Copper-(II) coordination compounds are prospective building blocks of magnetic materials for future technologies and biologically active compounds. Their magnetic properties are greatly influenced by coordinating ligands, counterions, cocrystallization partners, and crystal arrangements. The self-organization of crystal structures containing [Cu-(Arg)-(B)]2+ cationic complexes is largely determined by the type of counteranions. Using NO3 - ions resulted in the formation of a new copper-(II) l-arginato 1D polymeric complex, with the following formula: {[Cu-(l-Arg)-(phen)-(μ-NO3)]-(NO3)·H2O}n. The results demonstrate the importance of interactions between NO3 - and the [Cu-(l-Arg)-(phen)]2+ coordination units in constructing the unit cell, stabilizing the structure and the spectroscopic and magnetic properties. The [Cu-(l-Arg)-(phen)]2+ cations are linked by NO3 - axial-axial bridges with Cu···Cu distance of 7.071 Å, which induced weak antiferromagnetic interactions between copper-(II) ions with S = 1/2. The O···H intermolecular interactions mostly control the molecular packing. The EPR (g ⊥ = 2.056, g || = 2.230) and vis (16970 cm-1) parameters confirm the elongated octahedral geometry (T = 0.76) and SOMO oriented in the xy plane N3O coordination sphere. Solid-state 13C NMR spectroscopy is used to characterize the distribution of spin density in organic ligands, with relativistic two-component (SO-ZORA) DFT calculations used to interpret experimental 13C NMR data. Our current N3O coordination polymer belongs to an interesting class of weakly coupled antiferromagnetic compounds.

The aim of this study was to deepen the knowledge on the changes in soil organic matter (SOM) properties under the long-term influence of organic and inorganic fertilization. Particular attention was paid to the humin fraction (HUM), considered to be a particularly stable and long-term sink of atmospheric carbon. The studies were conducted on soil samples from the Broadbalk Winter Wheat experiment running continuously for 180 years, which were analysed using unique chemical and spectrometric methods (13C-CPMAS NMR; C and N K-edge Xanes; EPR; TC-GC/MS; fluorescence; UV-Vis, and others). Long-term manure fertilization treatment confirmed the greatest increase of soil Cat a level comparable to permanent grassland. The manuring significantly increased the HUM-C-content in comparison to the inorganically-fertilized NPK treatment and the control (no inputs) (7.02 g kg-1, 4.37 g kg-1 and 1.72 g kg-1, respectively). The manuscript documented that the proportion of HUM in total organic carbon (TOC) increased twofold with NPK fertilization and one and a half times with manure fertilization, but surprisingly not after the application of both, shedding new light on the mechanisms of C stabilization. The manuscript indicated for the first time by multivariate statistical analyses that HUM-C enrichments from manure were linked with increasing proportions of heterocyclic N compounds. These findings have profound implications for broader sustainability, directly linking to climate change mitigation and food security. It is concluded that offsetting mineral fertilizer by manure, where this is possible and feasible, is an option for sustainable soil C increase.

Copper(II) coordination compounds are prospective building blocks of magnetic materials for future technologies and biologically active compounds. Their magnetic properties are greatly influenced by coordinating ligands, counterions, cocrystallization partners, and crystal arrangements. The self-organization of crystal structures containing [Cu(Arg)(B)]2+ cationic complexes is largely determined by the type of counteranions. Using NO3 - ions resulted in the formation of a new copper(II) l-arginato 1D polymeric complex, with the following formula: {[Cu( l-Arg)(phen)(mu-NO3)](NO3)& centerdot;H2O}n. The results demonstrate the importance of interactions between NO3 - and the [Cu(l-Arg)(phen)]2+ coordination units in constructing the unit cell, stabilizing the structure and the spectroscopic and magnetic properties. The [Cu(l-Arg)(phen)]2+ cations are linked by NO3 - axial-axial bridges with Cu & centerdot;& centerdot;& centerdot;Cu distance of 7.071 & Aring;, which induced weak antiferromagnetic interactions between copper(II) ions with S = 1/2. The O & centerdot;& centerdot;& centerdot;H intermolecular interactions mostly control the molecular packing. The EPR (g perpendicular to = 2.056, g || = 2.230) and vis (16970 cm-1) parameters confirm the elongated octahedral geometry (T = 0.76) and SOMO oriented in the xy plane N3O coordination sphere. Solid-state 13C NMR spectroscopy is used to characterize the distribution of spin density in organic ligands, with relativistic two-component (SO-ZORA) DFT calculations used to interpret experimental 13C NMR data. Our current N3O coordination polymer belongs to an interesting class of weakly coupled antiferromagnetic compounds.

