Properties of humus-like substances isolated from organic wastes and their effects on structures of soil humus by Fourier transform infrared spectroscopy

ABSTRACT

The structures of soil humus (HS) amended with organic wastes (OWs) were closely related to properties of OWs-derived humus-like substances (HSL). This work evaluated the properties of HSL isolated from mushroom residue (MR), chicken manure (CM), sheep manure (SM), tree leaves (TL), maize straw (MS) and fodder grass (FG) and studied the structures of soil humic acid (HA) and fulvic acid (FA) amended with these OW. FTIR results showed that the relative intensities at 1,640 cm⁻¹ peaks of TL-, FG- and SM-derived HAL were higher than other CM-, MS- and MR-derived HAL (p < 0.05), while the 2,930/1,640 ratios were lower (p < 0.05). Relatively lower E₄/E₆ ratios and ΔlogK values of TL-, FG- and SM-derived HAL were recorded (p < 0.05). Relative intensities at 1,620 cm⁻¹ peaks of soil HA and soil FA amended with TL, FG and SM were higher than other OWs, while the 2,930/1,620 ratios were significantly lower (p < 0.05). The 2,930/1,620 ratio of soil HA and soil FA amended with MS and CM was the highest, respectively. In conclusion, the properties of OWs-derived HSL play important roles in functional groups of soil HS amended with these OWs.

KEYWORDS:

• Humic-like acid
• fulvic-like acid
• humic acid
• fulvic acid
• functional group

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was financially supported by the National Key Research & Development Program of China [2018YFD0500205, 2018YFD0300203, 2017YFD0201801].