Quantification of Organic Carbon in Soils of the Derived Savannah Using Four Different Methods

Background and Objective: Several methods of organic carbon determination exist including wet combustion (Walkley Black, Tube digestion and potassium permanganate) and dry combustion (loss on ignition) method. Each method is characterized by both advantages and limitations. This study aimed at quantifying the amount of organic carbon in soil of the Derived Savannah. Materials and Methods: The organic carbon was determined using four different methods: Walkley Black Method, Tube Digestion Method, Loss on Ignition Method and Potassium Permanganate Method. The soil was sampled across two different locations with different properties. The soil samples were analyzed and the obtained results were subjected to descriptive statistics and linear regression using the JMP Statistical package. Results: Different amount of organic carbon was determined by the methods. The loss on ignition determined the highest amount of 9.96 g kg^–1 while, 5.81 g kg^–1 was determined using Walkley Black. The use of permanganate and tube digestion was observed to determine 4.34 g kg^–1 and 2.18 g kg^–1 organic carbon, respectively. The results of the regression coefficient were observed to be >0.6 with the loss on ignition having a very good fit with an r² value of 0.99. Conclusion: The high amount of organic carbon produced by the loss on ignition and potassium permanganate could encourage their use for soils of savannah in addition to the little or no waste generated by this method.