Organo-mineral Complexes Research Articles

Modeling Soil Organic Carbon Content Using Mid-Infrared Absorbance Spectra and a Nonnegative MCR-ALS Analysis

A new approach based on mid-IR absorbance spectra is proposed for modeling total organic carbon (TOC) content of soils. This approach involves a first-time bilinear decomposition of soil mid-IR absorbance spectra using nonnegative multivariate curve resolution (MCR) with an alternating least squares (ALS) algorithm. An MCR-ALS-derived component signifies a chemically meaningful combination of soil constituents. A new mechanistic model has been developed to link the soil composition, expressed in terms of ratios of MCR-ALS-based concentration scores of the identified components, to soil TOC value. Nonnegative MCR-ALS decomposition, performed for 213 mid-IR absorbance spectra of soil samples collected in the north and south of Israel, yielded four components. Fitting the mechanistic model-derived TOC to the experimental TOC values exhibited a TOC content threshold that affected model performance. TOC content <1.0 % w w-1 was represented by the root mean square deviation of 0.18% and 62% of the variance explained, whereas for larger TOC values, a sharp decline in model performance was observed. The existence of this TOC threshold in determining model performance suggested that successful TOC modeling (below 1%) could be indirect and related to IR spectral fingerprints of minerals binding soil organic matter (SOM) and forming organo-mineral complexes. Thus, a SOM fraction having weak interactions with soil minerals was poorly accounted for in a particular set of soil samples. This dependency of the model performance on soil TOC range proposes that it might be possible to differentiate between soil samples based on their different dominating SOM pools, mineral-associated ones and those having weak interactions with minerals. Further studies, especially in soils with high SOM content, are needed to validate our findings.

Use of Guanidine-Containing Organomineral Complexes for Protection of Soft Polyvinyl Chloride Compounds from Photo- and Biodegradation

Use of Guanidine-Containing Organomineral Complexes for Protection of Soft Polyvinyl Chloride Compounds from Photo- and Biodegradation

Iron-modified biochars and their aging reduce soil cadmium mobility and inhibit rice cadmium uptake by promoting soil iron redox cycling

Iron (Fe) modified biochar has been widely used for cadmium (Cd) contaminated soil remediation. However, the accompanying anions introduced during the modification process potentially affect the behavior of Cd in soil. In this study, we investigated the distinct Cd immobilization mechanisms by Fe2(SO4)3 modified biochar (FSBC) and Fe(NO3)3 modified biochar (FNBC) in a two-year pot experiment. Results showed that both FSBC and FNBC significantly reduced Cd concentrations in rice grains by 23%–42% and 30%–37% compared to pristine biochar (BC). Specifically, NFBC promoted the formation of amorphous Fe oxides by enhancing the NO3−-reducing Fe(II) oxidation process, which significantly increased Fe/Mn oxide-bound Cd and decreased soil CaCl2-extractable Cd. For FSBC, the introduction of SO42− significantly promoted the formation of Fe plaques by enhancing the Fe(III) reduction process, which blocked the Cd transfer from the soil to the rice roots. More importantly, after two years of biochar application, an organo-mineral complex layer is formed on the biochar surface, which immobilized a large amount of Cd. The Cd immobilization on the surface of aged biochar could be due to the fixation by the secondary Fe oxides within the organo-mineral layer and the complexation by the surface functional groups. The result of laser ablation inductively coupled plasma mass spectrometry showed that the Cd content on aged FNBC and FSBC was 5.9 and 2.6 times higher than on aged BC. This might be attributed to the Fe-modified biochar's higher electron exchange capability (EEC), which promoted the development of organo-mineral complexes. Notably, the EEC of biochar was maintained during its aging process, which may keep the biochar surface active and facilitate continual Cd immobilization. This study revealed the complex mechanisms of soil Cd immobilization with Fe-modified biochar, providing new insights into sustainable biochar environmental remediation.

