Summary
The main source of nitrogen in the water of the soil of the eco-system of the Amazon Campina are the decomposing material, (litter), rain, water running of the vegetation and the biproducts of the metabolism of micro-organisms. Water samples taken from water table from four white sand sites (regosol) were analized for the components of nitrogen (Ammonia, nitrites, nitrates) and the concentration of the organic nitrogen and the total nitrogen were calculated. There was a greater concentration of nitrogen of an organic origin present than that from other origins. Ammoniac nitrogen was the principal product of the formation of organic material by micro-organisms and it had the second largest concentration, while nitrates and nitrites were almost always absent because of the acidity of soil (pH 3,0). There are annual and seazonal variations in the nitrogen compounds. The highest quantities are obtained in the middle of dry season owing immobilization of water table. In the natural conditions on white sand nitrogen is not a limiting factor for the development of the natural vegetation.