Fulvic Acid Concentration Research Articles

Влияние препарата Юнигель Плантум на качество урожая листового салата

Greenhouse farming is an innovative model of agriculture that promotes sustainable production. Advanced greenhouse complexes use hydroponics, which makes it possible to grow vegetables and salads as far north as in Russia’s polar regions and on Sakhalin Island. To improve the yield and quality of lettuce, local farmers need an efficient mineral wool substrate and hydroponics. Biodegradable gels in combination with soil microorganisms are known to stabilize and prolong the effect of organic and mineral complexes. The research featured Aficion green lettuce grown hydroponically in a greenhouse. The control plants were grown in line with the industrial technology, which involved a four-fold weekly foliar treatment with a combination of Ecogel and Agrocen at 0.5 and 0.15%, respectively. The experimental samples were grown on substrate treated with Yunigel Plantum at 0.03 g per pot. The weight of lettuce leaves without roots was determined after cutting; their moisture content was determined after drying to a constant weight. The quality of leaf lettuce was assessed by the content of solids (State Standard GOST 31640-2012), crude protein (GOST 13496.4-2019), and amino acids (M 04-87-2009). The effect of Yunigel Plantum on quality and yield was evaluated by the ripening period, weight, root development, root hair development, moisture content, protein, and amino acids. The study also involved the effect of three different concentrations of humic and fulvic acids (Beres-8) to identify the optimal concentration. Yunigel Plantum_12 increased the yield and growth rate by 20%: as it boosted the root development, the experimental lettuce absorbed nutrients and became rich in essential amino acids. Yunigel Plantum can be recommended for greenhouse lettuce farming since it proved able to increase the yield and improve the nutr itional value of lettuce.

Impact of fulvic acids on lead adsorption and transport behavior in cationic surfactant modified bentonite-loess liners.

The high concentration of fulvic acid (FA) derived from natural matter in landfill leachates has generated increasing interest, as it plays a significant role in influencing the mobility of potentially toxic elements in landfill groundwater environments. This study examines the adsorption and transport behavior of FA on landfill unmodified and modified loess soil liners, analyzing key factors (initial concentration, organ-bentonite content, reaction time, and soil-water ratio) using a Box-Behnken design-based Response Surface Methodology (RSM-BBD). Additionally, the research objective includes evaluating the adsorption of lead (Pb2⁺), providing a comprehensive assessment of the soil liners' performance against both organic and inorganic contaminants. RSM-BBD analysis showed that the higher the hexadecyltrimethylammonium chloride-modified bentonite (HTMAC-B) content, the larger the adsorption capacity of the mixed soil for FA, which proved that FA was mainly adsorbed on the HTMAC-B. Loess + HTMAC-B exhibited the highest capacity, which can be 30.6 times that of loess. The presence of Pb2+ notably enhanced the adsorption capacity of FA on the loess with HTMAC-B mixture. However, the increase in HTMAC-B content resulted in a decrease in the equilibrium adsorption of FA in the FA-Pb2+ dual-contaminant system, mainly due to the reduction of adsorbed COO-Pb+ and (COO)2-Pb complexes. When the HTMAC-B content reached 20%, the breakthrough time of Pb2+ in the modified liner was shortened by 82%. The use of 5% content of HTMAC-B was identified as appropriate to achieve excellent retardation performance for multi-component pollutants such as organics, organic acids and potentially toxic elements. These insights contribute to understanding how geochemical mitigation of humic substances affects the mobility of potentially toxic elements, and from an engineering perspective, the alternative materials presented in this study may facilitate the construction of thinner liners that meet system requirements while exhibiting excellent adsorption performance for multi-component contaminants.

