Carpathian Journal of Earth and Environmental Sciences

Phosphorus (P) is essential to all known life forms because it is a key element in many physiological and biochemical processes. In this study, different physiographic units of Atabey Plain have developed soils with varying characteristics. The variability in land use and fertilizer input management causes changes in the availability and geochemical fractions of phosphorus. In this study, 29 surface soil samples (0-20 cm) were taken from various fruit orchards to investigate the plant cover-related inter-fraction mobility and availability of P as a function of soil characteristics. Sequentially extracted geochemical P fractions were: sodium bicarbonate [NaHCO₃-P (organic Po, inorganic Pi, and Total Pt)], sodium hydroxide [NaOH-P (Po, Pi, and Pt)], citrate bicarbonate dithionite (CBD-P), hydrochloric acid (Ca-P), and residual (Res-P) phosphorus. In order to study the relationship of phosphorus fractions with soil properties, chemometric analyses were performed. According to the results, the average concentrations of the fractions in descending order were: Ca-P (200-1029 mg kg^-1) > Res-P (55.3-449 mg kg^-1 ) > CBD-P (56.5-204 mg kg^-1) > NaOH-Pi (26.0-206 mg kg^-1) > NaHCO₃-Pi (4.38-93.4 mg kg^-1) > NaOH-Po (0.55-30.0 mg kg^-1) > NaHCO₃-Po (0.26-7.56 mg kg^-1). The added fertilizer P was likely to be converted to NaOH-P in the short term and Ca-P and/or CBD-P for a relatively longer time. It was determined that the fractal distribution of these fractions varied according to the land use pattern and soil properties such as texture, organic matter, carbonates, and iron and manganese oxide minerals.