Development of a Closed, Cost- and Energy-Saving Hydroponic System for Hillside Tomato Production

Abstract

To avoid problems, such as lifting soil and soil borne diseases, when growing tomatoes on hillside fields, we developed a hydroponic system for sloped land. First, we investigated an irrigation system. The drip tubes were set on contour line. After the water valve was closed, a considerable amount of drainage leaked from the lowest line. We changed the type of drip tube to that providing drainage shut off below a certain pressure and inserted check valves into the line. As a result, drainage from the lowest line stopped. Second, we developed a hydroponic system by application of the irrigation system. The supply of nutrient solution and fertilizer injectors were powered solely by water pressure, without the use of electric power or pump. As a result of growing tomatoes using the system, the yield of higher positions on the sloped greenhouse was less than that of the lower positions because of the insufficient water pressure. However, after securing the water pressure, there was no difference in yield at different positions. Finally, we developed a closed hydroponic system by improving the system. Drain of the nutrient solution was collected by slant of the ground into a reservoir tank. During the supply of nutrient solution, the collected drain in the tank was injected into the fresh solution by an aspirator that was powered by a current of water. Tomatoes were grown for about 7 months and the yield was 12.8 ton 10a^-1 using this system.