The aim of the study was to reveal the effect of agroecosystems management on soil physical properties and stability of soil organic matter (SOM). A 55-year-long-term field experiment in Kaunas, Lithuania, allowed for a comprehensive assessment of the effects of rye and maize monocultures, with and without mineral fertilisation, intensive six-year crop rotation and bare fallow on soil properties in the 0-20 cm layer. Soil physical parameters (soil water retention, water repellency, and aggregate stability) and SOM characteristics, including total organic carbon content (TOC), fractional composition (fulvic acids, humic acids, humin), and molecular properties of humin were examined using elemental analysis, UV-Vis, fluorescence spectroscopy, and 13C-CPMAS NMR. The results confirmed that bare fallow reduces aggregate stability and limits TOC content. In contrast, intensive six-year crop rotation increased aggregate stability, water retention and TOC content while plant-available water remained unchanged, highlighting the significant environmental benefits of crop rotation. However, fertilised rye monoculture exhibited a higher amount of plant-available water. Monocultures caused an increase in soil water repellency at low soil moisture. The favourable increase in TOC in response to crop rotation resulted in increased humic and fulvic acids share, while the humin structure in these soils indicated a more aliphatic structure. Humin properties in non-fertilised monocultures, especially rye, was similar to that in fallow, reflecting a higher proportion of well-transformed humic material. The results showed that the integration of legumes, organic fertilisers, and crop diversity is crucial for long-term soil health and resilience to climate stress in agroecosystems.

Sustainable management of permanent grasslands requires evidence-based selection of fertilization practices that support long-term soil organic matter quality and ecosystem function. This study addresses the need to identify optimal agricultural practices in permanent grasslands and the effects of organic and inorganic fertilizers on soil humic substances (HS) composition and stability. Grassland plots were amended after cutting with mineral fertilizer (NPK), farmyard manure (FYM), cattle slurry (CS), or digestate (DIG), and humic acids (HA) were isolated using the standard International Humic Substances Society procedure. The elemental composition, total carbon and nitrogen contents, C/N ratio, and selected biogenic elements were determined using routine laboratory methods, while infrared spectroscopy, fluorescence excitation-emission matrix analysis, and electron paramagnetic resonance spectroscopy were applied to characterize chemical structure and semiquinone radical concentrations. Principal component analysis (PCA) indicated distinct clustering of fertilization treatments, which was supported by a statistically significant effect (p < 0.05) based on ANOVA. The results suggest that the fertilization regime was associated with variation in HS composition and radical abundance. DIG and NPK treatments showed lower O/C ratios and radical concentrations, potentially reflecting more reduced humic acids. In contrast, FYM and CS treatments tended to exhibit higher radical concentrations and O/C ratios. These findings highlight the importance of fertilizer type in shaping soil organic matter dynamics in managed grassland ecosystems and provide a scientific basis for the development of sustainable soil management strategies and environmentally sound fertilization practices in permanent grassland systems.

