Magdalena Banach-Szott

Humus substances are an important part of stable soil organic matter, which is also influenced by the soil tillage system, particularly indirectly through the mechanisms of stabilisation. This study evaluated relationships within the humus substances–cations–soil texture system and differences between invasive and non-invasive tillage systems in four soils. The influence of exchangeable cations (K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe³⁺, Al³⁺) and particle size distribution (sand, silt, clay) on quantity (humic and fulvic acids) and quality (ratio of HA/FA, degree of humification, colour coefficients) of humus substances was studied. In reduced tillage, the humus substances interacted mainly with iron and aluminium. Higher humus substance contents were associated with higher K⁺; the influence of Ca²⁺ was greater in coarse-grain soils (Haplic Chernozem, Eutric Regosol); and Al³⁺ was positively correlated with humic acids and negatively with fulvic acids. The statistical associations indicate that in conventional tillage, humus substances interacted mainly with Ca²⁺. Higher humic acid contents indicate an association pattern with higher Na⁺ contents; the relationship of Ca²⁺ appears more pronounced in fine-grained soils (Mollic Fluvisol, Haplic Luvisol); and Al³⁺ was positively correlated with fulvic acids and negatively with humic acids. The soil tillage system influenced the humus substances indirectly by a combination of factors—cation composition and soil texture in different ways. In reduced tillage, clay and silt were statistically associated with iron and aluminium; in conventional tillage, there were two branches: clay with divalent cations and silt with trivalent cations. The soil tillage system can modify the impact of carbonates on humus substances and thus indirectly change the character of transformation processes in the soil. Depth is very important in evaluating the influence of the soil tillage system.

In achieving sustainable development goals, soils play a key role in environmental protection, natural resources, and food security. Peatlands are particularly important here, as they function at the interface between terrestrial and aquatic ecosystems and store large amounts of organic matter. However, organic soils are highly susceptible to transformation and degradation; therefore, their degradation caused by, among others, drainage properties is a high risk to both the environment and agriculture—it disrupts the ecosystems, causes greenhouse gas emissions, and eutrophicates the hydrosphere. Soil degradation in drained peatlands is associated with the transformation of soil organic matter (SOM), which in organic soils is the dominant component of the solid phase of the soil. The aim of our study was to assess the properties and degree of organic matter transformation in drained temperate peatland soils, with particular emphasis on sequential fractionation of SOM and humic acid properties. Due to the fact that in Poland, as many as 90% of non-forest peat bogs have been drained, we compare the mursh horizons that formed after peat bog drainage with the peat horizons that constitute the parent rock (where anaerobiosis occurs and morphological changes in the soil material are absent due to peat bog drainage). Studies were conducted on 11 soil profiles located in central-eastern Poland. Basic physicochemical soil properties were determined: pH, bulk density, contents of ash, SOM, total carbon (TC), and total nitrogen (TN). Sequential carbon fractionation was used to qualitatively analyze organic matter, which allowed for the identification of labile fractions, lipid fractions, humic substances (fulvic and humic acids), and residual fractions. Humic acids (HAs) were extracted using the Schnitzer method and analyzed for their elemental composition and spectrometric parameters in the VIS range. It was demonstrated that SOM transformation in drained temperate peatland soils was correlated with comprehensive changes in the soil’s physical and chemical properties. Compared to peat horizons, topsoil horizons were characterized by higher ash content and density, lower SOM content, and a lower TC/TN ratio. Qualitative SOM transformation during aerobic SOM transformation after draining the studied peatlands consisted of an increase in the amount of labile fractions and humic substances and a decrease in the lipid and residual fractions. The research results have shown that the HAs properties depended on the depth. HAs from topsoil horizons, compared to peat horizons, were characterized by a lower “degree of maturity,” as reflected by the values of atomic ratios (H/C, O/C) and absorbance coefficients (A_4/6 and ΔlogK). It was found that the share of the distinguished SOM fractions and HAs properties were closely correlated with the physical and chemical properties of the soils. The study demonstrated the usefulness of the sequential carbon fractionation method for assessing the effects of dewatered peat transformation. The obtained results could contribute to the development of good practices ensuring high quality of organic matter and stability of ecosystems, as well as to the development of methods for limiting the mineralization of organic matter (SOM), greenhouse gas emissions, and the loss of organic soils in agricultural areas.

