Combining humic acid with phosphate fertilizer affects humic acid structure and its stimulating efficacy on the growth and nutrient uptake of maize seedlings

Abstract

This paper analyzed the compositional and structural changes of humic acid (HA) after combined with phosphate fertilizer (PHA), and investigated its effects on the growth of maize seedlings with four humic acid concentrations. The results showed that the atomic ratios of O/C and (O + N)/N of PHA were significantly lower than those of HA, which indicated that PHA had poor hydrophilicity compared with HA. The spectra of FTIR and NMR results suggested that the relative content of carboxyl group in PHA was higher than that in HA. X-ray photoelectron spectroscopy technology showed that the relative amount of C–C in PHA was lower than that in HA, while C–H was the opposite. The above changes were attributed to the crack of HA structure during the preparation of humic acid enhanced phosphate fertilizer, which was verified by the results from the determination of gel permeation chromatography that there were more low molecular weight components in PHA than that in HA. However, compared with HA, PHA showed a worse effect in promoting growth and the uptake of nitrogen, phosphorus and potassium by maize seedlings. This worse effect might be attributed to the poor hydrophilicity and unsuitable addition amount of PHA.

Humic Acid Modified by Being Incorporated Into Phosphate Fertilizer Increases Its Potency in Stimulating Maize Growth and Nutrient Absorption

“…It is well-established that high temperature can substantially alter the structural composition of HA (Zhou et al, 2019 ), while a lot of heat is generated by exothermic neutralization reactions between phosphoric acid and alkaline compounds during the production of phosphate fertilizers (Peng and Xiang, 2017 ). Hence, the incorporation of HA into the phosphate fertilizer can change its structure, which has been verified by our previous study (Jing et al, 2020 ). The change likely leads to differences in the effects and potency of PHA on plant growth compared to carbon equivalent concentrations of HA.…”

“…Humic acid was extracted from weathered coal (45°23′ N, 119°15′ E; Huolinhe, Tongliao, Inner Mongolia Autonomous Region, Northeast China) according to the method conducted by Zhang et al ( 2017 ). Subsequently, HAP incorporated with 0.5% HA was manufactured, and PHA was extracted from HAP and purified as described by Jing et al ( 2020 ). In brief, 56.03 g of potassium hydroxide was added to the mixture containing 0.50 g of HA and 46.47 g of phosphoric acid (85% in v / v ) under continuous stirring, and the reaction product was immediately pulverized and grounded through a 0.85 mm sieve to obtain the HAP fertilizer.…”

“…The contents of carbon, hydrogen, oxygen, nitrogen, and sulfur in HA and PHA were determined using an element analyzer (Vario Micro Cube, Elementar Analysensysteme GmbH, Germany). The relative proportions of C-containing functional groups and the molecular weight distributions of HA and PHA were determined using solid-state 13 C nuclear magnetic resonance spectrometer (Bruker AVANCE III HD 400 MHz, Switzerland) and gel permeation chromatography (GPC, Shimazu LC-20A, Japan) as described by Jing et al ( 2020 ). The data of the above parameters are presented in Table 1 and Supplementary Figure S1 .…”

Characterization of Ultrafiltration-Fractionated Humic Acid Derived from Chinese Weathered Coal by Spectroscopic Techniques

“…The XPS survey spectra exhibited three prominent peaks around 285 eV, 400 eV, and 532 eV due to carbon, nitrogen, and oxygen, and their corresponding high-resolution spectra were acquired with a step size of 0.1 eV. For calibration purpose, the peak of C 1 s electron binding energy was corrected at 284.8 eV [31]. A non-linear least squares curvefitting program (XPSPEAK software, Version 4.1) was used for XPS spectral deconvolution and spectra analysis [32].…”

Extraction and Characterization of Humic Acid Based on Coal Mining Waste

“…There are commercialized developments for the production of humic concentrates obtained from peat for hair and scalp care [15], or Faberlic's complex of humic acids of the ProHumin trademark for supplying the body with missing components that effectively cope with viruses and improve the functioning of all systems in the body [16]. In addition, one of the main areas of application of humic substances is the synthesis of organomineral and chelated fertilizers [17][18][19][20], the production of feed additives for animals and birds [21,22], sorbents, ion-exchange materials for wastewater treatment [23][24][25], and caustic biolites for use as stabilizers of mineral suspensions used in the production of building materials [26,27].…”