Determination of the effect of agricultural practices on copper and zinc fractions in soils of apple orchards in Isparta province using sequential extraction

In order to determine copper (Cu) and zinc (Zn) pollution caused by the use of Cu and Zn based fungicides and phosphorus fertilizers in apple orchard soils and to examine the relationships of these elements with soil properties and leaf plant nutrient content, apple orchards from Eğirdir and Gelendost, which are the leading districts of Isparta province in apple production, soil samples were taken from two different depths, 0-20 and 20-40 cm and leaf samples were taken from the same orchards. Apple orchards of different ages (0-5, 5-10, 10-15, 15-20 and >20 years) were selected for sampling. In addition, soil samples were taken from places near apple orchards (pasture and field without fungicide application) for control purposes. In order to evaluate the behavior, mobility, bioavailability and phytotoxicity of copper and Zn elements in the soil, total and available Cu and Zn and 7 different Cu and Zn fractions (water soluble and exchangeable, bound to carbonates, bound to Mn oxides, bound to amorphous Fe/Al oxides), bound to crystalline Fe oxides, bound to organic and sulfides, residual fractions) were determined. As the orchard age increased, there was an increase in the total Cu, available Cu and Zn content, and the proportional distribution of the available fractions of Cu and Zn (WS, Car and MnO). Especially in apple orchards in the older age group, higher values were found in terms of total and available Cu amount compared to the control sample. The positive correlation between available P and available Cu and Zn showed that there was Cu and Zn contamination caused by fertilization (especially phosphorus fertilizer) and fungicide in the soil, and it was concluded that measures should be taken for the sustainability of the soils.