Properties of humic acids depending on the land use in different parts of Slovakia

Abstract

Many studies report organic carbon stabilization by clay minerals, but the effects of land use and soil type on the properties of humic acids (HAs) are missing. The aim of the paper is to determine the effects of land use and soil types on the characteristics of HAs, which have a considerable influence on organic matter quality. It was hypothesised that the effect of the land use on HAs properties depends on the particular size distribution. The research was performed in three ecosystems: agricultural, forest, and meadow, located in Slovakia. From each of them, the samples of 4 soil types were taken: Chernozem, Luvisol, Planosol, and Cambisol. The soil samples were assayed for the content of total organic carbon (TOC) and the particle size distribution. HAs were extracted with the Schnitzer method and analysed for the elemental composition, spectrometric parameters in the UV-VIS range, and hydrophilic and hydrophobic properties, and the infrared spectra were produced. The research results have shown that the properties of HAs can be modified by the land use and the scope and that the direction of changes depends on the soil type. The HAs of Chernozem and Luvisol in the agri-ecosystem were identified with a higher “degree of maturity”, as reflected by atomic ratios (H/C, O/C, O/H), absorbance coefficients, and the FT-IR spectra, as compared with the HAs of the meadow and forest ecosystem. However, as for the HAs of Cambisol, a higher “degree of maturity” was demonstrated for the meadow ecosystem, as compared with the HAs of the agri- and forest ecosystem. The present research has clearly identified that the content of clay is the factor determining the HAs properties. Soils with a higher content of the clay fraction contain HAs with a higher “degree of maturity”.

Humic acids in permanent grasslands of the Czersk Meadows Complex, north Poland

“…This is evidence of sufficient content of hydrophobic substances to create stable soil aggregates and of the necessary content of hydrophilic components that form the main reserve of readily available nutrients and that are easily distributed throughout the soil profile. In line with the results of Preuße (2000), Dębska et al (2010), Becher et al (2021) and Banach-Szott et al (2021b), the hydrophilic-hydrophobic properties of HAs are related to the degree of humification of organic matter. Based on the obtained results, it is found that the degree of maturity of HA molecules increases with depth.…”

“…This makes it possible to determine the degree of maturity of HA molecules (Sanchez--Monedero et al, 2002;Gonet et al, 2007;Canellas et al, 2010;Boguta et al, 2016). It is worth adding that the examined HA molecules had similar H/C ratios to those obtained by Zdenek and Tesarova (2004), Drąg et al (2007) and Banach-Szott et al (2021b). Dergacheva et al (2012) emphasize that the value of the H/C ratio depends on the conditions under which the HAs formed.…”

Humus is a guarantor of the stability of agroecosystems

“…To determine the exact position of the absorption maxima on such spectral curves, the dependence of the first derivative of the optical density on the wavelength is used under the condition dD/dλ = 0 [5]. The presented curves are characterized by a developed maximum in the range of 230-255 nm, which is determined by benzene fragments with a developed auxochromic substituent, for example, with a carboxyl group [1]. There is also a certain jump in the region of 275 nm, which is explained by the presence of phenolic compounds.…”

Effect of Differently Matured Composts from Willow on Growth and Development of Lettuce

“…Both the results of chemical analyses and vegetation experiments indicate the potential usefulness of willow composts as an alternative fertiliser product [25,27,28]. This is particularly important in terms of carbon sequestration [5,14] and stabilization [5,8,9,[46][47][48] of soil organic matter by low-cost, widely used and effective methods of wood-based substance management. While the use of semi-dynamic composting in open piles to process this type of substrate is widely accepted, the most discussed and controversial seem to be the physicochemical parameters [23,46,47] and the effect of the obtained product on plant growth and development.…”