Métodos para a determinação de carbono orgânico em solos

Abstract

Soil organic matter (SOM) comes mostly from plant organisms, whose rate of decomposition is variable depending on the different plant species that differ from each other. There are several methods to determine carbon in soil samples, however, it is essential to improve and adapt the methods of carbon determination, to reduce costs and unnecessary disposal of chemical waste. In this sense, the present work aimed to compare three methods of determination of organic carbon in Red Yellow Argisol submitted to different managements. Soil samples were collected in the municipality of Guarantã, São Paulo, with sandy texture, at a depth of 0-20 cm. Three composite samples were collected, with a composite sample being the combination of ten simple samples. Soil carbon contents were determined by wet combustion methods - titration and spectrophotometer, and dry combustion - muffle. Data were submitted to analysis of variance and subsequently to Tukey's test (p≤0.10). The CO levels obtained by the three methods did not correlate with each other in the different studied areas. The muffle and spectrophotometer methods tended to overestimate the CO contents in relation to the reference method (titration). The recovery factor of the methods varies with the areas studied.