Effects of Some Organic Fertilizers and Agryl Cover on Yield, Quality and Leaf Nutrient Content and Soil Productivity in Organic Lettuce Growing

This study was carried out at the organic land of Ege University Faculty of Agriculture, Department of Horticulture during the spring and autumn seasons. Three organic fertilizers were tested under two growing systems to determine yield, quality, plant growth and soil fertility in Romaine lettuce (cv. Yedikule) and lettuce (cv. Arapsaçı) production. Experiments were conducted with 6 groups composed of two growing systems [under Agryl cover (A+) or open field conditions without Agryl (A-)] and three fertilizers [Biofarm (B), Biofarm + Humic Acid (BHa) and Biofarm + Leonardite (BL)] in two years and growing seasons (2005-spring and 2006-autumn) with factorial design. In both years, total yield and average plant weight increased with the use of agryl cover while among the tested fertilizers, BHa and B applications gave the highest yields in the 1st and 2nd year, respectively. Agryl cover affected plant length among the measured quality characteristics. Mean nitrate content of organic lettuces was found quite low than the limits. Effects of agryl cover and fertilizers on leaf nutrient content were significant whereas fertilizer treatments increased soil microbial biomass-C and organic matter content in the first yield. It was concluded that these treatments could be recommended to use in organic lettuce production due to the positive effects of agryl cover on yield and organic fertilizers on yield, quality and soil fertility.