Impact of Crop Variety Grouping and Rotation Block Placement by Large-Scale Operators on Water Allocation

Abstract

In Japan, the number of farmers is decreasing. In response to the scarcity of agricultural workforce, farmlands are being accumulated among farmers to maintain the agricultural infrastructure. This approach is changing the structure of agriculture in Japan, but the current water supply plan does not consider the impact of this change in agricultural structure. This study was conducted to determine the influence of multiple rice varieties and the placement of rotation crop blocks on water allocation within a district in open canal district with a farmland accumulation rate of approximately 70%. It was found that the multiple-crop grouping by large-scale farming operations enabled a clear division of the timing of puddling for each small irrigation canal. Grouping of crop varieties by large scale farming enterprises is an effective method to reduce water shortage even under the situation where farmland will be further accumulated in the future. Furthermore, it is suggested that the arrangement of rotation crop block may lead to the decrease in the occurrence of water shortages.