Effect of Channel Length and Flow Rate of Supplied Lake Water on Yield of Water Spinach and Nitrogen Removal in Vegetable Production System using Eutrophic Lake Water

Abstract

The effect of the flow rate of the supplied lake water and channel length on the changes in the NO₃-N concentration of the solution in the channel, amount of suspended solid(SS)precipitated in the channel and yield of water spinach was investigated in the channel constructed in a lake-side greenhouse using the eutrophic Tega-lake water. It was observed that SS precipitation in the channel promoted the growth of water spinach and that the crop took up the nutrients from SS that precipitated in the channel as well as from the dissolved ions in the solution. The amount of SS that precipitated in the channel was affected by the SS amount of supplied lake water and the water flow rate. When the channel length was less than 20 m with a water flow rate of 10-20 L/min, the yield of water spinach was higher and growth was uniform from upstream to downstream in the channel. In addition, nitrogen was efficiently removed from eutrophic lake water.