Compost with High Soil Conditioning Potential Obtained by Composting Using a Portable and Low-Cost System

A simple and functional home composting process was investigated. This study consisted of three experiments altering the proportion of manure and sawdust, the former used as a nutrient and the latter as a desiccant. The mass proportions of manure–sawdust added weekly to the composting process were 1:1, 1:3, and 3:1 in the compost bins. The food waste used was provided daily by the IECT/UFVJM restaurant and added in equal parts, approximately 32 kg, to each of the three compost bins for a period of approximately 120 days. The bacterium Bacillus subtilis from the soil’s natural microbiota was added every fortnight to the three compost bins in a fixed volume solution equivalent to 150 mL. In the composting process carried out in compost bin 2, the compost with the highest final yield on a wet basis was obtained, at 39.89%. However, the compost produced in compost bin 3 had the highest compostable organic matter content at 24.66%, only 4.86% of the organic matter resisted composting, and it also had the best organic carbon/nitrogen ratio, at 32/1. Furthermore, this most promising compost, produced in compost bin 3, showed fulvic acid, humic acid, and total humic extract contents of 5.21%, 5.21%, and 10.42%, respectively, with these values being three to four times greater than that required by national legislation. The micro- and macronutrient content is also adequate, and only the NPK value needs to be maximized in this compost product for immediate commercialization. In this sense, we encourage the sustainable production of compost via home composting in the system investigated here for use as a soil conditioner capable of significantly improving its properties for safe development in regenerative agriculture.

ОЦЕНКА БИОЛОГИЧЕСКОЙ ЭФФЕКТИВНОСТИ ГУМИНОВОГО СТИМУЛЯТОР РОСТА ПРИ ВОЗДЕЛЫВАНИИ СОИ

The research was conducted to determine the effectiveness of the use of a multifunctional humic growth stimulator potassium lignohumate brand "AM" with a high content of fulvic acids on soybean productivity in irrigated conditions. The work was carried out in 2021-2023 on a pilot irrigated area in the north of the Astrakhan region. The soil of the experimental area is light chestnut, brackish. The humus content in the arable layer was 0.9%, mobile phosphorus and potassium (according to Machigin) - 24.3 and 441.5 mg/kg of soil, respectively, the granulometric composition is medium loamy. The scheme of the field experiment included the following options: without treatment (control); potassium lignohumate of the AM variety in doses of 30, 50 and 70 g/ha. Over the years of research, the average daily air temperature ranged from +16.5 to +26.9 °C. July and August were quite hot, with maximum temperatures ranging from +34.1 to +38.7 °C. The relative humidity ranged from 41.6 to 47.7%. The average amount of precipitation during the growing season ranged from 12.0 to 22.7 mm. The soil temperature at a depth of 0.05 to 0.15 m ranged from 24.3 to 26.8 °C. The maximum number of grains per plant (138.3 pcs.), the mass of grains per plant (22.3 g) and the mass of 1000 seeds (212.3 g) were noted in the variant with a dose of 50 g/ha. Based on the results of a three-year study of productivity, variants with doses of 50 and 70 g/ha with a yield of 4.5 t/ha were identified.

Irrigation Promotes Arsenic Mobilization via Goethite: Insight from the Perspective of the Solid–Liquid Interface Interaction Process

Dramatic changes in the farmland soil–groundwater environment caused by irrigation affects the geochemical behavior of arsenic (As). However, the mechanism of As mobilization during soil–groundwater interactions remains unclear. This study explored the effects of phosphate (PO43−), fulvic acid (FA), and oxic/anoxic conditions on As mobilization through batch and column experiments. The results indicated that a saline–alkali environment and the involvement of PO43−/FA suppressed the adsorption capacity of goethite for As(III) in the water environment and that PO43− had a primary effect. An increase in the PO43−/FA concentration further increased its inhibition. Notably, oxic/anoxic conditions did not affect the adsorption capacity of goethite for TAs in the presence of high concentrations of PO43−/FA. In the soil environment, periodic irrigation led to regular fluctuations in the As content in the soil pore water. The addition of PO43− to irrigation water resulted in a higher content of As in the pore water in the short term. In contrast, the addition of FA greatly increased the long-term mobility of As. This study highlighted that irrigation amplifies As mobility in soil–groundwater systems, particularly in saline–alkali environments, and PO43−/FA addition exacerbates this effect, posing risks to agricultural safety. The systematic management of irrigation practices is recommended to mitigate these risks.

