THE EFFECT OF THE PHOSPHORUS DOSAGE AND INCUBATION TIME ON THE PROCESS OF RETARDING AVAILABLE PHOSPHORUS FORMS IN A SANDY SOIL

摘要

The object of the study was to evaluate the effects of the phosphorus dosage and incubation time on available phosphorus forms and the content of exchangeable aluminium in Dystric Cambisols under conditions of a model laboratory experiment. Mineral phosphorus [Ca(H_2PO_4)2] was added in 5 different doses to soil, incubated for 30 or 60 days at 18°C. Soil samples were analysed for available phosphorus forms, total phosphorus and the content of exchangeable aluminium. It was found that the content ofavailable phosphorus forms depended significantly on the phosphorus dose and the incubation time. A higher content of available phosphorus was assayed after a longer incubation time. Exchangeable aluminium occurring in the samples reduced available phosphorus concentration from 1.7 to 78.2% of the amount introduced as the fertiliser.