STUDY OF NUTRIENT DYNAMICS IN FLOODPLAIN SOILS OF THE CAREIRO ISLAND - CENTRAL AMAZONIA

In contrast to the upland ''tara firme'' terrain, the floodplain varze a in the Amazon is the zone that is used for supporting rational agric ulture without use of fertilizers. Following the dynamics of the main soil nutrients, two distinct floodplain environments were selected, na mely high and low varzea. Soil samples were collected throughout the w hole year of 1987. No significant differences were found in the concen trations of the main nutrients for samples taken during different peri ods. However, the concentrations of Ca, Mg, Na, Al, H, Cu, Zn and Mn i n the low varzea were always higher than in the high varzea. This coul d be a result of the deposition effect during former flood periods, be cause the low varzea is exposed more to seasonal flooding. The study o f the main nutrients analysed in the varzea floodplain soils shows a h igh natural fertility.