Equations for Predicting Soil Organic Carbon Using Loss‐on‐Ignition for North Central U.S. Soils

Samples of 255 noncalcareous A, Ap, and AB horizons from selected major land resource areas (MLRA) in the north central USA were used to develop equations for predicting organic C content, as determined with a Leco C analyzer, from weight loss‐on‐ignition (LOI). Organic C concentrations of the samples ranged from 1.09 to 114.6 g kg −1 Within each MLRA, strong linear relationships were observed between LOI and organic C measured by the Leco instrument, with r 2 ranging from 0.94 to 0.98. Predictive equations developed by least‐squares regression were significantly different for individual MLRA's. Loss‐on‐ignition is a rapid, inexpensive, and accurate method for estimating organic C concentration in soils of the north central USA. We recommend that unique predictive equations be developed for individual soil‐geographic regions.