The research of organic matter content in major subtypes of black soils of the Central Ciscaucasia, namely: ordinary carbonated, ordinary regular (not boiling from the surface), leached and alkalized-firm (similar to vertisols) on virgin and on arable soils, has been performed. It has been found that within 70-100 years of soils exploitation in the system of agrobiocenoses, the content of humus in the upper horizons of soils has reduced by 16-38 % for carbonated, 25 to 33 % for regular, 6-21 % for leached, and 8-24% for alkalized-firm black soil. This trend has not been observed below the illuvial zone. Humic acids contain significantly less fulvic acids, and the humic to fulvic acids ratio (HA:FA) increases in arable soil, as compared to virgin soils from 1.52 to 2.77 for carbonated, from 1.74 to 2.17 for regular and from 1.72 to 2.00 for leached black soils. In alkalized-firm soils, the difference for this indicator has not been detected.
The formation of humic substances (humic and fulvic acids) is not a straightforward process, and it is differ- ent between soils, sediments, lakes, etc. These substances can originate from the agglomeration and decay of lignin precursors (retaining some degree of aromaticity), or from the polycondensation of glycerides, among others . Stevenson (1982)  has also postulated that microorganisms can synthesize polyphenols from non-lignin carbon sources which could be converted into quinones, and combine with other metabolites, such as amino acids or peptides, to from humic polymers. The fulvic acids could be created first, since they are smaller in structures. It is conceivable that fulvic acids agglomerate into the larger humic acids, aided by microbial de- cay and re-condensation. In our cultures, the incubation time might be too short to observe this directly.
11 Read more
humic substances were 5.9 and 7.9 kDa, respectively, and proportion of this low-molecular fraction reached 97%. This corresponds to the fact, that the main fraction of HS in surface waters constitute fulvic acids. Using soil extraction in CaCl 2 we obtained the fraction of organic carbon similar to the humic substances contain in DOC. Diﬀ erences in quantity of humic substances extracted from soils among CaCl 2 (mean 0.42 ± 0.39), Britton-Robinson buﬀ er (34.9 ± 11.2) and sodium pyrophosphate
Thus, the forest brown soils are characterized by sufficient or high content of organic substances, which gradually decreases along with the profile depth. Fulvic acids and grey humic acids prevail in the content of humic acids. In low horizons they are with the considerable amount of humin acids and low optical concentration of humin acids.
Numerous studies carried out both in open field and laboratory scale have provided experimental evidence for a beneficial action of humic substances (HS) on plant growth and mineral nutrition. In fact, many products containing diverse concentrations of humic substances, mainly humic and fulvic acids, are marketed as plant growth enhanc‑ ers all over the world. However, the incorporation of molecules containing humic substances into the granules of compound NPK fertilizers is not a common practice mainly due to technical difficulties and problems associated with the manufacture process of these mineral fertilizers. These problems are normally linked to the potential deleterious effects of granulation conditions (principally, heat and pH) on the structure and properties of molecules containing humic substances. In this review, we discuss several strategies for the incorporation of active molecules containing humic substances into granules of NPK compound fertilizers as well as the main constraints that have to be consid‑ ered in this process, which normally depend on the agronomical results intended with the preparation of special humic‑containing NPK compound fertilizers. We also discuss why, in our opinion, the beneficial action of HS in NPK compound fertilizers is more related to the “so called” indirect effects of HS on plant growth than to the “so called” direct effects.
15 Read more
Figure 1. Average chlorophyll content in (a) bine and (b) branch leaves three weeks after the first application; (c) bine and (d) branch leaves six weeks after the first application. Average of years 2014–2017; in relative percent- ages of the control treatment. LEX – Lexin; LEXZ – Lexenzym; ASC – Ascophyllus nodosum; AUX – pure auxin; HK – humic acids only; FK – fulvic acids only; LIG – Lignohumate Max; UTC – untreated control; means with the same letters are not statistically significant
ABSTRACT: Top-soil samples were taken from four mountain forest ecosystems in the Bohemian Forest to compare the processes in European beech-mixture (fs) and Norway spruce (Pa) dominating ecosystems. Selected plots can be grouped into two types of forest ecosystems which are conditioned by position on the natural altitudinal gradient. Several chemical features (content of organic matter, properties of humic and fulvic acids, releasable P, Ca, Mg, Fe and Al content) were com- pared with the species structure of oribatid mite communities in the same samples. Strict differences between both ecosystem types were discovered. Statistically significant differences were detected in Mg content (0.42 mg/g in fs ecosystems compared to 0.30 mg/g in Pa ecosystems) and in organic matter quality (the ratio of carbon content in humic acids to carbon content in total humus acids was 0.53 in fs ecosystems and 0.66 in Pa ecosystems) and quantity (e.g. content of humic acid carbon was 59 and 86 mg/g in fs and Pa ecosystems, respectively). Different dynamics of organic matter decomposition and nutrient movement lead to some opposite correlations among the soil chemical features: correlation between total ash and soluble ash (r = +0.96 and –0.86 in the fs and Pa ecosystems, respectively) and total ash – P content correlation (r = +0.76 and –0.92 in the fs and Pa ecosystems, respectively) can be mentioned as examples. The oribatid mite communities are markedly distinct in both ecosystem types, although parameters of species diversity and abundance are similar. Different correlations were revealed between the parameters of mite community structure (e.g. species diversity and total mite abundance) and top-soil chemical features. The correlation structure is different in both ecosystem types. It indicates differences in leading variables determining the oribatid community structure in the beech mixture ecosystem or in the Norway spruce one.