Greenhouse gasses emission, depletion of nutrients and soil degradation are major factors that are deteriorating soil health. A global challenge to agriculture is the production of enough crops while reducing the impact of intensive chemical inputs on the environment. Humic acids (HA), a main fraction of humic substances produced through humification of organic matter, are considered as multi-functional biostimulants playing an important role in sustainable and climate-smart crop production systems. Recent developments in molecular spectroscopy, humeomics, and soil–plant systems biology have significantly changed our understanding of HA; from inert recalcitrant macropolymers to supramolecular assemblies that are dynamic and govern soil physicochemical properties, microbial activity and plant physiological responses. This review critically synthesizes the available evidence on structure–function relationships of HA with soil fertility restoration, nutrient-use efficiency, crop productivity and environmental sustainability. Emphasis is placed on mechanisms involved in humic acid-mediated soil aggregation, cation exchange capacity improvement, nutrient chelation and modification of root architecture, hormonal signaling and stress tolerance. Nutrient-use efficiency can be improved through HA applications and lower synthetic fertilizer inputs, as well as long-term stabilization of soil carbon and immobilization of heavy metals through the formation of stable organo-mineral complexes. Despite these benefits, substantial variability in HA sources, extraction protocols and molecular composition as well as adoption methodologies continue to limit their reproducibility and widespread application. Knowledge gaps, such as the standardization of molecular characterization, omics-level validation of the plant and microbial responses, long-term field-scale assessment for carbon (C) permanence and agronomic performance of HA are discussed in this review. It also proposes future research and policy needs to develop humic-based amendments for resilient low-input agricultural systems.

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.

Fluopyram is a fungicide commonly applied in farming which has led to contamination of soils, crops, and surface water. However, adsorption and degradation processes of fluopyram in soils - crucial for understanding its environmental fate - have not been fully studied. The Koc values obtained for six typical Polish soil profiles and three topsoils from northern and southern Europe, were in the range of 89.8-294.7 mL g-1 for the topsoils and 110.0-2328.0 mL g-1 for the subsoils. Microbial degradation of fluopyram in soils was combined with its time-dependent adsorption that was completed within 5-8 weeks. The half-life values estimated at 20 °C using the two-site nonequilibrium adsorption model coupled with the first-order degradation, and next corrected to the soil water contents at 10 kPa, were in the range of 207-887 d for the topsoils and 1007-4268 d for the subsoils. Neglecting the process of slow adsorption of fluopyram in soils led to large reduction of the calculated half-lives. The regression analysis indicated that its adsorption range and degradation rate can be predicted based on the soil physicochemical and microbiological properties. As follows from the simulations with FOCUS PELMO using the Hamburg scenario, annual application of fluopyram can cause contamination of groundwater and its concentration in the topsoil is much higher than that predicted previously. High concentration of fluopyram in the topsoil and its adsorption by fulvic acids denote a large risk of its transport into the surface water and its uptake by crops.

The six phenoxyalkanoic acid herbicides currently used in the European Union have similar molecular structures. Therefore, we assumed the soil components involved in the adsorption mechanisms of these herbicides to be identical. The values of the adsorption distribution coefficient Kd, obtained via batch experiments involving typical Polish Arenosol, Luvisol, and Chernozem profiles with a native pH of 4.2–7.7, were examined using Lasso regression, as well as adsorption on isolated fractions of humic substances, Al2O3, and goethite. The neutral forms of the herbicides were adsorbed on the surface of fulvic acids available to them, covering soil mesopores with a size of > 2.5 nm. The models revealed that fulvic acids had a lognormal-like distribution in soil pores. Herbicide anions were adsorbed on the pH-dependent sites of Al oxyhydroxides and on the sites created by the Al+3 species adsorbed on the surface of fulvic acids (both sites were active up to pH 7.5), the sites of humic acids associated with the adsorbed Al3+ species, sites of Fe oxyhydroxides (active at pH < 5), and, to a limited extent, sites of humins. Two models describing the adsorption of phenoxyalkanoic acid herbicides in soils were created. A simpler model was based on humic substance fractions and the variables related to the potential acidity of soils. In the more extensive model, humic substance fractions and Al and Fe oxyhydroxide contents were used as predictors, and, where necessary, the predictors were combined with the modified Henderson–Hasselbalch formula to estimate the activity ranges of pH-dependent sorption sites. The study findings revealed that fulvic and humic acids were the main adsorbents of phenoxyalkanoic herbicides in soils, indicating that transporting of the herbicides with dissolved organic matter is an important mechanism of groundwater and surface water contamination with these chemicals.

