抄録
From the viewpoint of the rice cropping season in Japan, Kyushu is usually classified as a district of the warm and late type. But the author's study revealed that there is about two months' difference in the beginning of the rice cropping season even in Kyushu itself a difference equivalent to that found between the northern and the southern ends of Japan. Detailed examination of the rice cropping season in Kyushu carried on by card method made clear that Kyushu is devided into the following four areas according to the type of their rice cropping season.
Ist. type area: South-western Islands containing Yakushima and Tanegashima. The area of the earliest type in Japan. IInd. type area: Medial Kyushu mountains and Seburi mountains in northern Kyushu. The area of the earliest type in Kyushu. Here the rice cropping season begins as early as in Tohoku, Hokuriku and San-in districts. IIIrd. type area: Northwestern coastal area and inland area of southern Kyushu. The typical area in Kyushu. IVth. type area: Southwestern coastal area (islands and coastal belt of the Yatsushiro Sea and coatsal lowlands around the Ariake Bay). The area of the latest type in Kyushu and in Japan.
Such regional differentiation of the rice cropping season as described above can be considered as the combined resultant of the following four factors, at least. (1) Climate: The air temperature. and the typhoon are the two predominantly influential climatic elements on rice cropping. (2) Irrigation water: Which is most prevailingly used, rainwarer, river or ravine water, irrigation-pond water, creek water, well water, etc.? (3) Relation to the winter crops: This hastens or retards the coming of the rice cropping season. (4) Variety of rice plant: What variety is cultivated? The author has described and discussed about these four factors in this article. A bare mention is made here only of the variety of rice-plant.
The common varieties in Kyushu as a whole are of high sensibility for sun light, of strong resistance to rice deseases and of grains hard to drop. This corresponds with the fact that Kyushu is the warmest district in Japan and often suffers from damage caused by typhoon. In the areas of the early type (South-western Islands and the mountainous lands), however, the varieties of early maturity or of strong resistance to coolness are cultivated as in Tohoku and Hokuriku districts.
