Validation And Comparisons Of Naoh And Na4p2o7 Extraction Methods For The Characterization Of Organic Amendments

The objectives of this study are to compare the chemical properties of organic matter (OM) in alkaline extracts of turkey litter compost, source-separated organic compost, and biosolid pellets, and to validate the use of humic acids (HAs) for analyzing the functionality (i.e., the ability to complex with nutrients) of OM. The humic fractions, including (HAs), fulvic acids (FAs), and alkaline nondissolved fraction (humin), were isolated either with NaOH or Na4P2O7 (PyroP) and the chemical properties were analyzed by solid-state C-13 NMR spectroscopy. The study showed that the proportions of each functional group of the combination of HAs, FAs, and humin were essentially identical to that of their HCl-treated original materials, except for a lower recovery of O-alkyl groups. Although the yield of HAs extracted with PyroP was lower than that with NaOH, their spectral characteristics were not significantly different. The functionality of the OM, assuming a correlation with the sum of the proportions of carboxyl and phenolic groups, was higher in both HAs and FAs than that in humin. Based on the proportion and functionality of the HAs in the OM, we conclude that the use of HAs extracted with either NaOH or PyroP is valid for studies of OM functionality. The study also shows that the functionality and stability of OM are highly source dependent. We predict that amendments of the more humified turkey litter compost would have higher potential to increase SOM levels and retain nutrients compared with the source-separated organic compost and biosolid pellets.