Soil phosphorus sorption properties in different fertilization systems

The study aimed at the evaluation of the accumulation and vertical distribution of different forms of phosphorus (P) in reference to phosphorus sorption properties subject to mineral (NPK), mineral-organic (NPK + M), and organic (M) fertilisation. It was carried out in a long-term experimental field in Skierniewice (Central Poland) conducted since 1923 under rye monoculture. Total P content in the M and NPK soil profile was similar and lower than in the NPK + M soil. The content of organic P in Ap and Eet horizons of both manured soils was similar and higher than in the NPK soil. The Langmuir P sorption maximum (Smax) in the studied soils ranged from 39.7 to 90 mg P/kg, while the Freundlich P sorption coefficient aF ranged from 6.9 to 41.9 mg P/kg. Higher variability of parameters related to the binding energy from the Lanqmuir (k) and Freundlich (aF) equations was determined between soil horizons than between the fertilisation systems. Nonetheless, in M and NPK + M soils, sorption parameters aF and Smax and binding energy (k, bF) were considerably lower than in the NPK soil. The content of water extracted P in manured soils was higher than in the NPK soil.