Эффективность применения гуминового удобрения с повышенным содержанием фульвокислот при возделывании сои на орошении в условиях Астраханской области

Введение. В статье приведены результаты по сравнительной оценке применения различных доз стимулятора роста при возделывании сои. Цель. Исследования проводили с целью определения эффективности применения многофункционального гуминового стимулятора роста Лигногумат калийный марки АМ с повышенным содержанием фульвокислот на урожайность сои в условиях орошения. Методы. Работу выполняли в 2021–2023 гг. на опытном орошаемом участке на севере Астраханской области. Почва опытного участка – светло-каштановая, подтип солонцеватая. Содержание гумуса в пахотном слое составляло 0,9 %, подвижного фосфора и калия (по Мачигину) – соответственно 24,3 и 441,5 мг/кг почвы, гранулометрический состав – среднесуглинистый. Схема полевого опыта: контроль (без обработки); Лигногумат калийный марки АМ, 30 г/га, 50 г/га и 70 г/га.Результаты. Анализ погодных условий определенно выявил, что вегетационный период проводимых исследований был чрезвычайно засушливым. Были выделены варианты расходующие меньшее количество воды на формирование товарной продукции - с нормой расхода 50 и 70 г/га. Коэффициент водопотребления составил в этих вариантах 625,8 м3/т, существенно отличаясь как от контроля, так и от варианта с меньшим расходом препарата. В результате исследования установлено, что максимальное количество зерен на 1 растение – 138,3 шт., масса зерен с 1 растения – 22,3 г., а массе 1000 зерен – 212,3 г. были получены в варианте с нормой расхода препарата 50,0 г/га. Выводы. Применение препарата Лигногумат калийный марки АМ в концентрации 50,0 г/га позволило получить урожайность сои 4,5 т/га за счёт улучшения структурных показателей урожая. Можно рекомендовать данный препарат в указанной норме применения для возделывания сои в условиях орошения для реализации генетического потенциала продуктивности сорта Волгоградка 1. Для цитирования: Тютюма Н.В., Бондаренко А.Н., Тютюма А.В. Эффективность применения гуминового удобрения с повышенным содержанием фульвокислот при возделывании сои на орошении в условиях Астраханской области. Аграрный вестник Северного Кавказа. 2025;15(1):60-68. https://doi.org/10.31279/2949-4796-2025-15-1-60-68 EDN COSMDW For citing: Tyutyuma N.V., Bondarenko A.N., Tyutyuma A.V. Effectiveness of Applying Humic Fertilizer with High Content of Fulvic Acids in Soybean Cultivation under Irrigation Conditions in the Astrakhan Region. Agrarian Bulletin of the North Caucasus. 2025;15(1):60-68. https://doi.org/10.31279/2949-4796-2025-15-1-60-68 EDN COSMDW

Soil Nutrient Dynamics under the Haritha Haram Ecosystem in Telangana State, India

Soil fertility plays a crucial role in sustaining ecosystem productivity and biodiversity. The “Telangana Ku Haritha Haram” afforestation program, initiated in 2015-16, aims to enhance green cover and improve soil health through large-scale tree planting. This study evaluates changes in soil nutrient dynamics across six Haritha Haram locations in Telangana between May 2023 and April 2024. Soil samples collected at a depth of 0-30 cm were analyzed for macronutrients (Nitrogen (N), Phosphorus (P), Potassium (K), micronutrients (Iron (Fe), Copper (Cu), Manganese (Mn), Zinc (Zn), Boron (B), Molybdenum (Mo), and organic matter components (Humic Acid and Fulvic Acid) using standard analytical methods. A significant increase in available nitrogen (252 to 284 kg ha⁻¹), phosphorus (41.5 to 44.1 kg ha⁻¹), and potassium (385 to 402 kg ha⁻¹) was observed. Micronutrient concentrations also increased. Additionally, humic and fulvic acid contents exhibited a slight increase. These changes are attributed to continuous organic matter accumulation from leaf litter and microbial decomposition, leading to enhanced nutrient availability. The findings highlight the positive impact of afforestation on soil fertility and emphasize the role of organic inputs in sustainable nutrient management within afforested ecosystems.