Mineral-associated organic carbon promoted phosphorus accumulation in long-term fertilized black soil

Soil phosphorus (P) pool is intimately connected to organic carbon (OC), especially mineral-associated OC (MAOC). However, the relationship and mechanism between MAOC fractions and P fractions and their response to fertilization remain unclear. According to a long-term field trial in black soil, topsoils from no-fertilizer control, chemical fertilizer (36 kg P ha-1), and straw addition (42 kg P ha-1) for 21 and 29 years were collected, and organo-mineral complexes (< 20 µm) were separated and analyzed. Compared to no-fertilizer control, chemical fertilizer resulted in soil acidification (soil pH 6.15–6.27), increasing the contents of the MAOC fraction bound to minerals by weak linkages in complexes. Straw addition maintained soil pH at 7.53–7.84, and the contents of some MAOC fractions (which were remaining water-soluble, bound by cations, encapsulated by resistant carbonate, and insoluble humin) were significantly higher than that of chemical fertilizer. Fertilization applications increased total P contents in organo-mineral complexes, with similar levels of total P observed between chemical fertilizer and straw addition. Chemical fertilizer mainly increased highly labile inorganic P (Pi) extracted from resin, NaHCO3 and NaOH, as well as organic P (Po) extracted by NaHCO3, and straw addition mainly increased moderately labile Pi extracted from dilute HCl. Correlation analysis showed that the increased and dominant MAOC fractions had positive relationships with the increased P fractions. X-ray absorption near-edge structure (XANES) spectroscopy further identified that chemical fertilizer increased the proportion of AlPO4, suggesting that MAOC promotes the retention of labile P via association with Al under weakly acidic conditions. Straw addition increased the proportion of Ca3(PO4)2 and Ca5(PO4)3OH; moreover, it also increased the maximum P sorption capacity of complexes, suggesting that MAOC enhances P sorption via association with Ca under weakly alkaline conditions and that adsorbed P will transform into more stable Ca-associated P. Our findings demonstrate that MAOC promotes P accumulation via association with different P fractions, and these processes are mineral and pH-dependent.

ВЛИЯНИЕ НОВОГО ОРГАНО-МИНЕРАЛЬНОГО КОМПЛЕКСА ГУМИТОН НА ПРОДУКТИВНОСТЬ И КАЧЕСТВО ЗЕРНА ОВСА

According to the data of microfield experience on soddy-podzolic neutral soil, it was shown that the treatment of oat crops with an organo-mineral complex based on Gumiton peat during the exit phase into the tube contributed to an increase in grain yield by 23% compared to the control. The content of crude protein, fiber and fat increased by 10.0; 11.6; 16.0%. The introduction of main fertilizer PhosAgro NPK (8:20:30) led to an increase in grain yield by 50.3% relative to the control. The content of crude protein, fiber and fat increased to the level of variants with use of Gumiton in the control. Processing of plots with PhosAgro NPK (8:20:30) Gumiton increased yields by 4.5% and indicators of protein, fiber, fat by 4.2; 6.5; 10.4%, respectively.

Pedological factors affecting pesticide retention in a series of tropical volcanic ash soils in the French West Indies

Specific pedoclimatic conditions in tropical environments have a considerable impact on pesticide fate. Tropical volcanic soils result from specific pedogenesis processes linked to successive volcanic projections; they are characterised by acidic conditions, high organic matter content, a specific mineralogical composition and the presence of organo-mineral complexes. The retention of pesticides in these soils is therefore often high but variable depending on the associated molecules and soil properties. Nevertheless, knowledge of pesticide sorption in these soils remains limited, and knowledge of the desorption process is scarce. The objectives of this work were to study the variability of the sorption and desorption coefficient of four pesticides currently used in banana and sugarcane crops on a set of representative tropical soils developed on volcanic ash (Guadeloupe, French West Indies). Adsorption and desorption isotherms were analysed for three ionizable pesticides (2,4-D, mesotrione, glyphosate) and a hydrophobic pesticide (difenoconazole) on ten soil samples from five soil profiles: one silandic andosol, one vitric andosol, two nitisols and one ferralsol. For ionizable pesticides, soil pH appears to be a first-order discriminating factor of the sorption capacity, and the organic carbon content appears to have a lesser impact on 2,4-D. For a strongly hydrophobic pesticides such as difenoconazole, the organic carbon content plays a major role in sorption. Desorption hysteresis has been observed regardless of the soils and the molecules considered, and tropical volcanic soils seem to be conducive to adsorption but show low to moderate release. The silandic andosol, which has the greatest sorption, buffers the dissemination of pesticides towards surface and groundwaters but also increases the risk of long-term contamination in the case of molecules that degrade slowly. Moreover, our results highlight that agronomic practices, such as liming, have a major impact on the sorption coefficient of pesticides and must be considered for when predicting sorption in a tropical volcanic context.