The purpose of this research was to determine the properties of humic acids isolated from soil samples taken from a 40-year static experiment—the experimental factors were fertilization with manure (30 t ha⁻¹; FYM) and nitrogen at rates of 40, 60 and 120 t ha⁻¹. From the soil samples (Luvisol), humic acids (HAs) were extracted and the following were determined: elemental composition, hydrophilic and hydrophobic properties and spectrometric properties in the UV–VIS and IR range. The HAs of the soil fertilized with manure and N compared to the HAs of the soil fertilized with N (without manure) were characterized by a higher degree of aliphaticity and, consequently, a higher share of hydrophilic fractions and lower values of internal oxidation. Based on the spectrometric parameters, it was indicated that the HA particles of the manure-fertilized soil are characterized by a higher share of undecomposed lignin fragments, a lower degree of humification and at the same time, a higher susceptibility to oxidation. The obtained relationships showed that the aromaticity and hydrophobicity of the HA molecules of the manure-fertilized soil can be increased at certain N doses (60 and 120 t ha⁻¹), which is particularly important in terms of the role that humic substances play in carbon sequestration.

Humin, as the most stable fraction in soil organic matter, determines possibility of sustainable environmental development by influencing, among other things, the binding and migration of different chemicals in soil. The aim of this paper was to determine changes in the properties of humins after interaction with three selected active substances of herbicides differing in structure and chemical properties (pendimethalin, metazachlor, and flufenacet) and two different commercial products. In accordance with OECD 106 guidelines, humins isolated from eight different soils were saturated with herbicide compounds under study. As humin is a non-hydrolyzable organic carbon fraction, solid state research techniques (elemental analysis, NMR, FTIR, EPR, and UV-Vis) were applied. The results clearly showed that the interaction between humin and herbicides increases the concentration of oxygen-containing groups and the internal oxidation (ω) in humin. For all investigated humins, a reduction in radical concentration was observed. Radicals in humins were not completely quenched; a certain concentration of radicals with unchanged structure always remained in the samples. Other spectroscopic analyses showed no significant changes in the structure of pesticide-saturated and non-saturated humins. This suggests that sorption of the studied compounds occurs on the humins only as a result of the interaction of physical forces on the surface of the studied organic matter fraction. Thus, interaction with the studied herbicides occurs as a surface phenomenon, and the inner core remains protected by the condensed structure and/or strong binding to the clay minerals.

The aim of the paper has been to investigate the effect of fertilization with nitrogen and microelements (Se and Cu, Mn, Zn) on the content of carbon (TOC) and nitrogen as well as dissolved organic carbon (DOC). The study was performed based on the soil sampled ( Albic Luvisol) from a two-factor field experiment: the first factor was nitrogen fertilization (0, 40 and 80 kg ha ⁻¹ ), the second one – variants of foliar and soil application of microelements and selenium. Soil was sampled from a depth of 0–30 cm at the beginning and the end of the growing season. Sampling 1 was after the start of spring vegetation, sampling 2 – after harvesting the crop from the field. Winter spelt (cv. Rokosz) was grown on the experimental plots, with winter rapeseed as the forecrop. In the soil samples the following were assayed: total organic carbon (TOC), total nitrogen (TN) with the Vario Max CNS analyser provided by Elementar and dissolved organic carbon (DOC). DOC was extracted with 0.004 M CaCl ₂ and was assayed and using the Multi N/C 3100 Analityk Jena analyser. In the soil samples analysed TOC, irrespective of the sampling date and the microelements application method, ranged from 8.38 to 10.60 g kg ⁻¹ . In general, the application of microelements into soil in combination with selenium resulted in an increase in TOC in the soil sampled at the end of the vegetation period as compared with the soil sampled at the beginning of it. Irrespective of the application method, there has been identified no effect of fertilization with nitrogen and microelements on total nitrogen and dissolved organic carbon in soil, which is important in terms of the stability and equilibrium of the soil system investigated.

