Abstract

Michel, K and Ludwig, B. (2009).

J. Plant Nutr. Soil Sci., 173, 55-60

Forty-one soil samples from the Eternal Rye long-term experiment in Halle, Germany, were used to test the usefulness of near-infrared spectroscopy (NIRS) to differentiate between C derived from_C3 and _C4 plants by using the isotopic signature^(13C) and to predict the pools considered in the Rothamsted Carbon (RothC) model, i.e., decomposable plant material, resistant plant material, microbial biomass, humified organic matter, and inert organic matter. All samples were scanned in the visible-light and near-infrared region (400-2500 nm). Cross-validation equations were developed using the whole spectrum (first to third derivative) and a modified partial least-square regression method. ^13Cvalues and all pools of the RothC model were successfully predicted by NIRS as reflected by RSC values (ratio between standard deviation of the laboratory results and standard error of cross-validation) ranging from 3.2 to 3.4. Correlations analysis indicated that organic C can be excluded as basis for the successful predictions by NIRS in most cases, i.e., 11 out of 16.