Tillage and mulching effects on carbon stabilization in physical and chemical pools of soil organic matter in a coarse textured soil

Characterization of soil organic carbon (SOC) in terms of size, storage inside aggregates and chemical recalcitrance is vital to understand mechanisms of its stabilization and to devise climate smart agricultural management practices. Tillage and residue retention are known to influence carbon (C) storage within soil aggregates and its accumulation as particulate organic matter as well as organomineral complexes. However, the effect of tillage and crop residue retention on C stabilization in coarse textured soils through various mechanisms is not well understood. We studied the effect of conservation agriculture involving no tillage with surface residue mulch (NTM) in maize-wheat sequence on particulate (POC) and mineral associated organic C (MinOC), C storage within aggregates and acid non-hydrolysable C (NHC) in a sandy loam soil. Compared to conventional tillage without residue retention (CTM0), the NTM improved SOC stocks by 23% in top 15-cm soil and significantly increased coarse POC (∼92 to 284%) and fine POC (67 to 123%) with relatively little effect on MinOC. This indicated that MinOC had relatively small contribution towards SOC stabilization in coarse textured sandy loam soils with limited potential to form organomineral complexes. The results further showed that the effects of NTM were brought about by improved aggregate stability and C preservation inside macroaggregates of size >1 mm. Furthermore, greater amount of SOC (2.64 g C kg−1) and macroaggregate associated C (0.35–0.59 g C kg−1) occurred in recalcitrant forms (NHC) under NTM compared to conventional (CT) and deep tillage (DT). The NTM also impacted the belowground C input through improved root length density (RLD) and development of fibrous roots expressed as specific root length (SRL), which influenced SOC build-up and stabilization. It is concluded that compared to the existing practice of CTM0, the conservation agriculture involving NT with residue retention leads to SOC sequestration in coarse textured soils. Its large scale adoption, besides helping in climate change mitigation will lead to soil health improvement.

Use of &lt;i&gt;Hermetia illucens&lt;/i&gt; hermicompost in the technology of growing legume microgreens

Relevance. The work describes the prospect of using black soldier fly zoohumus as an organic fertilizer to activate the growth of microgreens of non-traditional legume species, including small-seeded ones, and the prospects of reducing the dose of mineral fertilizers.Methods. An experiment was carried out with a comparative study of changes in the morphometric and chemical parameters of plant growth at the full recommended dose of mineral fertilizers, and at 25% of their use, but with the addition of 1% liquid extract of zoohumus, also enriched with essential elements. The duration of the experiment was 21 days. The plants were grown in a closed grow tent, with intensive light culture and control of the internal microclimate of the working area.Results. Among the six studied non-traditional legume species grown for microgreens, the most responsive to combined treatment with an organomineral complex was Onobrychis viciifolia. Trifolium rubens showed the worst result in terms of biomass. Analysis of changes in the profile distribution of essential elements in the resulting green biomass, carried out using inductively coupled plasma atomic emission spectroscopy (ICP-AES), revealed iron and zinc ions as potential targets associated with yield shortfalls in juvenile shoots. Since in global food systems these microelements are the most common nutrients noted for the manifestation of “hidden hunger”, especially among children under 5 years of age and women of childbearing age, when creating a nutritional biocomposition based on black soldier fly zoohumus for growing non-traditional types of legumes, further the emphasis should be on them. No significant differences were found in the number of macroelements.Results. The results of the study confirmed the high efficiency of using humic fertilizers in conditions of low soil fertility and revealed the selective sensitivity of vegetable crops to humic preparations of various origins.

Immunoanalytical Detection of Conserved Peptides: Refining the Universe of Biomarker Targets in Planetary Exploration.

Ancient peptides are remnants of early biochemistry that continue to play pivotal roles in current proteins. They are simple molecules yet complex enough to exhibit independent functions, being products of an evolved biochemistry at the interface of life and nonlife. Their adsorption to minerals may contribute to their stabilization and preservation over time. To investigate the feasibility of conserved peptide sequences and structures as target biomarkers for the search for life on Mars or other planetary bodies, we conducted a bioinformatics selection of well-conserved ancient peptides and produced polyclonal antibodies for their detection using fluorescence microarray immunoassays. Additionally, we explored how adsorbing peptides to Mars-representative minerals to form organomineral complexes could affect their immunological detection. The results demonstrated that the selected peptides exhibited autonomous folding, with some of them regaining their structure, even after denaturation. Furthermore, their cognate antibodies detected their conformational features regardless of amino acid sequences, thereby broadening the spectrum of target peptide sequences. While certain antibodies displayed unspecific binding to bare minerals, we validated that peptide-mineral complexes can be detected using sandwich immunoassays, as confirmed through desorption and competitive assays. Consequently, we conclude that the diversity of peptide sequences and structures suitable for use as target biomarkers in astrobiology can be constrained to a few well conserved sets, and they can be detected even if they are adsorbed in organomineral complexes.