Wheat is the cereal most susceptible to lodging, particularly during the flowering period and at the early ripening stage. The use of plant growth retardants (PGRs) is especially recommended when intensive nitrogen (N) fertilisation is applied, which increases the susceptibility of plants to lodging. This paper presents the results of tests into the effects of PGRs (PGR0—control; PGR1—chlormequat chloride (CCC) + trinexapac-ethyl (TE); PGR2—chlormequat chloride (CCC) + ethephon (ET)), and N dose—N0, N20, N40, and N60 [0, 20, 40, and 60 kg N ha⁻¹] on the content of selected plant secondary metabolites (PSM) in the Indian dwarf wheat (Triticum sphaerococcum Percival) of the Trispa cultivar, and on the abundance of insect pests. In the developmental stage of wheat (BBCH 39), insects were collected with an entomological net. The study also investigated the effect of experimental factors on the physicobiochemical properties of the soil (pH in KC, granulometric composition, total organic carbon TOC, total nitrogen TN, fractional composition of humus, and the activity of enzymes). An increase in the plant secondary metabolite (PSM) and FRAP (ferring reducing ability of plasma) contents following the application of PGRs and N fertilisation already from as low a rate as 20 kg ha⁻¹ was demonstrated. A significant positive correlation was noted between the abundance of Oulema spp. and the contents of total polyphenols, chlorogenic acid, and FRAP. No such relationship was noted for Aphididae or Thysanoptera. TOC content was higher on the plots on which N fertilisation was applied at the highest rate and after the application of PGRs. The factor determining the TN content was N fertilisation. Soil samples of the PGR0 N0 treatment were characterised by the greatest proportion of carbon in the humic and fulvic acid fractions and by the smallest proportion of carbon in the humin fraction. N fertilisation increased the proportion of carbon in the humin fraction on the plots on which no PGRs were applied. The study demonstrated an increase in the activity of oxidoreductive enzymes following the application of higher N rates. The application of PGRs resulted in no inhibition of enzymes in the soil compared to the control (PGRs0).

The research objective was to determine basic soil properties and the stability of humic acids (HAs) in individual layers of the A horizon of meadow soils. Soil samples were collected from the unique Czersk Meadow Complex in north Poland, 25 years after the end of “slope-and-flooding” irrigation that had lasted for 150 years. It is a continuation of research being carried out on the Czersk Meadows. In the previous studies (Banach-Szott et al. 2021a), continuously irrigated soils were analysed. The total organic carbon content (TOC), total nitrogen content (Nt) and grain size composition were determined in soil samples. Humic acids were extracted by Schnitzer method and analysed for: elemental composition, spectrometric parameters in the UV-VIS range and hydrophilic and hydrophobic properties. The tested soils consisted largely of sand fraction, with only small amounts of clay. The TOC, Nt and TOC/Nt ratio values all depended on soil sampling depth and distance from irrigation ditch. The TOC, Nt and TOC/Nt ratio were all highest for soils collected from a depth of 0–10 cm and for those taken 25 m from the irrigation ditch. The research revealed that the HA molecules of soils collected from a depth of 0–10 cm had higher H/C ratios and spectrometric parameters and lower values of the ω parameter and HIL/HOB ratio than those from deeper layers. This indicates that the degree of maturity of HAs increases with depth. On the basis of the obtained atomic ratios (H/C, O/C, O/H), ω parameter and spectrometric properties (A2/6, A4/6 and ΔlogK), the degree of maturity for HAs molecules was highest in the soil samples taken furthest from the irrigation ditch. The results indicate that relatively high-stability HAs were formed by the processes of transformation of the organic matter of the mineral meadow soils.

One of the main tasks in the search for environmentally friendly crop-growing methods is to increase soil fertility by improving its physical, chemical and biological parameters. The aim of this study was to determine the effect that the long-term annual application of different types of soil fertility agents (exogenous organic matter: 1. manure, 2. straw in combination with nitrogen fertilization and liming and 3. the addition of biostimulants) had on organic matter properties, including humic acid (HAs) properties. The research was carried out on the basis of soil samples from a ten-year pot experiment which was set up as single-factor pot experiment with four replications. PVC pots with perforated bottoms were filled with soil samples taken from the tilled layer of an arable field where winter wheat was grown in monoculture. The pots were exposed directly to the weather and were left without vegetation. The soil samples were assayed for the content of total organic carbon (TOC), total nitrogen and fractional composition of humus. HAs were extracted with the Schnitzer method and analyzed for the elemental composition, spectrometric parameters in the FT-IR and UV-VIS range and hydrophilic and hydrophobic properties. In addition, EPR spectra were produced. The results showed that the content of organic matter compared to soil without additives increased with the use of manure and the use of straw in the CaO variant and in the form of a mulch. The content of dissolved organic carbon (DOC) ranged from 124.6 to 286.1 mg kg⁻¹ and had strong positive correlation with TOC content. The values of the ratio of carbon content in humic acids to carbon content in fulvic acids (CHAs/CFAs) ranged from 0.71 to 0.99. The use of a biostimulator—with or without the addition of straw—increased carbon sequestration in humic acid molecules, as well as their oxidation level and their share of hydrophobic fractions with the longest retention time. Thus, the addition of UGmax intensifies humification processes, leading to the formation of stable humic acid molecules.

