Validation and comparisons of NaOH and Na₄P₂O₇ extraction methods for the characterization of organic amendments

Abstract

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 (HA) for analyzing the functionality, i.e., the ability to complex with nutrients, of OM. The humic fractions, including humic acids (HA), fulvic acids (FA) and alkaline non-dissolved fraction (humin), were isolated either with NaOH or Na 4 P 2 O 7 (PyroP) and the chemical properties were analyzed by solid-state 13 C NMR spectroscopy. The study showed that the proportions of each functional group of the combination of HA, FA 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 HA 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 HA and FA than that in humin. Based on the proportion and functionality of the HA in the OM, we conclude that the use of HA 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 to the source-separated organic compost and biosolid pellets.

Analysis of Molecular Structure Changes in Humic Acids from Manure-Amended Soils over 17 Years Using Elemental Analysis and Solid-State 13C Nuclear Magnetic Resonance Spectroscopy

“…While concerns related to the possibility of structural alterations to the SOM through these operational extractions have been raised [21], there is a growing body of literature that shows that structural information at the molecular level obtained from alkaline-extracted fractions can provide valuable insights into soil processes and their environmental controls [22][23][24][25]. Work by our group has also validated the use of alkaline-extracted HA fractions for studying the functionality of the SOM [26].…”

“…The humic acid (HA) extracts were prepared from the soils based on the standard method of the International Humic Substance Society (IHSS) [26].…”

The effect of agroecosystem management on the distribution of C functional groups in soil organic matter: A review

“…The temporal period of each management on each C functional group and the A/O and A/Aroma ratios by fertilizations were not significantly different (see Table S 2 in the supplemental material); therefore, all data were used for further analysis. Although some recent studies showed that SOM fractions such as humic acids could be a good soil quality indicator representing SOM (e.g., Audette et al 2021 ; Danchenko et al 2020 ; Novotny et al 2020 ; Savarese et al 2021 ), significant differences between soil samples and SOM fractions were observed for alkyl groups and the ratio of A/O (see Table S 3 in the supplemental materials); therefore, only the data from the studies that analyzed bulk soil samples (i.e., 227 pairwise data from 10 studies) were used for the further analysis.…”

A Novel Method of Self-Cross-Linking of Syringaldehyde with Activated Methoxy Groups via Cross-Coupling for Lignin-Based Wood Adhesives

“…Furthermore, NMR provides precise information about the interatomic interaction that cannot be obtained using other structural techniques. , SA shifts are for the alkyl groups (0–50 ppm), O -alkyl groups (50–110), aromatic groups (110–165 ppm), and carbonyl groups (165–200 ppm). , In particular, the spectra of A-SA and C-SA revealed peak changes corresponding to alkyl groups. A-SA exhibited a new peak around δ = 0.37 ppm attributed to the Si–Me 3 linkage.…”