The rate of food self-sufficiency of Japan drops below 50 percent. Is it because the farmland is few in Japan? It is not so. The utilization rate of cultivated land has decreased, and a lot of abandoned cultivated lands exist. Data according to old cities, towns, and villages in Chiba Prefecture was used and analyzed. Whether to cause the abandoned cultivated land in any factor? The computational method is a decision tree analysis method. A target variable is a cultivation abandonment area rate. A target variable was analyzed by the regression tree like a quantitative variable. The abandoned cultivated land rate was converted into amount of rank series at the same time. Amount of rank series was made a target variable and it calculated with the classification tree. The variable that relates to the cultivation abandonment as a result of two analyses is a cultivated acreage a household. The scale expansion will prevent the cultivation abandonment.
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