Métodos para determinação do carbono orgânico em solos de Alagoas

Abstract

Currently, different methods of soil organic carbon determination have been used without taking into account the risks they can provide to the environment and the high cost of the analyzes. Faced with the need to adopt an alternative method that is less polluting, cheap, and efficient, some procedures are being tested. The objectives of this study were to determine the carbon content and soil organic matter by different methods, to apply descriptive statistical to data, correlating the methods and determine the similarity or difference between the alternative methods and Elemental Analysis (standard method). Additionally, due to its widespread use, the method of modified Walkley & Black was also considered as standard and compared with others. The experiment was conducted in areas of native forest in the regions of the Alagoas Backcountry, Agreste and Coastal. Forty-eight (48) composite soil samples were collected at 0 - 20 cm of depth. The carbon content in the soil was determined by the methods of wet combustion - modified Walkley & Black, Colorimetric and dry combustion – Elemental Analysis and Gravimetric analysis. Data were analyzed using descriptive statistical analysis, determination coefficients and correlation of the curve and the F Graybill test, t test for the medium error and linear correlation coefficient compared to the average error analysis. The Colorimetric methods and modified Walkley & Black tend to underestimate the organic carbon content, respectively in 55.44 and 16.27%, respectively, while the Gravimetric tends to overestimate the total carbon content with 15.02%, compared with the Elemental Analysis. The Gravimetric method presented identity with the Elemental Analysis. Although it was not observed identity when the Colorimetric method compared with the other methods, the high values for the coefficient of correlation indicate the possibility of using more environmentally and financially viable methods in routine laboratory analysis.