This paper focuses on solvatochromic studies of a new synthesised BODIPY dye with piperonal and ortho-hydroxy aryl Schiff base substituents (BD-2-Schiff). The studied dye has been analysed by spectroscopic and computational techniques to have a deep insight into the impact of the solvents’ polarity and the specific interactions on the dye characteristics. The synthesized dye turns to be sensitive to external specific interactions, caused by protic solvents and acid, which change spectral characteristics of BODIPY-2-Schiff. The calculations by the density functional theory (DFT) and the time-dependent density functional theory (TD-DFT) have been accomplished for the interpretation of the obtained experimental results. The synthesized dye has been evaluated as a photosensitizer for the light induced inactivation of Staphylococcus aureus (S. aureus) and Acinetobacter baumannii (A. baumannii). The synthesized BODIPY dye has shown a significant photocidal activity (above 90 %) against these pathogenic bacteria at low microgram concentrations and excitation with low doses of visible light (0.72 J/cm2; λ = 519 nm).

The aim of this study was to assess the effect of long-term catch crop application on the structural properties of humin, which is considered the most recalcitrant fraction of soil organic matter. Soil samples from a 30-year field experiment on triticale cultivated with and without catch crops were analysed to determine the total organic carbon content and fractional composition of humic substances. Meanwhile, humin isolated from bulk soil was analysed to determine its elemental composition and spectroscopic properties measured with UV-Vis, fluorescence, and 13C-CPMAS-NMR. It was found that catch crop farming enhanced the formation of highly reactive humus substances, like low-molecular-weight fractions and humic acids, while decreasing the humin fraction. The higher H/C and O/C atomic ratios of humin and the UV-Vis, fluorescence, and 13C-CPMAS-NMR results confirmed a higher share of oxygen-containing functional groups in humin isolated from the soil with catch crop rotation, also corroborating its greater aliphatic nature. Under the conditions of our field experiment, the results indicated that organic residues from catch crops quickly undergo the decay process and are transformed mainly into highly reactive humus substances, which can potentially improve soil health, while mineral fertilisation alone without catch crops favours the stabilisation and sequestration of carbon.

The purpose of the research was to determine the molecular properties of humin (HUM) determined by elemental composition, as well as spectroscopic 13C Magic Angle Splitting Cross Polarisation Nuclear Magnetic Resonance (13C MAS CP NMR), Fourier transformed infrared, electron paramagnetic resonance and scanning electron microscope energy-dispersive x-ray (SEM-EDX) techniques. Soil samples were isolated from the mollic horizon of Phaeozem and Chernozem arable soils derived from different parent materials in Poland. The HUM was isolated as the fraction that was remined after exhaustive extraction of the humic and fulvic acids by NaOH and was followed by removal of the mineral fraction with HF/HCl treatment. The results obtained indicated that the HUM structures isolated by the adopted method are a chemically heterogeneous conglomerate, composed of a complex of many strongly combined units of organic substances. This fraction indicated a highly condensed structure with a predominance of aromatic components (predominating over chain forms ranging from 7.05% to 10.32%) and hydrophobic reactive moieties. The share of hydrophobic forms ranges from 77.41% to 80.83%. The ash content, ranging from 22.89% to 54.50%, as well as SEM-EDX used indicated that the HUM isolated with the adopted procedure is strongly associated with the mineral components of the soil. The aromatic part of HUM is strongly associated with the mineral components of the soil, what provides their stability in the environment. These observations confirm the high resistance of HUM to decomposition and indicate the great importance of this fraction in carbon sequestration and preventing soil degradation.

