Phosphorus adsorption and its relationship to the physical and chemical characteristics with different soil classes

In order to determine the characteristics of phosphorus adsorption using the Langmuir and Freundlich isotherms and its relationship with some of the chemical and physical properties of soils, a study was developed at the Embrapa Soil Laboratory with soil samples (0 - 30 cm) from four classes of topsoil: Orthic Chromic Luvisols, Eutrophic Cambisols, Fluvic Neossol and Eutrophic Cambisols Typical. The hyperbolic model of the Langmuir isotherm was fitted by the non-linear regression technique. We performed a correlation analysis between the isotherm parameter values and soil characteristics that reflected the Phosphate Maximum Capacity. The values of remaining phosphorus ranged from 16.28 to 43.73 mg L-1 for the soils. For the Langmuir isotherm, the maximum phosphorus adsorption capacity (MPAC) values ranged from 0.2793 to 0.3954 mg g-1 of soil. The RY soil had the largest amount of adsorbed phosphorus (0.3954 mg g-1), giving this soil a high MPAC.   Key words: Tropical soils, phosphorus, buffering capacity.