Abstract
We present an overview of the roles of cultivated land in the formation of the water environment, and suggest strategies for the conservation of this environment on the coast of the Ariake Bay, Kyushu, Japan. Various types of irrigation and drainage systems in this area form unique features of the water environment there. The waters in the Yabe River irrigation area and on the Shiroishi Plain are highly contaminated with nitrogen, which drains from tea plantations in the former and upland fields in the latter. Rush fields on the Yatsushiro Plain are another major source of nitrogen. Reusing agricultural drainage and domestic effluent for irrigation of paddy fields is an effective way to reduce the nitro gen load from such agricultural areas.
