accordance with the puddling day of each field in the area, and the results of this estimation enabled to express the changes in the water requirement in the area comparatively well. By using the estimation method, difficulty in puddling during a short period of time under uniform rice cultivation and need for alleviating the peak of water use (hereafter referred to as water use dispersion) in this area, were reveled. For the water use dispersion, cultivation combining transplanting and direct seeding is recommended. In this case, under the planned water intake of this area, a ratio of 40 to 60% of direct seeding cultivation and a rate of 2 to 3 ha/d of puddling were considered to be suitable for keeping the water use