A PRELIMINARY COMPARATIVE INVESTIGATION OF PHOSPHORUS IN IRISH GRASSLAND AND IN SPANISH SOILS

Resumen

Sequential fractionation has been performed on soils by step-wise extraction with anion-exchange resin, bicarbonate, sodium hydroxide and acid solutions. Extracted phosphorus in inorganic and organic forms have been separately estimated. Soils from Wexford (Ireland) and from La Coruña, all Inceptisols, gave similar phosphorus distribution patterns that differed from these shown by soils (Entisols) from the Seville región. Relative contribution of organic forms in the Inceptisols reflected the role that organic matter plays in these soils. Inorganic phosphorus, extractable by resin and by bicarbonate, increased with fertilisation, whereas residual P decreased. Phosphorus extractable with acid was the dominant form in Entisols. The susceptibility to leaching of phosphate from soil in columns, was significantly related to its extractability using anion-exchange resin, and this relationship extended across all soils examined