Effects of long-term application of inorganic fertilizers and organic amendments on the turnover rates of fractionated soil organic carbon and their determining factors in paddy fields

ABSTRACT To investigate how the long-term application of inorganic fertilizer and organic amendments affects the turnover rates of organic matter in physico-chemically fractionated components in paddy soils and how their rates are related to their amounts, we studied the effect of variable management of inorganic fertilizer and organic amendments for > 50 years on the ∆14C values of accumulated soil organic carbon (SOC) in fractionated components of 5 soil samples from three paddy fields. SOC was fractionated into four components based on their physico-chemical properties: (1) light fraction (LF) derived from plant residues, (2) heavy fraction (HF) containing stable aggregates, (3) oxidizable fraction (OxF) and (4) non-oxidizable fraction (NOxF) forming organo-mineral complexes with fine-textured minerals. The ∆14C values were determined by accelerator mass spectrometry using graphitized samples. The ∆14C values of SOC in NOxF (from −305‰ to − 90.5‰) were much lower than those of HF (from −123‰ to − 3.7‰) and OxF (from −215‰ to 21.0‰). Lowest values for NOxF suggested slowest turnover rates as expected, and higher and comparable values for OxF and HF implied much faster turnover rates of SOC in OxF compared with upland soils. This could be one of the characteristics of SOC dynamics in paddy soils, probably reflecting repeated puddling of plow layer soils. ∆14C values in all the fractions increased in response to the application of inorganic fertilizer and organic amendments, suggesting faster turnover rate. Soils with clayey and weathered characteristics had the lowest ∆14C values, or slowest turnover rates among the study fields. The relationship between the ∆14C value and the amount of accumulated C for HF, OxF and NOxF indicated that the more the SOC accumulated, the faster the turnover rate of the SOC was, regardless of the fractions, and the relationship of the HF was considerably different from those of OxF and NOxF. In conclusion, these results can be the basis for understanding the C dynamics and for improving soil fertility status and soil C sequestration in paddy soils.

Effects of long-term application of inorganic fertilizer and organic amendments on the amounts of fractionated soil organic carbon and their determining factors in paddy fields

ABSTRACT To investigate how the long-term application of inorganic fertilizer and organic amendments affects the accumulation of organic matter in physico-chemically fractionated components in paddy soils and how the accumulation is determined by soil properties and anthropogenic carbon input, we studied the effect of variable management of inorganic fertilizer and organic amendments for > 50 years on the amounts of accumulated soil organic carbon (SOC) in fractionated components in three paddy fields. SOC was fractionated into four components based on their physical and chemical properties: (1) light fraction (LF) derived from plant residues, (2) heavy fraction (HF) containing stable aggregates, (3) oxidizable fraction (OxF) and (4) non-oxidizable fraction (NOxF) forming organo-mineral complexes with fine-textured minerals. On average, the amount and percentage of accumulated C in the four fractions were as follows: OxF (6.63 gC kg−1 soil, 46%) > NOxF (5.32, 35) > LF (1.68, 12) > HF (1.12, 7.2), suggesting about 80% of SOC was in fine, stable fractions. The amount of accumulated C in all fractions increased slightly with the application of inorganic fertilizer, while it increased considerably with the use of organic amendments. In addition, the application of fertilizers and amendments raised the proportion of C content in LF and HF, which are labile and related to soil fertility. Stepwise multiple regression analysis using two principal component analysis scores of soil properties and anthropogenic C input further revealed that the labile fractions (LF and HF) were more strongly determined by the management of fertilizers and amendments, while the stable fractions (OxF and NOxF) were more strongly determined by soil-specific properties, mainly the amorphous nature of the soil. These results indicate that the use of certain amounts of organic amendments would be recommended to carry out rational management to improve soil fertility and C sequestration in paddy fields, with the application of amorphous minerals as an additional option.

