13C-LABELLING FOR NMR STUDIES OF SOILS: CPMAS NMR OBSERVATION OF 13C-ACETATE TRANSFORMATION IN A MINERAL SOIL

Abstract

Few NMR studies with whole soil have been successfully attempted. Solid-state 13C NMR spectra were obtained for Bainsville clay loam, an orthic humic gleysol with 3% C, using the CPMAS technique (cross-polarization magic-angle spinning). Results for the whole soil were limited by polar signal/noise and lack of resolution, possibly due to line-broadening by Fe. Better results were obtained by employing a < 50 .mu.m fine-size fraction, and difference spectra techniques, allowing observation of added 13C-labeled acetate and its transformation during incubation.