Yield and quality of leafy vegetables grown with organic Fertilizations

Vegetable production with organic farming has been practiced by many farmers in Japan. However, one of the problems is the yield lower than that by chemical farming. In this study, Two leafy vegetables were grown with organic fertilization in comparison with chemical fertilization, to see what accounts the yield limitation and how different in quality of the leafy vegetables between organic and chemical fertilizations. Leaf-picking harvest was adopted to extend the growth and harvest period. Growth at the early stage was lower in organic than in chemical fertilization treatments, which was attributed to the lower available nutrients in organic fertilizer. However, at later stages both the two vegetables in organic fertilization treatments grew better and resulted in a final higher total yield than those in chemical fertilization treatments, which was attributed to the high nutrient sustainability of organic fertilizer and the improved biological properties of the soil. Leaf concentrations of sugars and vitamin C were significantly higher and nitrate was lower in organic-fertilized than chemical-fertilized vegetables. It is possible for organic farming to produce vegetables with a high quality and a yield higher than or similar to that of chemical farming if the nutrient supply is sufficient. The yield of leafy vegetables was higher than that of chemical farming when the leaf-picking harvest was adopted to extend the growth and harvest period.