M.B. ALMENDRO-CANDEL, J. NAVARRO-PEDREÑO, M.M. JORDÁN-VIDAL, I. GÓMEZ-LUCAS
Departamento de Agroquímica y Medio Ambiente. Universidad Miguel Hernández. Edificio Torreblanca. Avda. de la Universidad s/n. 03202 Elche (Alicante). e-mail: mb.almendro@umh.es
Abstract. The precipitation of calcium phosphates slightly soluble in calcareous soils makes diminish the bioavailability of this macronutrient, that is why it is necessary the use of fertilizers. The sludge from the waste water treatment not only contributes with important quantities of phosphorus, but also reduce the pH, increasing the availability. The loss of these nutrients can contaminate underground waters. In order to evaluate the mobility of the phosphorus a study was realized in columns of soil in those who different doses of residue were applied. The pH was analyzed, which diminishes even in 0,76 units, assimilable and soluble phosphorus in intervals of 15 cm of depth, obtaining, respectively, maximum values of 251 mg P·kg-1 d.m. and 1355 µg P·kg-1 d.m., as well as the phosphorus in the leachates at the end of the columns, that the value of 98 µg P·L-1 was not overcome.
Key Words: assimilable phosphorus, soluble phosphorus, pH, sewage sludge, calcareous soil