The research objective of this study was to determine whether and to what extent the form of use of Fluvisols (arable soil and grassland) of a Lower Vistula floodplain valley (Fordonska Valley, Poland) determined their relative organic matter properties, as compared with nearby riverbank sediments. Riverbank sediments were sampled from a depth of 0–20 cm, and soil samples from 0 to30 cm, all in three replicates. Basic physico-chemical soil properties were determined: texture, pH, and the contents of total organic carbon (TOC), total nitrogen (TN), dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). Humic acids (HAs) were extracted by the Schnitzer method and analysed to assess their spectrometric parameters in the UV–VIS range and hydrophilic and hydrophobic properties. Riverbank sediment samples contained significantly lower TOC and TN contents than Fluvisols, regardless of land-use type. The TOC, TN, DOC and DON contents and properties of humic acids in the Fluvisol surface layer depended on land-use type, because the arable soils had significantly lower TOC, TN, DOC and DON contents than the grasslands, despite having a similar grain size (texture). Based on the A_2/4, A_2/6, A_4/6 ratios, it was found that HA molecules isolated from the humus horizon of arable soils had a higher degree of maturity than HAs isolated from grassland soil samples. The spectrometric properties of humic acids isolated from riverbank sediments showed a higher degree of maturity than those from Fluvisols. This research showed that the properties of humic acids in Fluvisols are determined by the quantity and quality of organic matter transported in suspended matter that accumulates annually in flood valleys during flood events. The current land-use type of Fluvisols significantly influenced the properties of organic matter, and thus of humic acids. Therefore, these properties can be used to evaluate the transformation of organic matter that occurs in Fluvisols depending on the type of use.

The still-advancing soil degradation and the related losses of soil organic carbon stocks due to the limited inflow of organic residues in agro-ecosystems encourage more and more soil protection. Establishing meadow ecosystems is one of the key methods of agricultural land use preventing losses of organic carbon in soils. Based on the research on the properties of humic acids, it is possible to determine the advancement of the processes of transformation and decomposition of soil organic matter. The obtained results may allow for the development of a soil protection strategy and more effective sequestration of organic carbon. Therefore, the aim of the research was to determine the properties of humic acids defining the quality of organic matter of meadow soils irrigated for 150 years with the slope-and-flooding system. The research was performed based on the soils (Albic Brunic Arenosol) sampled from Europe’s unique complex of permanent irrigated grasslands (the same irrigation management for 150 years), applying the slope-and-flooding system: the Czerskie Meadows. 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 (ultraviolet-visible) range, hydrophilic and hydrophobic properties and the infrared spectra. The research results showed that the HAs properties depend on the depth and the distance from the irrigation ditch. The HAs of soils sampled from the depth of 0–10 cm were identified with a lower “degree of maturity” as compared with the HAs of soils sampled from the depth of 20–30 cm, reflected by the values of atomic ratios (H/C, O/C, O/H), absorbance coefficients, and the FT-IR (Fourier transform infrared) spectra. The mean values of the H/C ratio in the HAs molecules of soils sampled from the depth of 20–30 cm were lower by 8.2% than those from the depth of 0–10 cm. The mean values of the absorbance coefficient A4/6 in the HAs molecules of soils sampled from the depth of 20–30 cm were lower by 9.6% than in the HAs molecules of soils sampled from the depth of 0–10 cm. The HAs molecules of the soils sampled 25 m from the irrigation ditch were identified with a higher degree of humification, as compared with the HAs of the soils sampled 5 m from the irrigation ditch. The results identified that humic acids produced in the many-year irrigated sandy soils were identified with a high degree of humification, which proves the relative stability of the soil’s organic matter. It confirms the importance of meadow soils for the carbon sequestration process. It should also be emphasized that the research area is interesting, although hardly described in terms of organic matter properties. Further and more detailed applicable research is planned, e.g., monitoring of total organic carbon content and comparing the properties of irrigated and non-irrigated meadow soils. Continuity of research is necessary to assess the direction of the soil organic matter transformation in such a unique ecosystem. The obtained results may allow for the development of, inter alia, models of agricultural practices that increase carbon sequestration in soils. In the long term, this will allow for greater environmental benefits and, thus, also increased financial benefits.