Spectroscopic Characterization of Fulvic Acid Under Different Cover Crop Systems

Abstract

Fulvic acids (FAs) are an important dynamic component of soils that may be affected by soil management. Carbon‐13 cross‐polarization total sideband suppression nuclear magnetic resonance (CP‐TOSS 13C NMR) was used to examine the effect of cover crop systems on the characteristics of fulvic acid fractions. FA was isolated from soils with the following treatments: 1) vetch/rye, 2) rye alone, and 3) check (no cover crops) with varying nitrogen fertilizers. Preliminary NMR results indicate that FA from the rye alone system both with and without nitrogen fertilizers contains less aliphatic carbon (0–108 ppm) than that from the other two treatments. Based on the elemental composition analysis result, C∶N ratio of FA from rye alone cover with or without nitrogen fertilizer is lower than FA from vetch/rye cover system. These data suggest that farming systems affect the FA compositions.