Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2000
Publication Date: N/A
Technical Abstract: Soil organic matter (SOM) is an important soil quality attribute, influencing the productivity and physical well-being of soils. It is important from both an economic and environmental standpoint to determine how changes in cover crop management will influence SOM and soil quality. The objective of this study was to determine quantitative, structural, and compositional changes of humic substances (humic and fulvic acid fractions) caused by cover-crop systems using Nuclear Magnetic Resonance spectroscopy (NMR) and Diffuse-Reflectance Infrared Fourier Transform Spectroscopy (DRIFT). Humic substances were extracted using alkali-techniques from soils under a vetch/rye, rye alone and a check (no cover crop) cropping system which were also treated with four nitrogen fertilizer rates. The NMR analyses revealed that cover crop did influence the quantity of carbon in aromatic compounds, proteinaceous and carbohydrate structures in the humic substances. Peak ratio analyses, determined from DRIFT analyses, showed that cover crop systems with different nitrogen fertilizer rates greatly influenced the O/R ratio of the humic and fulvic acid fraction. Results from this investigation showed that the structural chemistry of humic substances was influenced by cover crop system and nitrogen fertilizer rate.