Annual application of cattle manure in a farmer's field in eastern Nebraska for 4 yr caused improved soil N and P supply and increased corn yield in less productive portions of the field. As a first step toward identifying the soil processes that led to these changes, the effects of manure addition on the chemical nature of soil organic matter were investigated by extracting two humic fractions from the field soil for subsequent analysis by recently developed techniques of solid-state ¹³C nuclear magnetic resonance (NMR)  spectroscopy. They included quantitative direct polarization, cross polarization/total suppression of sidebands, ¹H-¹³C two-dimensional heteronuclear correlation NMR, ¹³C chemical shift anisotropy filtering, and other spectral editing techniques for identifying specific functional groups in soil organic matter.  Results show that the chemical nature of each humic fraction did not differ between a treatment in the farmer's field that received N as inorganic fertilizer and an unfertilized control treatment.  A Ca-bound humic fraction from a manure N fertilizer treatment was enriched in nonpolar aliphatic compounds, most likely fatty acids, compared to the other two treatments.  Manure application did not affect the chemical natures of the humic fractions in any further way, suggesting that the principal benefit of manure addition to soil nutrient supply involved either (i) labile components originating from the manure that had already decomposed by the time of sampling, or (ii) the quantity of soil organic matter, not its quality.