Effects of Organic Material Types on Temporal Changes in Characteristics of Humic Acids Extracted from a Chernozem

Abstract

Returning organic materials to fields is an effective management practice for improving soil quality in agroecosystems. In the case of scarce organic material resources, choosing the optimal material type for improving the quality of a soil type is an urgent problem to be solved. The objective of this study was to evaluate the temporal variations in the spectroscopic characterization of humic acids (HAs) over a period of 90 days after applying biotechnologically extracted fulvic acid (BFA), well-decomposed sheep manure (M), corn stover pellets (Ps) and corn stover powder (Pr) at equal C amount to a chernozem under laboratory conditions, measured by Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible spectrophotometry (UV–Vis). The results indicated that the BFA and Pr with higher C contents (68.9 and 59.8 g kg−1, respectively) were more beneficial to the C mineralization of HAs. M, applied in the largest amount, together with the highest available N, P, and K contents (575.4, 160.1, 478.9 mg kg−1, respectively), and its more easily consumed carbohydrates as well as well-decomposed status, was more likely to promote the condensation of HAs. BFA carried more hydrophilic groups into the HAs, while Ps did not introduce high levels of adsorbed H2O molecules and aromatic C=C (or C=O) groups. Ps did not affect the molecular structure of HAs after incorporation into the chernozem. At the equal C input amount, M had the greatest benefit, whereas the beneficial effect of Ps was the least, in improving the chernozem quality.

Organic Matter and Mineral Composition of Silicate Soils: FTIR Comparison Study by Photoacoustic, Diffuse Reflectance, and Attenuated Total Reflection Modalities

“…The same is valid for accompanying bands at 1945 and 1885 cm −1 , which may be the manifestation of nearly equal quartz and illite/smectite contributions [52,123]. On the contrary, the bands at 1975, 1820, 1775, and 1730 cm −1 have different intensity for soil fractions and soil types and could be assigned to C=O stretching vibrations of various oxidized moieties of SOM, mainly carboxylic acids, and are consistent with the data from isolated humic substances [41,132]. These well-defined overtones and combination bands of silicate matrix are also manifestations of the saturation effects at the primary lattice vibrations of SiO 2 in DRIFT and FTIR-PAS modalities.…”

FTIR Photoacoustic and ATR Spectroscopies of Soils with Aggregate Size Fractionation by Dry Sieving

“…This region is the most difficult from the viewpoint of assessment, as it contains many bands attributed to SOM and overtone and combination bands of the soil matrix. The triplet of 1980, 1860, and 1780 cm –1 is a quartz matrix signature. , However, the band at 1860 cm –1 may belong to humic and other organic compounds (−CO stretching vibrations , ), and the band at 1785 cm –1 may be attributed to −CO stretching vibrations . Apart from the water band at 1640–1620 cm –1 , the broad band at 1750–1500 cm –1 contains stretching vibrations of carbonyl, bending deformation −NH 2 at 1680 cm –1 , stretching −CC– vibrations, and stretching −CO vibrations − as well as combination quartz bands at 1710–1680 and 1620–1610 cm –1 .…”

“…The triplet of 1980, 1860, and 1780 cm −1 is a quartz matrix signature. 38,59 However, the band at 1860 cm −1 may belong to humic and other organic compounds (−CO stretching vibrations 66,67 ), and the band at 1785 cm −1 may be attributed to −CO stretching vibrations. 68 Apart from the water band at 1640−1620 cm −1 , the broad band at 1750− 1500 cm −1 contains stretching vibrations of carbonyl, bending The band at 1620 cm −1 is also referred to stretching CO vibrations and bending amine vibrations.…”