CHARACTERIZATION OF SOIL ORGANIC CARBON IN TWO CALIFORNIA GRASSLAND CHRONOSEQUENCES USING SOLID-STATE (CP/MAS) 13C-NMR

Demineralized A horizon soils from a series of marine terraces at Santa Cruz, California, exhibit very little change with terrace age in the proportions of the principle organic carbon compound classes measured with solid-state (CP/MAS) 13C-NMR, compared to those from the Mattole terrace chronosequence near Eureka, California. The older Mattole terraces have higher proportions of unsaturated alkyl and aromatic carbon groups than the more recently formed terraces. Precipitation at Mattole is nearly double that at Santa Cruz which results in increased weathering of parent material. Our NMR results suggest that weathering patterns shape the specific types of carbon stored within the soil mineral matrix.