16 Read more
citric acid were defined according to the procedure in . Ash content according to State standard 26714-85, nitrogen by State standard 26715-85, humidity by State standard 26712-85, organic matter by State standard 27980-80. Water-soluble fraction content of organic matter recovered from product by water was determined by filtration and evaporation in water bath, drying solid residue to constant weight subsequent burning to calculate ash content. Humic acids were leached processing product by 0.1 N solution of alkali and acidification of obtained solution by mineral acid [12-13]. The solid phase after separating from it alkali soluble organic matter is residual organic matter. The latter was washed carefully by distiller water then dried to constant weight and determined outlet in towards to organic weight. Difference between amount of alkali soluble organic matter and humus acid gives us content of fulvic acids in the compost.
The type and amount of organic matter present in industrially contaminated soils will influence the risk they pose. Previous studies have shown the importance of humic and fulvic acids (important components of soil organic matter) in increasing the solubility of toxic metals but were not carried out using toxic metal levels and the pH range typical of industrially contaminated soils. This study investigated of the influence of three humic substances (humates, fulvates and humins) on the solubility of copper(II) ions in kaolinitic soil spiked with Cu at levels representative of industrially contaminated soil.
30 Read more
In 4-year trials, soybean seeds were treated with the following biologically active substances: Lignohumate B (a mixture of humic acids and fulvic acids); Lexin (a mixture of humic acids and fulvic acids enriched with aux- ins); brassinosteroid (a synthetic analogue of natural epibrassinolide 24) and so-called ‘Complex seed treatment’ (a mixture of a saturated solution of sucrose, Lexin, the fungicide Maxim XL 035 FS and an adjuvant on the basis of pinolene). After harvesting soybean seeds from the individual treatments, they were analysed for oil, protein and fibre contents. The results show that the most effective method was the ‘Complex seed treatment’ which, compared to the untreated variant, significantly increased not only the yield but also the oil content of the seeds.
mmol-eq/g. The content of acid groups of the fulvic acids extracted from the HPE by water was equal to 6, 5±0,2 mmol-eq/g. According to IR spectra the FA and the HPE are riched in alcohol and phenolic groups. The hydrophobicity index (HI) calculated as a ratio of absorption at 2328 cm -1 (contribution of the nonpolar fragments of the skeleton) to absorption at 1050 cm -1 (contribution of polar C-O bonds) was equal to 0,87 for the fulvic acids and 1,11 for the HPE, consequently. The variation of sorption capacity of the HPE in relation to biogenic metals was observed in the following order (mmol-eq/g): Cu (7,6)>Zn (5,6)>Ca (4,3)>Fe (3,1). It may be proposed that not only carboxylic and phenolic groups but quinoid and amide groups participate in the complexation. The improving of energy metabolism catalyzed by lactate dehydrogenase, the decreasing of lipoperoxidation characterized by dose- dependent reduction of malonic dialdehyde level (by 30-70%) and the increasing of SOD activity were estimated in vitro by blood of rats.
DOC in water is operationally defined by the water industry as the fraction of organ- ic matter that passes through a 0.45 µm filter. Although this classification has recently been subject to criticism, partly due to the inadequacy of such filters in removing col- loidal material, it still remains as the practical definition . DOC consists of two ma- jor components; the non-humic and the humic. The non-humic material encompasses a series of biomolecules that include lipids, carbohydrates, polysaccharides, amino ac- ids, waxes and proteins  whilst humic substances can be described as naturally oc- curring, refractory, macromolecular, heterogeneous organics . These can be further sub-divided into three components. Firstly, humic acids are fully solvated when pH > 2 but not below and they have relatively high molecular weight (5000 - 500,000 Da). Se- condly, fulvic acids are water soluble at any pH and have smaller molecular weights: 600 to 5000 Da. . The third and last component is collectively referred to as “the humins”. This is the insoluble portion of DOC which is normally removed either by fil- tration or flocculation.
