EFFECT OF SOIL CONTAMINATION ON THE ROLE EARTHWORMS PLAY IN THE LIBERATION OF POTASSIUM

The earthworm role in organic matter degradation and in the liberation of elements in particular N and P has been known and well-established . However, certain studies show contradictory results regarding potass ium. This work consisted in a study on the effect of an anecique speci es of earthworm (Lumbricus terrestris L.), in the laboratory, on the a vailability of K in different soils contaminated by four trace element s (Cd, Cu, Pb and Zn). The results of the experiment show that the soi l pollution by these elements has an indirect effect on the availabili ty of K, In fact, soil contamination has a negative effect on the grow th of earthworms and consequently on their activities in the soil. In addition, the potassium seems to be an element that can be regulated b iologically by earthworms.