A Physicochemical and Biological Composite Environment for the Humification of Crop Straw in Compost

To examine the humification characteristics of crop residues, three types of crop residues—wheat, maize, and rice—were selected for experimentation. The latter two were subjected to steam explosion (SE) and nitrogen addition SE, respectively. Each of the three types of straw was inoculated in accordance with a specific microbial addition protocol. Furthermore, environmental controls, including the oxygen concentration and temperature type, were employed to enhance the variability of the samples. The results demonstrate statistically significant discrepancies in the concentrations of humic acid (HA) and fulvic acid (FA) between the three samples. Following a 96 h composting process, the highest concentrations of fulvic acid (FA) and humic acid (HA) in the samples were recorded at 10.4% and 15.8%, respectively. This result indicates the successful conversion of crop straw into a high-quality humic acid fertilizer product. Infrared spectroscopy data indicate that the breaking of carbon–carbon bonds and the ring opening, as well as the substitution of benzene rings, occurred during composting, and FA and HA substances were gradually formed. The results indicate that humus production is subject to raw materials, the pre-treatment of materials, the differentiation of strains, and methods of controlling environmental factors.

Effect of alkali on fulvic acid extracted from peat methane fermentation residue

To explore a new method of peat valorization and to promote the reuse of peat methane fermentation residue, the effects of extracted fulvic acid (FA) with different extractants and from peat methane fermentation residue were studied. With peat used as a raw material, biomethane fermentation was carried out first, extracting FA using alkaline dissolution and acid precipitation method, and then FA was extracted with NaOH, KOH, LiOH, and Na4P2O7 from peat methane fermentation residue. FA extracted by the chemical method (CM) and biomethane fermentation method (BFM) was calculated to the productivity with content. FA extracted by BFM has a lower productivity and a higher content. The productivity of FA obtained by BFM is lower than FA by CM, because part of FA was consumed through peat fermentation. And the productivity of FA extracted by BFM with KOH is as high as 7.11%. The content of FA extracted by the BFM method was higher than that by the CM method, and the content of FA extracted by LiOH was the highest (1.69%). The research results show that the extraction of FA by BFM has a certain reference for realizing the reuse of peat methane fermentation residue.

Humus formation as a process of plant residues transformation

The study aims to confirm the specificity of humic acids extracted from various substrates with different extractants, by applying mathematical models. Methods. The article analyses some classical methods used for isolating humic acids during the plant residues transformation; the methods were assessed by mathematical modeling. Such interdisciplinary approach, i.e. combining soil organic matter biochemistry and mathematical modeling, helped establishing an evidence base for humus specificity. Using up-to-date OriginPro software for data analysis and high-quality visualization, the study analyzes earlier published results of the experiments investigating the decomposition of plant residues as primary humus precursors. Model experiments examining the humification of plant residues (clover leaf biomass) were conducted under controlled conditions in sod-podzolic light loamy soil and quartz sand. Humic substances were extracted using distilled water and 0.1 M sodium pyrophosphate solution. Humus carbon content was determined by the wet combustion method with titrimetric determination. Results. The study provided experimental evidence of humic substances specificity, based on the differences in their extraction from soils by various extractants, and modeled mathematically. The nature of humus is discussed from the perspectives of soil biochemistry and mathematical modeling of plant residue transformation into specific humic compounds. It was shown that, in both soil and inert media, the early-stage dynamics of humic compound formation was well approximated by a simple linear trend. Moreover, the accumulation rates of humic and fulvic acids were nearly identical across environments. As the mass of the organic substrate decreased, the transformation process transitioned to a saturation phase. Conclusions. Experimental data revealed that the amount of humic acids formed during plant residues transformation depended on the mineralogical and chemical composition of the medium. It was demonstrated that using different extractants to extract humic substances from soil and inert media (quartz sand) not only supported the notion of the existence of specific humic compounds, but also highlights the distinct formation pathways of their individual groups. Notably, there was revealed a shared feature across environments, i.e. that the humic compounds formation during organic matter transformation was well approximated by a simple linear model. It was found that at early transformation stages the rates of increase in humic and fulvic acid content were almost identical in both soil and inert media.

Investigating the mechanism of auxin-mediated fulvic acid-regulated root growth in Oryza sativa through physiological and transcriptomic analyses.

