Reactions of Apple Tree and its Fruit to Compost Use in Central Anatolia, Turkey

Abstract

Many soils in Turkish apple orchards are low in organic matter and nutrients, resulting in poor soil structure and Zn and Fe deficiencies in the fruit trees. Adding municipal waste compost, albeit with some heavy metal content, may improve soil structure and nutrient levels. This study investigated whether the use of municipal waste compost, with or without a chemical fertilizer, in an apple orchard in semi-arid Central Anatolia, Turkey, would improve soil fertility, yields and fruit quality without causing adverse heavy metal accumulations in the soil, leaves or fruit. In a 3-year period (2006-2008), three compost doses and three chemical fertilizer doses were applied annually as treatments in a randomized plots experimental design with five replicates; each plot contained 1 tree. Leaf and soil samples were collected each year at the end of July; soil was sampled from depths of 0-30 cm and 30-60 cm within the area of the tree canopy projections. Fruit was sampled at the end of September. The soil, leaf and fruit samples were analyzed for nutrients and heavy metals, and fruit yields and yield components were determined. Compost application increased electrical conductivity values and contents of organic matter, available nutrients, and heavy metals in the soil, as well as the contents of nutrients and heavy metals in the leaves and fruit; however, heavy metal contents of soil and plant were within safe limits. Moreover, compost use enhanced fruit yield and quality, and could reduce the need for chemical fertilizers by as much as 50%. Longer-term studies or monitoring are recommended in order to safeguard human health and the environment.