This study is exploratory research on a relationship between changes in cultivated area of major crops and farm income by regions. We investigated level of income, volatility of income, and migration of suitable region by climate changes as factors influencing changes in cultivated area. Research processes are as follows. First, we classify the regions where cultivated areas are expanded or reduced through the trends of cultivated area by region and crop during recent 10 years. Second, we compare the changes in income related factors between groups during the same periods. Finally, the results from portfolio analysis show changes in stable income-based optimal crops. From these procedures, we found that the changes in cultivated area are not simply explained by income-related factors. In cases of vegetables, however, we also found that high volatility of income could contribute to reduce cultivated area of the crops. The results from portfolio analysis are not always consistent in all of cases. This means that crop selection can be decided by other factors than stable income.

This research is about visualizing data for efficient use in agriculture, by measuring the understanding of graphs according to their features. A questionnaire consisting of one graph, either a bar graph or line graph, and a question about data, was made. According to the results, the time spent answering the question did not differ between the line graph and the bar graph. However, the rate of correct answers differed: that of the bar graph was 50% and the line graph was 0%. This implies that participants answered using the bar graph more accurately regarding whether the data involved understanding the absolute value. From this result, it is clear that using proper features of graphs according to the characteristics of data improves the understanding of information. In addition, a strategy to utilize information and communication technology in agriculture effectively was discussed.