As rice is one of the most crucial staple food sources worldwide, enhancing rice yield is paramount for ensuring global food security. Fulvic acid (FA), serving as a plant growth promoter and organic fertilizer, holds significant practical importance in studying its impact on rice root growth for improving rice yield and quality. This study investigated the effects of different concentrations of FA on the growth of rice seedlings. The results indicated that 0.05 g/L FA could promote the growth of rice seedlings, while 0.5 g/L FA inhibited root growth, reduced cell activity and enzyme activity in the root tips, and accumulated reactive oxygen species in root cells. To further elucidate the molecular mechanisms underlying these effects, we performed transcriptomic analysis and found that auxin (Aux) may be involved in the growth process mediated by FA. Furthermore, transcriptome heatmap analysis revealed a significant upregulation of the Aux/indoleacetic acid (Aux/IAA) gene family after FA treatment, suggesting that this gene family plays a crucial role in the impact of FA on root growth. Additionally, by detecting endogenous Aux content and adding exogenous Aux inhibitors, we confirmed the involvement of FA in rice seedling root growth as well as in the synthesis and transduction pathway of Aux.

Optimization of fulvic acids production from oil palm empty fruit bunches using microwave extractor

Fulvic acid (FA) derives from a non-renewable source, Shilajit, known as highly commercial values for its benefit for human health. Fulvic acid can also be extracted from materials such as coal, lignite, and peat. Extraction methods of FA generally use solid acids and bases, ion exchange chromatography, and their combinations. However, these methods cause corrosion, low purity, and environmental pollution. The FA extraction using organic solvents is common, but low yielded, and many organic solvents are toxic. Therefore, an effective way to separate organic solvents from FA must be determined. This research aims to extract the FA from renewable biomass, namely oil palm empty fruit bunches (OPEFB), using a microwave extractor combined with hydrogen peroxide. The advantage of using a microwave is its quick and efficient extraction process. Hydrogen peroxide is an environmentally friendly solvent that can be converted into water and oxygen. Fulvic acid extraction was optimized using expert design with the Response Surface Methodology method with optimization of four 4 factors (H2O2 concentration and volume, reaction time, and microwave power). The extracted FA was then characterized using FTIR, H-NMR, and Fluorescennce spectroscopy. The highest FA concentration namely 24.716%, was obtained using H2O2 at a concentration of 30.46% with a volume of 137.4139 mL, reaction time of 9.384 minutes, and microwave power of 351.39 W. Fourier-Transform Infrared Spectroscopy peaks at 3213 cm-1, 2935.47 cm-1, and 2825.13 cm-1 in the OPEFB-FA sample indicate existence of FA. The fluorescent emission intensity ratio between 450/500 nm wavelengths of OPEFB-FA was 0.719.

Fulvic acid removal from landfill contaminated groundwater by a permeable reactive barrier: From laboratory to field-scale analyses

Fulvic acid removal from landfill contaminated groundwater by a permeable reactive barrier: From laboratory to field-scale analyses

Humic Substances from Waste-Based Fertilizers for Improved Soil Fertility

This research explores how different organic waste transformation methods influence the production of humic substances (HSs) and their impact on soil quality. Using olive and orange wastes as substrates, the study compares vermicomposting, composting, and anaerobic digestion processes to determine which method produces the most humic-substance-rich products. The characterization of HSs in each product included analyses of total organic carbon (TOC), humic and fulvic acid content, humification rate, humification degree, and E4/E6 ratio, with HSs extracted using potassium hydroxide (KOH) and analyzed via Diffuse Reflectance Infrared Fourier-Transform (DRIFT) spectroscopy to assess structural complexity. The results revealed that the chemical composition of the input materials significantly influenced the transformation dynamics, with orange by-products exhibiting a higher humification rate and degree. Vermicomposting emerged as the most efficient process, producing fertilizers with superior humic content, greater microbial biodiversity, and enhanced cation exchange capacity, thus markedly improving soil quality. Composting also contributed to the stabilization of organic matter, albeit less effectively than vermicomposting. Anaerobic digestion, by contrast, resulted in products with lower levels of HSs and reduced nutrient content. Aerobic processes, particularly vermicomposting, demonstrated the most rapid and effective transformation, producing structurally complex, stable humus-like substances with pronounced benefits for soil health. These findings underscore vermicomposting as the most sustainable and efficacious approach for generating HS-rich organic fertilizers, presenting a powerful alternative to synthetic fertilizers. Furthermore, this study highlights the potential of organic waste valorization to mitigate environmental pollution and foster circular economy practices in sustainable agriculture.