The ability of soils to aggregate, more than the state of aggregation, promotes protected soil organic matter formation

Efforts to increase soil organic carbon (SOC) are pursued as a viable climate change mitigation strategy. Boosting SOC stocks requires increasing plant carbon (C) inputs and promoting their persistence in SOC. In well aerated mineral soils, water soluble inputs are expected to stabilize through chemical binding to minerals, forming mineral-associated organic carbon (MAOC) before or after microbial transformation, while structural inputs are expected to stabilize as particulate organic carbon (POC) via protection in soil aggregates. Although ample research is centered on the effects of soil aggregation, its disturbance (e.g., tillage), and microbial processing on SOC cycling, we still lack mechanistic understanding of how plant C input type (i.e., soluble versus structural) and disturbance (i.e., aggregate disruption) independently and in interaction affect POC and MAOC formation and stabilization in soils with inherently different degrees of aggregation.To this end, using 13C enriched structural and soluble plant inputs, we traced SOC formation and stabilization in a lab incubation experiment in soils with differing levels of aggregation, and capacity to form aggregates after disturbance. Our results showed that soluble plant inputs contributed substantially to MAOC and that higher formation and persistence of MAOC occurred in the highly aggregated soil. Moreover, the highly aggregated soil retained more soluble inputs stabilized as MAOC when disturbed. Disturbance in this fine textured, organic carbon rich soil stimulated regeneration of aggregates around structural plant inputs leading to greater persistence of aggregate-occluded POC. Soluble plant inputs, specifically, as well as structural plant inputs in the highly aggregated disturbed soil, compensated for SOC lost due to disturbance alone.Overall, this study provides mechanistic evidence suggesting that management strategies for SOC accrual should consider soil type, aggregation potential, and plant attributes to inform decisions surrounding tillage frequency and cropping regimes. Our mechanistic findings require testing. If confirmed in the field, they would suggest that no disturbance in tandem with high structural plant C inputs would benefit most SOC accrual in systems with soils that have little capacity to form organo-mineral complexes, including large aggregates. On the contrary, with sustained plant inputs, occasional disturbance in systems with soils that have a high capacity to form organo-mineral complexes can promote both POC and MAOC formation and stabilization.

Structural forming of soil composites using as a pavement subgrade strengthening

The article substantiates the possibility of obtaining composite materials with improved functional properties to strengthen the subgrade, containing technogenic soil stabilized by an additive based on a gelling polymer. The introduction of technogenic soils into composites will not only reduce the consumption of expensive materials, but also solve a complex of acute environmental problems. Composite materials can be used in the construction of structural layers of road pavements, foundations of buildings and structures, sites for various purposes, for the prevention and elimination of defects in the foundations of engineering structures during their construction, reconstruction and repair, including in permafrost areas. Stabilized technogenic soils are more durable, frost-resistant and waterproof, which makes them applicable for creating impervious curtains in hydraulic structures and sealing storage facilities for hazardous substances. The cryogenic effect on a composite material allows one to vary its properties within a wide range and modify its macroporous structure. Studying the process of structure formation of the resulting organic-inorganic materials, consisting of macromolecules of high-molecular substances and inorganic inclusions that have undergone cryogenic treatment, will make it possible to specifically regulate their performance characteristics. The best values of strength characteristics were obtained for samples with a stabilizing additive concentration of 100 g/l. The resulting composite materials are hydrophobic, frost-resistant, characterized by a compressive strength of 2.3–6.5 MPa and a thermal conductivity of 0.19–0.20 W/(m·K). Data from differential scanning calorimetry and thermogravimetry and IR spectroscopy revealed that the binding of mineral particles by a stabilizing additive occurs due to the formation of organomineral complexes with the participation of clay minerals and the restructuring of hydration shells. SEM data indicate that crystallinity zones formed due to hydrogen bonds of hydroxyl groups of neighboring polymer chains can participate in the formation of the composite structure. An increase in the number of cryogenic treatment cycles promotes additional structuring and strengthening of the polymer phase due to the formation of additional nodes of the supramolecular network, ordering of crystallinity zones and the appearance of compacted areas in the structure. Computed X-ray tomography revealed an increase in the density of the composite upon drying, which helps to increase its strength characteristics. The structure of the sample is characterized by heterogeneity of the pore space, which is characterized by the presence of both fine-porous and large-porous regions, which determines its thermophysical properties.

