Edafología. Volumen 7-3. Septiembre 2000. pág 21-29.

ABSTRACT

The aim of this work was to test the effects of different doses of sewage sludge on the evolution of N, P and K contents in a humic cambisol, besides their effects on the productivity of two successive cultures: Hordeum vulgare L. cv. Atlas, followed by Zea mays L. var. INRA 2600. Effects were compared to a control and also to a soil that was fertilized inorganically.

Supplementation with sewage sludge increased N contents of the soils. At the end of the experiment, treated soils showed higher N levels than those inorganically fertilized and the control.

All the experimental parcels had larger amounts of assimilable P than the control. P contents increased correlatively with dose size.

The soil that was fertilized inorganically showed higher P ammounts than the others all along the experiment. During the second culture, P availability was higher in the soils treated with sewage sludge, due to a decrease in acidity caused by the incorporation of such material.

Once concluded the experiment, the soils treated with sewage sludge had higher levels of assimilable K than those inorganically fertilized and the control. This result suggests that K availability is improved by the addition of sewage sludge to the soil.

Production of dry matter increased correlatively to the ammount of sewage sludge suplied. The least yield was observed for the control.

The mean productivities of corn yield are higher for the soils treated with sewage sludge than those of inorganically fertilized soils and the control, because sewage sludge increase the levels of other nutrients that inorganic fertilization can not provide.

Key words: Soil, Sewage sludge, Nitrogen, Phosphorus, Potassium, Production