The possibility of tomato cultivation in greenhouse using treated waste water from a rural sewage treatment plant

The lack of water resources necessary for agricultural production is a major problem in the world, and there is great expectation for water-saving cultivation technology such as utilization of reclaimed water and reduction of irrigation water. In Japan, it is relatively easy to use high-quality groundwater and river water for agricultural water; therefore, water consumption has hardly been taken into consideration. However, excessive irrigation has many problems such as not only wastage of water resources but also reduction of fertilizer utilization efficiency and increase of environmental burden due to penetration of fertilizer components into underground water. Moreover, in areas with poor water resources such as island areas suffering from chronic water shortage, there is a high interest in using sewage treatment water as agricultural water. Therefore, even in Japan, it is extremely important to establish irrigation technology with high water utilization efficiency and it is also important to develop technology for utilization of water sources that have not been used so far for agricultural production such as treated water of settlement drainage or groundwater with high salt concentration. In this research, we grew tomato in greenhouse (7.2×20 m) using treated waste water from a sewage treatment plant in Miho with two irrigation technologies: OPtimal Sub-surface Irrigation System (OPSIS) and drip irrigation systems. We found that there were no significant differences in the growth of tomatoes due to the difference in the water source or irrigation technologies. These results mean that it would be possible to take agricultural settlement drainage as one of the water resources for irrigation water.