Influence of fallow and of pasture on the nutrient dynamics in recently deforested Oxisols of Eastern Amazonia

Abstract

The present paper deals with the effects of six and eight years of fallow and of nine years of cultivated pasture, on nutrient dynamics in deforested Oxisols of Eastern Amazonia. Electroultrafiltration (EUF) method was used, in order to propose efficient systems to improve soil fertility in this area. Forest burning brought about immediate increase of soil pH, whereas subsequent decrease in extractable EUF-A1 and increase in exchangeable K and Ca were noticed. Pasture installation after deforestation has shown appreciable prospect to maintain an adequate level of soil fertility since it increases pH and reduces the EUF-A1 content. As compared with the soil left under fallow for eight years, higher pH values, lower amount of extractable A1, higher amounts of mobile P and K, higher biological soil activity, and stable amounts of available nitrogen were observed in the pasture soil.