The Use of Sewage Sludge as an Organic Matter Source in Apple Trees

Abstract

The objective of this experiment was to evaluate the effects of different doses of sludge on fruit yield, growth, nutrition and heavy metal accumulation of apple trees on a calcareous soil 1999-2003. Sewage sludge was added to the soil at rates of 0, 10, 20, 40 and 60 kg tree(-1). Manure was applied to the soil at a rate of 25 kg tree(-1). According to four-years data, cumulative application of sewage sludge to apple trees significantly increased fruit yield, trunk cross-sectional area, shoot growth and leaf N, Mg, Fe, Mn, Zn and Cu contents at the end of the study. Leaf Ni slightly increased with sludge addition in 2003 only. The four-year results of this study indicated that repeated sewage sludge application to apple trees did not cause toxicity in leaves and fruits. However, long-term sewage sludge application may result in the accumulation of Zn, Cu and Ni in the soil and plant.