Humin (HUM) is the most stable fraction of the soil organic matter, whose properties determine the soil health and sustainable development of agroecosystems. The aim of the paper was to determine changes in the properties of the HUM after interaction with selected pesticides, which can be visualized using photoluminescence methods. The HUM was isolated from the mollic horizon of Phaeozems arable soils derived from different parent materials in Poland. The isolated and purified HUM were saturated in a batch experiment with selected herbicides and insecticides, then analyzed for chemical composition and spectroscopic properties: Electron Paramagnetic Resonance, fluorescence, and delayed luminescence. The research showed that the interaction of the HUM with selected pesticides caused significant changes in the elemental composition of the HUM; however, no changes in their aromaticity/aliphaticity were found. The impact of pesticides was also marked by a reduction in the concentration of radicals, fluorescence and delayed luminescence intensity and properties. Changes in spectroscopic characteristics and their relationship with soil organic matter (SOM) structure properties require further research so that their results can be used in the management of agroecosystems in accordance with the principles of sustainable development.

The aim of the research was to investigate interactions between pendimethalin (PE), an active substance of plant protection products, and the humin fraction (HM), which is the most recalcitrant component of soil organic matter. The soil material used for the study was collected from the mollic horizon of two Chernozems different in physicochemical properties. HM was obtained in the solid state after discarding humic acid (HA) and fulvic acid (FA) and digesting the mineral fraction in an HF-HCl mixture. Pure PE and two commercial products containing the substance (Penfox 330 EC and Stomp Aqua 455 SC), dissolved in hexane and added to the HM, were used in the research. The batch sorption experiment was carried out in accordance with OECD Guidelines for the Testing of Chemicals No.106. Spectroscopic methods (UV-Vis-nearIR and fluorescence) were used to assess the molecular characteristics of HM exposed to pesticides. The study showed significant differences in the molecular structures of the tested HM as a result of interactions with the pesticides used. The results revealed that PE had a different effect than the commercial products, and proved that the composition of commercial products significantly modified the strength and ability of organic matter to bind pesticides. This is probably related to the presence of adjuvants that are more competitive in forming bonds with the active sorption sites of HM, and thus strengthen or weaken the process of forming pesticide-HM complexes. As a result, the diversity of the molecular structure of HM and the presence of accompanying substances in commercial pesticide products interact, leading to different sorption mechanisms and durability of the resulting products.

A new heteroleptic [CuBr( L - Arg)(bpy)]Br & sdot; 2H 2 O ( 1 ) ( L -Arg= L -Arginine, bpy=2,2'- bipyridine) complex has been synthesized and its molecular and supramolecular structure aspects have been discussed based on the X-ray single crystal structure and Hirshfeld analyses. In addition, the properties of complex 1 have been elucidated using different spectroscopic methods (FT-IR / FIR, Raman, NIR-Vis-UV, Q- / X- band EPR) and magnetic measurements. In this complex, the bromide anion occupies the apex of a slightly distorted square pyramid (tau = 0.12). The [CuBr( L - Arg)(bpy)] + complex units exhibit a ribbon-like organization, with Cu(II) metal centers located at the corners of triangles where the shortest Cu center dot center dot center dot Cu distance is 5.579 & Aring;. The aromatic moieties of bpy are aligned nearly parallel leading to pi & sdot;& sdot;& sdot; pi interactions. Both, non-bonded and coordinated, Br - ions act as hydrogen -bond acceptors for guanidinium groups. Hirshfeld analysis indicated the importance of the Br center dot center dot center dot H (17.9 - 18.4 %), O center dot center dot center dot H (14.9-15.2 %), and H center dot center dot center dot H (42.3-43.1 %) interactions in the molecular packing of the studied complex. Atoms in molecules (AIM) calculations indicated mainly the closed shell character for the Cu-N, Cu-O and Cu-Br coordination interactions. The G value calculated using the Q -band EPR spectra parameters g || = 2.235 and g perpendicular to = 2.05 is 4.7, what indicating negligible coupling and that local tetragonal axes are aligned parallel. A negative value of Weiss temperature theta CW = -0.32 K indicates the presence of weak antiferromagnetic coupling between the neighboring Cu(II) ions mediated through hydrogen bonds and pi-pi stacking of aromatic moieties of bpy. The value of g av = 2.113 obtained from Q -band EPR spectra is consistent with that corresponding to the Curie constant ( C = 0.4138 emu K mol -1 ), i.e.g = 2.101, and that obtained from the best fitting to the Brillouin function: g = 2.139.

