On the Citrus Industry in Oosima-gun, Yamaguti Prefecture

This report presents the historical as well as present status of the citrus cultivation in Oosima gun and also measures for the improvement of the industry. (1) The total area of Oosima-gun is 137.7 sqare kilometers with the population of 57,000. Being quite densely populated the island has 409 persons per square kilometer, that is about double the population density of the Japan. Its arable land amount to 3,551.24. hectares, 47.4 of the total area, but the land being hilly, the degree of land utilization for cultivation is low, only 33.7 ares per family in average. Therfore farming based on rice and wheat crops present no bright future for the population of the island. Furthermore the sericulture and tobacco culture have become less popular among the people after the Second World War and now they are being replasced by the cultivation of citrus fruits. (2) The climate as well as the soil of the island and other surrounding condition are more suitable to the citrus cultivation. The history of the citrus industry is traced back to 100 years ago when the plant was introduced to Hikuma Village and it has now become a big centers of the industry in Yamaguti Prefecture. (3) The citrus industry of the island had well developed up until the Second World War,but during the War it greatly declined being deemed as an unnecessary and non urgent industry in addition to the lack of labor and operration materials. But after the War the industry recovered gradually its activity and redevelopment. At present the total area of the land for the industry has increased to 850 hectares, 21% of the whole arable land and the number of families engaged in it amounts to 6,000, 70% of the total and the fruit has now become the most important marketable commodity for the farmers of the island. The species cultivated are mostly Uushu mandarin with small quantity of navel orange and Natsu-daidai. (4) Recently 100,000 plants are being planted annually. In the selection of the plant land however, it is important to choose the places where are less affected by typhoons, and with thick surface soil, good drainage with ground inclination less than 30 degrees. It is also essential to have the lands collective and modernized so as to enable cooperative operations of preventing diseases and insect pests as well as for better irrigation. (5) The most important factor which may control the future of the citrus industry of the island would be how to lessen damages due to typhoons. It will therefore be necessary to have further study in the installations for minimizing typhoon damages.