Effects of utilization of water extract from coffee grounds on the growth and chlorophyll content of Japanese mustard spinach

We are investing effective utilization of the food wastes for agriculture and focusing on coffee grounds which is disposed of in a large quantity and difficult to reuse. There are obstacles in using coffee grounds for agricultural materials, because coffee grounds are high carbon to nitrogen (C/N) ratio and may contain a kind of plant growth inhibitor, therefore here we used water extract from coffee grounds. Growth of Japanese mustard spinach ( Brassica rapa var. prviridis ) was enhanced by applying the water extract from coffee grounds, and the growth ratio was almost the same as plants applied commercial liquid fertilizer. The water extract from coffee grounds showed higher values in nitrogen, phosphoric acid, potassium, and minerals than the commercial liquid fertilizer, the plants, however, might not use these nutrients enough. Chlorophyll content in the plants applied the water extract from coffee grounds was higher than plants applied the liquid fertilizer, but there was no correlation between chlorophyll content and growth of plants.