IntroductionHumic substances (HS) are increasingly being applied as crop plant biostimulants because they have been shown to increase plant productivity, especially under environmentally stressful conditions. There has been intense interest in elucidating the HS molecular structures responsible for eliciting the plant biostimulant response (PBR). The polar and weakly acidic carboxylic (COOH) and phenolic hydroxyl (ArOH) functional groups play major roles in the acid nature, pH dependent solubilities, conformation, and metal- and salt-binding capabilities of HS. Reports on the role played by these groups in the PBR of HS found growth parameters being both positively and negatively correlated with COOH and ArOH functionalities.Materials and methodsTo investigate the role of COOH and ArOH in HS biostimulant activity we used a humic acid (HA), purified from an oxidized sub bituminous coal to prepare HAs with COOH groups methylated (AHA), ArOH groups acetylated (OHA), and with both COOH and ArOH groups methylated (FHA). The original HA was designated (NHA). The four HAs were subjected to elemental, 13C-NMR, FTIR, and EPR analyses and their antioxidant properties were assessed using the trolox equivalents antioxidant capacity assay (TEAC). 13C-NMR and FTIR analysis revealed significant alkylation/acetylation. To determine the effects of alkylating/acetylating these functional groups on the HA elicited PBR, the HAs were evaluated in a plant bioassay on corn (Zea mays L.) seedling under nutrient and non-nutrient stressed conditions. Treatments consisted of the four HAs applied to the soil surface at a concentration of 80 mg C L−1, in 50 ml DI H2O with the control plants receiving 50ml DI H2O.ResultsThe HA-treated plants, at both fertilization rates, were almost always significantly larger than their respective control plants. However, the differences produced under nutrient stress were always much greater than those produced under nutrient sufficiency, supporting previous reports that HA can reduce the effects of stress on plant growth. In addition, for the most part, the HAs with the alkylated/acetylated groups produced plants equal to or larger than plants treated with NHA.ConclusionThese results suggests that COOH and ArOH groups play a limited or no role in the HA elicited PBR. Alternatively, the HA pro-oxidant to antioxidant ratio may play a role in the magnitude of the biostimulant response.