ИЗМЕНЕНИЕ ЭЛЕМЕНТНОГО СОСТАВА МЫШЕЧНОЙ И КОСТНОЙ ТКАНИ БРОЙЛЕРОВ НА ФОНЕ СКАРМЛИВАНИЯ ИМ КОМПЛЕКСНОЙ ОРГАНОМИНЕРАЛЬНОЙ ДОБАВКИ

Due to the prohibition of the use of antibiotics in poultry feeding, its health and optimal level of productivity can be ensured through the use of alternative means, including prebiotics, organic acids and amino acids. Thus, the inclusion of an organo-mineral complex in the diet of broiler chickens can significantly improve their metabolic state, productivity and elemental composition of meat.

ПРИМЕНЕНИЕ ОРГАНОМИНЕРАЛЬНОГО КОМПЛЕКСА ГУМИТОН ПРИ ВОЗДЕЛЫВАНИИ ОВСА НА ДЕРНОВО-ПОДЗОЛИСТОЙ ПОЧВЕ

Based on the data of a field experiment on sod-podzolic sandy loam soil in the Kaluga Region, it was shown that the use of the organo-mineral complex Gumiton had a positive effect on the biometric indicators of growth and development of oat plants, yield and quality of vegetative mass. When oats were treated with Gumiton in the boot-up phase, the vegetative mass yield increased by 13 %, in the earing phase - by 46 %, and with a double treatment of plants in both these phases - by 48 %. A single treatment with Gumiton in the boot-up phase did not lead to an increase in grain yield, but increased the straw mass by 21.5 % in relation to the control; when treated in the earing phase of oats, the grain yield increased by 17 %, and the straw mass - 23.5 %. Treatment of crops with Gumiton in the oat boot phase contributed to an increase in the ash content in grain by 12 %, double treatment – by 18 %. The content of crude protein in grain did not change either with a single application of Gumiton in different phases of plant development or with double spraying. The fiber content in grain increased with the use of Gumiton in the boot phase of oats by 21.5, at the panicle stage – by 13, and with double treatment – by 31 %. Double spraying of oat crops with Gumiton led to a 17 % decrease in the fat content in the grain.

Effectiveness of new agromeliorations under barley cultivation in radionuclide soil contamination

Based on the results of three-year production tests, the effectiveness of new agromeliorants (PhosAgro NPK complex fertilizer and Gumiton organo-mineral complex) was evaluated when growing barley on radioactively contaminated sandy loam soddy-podzolic soils of Novozybkovsky district of Bryansk region. It is shown that non-root treatment of barley crops in the earing phase with Gumiton (1 l/ha) without the use of fertilizer contributed to an increase in grain yield by 17-29% relative to the control, depending on the year. The introduction of PhosAgro NPK fertilizer (0.3 t/ha) gave an increase in yield of 22-39%. The combined use of fertilizer and the drug increased the yield by 18-72%. The multiplicity of the decrease in the intake of 137Cs in grain during the treatment of crops with Gumiton was up to 2.3 times, with the combined use of the drug and fertilizer - up to 4.7 times compared with the control. The use of Gumiton and PhosAgro NPK guaranteed the production of grain with a content of 137Cs corresponding to the standards of Sanitary Rules and Regulations 2.3.2. 2650-10. The conditional net income per 1 ruble of costs for processing barley crops with Gumiton amounted to 3.75-17.6 rubles, depending on the year. Both the introduction of PhosAgro NPK and the treatment of barley crops with Gumiton did not significantly affect the grain quality indicators: the content of protein, ash, fat, fiber. Thus, it is shown that the organo-mineral complex Gumiton and complex fertilizer PhosAgro NPK are effective agromeliorants in barley cultivation technologies in conditions of radioactive contamination of soils.

The mechanism of organic matter accumulation in the archipelago marine sediments: Insights from the Middle Devonian Givetian mudstone with low TOC in the Youjiang Basin, South China