Enhancing Oxygen-Dissolving Capacity of Rotary Drum Food Waste Composting: Tumbling Process Optimization and Experimental Validation with Discrete and Finite Element Methods

An optimized tumbling process can significantly improve the oxygen dissolving capacity of composting and fertilizer quality: by increasing the fluffiness of the lower layer of the pile, localized anaerobic fermentation can be avoided, thereby enhancing compost quality. This paper presents a method for improving the oxygen dissolving capacity of rotary drum food waste composting through a combination of simulation optimization and experimental validation. First, the discrete element method was used to optimize the key parameters of the tumbling process. The response surface method was then employed to analyze the composting test results and determine the optimal conditions. To ensure the reliability of the equipment under this method, failure risk analysis was conducted using the finite element method. The simulation optimization results showed that with a rotary drum reactor speed of 3.5 r/min, a horizontal angle of inclination of 2.5°, a mixing blade angle of inclination of 43°, and a blade pitch of 580 mm, the fluffiness of the lower layer of the pile increased by 8.515%, achieving the best tumbling and indirectly enhancing oxygen dissolving capacity. The maximum deformation of the load-bearing components was only 0.0548 mm, and the minimum safety factor was 4.408 (≥1 is considered safe). A 14-day composting experiment was conducted to validate the optimized parameters. The results showed that the maximum temperature of the compost pile reached 68.34 °C (lasting 7 days), with the pH, moisture content, C/N ratio, humus substances, humic acid, and fulvic acid contents of the fertilizer all meeting or exceeding the levels recommended by Chinese national standards. These findings indicate that the optimized tumbling device effectively improved the stability and dissolved oxygen efficiency of food waste composting, providing valuable practical insights and a research foundation for enhancing oxygen efficiency in the composting of other organic wastes.

The impact of reservoirs on the soils of adjacent areas: overview of global and local aspects

Abstract This study aims to analyze the impact of reservoirs on the soils of surrounding areas to elucidate potential ecological consequences. To achieve this goal, a territorial analysis of the soil surrounding such reservoirs as the Kyiv, Kaniv, Kremenchuk, and Kakhovka, which constitute the Dnieper Cascade of Reservoirs, was conducted. The study found that the average soil pH changes in reservoirs range from 6.0 to 7.5, while nitrogen and phosphorus content in the soil varies from 0.2% to 1.5% and from 0.1% to 0.5%, respectively. Average changes in the content of humic substances and fulvic acids in the reservoirs range from 1.0 to 3.5 and from 0.2 to 1.5 mg/L, respectively. Furthermore, it was found that the creation of large reservoirs on the Dnieper River is accompanied by significant consequences for shoreline soils. The geomorphological study of the reservoirs within the Dnieper Cascade revealed their diversity in terms of shoreline types. Some have more erodible shores, indicating vulnerability to erosion, as observed in the Kakhovka Reservoir, while others have more neutral shores less susceptible to erosion, such as the Kremenchuk Reservoir. The distribution of humic substances in the reservoirs of the Dnieper Cascade is determined by the hydrological structure and water inflows, with the highest concentrations in the upper regions. Decreased flow velocity in the lower part of the cascade leads to the deposition of humic substances in bottom sediments. The threat to ecological systems is exacerbated by incidents such as the catastrophe at the Kakhovka Hydroelectric Power Station in 2023, which triggered a serious ecological crisis with a wide range of consequences. Consequently, the application of a comprehensive approach to water resource management and environmental protection becomes crucial. This entails meticulous planning of construction, implementation of ecological technologies, and engaging the public in the water resource management process.