SOMPACS is a project recommended by EJP SOIL for funding under the 1st External Call "Towards Healthy, Resilient and Sustainable Agricultural Soils". The goal of this project is to assess management practices that enrich organic matter pools that are resilient to rapid microbial decomposition. The project started in 2022 as a consortium of 12 research institutions from Poland, Germany, Ireland, Lithuania, UK, Italy and USA for a period of three years. Soil and vegetation samples from eight long-term experiments that differ in soil management practices (i.e., conventional vs. no-tillage; mineral vs. organic fertilization; with and without catch crop; and arable land vs. undisturbed grassland) are investigated. Study sites include: 22- and 54-year long experiments in Lithuania; 26-year long experiment in Italy; 30- and 40-year long experiments in Ireland; 30- and 46- and 100-year long experiments in Poland; and 178-year long Broadbalk experiment in Great Britain. Additional experimentation includes assessing the impact of root growth promoting amendments (commercially available humic substances, biochar and biogas digestate) on stable organic matter pools. In parallel with soil sampling, plant productivity are measured in all field experiments. This investigation is couples fields studies with small-scale experimental plots and laboratory incubations under controlled conditions. In addition to assessing basic soil properties, the following state-of-the-art analyses are conducted: SOM composition and stability by Py-GC-MS; fractionation of aggregate size classes and C pools of increasing physicochemical protection; isotopic analysis of δ13C and δ15N performed on different SOM pools; microbiological properties (community-level physiological profiling, selected functional genes involved in C and N cycles, microbiome and mycobiome analyses by next-generation sequencing, genetic diversity using terminal restriction fragment length polymorphism); enzymatic activity; soil water retention and soil water repellency; mineral composition of clay fraction; (8) soil structure stability. SOM composition and stability by Py-GC-MS; fractionation of aggregate size classes and C pools of increasing physicochemical protection; isotopic analysis of δ13C and δ15N performed on different SOM pools; microbiological properties (community-level physiological profiling, selected functional genes involved in C and N cycles, microbiome and mycobiome analyses by next-generation sequencing, genetic diversity using terminal restriction fragment length polymorphism); enzymatic activity; soil water retention and soil water repellency; mineral composition of clay fraction; (8) soil structure stability. The most resistant SOM pool (humin) are isolated by different methods (isolation vs. extraction) and examined for chemical composition and structure, using spectrometric and spectroscopic techniques (mass spectrometry, NMR, FTIR, EPR, UV-Vis-NIR, fluorescence). The carbon stocks in the soil profile will be evaluated and the carbon extractable in cold water will be determined to assess the potential carbon leaching and microbial availability. Additionally, in-field soil carbon dioxide (CO 2 ) fluxes from selected experiments is monitored. Thus far, soil samples (0-100 cm depth) were collected and the humin fraction from surface A horizon was isolated for spectroscopic studies. Crop yield and vegetation productivity was also assessed. The research was financed by NCBR (EJPSOIL/I/78/SOMPACS/2022).

In this work, we reported four new copper(II) halo-benzoate complexes (2-chloro-4-nitrobenzoate (2-Cl-4-NO2-BZ), 3,5-DICBZ, 2-chloro-5-nitrobenzoate (2-Cl-5-NO2-BZ), 3,5-difluoro benzoate (3,5-DIFBZ), and 3,5-dichlorobenzene (3,5-DICBZ) respectively in complexes 1-4) with N,N,N',N'- tetramethylethylene diamine (temed) N-donor ligand in order to study the interesting coordination features and biological evaluation of such complexes under ambient reaction conditions. All the complexes 1-4 were characterized by elemental analyses, and spectroscopic techniques, including FT-IR, UV-vis, and EPR etc. Single crystal X-ray structure determination (SCXRD) of complexes revealed the distorted octahedral geometry in all complexes. Notably, the halobenzoate ligands exhibited a bidentate chelation mode in complexes 1 and 2, while they showed a monodentate mode in complex 3. In complex 4, the carboxylate ligand exhibited both monodentate as well as bidentate coordination. Furthermore, detailed packing analyses of complexes 1-4 highlighted the significance of halogen bonding in lattice stabilization besides hydrogen bonding and pi center dot center dot center dot pi interactions as evidenced by Hirshfeld surface analyses and crystal analysis. Moreover, packing analyses displayed that complex 1 exhibited a layered or wave-like arrangement, while complex 2 featured a helical arrangement supported by a supramolecular halogen-bonded network guided by Cl center dot center dot center dot O interactions. Complex 3 displayed a zig-zag layered arrangement with a stacking topology, and Complex 4 showcased a ribbon-like arrangement stabilized by F center dot center dot center dot F and Cl center dot center dot center dot Cl halogen bonding interactions. Furthermore, sigma hole on halogen atoms has also been examined (which play an important role in halogen bonding) by electrostatic-potential isosurfaces. In order to exploit the biological efficacy of complexes 1-4 owing to the inherent biological activity of copper metal, molecular docking analyses against gram +ve bacteria i.e. S. epidermidis (PDB ID; 8DO6), B. subtilis (1QD9), as well as two gram -ve bacteria, namely, P. aeruginosa (5WZE) and S. dysenteriae (1DM0), have also been carried out. Interestingly, values of docking scores and inhibition constant of all complexes 1-4 (with a maximum binding score (inhibition constant) of -9.8 kcal/mol (0.063 mu Mol) in 1 against 8DO6 and 1DM0) revealed higher biological efficacy than that of standard drugs.