13 Read more
potential remained sufficiently stable over 6 h, and good reproducible readings in several sets of titration experi- ments in the system of the carboxylic acid-Eu complexa- tion were obtained . Similarly, the reading potential values remained constant after repetitive use of ISE in the present humic substance system, suggesting an unde- sirable reaction such as the sorption and the dissolution of humic substance for the ISE did not occur. Here, in order to investigate the dynamic response time of the ISE, the potential change in the test solution before and after the addition of Eu 3+ was recorded with time. As shown in
Soil humic acids (HA) are essential for the stabile aggregates formation, good chemical and biological properties. It directly inﬂ uences soil water regime and aeration. Their chemical composition depends on plants residues composition, soil tillage practices, fertilizing, crop rotation system, liming and others (Gerzabek et al., 2006). Soil structure has a signiﬁ cant impact on the ability of the soil to support plant, further directly inﬂ uence carbon cycle and nutrient regime, retention and water movement, and erosion processes. The soil structure is one of very important soil properties and depends on the capability of soil particles to aggregate or disaggregate and create structural aggregates. It is the result of joint action of physical, chemical, and biological processes taking place in soil, which is based on the ability of soil particles combine solid phase or break up larger units of soil mass and thereby creating structural aggregates (Bronick and Lal, 2005). Aggregates
i.e., soils + PAHs, were incubated for 180 and 360 days at the temperature of 20–25 ºC and at constant moisture of 50% of field water capacity. Humic acids were extracted from the soil samples prior to and after 180 and 360 days of incubation. The following analyses were performed for separating humic acids: elemental composition, UV-VIS and IR spectrophotometric analyses, susceptibility to oxidation. Results demonstrated that a single introduction of fluorene, anthracene, pyrene and chrysene at very high rates into soils affects the properties of humic acids. There was mostly recorded a de- crease in coefficients of absorbance A 2/6 and A 4/6, an increase in the parameter defining
One of the most accepted methods i.e., CTAB extraction buffer method was followed . The method used the detergents like CTAB and SDS for the direct cell lysis. This method could extract the DNA somewhat efficiently but could not remove the humic acid content. The high content of humic acid could interfere with other processes like PCR amplification and restriction digestion. To remove the humic acids different pre and post treatments with aluminium sulphate, aluminium ammonium sulphate, calcium carbonate and PVPP were given in conjunction with CTAB extraction buffer but humic acid was not efficiently removed..One more method of mechanical lysis by bead beating  was also used but the method showed negligible removal of humic acids . Most promising method seemed to be extraction by modified CTAB extraction buffer method complemented with 0.5 volumes of 50% PEG and 0.1 vol of 1M NaCl precipitation and purification by one step post treatment with 2% CaCl 2 .The role of Cacl 2 in purification of the extracted soil DNA is that it prevents the
13 Read more
Polymerization of HA in the presence of laccase could be also surmised to be responsible for the observed addi- tional peak. Appearance of new HA peaks with corre- sponding peak MW of 18.8 and 40.9 kD at pH 5.0 (elu- tion volumes 39.6 and 32.3 ml) or with 18.8 kD at pH 6.5 (elution volume 39.6 ml) was also evident for the forma- tion of HA fractions with larger peak MW comparing with initial humic material. This is in agreement with recent results that have shown an increase in molecular size of humic matter following an oxidative polymeriza- tion reaction catalyzed by the peroxidase . As laccase under study was demonstrated to have the maximum catalytic activity at pH 4.5 , the enzymatic activity was therefore supposed was greater at pH 5.0 than at 6.5. In comparison to pH 6.5, the intensity of the additional peak was higher at pH 5.0 (Figure 2). This finding could
Hexavalent chromium contamination of groundwater is a worldwide problem caused by anthropogenic and natural processes. We report the rate of Cr(VI) removal by two humic acids (extracted from Miocene age lignite and younger peat soil) in aqueous suspensions across a pH range likely to be encountered in terrestrial environments. Cr(VI) was reduced to Cr(III) in a first-order reaction with respect Cr(VI) concentration, but exhibited a partial order (~ 0.5) with respect to [H+]. This reaction was more rapid with the peat humic acid, where Cr(VI) reduction was observed at all pH values investigated (3.7 ≤ pH ≤ 10.5). 13 C NMR and pyrolysis GC-MS spectroscopy indicate that the reaction results in loss of substituted phenolic moieties and hydroxyl groups from the humic acids. X-ray absorption spectroscopy indicated that at all pH values the resulting Cr(III) was associated with the partially degraded humic acid in an inner-sphere adsorption complex. The reaction mechanism is likely to be controlled by ester formation between Cr(VI) and phenolic/hydroxyl moieties, as this initial step is rapid in acidic systems but far less favourable in alkaline conditions. Our findings highlight the potential of humic acid to reduce and remove Cr(VI) from solution in a range of environmental conditions.
13 Read more
All twelve samples of porous material without humic acids were wettable (WDPT ≈ 1 s) for the range of water content w = 030% and the drying temperatures of 30, 60, 90, 150, 210, and 270°C. Establishment (re-establish- ment) of water repellency was observed after drying the samples at temperatures of 30, 60°C (in both cases 36 of the 48 samples containing humic acids were water repel- lent) and after drying at 210°C (only a few samples with the higher humic acids contents were slightly water re- pellent).
acid (RSHA) was isolated in the same way from a Ritzville silt loam, obtained from Paci®c Northwest National Laboratories (Richland, WA). This soil contained (w/w) 43.3% sand, 43.6% silt, 12.3% clay, and 0.7% organic C. Pilayella littoralis humic acid (PLVHA) was obtained from the Barnett Institute (Northeastern University, Boston, MA), where it was isolated from a brown alga by a procedure described by Ghabbour et al. 23 The other HAs used were reference materials obtained