Abstract
We proposed a system to cultivate rice for animal feed with circulated irrigation of treated municipal wastewater, aiming at resource circulation among agriculture, livestock farming and urban area. The feasibility of the proposed system was evaluated through the experiment using the simulated paddy field. As the result, the system achieved removal of more than 3 times larger amount of nitrogen from treated wastewater than the similar system cultivating rice for food, which we previously proposed. About 40 % of the removed nitrogen was absorbed by rice plants and this was common to the system without circulated irrigation. On the other hand, circulated irrigation clearly increased the amount of nitrogen released to the atmosphere. Although the yield and quality of cultivated rice were not significantly improved by circulated irrigation, the result of this experiment demonstrated the potential to improve them by adding more treated wastewater in the latter half of cultivation period for earing and bearing.