Despite the fact that the mean values of total organic carbon (TOC) content in the Luofu Formation are relatively low, at or below 1.0 wt%, it still has the potential to be a veritable source rock. To elucidate the influences of various paleogeographic factors on sedimentary environments, 25 samples from Well A on the slope and 32 samples from Well B in the basin centre were selected for study. The samples were analyzed by thin section microscopy and field emission-scanning electron microscopy, along with X-ray diffraction and geochemical analyses (TOC content, sulfur content, organic petrography, inorganic carbon isotope and major and trace elements) in order to understand variations in and controls on the mineralogy, lithofacies, depositional environments, as well as the organic matter accumulation mechanism. The results of our study indicate that mudstone of the Luofu Formation was deposited into 4 lithofacies groups, namely as the siliceous lithofacies, mixed lithofacies, argillaceous lithofacies and calcareous lithofacies. The siliceous lithofacies mudstone was developed in the deep-water columns, while the mixed lithofacies mudstone was deposited on shallow-water columns. The organic matter accumulation model of the Luofu Formation can be further divided into the following four stages, each with its own unique characteristics: (1) The organic matter accumulation was caused by the relatively high productivity and dysoxic basin bottom water columns; (2) The organo-mineral complexes may promote the organic matter accumulation to some extent; (3) The organic matter enrichment was facilitated by the dysoxic/anoxic conditions and relatively high productivity from the basin to the slope; (4) The organic matter was preserved at shortened exposure duration of oxic conditions on the slope. The correlations between various geochemical indicators (redox, paleoproductivity and terrestrial debris flux) and TOC content suggest that oxic water columns and low productivity are the main reasons for the widespread mudstone with low TOC. The organic-rich mudstone, as the target stratigraphic section for exploration, may be deposited in the basin bottom water columns away from upwelling and close to hydrothermal activity in stage 3.

Productivity and grain quality of winter bread wheat varieties in the irrigated zone of the Republic of Dagestan when using biological products

In the conditions of the Terek-Sulak lowland of the Republic of Dagestan, we studied the effect of biological products on productivity and grain quality of winter bread wheat varieties developed by the National Grain Center namedafter P.P. Lukyanenko and the North Caucasus Federal Scientific Agrarian Center in 2019–2022. An analytical review of the references indicates that the use of new varieties and biostimulants are important factors in improving productivity of grain crops, which ensure the profitability of their use at low costs. The trials were carried out on 5 winter bread wheat varieties with different application schemes of the organomineral complex ‘Biostim zernovoy’ in accordance with the B. A. Dospekhov’s field trial methodology. Weather conditions during the years of the trial were generally favorable. The spring-summer development of plants took place with slight differences in heat supply, with HTC fluctuations from 0.37 to 0.58. The purpose of the current study is to identify the adaptive potential of winter bread wheat plants and to establish the most optimal scheme for the use of biological products to increase the potential productivity of varieties. As a result of three years of study, there has been found that the productivity of crops depends not only on the variety, but also on the methods of using the biostimulant and their combinations. The maximum productivity has been provided by the variety ‘Karolina 5’ (6.44 t/ha), which was 0.87 t/ha larger than the control. The combination of pre-sowing seed soaking with potassium humate ‘Sufler’ and treatment of wheat crops with the biostimulant ‘Biostim zernovoy’ provided productivity increase on average for all varieties of 0.63 t/ha, and the largest for the variety ‘Karolina with 0.71 t/ha. Calculations of environmental adaptability parameters showed that the varieties ‘Karolina 5’ and ‘Alekseich’ are the most adapted ones to specific soil and climatic conditions and the level of technology used and, in this regard, can be used for zonation of winter wheat in the irrigated zone of the Republic.

Prospects for Application of Guanidine-Containing Organomineral Complexes as Biocidal Functional Additives for Waterborne Polymer Materials

Prospects for Application of Guanidine-Containing Organomineral Complexes as Biocidal Functional Additives for Waterborne Polymer Materials

Prospects for Application of Guanidine-Containing Organomineral Complexes as Biocidal Functional Additives for Waterborne Polymer Materials

The possibility of using organomineral complexes of polyhexamethylene guanidine hydrochloride as a functional additive for a waterborne paint based on polyvinyl acetate has been investigated. Organomineral complexes containing 20 and 30 wt % guanidine polymer have been obtained, with intercalation of polyguanidine chains into the interlayer space of montmorillonite being observed. It has been revealed that the stability of the polymer film to water is retained when organomineral complexes are introduced into a polyvinyl acetate dispersion, whereas the water resistance of the film sharply decreases when free polyguanidine is added. There was no significant influence of organomineral complexes on the rheological characteristics of the dispersion and its sedimentation stability. Testing of waterborne paints with various additives has shown that introduction of organomineral complexes into the material prevents the coating from fouling by biofilms of gram-positive bacteria Staphylococcus aureus and Rhodococcus erythropolis, with the hardness, water resistance, and water-vapor transmission of the coatings being retained at a satisfactory level.