Phosphate buffer capacity in sone great groups of soils in Buenos Aires (Argentine)

Oiga S. Heredia1 y Lidia Gluffré1

In Buenos Aires province (Argentina) there are soils with defficient extractable phosphorus levels, a problem that has increased in the last years due to intensification of agricultural practices. As soils differ in their responseto application of phosphate fertilizers, the scope of this work was to evaluate phosphate buffer capacity (PBC) in 87 soils that belonged to different great groups of soil taxonomy. PBC in Mollisols ranged from 6.2 to 36.6 μg g-1 of P. Highest values were obtained for Rendolls and lowest values for Udipsamments with intermediate values for Argiudolls and Hapludolls. PBC presented a significant correlation with sorption indexes P25 and P50. In soils high in native phosphorus or exchangeable sodium content calculation of PBC wasn't possible due to high desorption values.

Keywords: soils, great groups, phosphate buffer capacity, P sorption indexes, pH.
1 Departamento de Suelos, Facultad de Agronomía, Universidad de Buenos Aires, Avenida San Martin 4453 (1417), Buenos Aires, Argentina.