Effects of Overhead Mixed Liquid Fertilizer Application on Sandy Soil Chemical Properties of Satsuma Mandarin Orchard

Abstract

Effects of mixed application of liquid fertilizer on the sandy soil chemical properties of a satsuma mandarin (Citrus unshiu Marc.) orchard were investigated. One-year-old trees of ‘Miyagawa Wase’/trifoliate orange rootstocks planted in a 50 L pot were used for the plots. Six plots were settled. One was a non-fertilized plot, the others were solid fertilizer (control) and four liquid fertilizer application plots. Liquid fertilizer was prepared by dissolving solid mixed fertilizer containing 15% nitrogen, 15% phosphorus and 10% potassium in water at 150- and 300-fold dilution. Each dilutions of liquid fertilizer were applied six times or eighteen times starting from the end of May during the one-year experimental period. Mixed Liquid fertilizer application lowered soil pH compared with solid fertilizer application and the tendency was greater at 150-fold than at 300-fold dilution. In relation to this, 150-dilution application of mixed fertilizer lowered exchangeable calcium and magnesium concentration in the soil. The more frequent the applications of liquid fertilizer, the more rapid the increases in the nitrogen content in the soil. Phosphorus and potassium concentrations in the upper soil layer increased in response to liquid fertilizer application. The downward movement of phosphorus and potassium from the upper to lower soil layers showed a pattern similar to that after solid fertilizer application. These findings indicate that the mixed liquid fertilizer application is effective in the immediate supply of inorganic nutrients but that lime application is necessary for soil pH amendment.