Phosphorus retention in soils of arid lands

María Adriana Carrasco R.1, José Opazo A.1, Inés Peralta V.1 y Luisa Vera Q.1

Adsorption of phosphorus through dilute solutions of KH2PO4 and Ca(H2PO4)2 was studied in arid an alluvial origin soil (Metropolitan and VI Regions). The phosphorus concentration ranged from 0.64 to 3.23 x 10-3 M. The phosphorus adsorption isotherms obtained were adjusted to the Langmuir equation (R2 = 94.1 and 94.3% for KH2PO4 and Ca(H2PO4)2 solutions, respeetively). The accompanying cation of phosphate poorly affeeted the values of maximum adsorption of P (b). Greater variations were found for the k constant in some soils. The phosphorus adsorption maximum was closely correlated with the contents of organic matter and silt for the soils from arid lands, and it was correlated with the organic matter, clay and free iron oxides for the alluvial soils.

Keywords: phosphorus, adsorption, arid lands, alluvial soíl.
1 Departamento de Ingeniería y Suelos. Facultad de Ciencias Agrarias y Forestales. Universidad de Chile. Casilla 1004. Santiago. Chile.