The constant influx of pesticides into soils is a key environmental issue in terms of their potential retention in the soil, thus reducing their negative impact on the environment. Soil organic matter (SOM) is an important factor influencing the environmental fate of these substances. Therefore, the aim of this research was to assess the chemical behavior of pesticides (flufenacet, pendimethalin, α-cypermethrin, metazachlor, acetamiprid) toward stable soil humin fractions (HNs) as a main factor affecting the formation of non-extractable residues of agrochemicals in soil. This research was conducted as a batch experiment according to OECD Guideline 106. For this purpose, HNs were isolated from eight soils with different physicochemical properties (clay content = 16–47%, pHKCl = 5.6–7.7, TOC = 13.3–49.7 g·kg−1, TN = 1.06–2.90 g·kg−1, TOC/TN = 11.4–13.7) to reflect the various processes of their formation. The extraction was carried out through the sequential separation of humic acids with 0.1 M NaOH, and then the digestion of the remaining mineral fraction with 10% HF/HCl. The pesticide concentrations were detected using GC-MS/MS. The pesticides were characterized based on the different sorption rates to HNs, according to the overall trend: metazachlor (95% of absorbed compound) > acetamiprid (94% of absorbed compound) > cypermethrin (63% of partitioning compound) > flufenacet (39% of partitioning compound) > pendimethalin (28% of partitioning compound). Cypermethrin and metazachlor exhibited the highest saturation dynamic, while the other agrochemicals were much more slowly attracted by the HNs. The obtained sorption kinetic data were congruous to the pseudo-first-order and pseudo-second-order models related to the surface adsorption and interparticle diffusion isotherm. The conducted research showed that the processes of pesticide sorption, apart from physicochemical phenomena, are also affected by the properties of the pollutants themselves (polarity, KOC) and the soil properties (SOM content, clay content, and pHKCl).

This paper provides new information on molecular properties of the humin fraction (HM) isolated from the mollic horizons of Phaeozem and Chernozem soils developed from different parent materials in the temperate climatic zone of Poland. In our work we did not extract this fraction by dissolution but isolated it by exhaustive extraction of humic and fulvic acids with NaOH and then removing the mineral fraction with HF/HCl treatment. Obtained HM reflects the properties of this fraction that naturally occurres in the soil environment. The assessment of the structural properties of the HM was carried out using the spectroscopic methods ( C CP MAS NMR, FTIR, EPR), HPLC, SEM-EDX, and elemental composition analyses. The C CP MAS NMR spectra of the HM showed the advantage of aromatic structures over other organic components. The FTIR spectra confirmed that the content of aromatic structures dominated over the aliphatic ones, ranging from 7.05 to 10.32%. The EPR study indicated evidence of an unpaired electron situated on the condensed aromatic moieties. The HPLC investigation revealed the dominance of hydrophobic fractions, ranging from 77.41 to 80.83%. The ash content, ranging from 22.89 to 54.50%, as well as SEM-EDS study indicate that the isolated HM is not a pure organic fraction but constituted strongly bound organo-mineral compounds, resistant to further treatment with an alkali and HF/HCl mixture. This fraction represents the most resistant pool of the SOM that plays a crucial role in soil carbon sequestration and due to high functional group content contributes to the maintenance of soil and its ecosystem services.