Estudo comparativo entre os métodos Walkey & Black e colorimétrico para análise de carbono orgânico no solo: uma revisão bibliográfica

Abstract

The influence of Soil Organic Material (SOM) on ecosystems and agriculture has been the object of analysis of several studies. The main constituent of SOM is Carbon, and the determination of Total Carbon (TCO) has been used in several studies to quantitatively estimate the soil organic fraction. Among them, there are some methods that stand out, either due to their greater effectiveness, in the ease of application or even by the low cost, such as the Walkey&Black and Colorimetric methods, objects of study of this work. Therefore, a comparative analysis was performed between the methods, with the objective of determining the advantages and disadvantages of each one. Thus, from the information obtained from the literature review, it was possible to observe that the values of TOC by the WB and Colorimetric methods are underestimated in relation to the commonly used reference method, which is the elementary analysis method. These lower indices found are due to the fact that both methods are not able to oxidize all forms of carbon present in the soil. It was also possible to conclude that although the Colorimetric method presents some of the disadvantages of the Walkley & Black method, such as the difficulty in total carbon oxidation and the need for more accurate calculations to determine the correction factor, it has a greater advantage in reaction to the older method since it eliminates some drawbacks. Among these, the use of less toxic reagents, easier and faster handling, eliminates possible operational issues such as the turning point of the titration used in the WB method.