Shelterbelts as a factor of soil formation in agrolandscapes of the southern part of the central Russian upland

The study aimed to identify the impact of shelterbelts on cultivated soils at three key sites in the forest-steppe zone of the southern part of the Central Russian Uplands. Automorphic chernozems were studied under 30 m wide longitudinally oriented broad-leaved shelterbelts; their plowed analogues – near the shelterbelts. The research was carried out in the area with heavy loamy and clayey typical chernozems. Over 60 years of shelterbelt growth, significant changes in the morphological, physical, and chemical properties of chernozems have occurred. Field soil moisture was analyzed during two growing seasons (2020–2021) showing that soils in the fields are moister to the west of the shelterbelts than to the east, primarily due to the western transport of air masses in the warm season. Compared to arable soils, those under shelterbelts demonstrated greater depth of the humus-accumulative part of the profiles (on average by 13 cm), signs of clay illuviation in the B horizons (glossy films and thin cutans), and fragmentary lightening of the middle and lower parts of the humus layer in the form of a weak skeleton deposit. There is a radial outflow of carbonates in soils under shelterbelts, compared to arable analogues. Three-meter deep soil profile contains on average 40–50 t/ha less carbonate carbon than the arable soils. These differences indicate an evolutionary transformation of soils under shelterbelts from typical chernozems to leached chernozems. Higher stocks of organic carbon have been recorded in the three-meter profiles of shelterbelt soils (on average by 27 t/ha) compared to arable soils. The composition of humus in chernozems under shelterbelts undergoes significant transformation towards a forest type: the content of fulvic acid increases in the 0–20 cm layer, and deeper layers show a maximum accumulation of humic acids, while the chernozem type of its vertical distribution remains characteristic of soils on arable lands. Lateral transfer of several substances (particularly phosphorus) from arable land towards shelterbelts soils has been established due to the desuction activity of tree root systems. Thus, shelterbelts activate a complex of autochthonous and allochthonous phenomena in soil cover, resulting in an obvious transformation of soils over a 60-year period.

Alleviative Effect of Exogenous Application of Fulvic Acid on Nitrate Stress in Spinach (Spinacia oleracea L.)

Salt stress could be a significant factor limiting the growth and development of vegetables. In this study, Fulvic Acid (FA) (0.05%, 0.1%, 0.15%, 0.2%, and 0.25%) was applied under nitrate stress (150 mM), with normal Hoagland nutrient solution as a control to investigate the influence of foliar spray FA on spinach growth, photosynthesis, and oxidative stress under nitrate stress. The results showed that nitrate stress significantly inhibited spinach growth, while ROS (reactive oxygen species) accumulation caused photosystem damage, which reduced photosynthetic capacity. Different concentrations of FA alleviated the damage caused by nitrate stress in spinach to varying degrees in a concentration-dependent manner. The F3 treatment (0.15% FA + 150 mM NO3−) exhibited the most significant mitigating effect. FA application promoted the accumulation of biomass in spinach under nitrate stress and increased chlorophyll content, the net photosynthetic rate, the maximum photochemical quantum yield of PSII (Photosystem II) (Fv/Fm), the quantum efficiency of PSII photochemistry [Y(II)], the electron transport rate, and the overall functional activity index of the electron transport chain between the PSII and PSI systems (PItotal); moreover, FA decreased PSII excitation pressure (1 − qP), quantum yields of regulated energy dissipation of PSII [Y(NPQ)], and the relative variable initial slope of fluorescence. FA application increased superoxide dismutase, peroxidase, and catalase activities and decreased malondialdehyde, H2O2, and O2− levels in spinach under nitrate stress. FA can enhance plant resistance to nitrate by accelerating the utilization of light energy in spinach to mitigate excess light energy and ROS-induced photosystem damage and increase photosynthetic efficiency.

Adsorption of Se(IV) on kaolinite and montmorillonite in the presence of fulvic acid

Adsorption of Se(IV) on kaolinite and montmorillonite in the presence of fulvic acid

Beyond the surface: microbiological and biochemical attributes as indicators of soil quality in Atlantic Forest ecosystem

Beyond the surface: microbiological and biochemical attributes as indicators of soil quality in Atlantic Forest ecosystem