Balanço geoquímico em uma microbacia hidrográfica sob plantio de eucalipto

Abstract

This work aimed to provide an approximation of the geochemical balance of nutrients in the experimental watershed in Aracruz, State of Espírito Santo, Brazil, for three management strategies. Data were obtained by measuring the chemical composition of: precipitation, chemical composition of rain, the spillway flow, water chemistry of the spillway, eucalyptus production, chemical composition of the harvested wood, and chemical composition of the applied fertilizers. These data were collected and measured regularly from 1995 until 2003.The content of nutrients in the rainwater was always very low. Harvesting was the main factor of nutrient removal from the catchment, particularly for Ca, K, and N. Barking out the trees in the field and leaving the barks in the field is an interesting practice not only from an economic point of view but also from an environmental sustainability standpoint. From the geochemical balance standpoint, the management applied seems to be very suitable as there are not significant gains nor losses of any nutrient, which points to an equilibrated condition. The adopted practice of leaving the bark of eucalyptus plantation in the field is highly recommended, promoting nutrient cycling and allowing fertilizer economy.