Characterization of Animal Manure Using Advanced Solid-State C-13 NMR Spectroscopy.

Knowledge of chemical structure of animal manure is necessary for its effective utilization. However, characterization of animal manure is challenging since it is a complex mixture and partially soluble. Solid-state C-13 NMR (nuclear magnetic resonance) spectroscopy is regarded as the best tool to investigate the complex structure of animal manure. In this presentation, new, advanced solid-state NMR techniques, developed especially for the structural elucidation of complex organic matter such as animal manure, are demonstrated. It includes 1) identification of specific functional groups using advanced spectral-editing techniques, 2) quantification of specific functional groups via direct polarization/magic angle spinning combined with spectral-editing techniques, 3) examination of the connectivities and proximities of specific functional groups using two-dimensional ¹H-¹³C heteronuclear correlation NMR combined with spectral-editing techniques, and 4) identification of domains and heterogeneities by proton spin diffusion.  The applications of this systematic protocol are demonstrated using   animal manure samples collected from farms under different management practices.