2014 Volume 27 Issue 6 Pages 354-361
Since the wastewater from swine farm contains considerable amount of nitrate-nitrogen, an appropriate treatment for the wastewater is necessary. However, the high cost of treatment makes the task uneasy. To solve this problem, we propose an environment-friendly recycling system for the wastewater by producing liquid swine manure (LSM) using a simple aeration process and by utilizing the LSM for rice cultivation. This study carries out substantiative experiments of wet-rice cultivation using the LSM, and especially evaluates the economical sustainability. A series of cultivation experiments between using the LSM and conventional chemical fertilizer shows that there were some differences in timing and strength in affecting the growth between them, but the yield differences were negligible. Further, an economic evaluation revealed that the use of the LSM saves approximately 2,000 yen per 10 ares. Questionnaire survey in the tasting events revealed that samplers’ impression of the rice grown with the LSM was good, and the rice was valued 7.6% higher on average than the price of the conventional rice. The economic gain estimated from the survey is approximately 7,000 yen per 10 ares.
