On the varieties of the rice plants cultivated in the Kamoike and the Gamagawara area, Suwa basin

Abstract

The area in consideration comprises 885 neatly arranged but almost about tennis court dimensioned paddy fields, several gentle brooks, numerous straight foot-paths and cart-roads together with about a dozen of lotus marshes in a region of 1.5km×0.6km in the Delta Plain south of Lake Suwa.In the autumn of 1935 the writer investigated the variety of the rice crop cutlivated at each field, which he entered, in a map of 1:7000. The numerous tiny hatched tetrahedrons were the paddy fields where the variety styled “Aikoku No, 20”—strong, manure-resistant and pest-resistant—were cultivated, the scattering black patterns were the lotus marshs and the rectangles without any hatching were mostly planted with the variety styled “Sekitori” (in Jap.) which yields good qualified rice but are weak against the attack of pest.In order to scrutinize the general tendency of the distribution, he twice dealt with Fig. 1 after Katsue Misawa's method, the result of which is shown in Fig. 2. The Arabic numerals in the figure indicate the average percentage of the rice fields planted with “Aikoku No. 20” with an unit of 10 percent. Although the appearance of this objective region is completely flat, there exist, however, slight differences in elevation. The areas where the “Aikoku No. 20” were prevelent—the centers of which were located at the northeast and the north-west sectors of Fig. 2—coinsides with the lowest therefore, sometimes water-stagnant fields which were formerly irrigated with nitrogen-rich water from many wells excavated there. This fact indicate that the variety of the crop is some-times of good service in revealing the regional characteristics of a given area.