With a declining birth rate and aging population, Japan is also seeing a decrease in farms, but their average size is increasing. In Tokachi, Hokkaido, which is an advanced agricultural area, the average farm size increases as elderly farmers stop farming. Typical farmers grow four crops, such as wheat, beans, sugar beets, and potatoes, mainly through crop rotation. Wheat has lower profitability per unit area, but is a labor-saving crop compared to others. Sugar beets and potatoes have higher profitability per unit area and are more labor-intensive than the other crops. Farmers decide their crop distribution to maximize their income under land and labor limitations. Previous studies have reported that when farm size increases, the areas for sugar beet and potatoes fall, and those for labor-saving crops such as wheat rise. It has been pointed out that such a change in crop structure decreases farmer income per unit area.

In this study, the author analyzes land use change using the 2004 and 2014 data of 111 family farms, which were all of arable farms in “A” Town, Tokachi. First, it shows the gaps of crop structures at each farm-size layer compared to the mode layer of “30-40 hectares.” Farms are divided into layers of “less than 20 hectares,” “20-30 hectares,” “40-50 hectares,” “50-60 hectares,” “60-70 hectares,” and “more than 70 hectares.” The comparison is done with data from 2004 and 2014, respectively. Second, the author shows the impact of farm size change on crop structure. For this analysis, farms are divided to layers of “more than 5 hectares size-down,” “less than 5 hectares change,” and “more than 5 hectares size-up,” from 2004 to 2014.

According to the first analysis, the layers of “less than 20 hectares” and “more than 70 hectares” had gaps from the mode layer in 2004. Both layers had a high percentage of beans and low percentage of potatoes compared to the mode layer. The gap at the layer “more than 70 hectares” is supported by previous studies. However, this gap disappeared in 2014. Between 2004 and 2014, a new potato harvester was developed, and farmers began to use it. Thus, they were able to grow more potatoes.

The next analysis concerns the crop structure change between 2004 and 2014. The percentage of red beans in “A” town was up from 2004 to 2014 because of a new variety and a new labor-saving harvester. All layers except for “more than 5 hectares size-down” changed, the same as in “A” town. Additionally, the percentage of sugar beet was down in “A” town and all layers due to the decline in price. There are two remarkable aspects in this analysis. First, the layer of “more than 5 hectares size-down” grew labor saving crops more in 2014 than in 2004. Managers in these farms had became old and had no successors, so they chose more labor-saving crops. Second, there was little change in crop structure at the layer of “more than 5 hectares size-up. They maintained the crop structure within a 5 percent change. However, when farms extended the land by more than 20 hectares, the area for wheat increased by over 5 hectares, while retaining its percentage in crop structure.

The results of this study reveal that improving productivity per unit area of labor-saving crops has strong impact on the income of both small and large farms.