Comparison of Wet Chemistry and Dry Combustion Methods of Organic Carbon and Sulphur Determination in the Dry Savanna Soils of Nigeria

• B.L. Abdulrahman

  Department of Soil Science, Bayero University Kano, Nigeria

  Author

With increasing soil nutrient depletion and planting of high nutrient demanding crops as a result of increasing population, there is a need for faster and more effective analytical methods to achieve balanced nutrition without detrimental effect to the soil. For this reason, the wet chemistry method of organic carbon and sulfur determination was compared with analysis by CHNS/O analyser. A total of 60 surface soil samples were collected from 10 farming communities across the northern Guinea and Sudan savannas of Nigeria, specifically from maize growing environment. These samples were processed and analyzed for organic carbon using the Walkley-Black method and sulphur using the turbidimetric method. The same samples were then analyzed using the Perkin Elmer CHNS/O anlyser which uses the combustion method. Plotting the result of Walkley- Black against CHNS/O organic carbon gave a coefficient of determination (R2) of 0.25 but turbidimetric sulphur against CHNS/O gave an R2 of 0.34. There was improvement in the comparison when the data set was separated by agroecology (northern Guinea savanna and Sudan savanna), by state (Kano, Kaduna and Katsina) and by farming community, with the highest R2 of 0.8 and a lowest of 0.4. It was also observed that there is higher repeatability with the CHNS/O analyzer than with the wet chemistry method of both organic carbon and sulphur determination, plotting the initial CHNS/O analyzer organic carbon and sulphur values against the repeated values gave an R2 of 0.91 and 0.89, respectively. A plot of the repeated values with the wet chemistry methods gave and R2 of 0.61 and 0.58 for organic carbon and sulphur, respectively. The result showed that the CHNS/O analyzer provides a more precise and timely analytical method for organic carbon and sulphur determination for savanna soils of Nigeria.

1. B.L. Abdulrahman, Department of Soil Science, Bayero University Kano, Nigeria

   Department of Soil Science, Bayero University Kano, Nigeria

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