Quantifying the underestimation of soil organic carbon by the Walkley and Black technique - examples from Himalayan and Central Indian soils.

Abstract

Soil organic carbon (SOC) is an important indicator of soil quality and productivity. The present study focuses on the comparative evaluation of the 'wet digestion' and 'oxidative combustion―infrared analysis' methods for determination of SOC with examples from parts of the Himalayan and Central Indian soils. It is found that the commonly used wet digestion (Walkley and Black) method underestimates the SOC significantly. The study estimates a correction factor quite different from the standard adopted in most of the investigations. Considering the importance of SOC stock and dynamics being used as inputs in models predicting global climate change and future global carbon cycle, it is emphasized that appropriate correction factors need to be developed for Indian soils, and applied to the SOC estimates obtained from the Walkley and Black method to improve the accuracy.