Abstract
Large scale rice cultivation in Hokkaido made rapid and remarkable development in the years around 1932. For this progress the Doko Kumiai, or the associations for the construction of irrigation system for the rice fields played an important part. The system of the associations was legalized in 1902, and they received financial support from the national government. With the exception of some old rice lands in the southern part, most of the rice growing areas in Hokkaido received the service from this system.
Considering the processes of the establishment and the areal distribution of the associations, we can get a general view of the regional developments of rice cultivation carried out through the achievements of extensive irrigation systems.
Upon studying the materials the present author pointed out the following facts in this paper.
1. The regional development of extensive rice cultivation in the early years was not a universal spread towards the north, but started from two base regions: namely the Kamikawa Basin and the east part of Ishikari Plain-the present core regions of rice cultivation.
2. The remarkable increase of the rice fields in the several years following 1900 was brought about by the accumulation of small scale reclamations into rice fields, and the rapid expansion of rice fields by the completion of large irrigation systems. There were only small scale reclamation works in south Hokkaido which resulted in the dilatory increacse of rice fields. While in Kamikawa and Sorachi Districts the completion of large scale irrigation systems contributed to the rapid expansion of rice fields.
3. While far-reaching expansion had been made into several remote areas, an internal progress also made within the very core region. After 1920, the reclamation works made a tremendous development in east Hokkaido, while in the core region during the same period, many areas in the hilly and peaty lands were reclaimed into rice fields.
