Search Results (185)

This study evaluated the effects of different types and rates of locally produced organic residues on soil organic matter (SOM) and soil health in highly degraded loamy soils of olive orchards in arid southern Tunisia. Three residues were tested: poultry manure, raw date palm waste, and composted date palm waste mixed with manure. A randomised field trial was conducted over three years. Two years after application, soil samples were analysed for physical and chemical properties, basal respiration, nitrogen mineralisation, microbial biomass, enzyme activities (dehydrogenase, phosphomonoesterase, β-glucosidase, urease, arylsulphatase), and community-level physiological profiles. All residues increased SOM and available phosphorus (Pi), with dose-dependent effects sustained over time, though significant increases were only observed at the highest application rates. The most notable improvements occurred in soils amended with composted date palm waste. In contrast, biological and biochemical parameters showed little response, even after remoistening to stimulate microbial activity. This limited response was attributed to the absence of vegetation and, consequently, of root exudates and plant residues. This will be further investigated by assessing changes in the same biological and biochemical properties following the implementation of an intercropping system, which is expected to enhance both SOM content and microbial activity in these soils. Full article

Biological nitrogen (N) fixation is an ecological method used to provide nutrition for crops and reduce fertilizer application in terrestrial ecosystems. Silver nanoparticles (AgNPs) are becoming environmental contaminants, and, thus, could negatively affect the activity and diversity of soil diazotrophs. To test this, a greenhouse pot experiment for growing maize was performed under different concentrations of AgNPs (0, 1, 5, 10, 20 mg kg⁻¹). We measured the N₂-fixation activity and abundance of nifH gene encoding the nitrogenase reductase subunit and analyzed the diversity, composition and co-occurrence networks of diazotrophic communities in maize rhizospheric soil. Results showed that a lower dose of AgNPs did not show significant influence on soil diazotrophs, while a higher dose of AgNPs decreased both soil N₂-fixation activity and nifH gene abundance, though diazotrophic diversity remained unchanged. AgNPs at 10 mg kg⁻¹ and 20 mg kg⁻¹ strongly shifted the community composition of diazotrophs, increasing the proportions of Bradyrhizobium and Paenibacillus, while decreasing Azospirillum and Rhizobium. Network analysis revealed weakened negative associations among species under AgNPs, with keystone taxa shifting from Bradyrhizobium, Geobacter, Azospirillum and Burkholderia to Bradyrhizobium, Paenibacillus and Skermanella under AgNPs. Soil-soluble Ag, dissolved organic carbon and soil pH were identified as the factors most closely driving the diazotrophic community composition. In conclusion, higher doses of AgNPs could inhibit N₂-fixation activity and shape the diazotrophic communities. These findings provide empirical evidence of AgNPs’ ecological impacts on soil microbial functions. Full article

Although drunken horse grass (Achnatherum inebrians) can be simultaneously infected by the foliar endophyte Epichloë gansuensis and colonized by Bacillus subtilis, it remains unclear whether Epichloë endophyte symbiosis influences B. subtilis colonization, as well as how their interaction affects nitrogen fixation and assimilation. The purpose of the present study was to investigate whether E. gansuensis endophyte infection facilitates the colonization of B. subtilis in the roots of host plants, with a focus on understanding the interaction effects of the E. gansuensis endophyte and B. subtilis on plant growth and nutrient absorption. In this study, we measured the colony growth rate of B. subtilis LZU7 when co-cultured with E. gansuensis strains. In addition to an in vitro test, we investigated the root colonization of Epichloë endophyte-infected plants (E+) and Epichloë endophyte-free plants (E−) with the GFP-tagged B. subtilis LZU7 in an inoculation test. Furthermore, we evaluated the interactions between E. gansuensis endophyte symbiosis and B. subtilis LZU7 colonization on the dry weight, nitrogen fixation, nitrogen converting-enzyme activity, and nutrients for E+ and E− plants by labeling with ¹⁵N₂. The results showed that the growth rates of B. subtilis LZU7 were altered and increased in a co-culture with the E. gansuensis endophyte. A significantly greater colonization of GFP-tagged B. subtilis LZU7 was detected in the roots of E+ plants compared with the roots of E− plants, suggesting that E. gansuensis endophyte symbiosis enhances the colonization of beneficial microorganisms. The combination of E. gansuensis endophyte symbiosis and B. subtilis LZU7 inoculation significantly altered the expression of the nitrogenase (nifH) gene, thereby promoting increased biological nitrogen fixation (BNF). The E. gansuensis endophyte infection and inoculation with B. subtilis LZU7 significantly increased δ15NAir in plants. Co-inoculation with the E. gansuensis endophyte and B. subtilis LZU7 significantly elevated NH₄⁺ accumulation in the roots, depleted the NH₄⁺ availability in the surrounding soil, and showed no measurable impact on the foliar NH₄⁺ content. The observed alterations in the NH₄⁺ content were linked to nitrogen-fixing microorganisms that promoted nitrogen fixation, thereby enhancing nitrogen uptake and contributing to greater biomass production in A. inebrians. Our findings highlighted the fact that a foliar symbiosis with the E. gansuensis endophyte enhances the recruitment of beneficial bacteria, and that the resulting interaction significantly impacts nitrogen fixation, assimilation, and allocation in host plants. Full article

Soil health is an important concept in promoting sustainable agriculture and food security, yet the absence of universally accepted benchmarks limits its utility in assessing soil function. This study explored the use of Conservation Reserve Program (CRP) soils as a potential benchmark to quantify the soil health gap (SHG) in Faribault County, Minnesota. Using the Soil Management Assessment Framework (SMAF), we evaluated physical, chemical, biological, and nutrient soil health indicators to derive a combined overall score that was used to quantify the SHG (i.e., benchmark soil minus test soil) between CRP and corn-based agricultural production (AP). Three paired farms were assessed, each consisting of CRP tall grass prairie established in 2001 and adjacent long-term AP. The results showed higher overall SMAF scores in CRP soils, with a mean SHG of 0.09. Land use had a strong influence on overall scores, largely driven by biological indicators such as soil organic carbon, microbial biomass carbon, and β-glucosidase activity. However, the SMAF demonstrated limited applicability in CRP systems, potentially under-representing their soil health status due to the SMAF’s agricultural emphasis and lack of ecosystem-specific factors such as pH. Full article

Although the broad-spectrum pesticide chlorpyrifos (CP) was banned in many developed countries, it is still widely used in developing countries. Its residues persist in the environment for unpredictable times. CP is toxic to various non-target organisms and humans and inhibits soil enzyme activity and bacterial and fungal abundance. This paper aimed to evaluate the effect of vermiremediation on soil chlorpyrifos content and soil fertility. The application of Eisenia fetida or vermicompost was studied in terms of soil chlorpyrifos concentration, microbial biomass content, and enzymatic activities in a 120-day trial. Pesticide application rates were 0, 25, and 50 ppm. The CP did not affect the earthworm survival rate at the tested doses. The earthworms markedly increased microbial biomass carbon and the activity of β-glucosamminidase, while the vermicompost had a noticeably positive effect mainly on alkaline phosphatase activity. Finally, although the vermiremediation techniques studied did not perform a bioremediation activity, they proved effective in improving the biological fertility of the soil in the presence of high concentrations of chlorpyrifos. Full article

Understanding soil properties that govern physicochemical and biological processes is essential for achieving high crop quality and yield. Organic matter is an important element of soil fertility and fertility in vegetable cultivation. In the process of decomposition of organic matter in the soil, humus of various quality is formed. The quality of humus depends on the content of individual acids (fulvic, humic and hymatomalanic acids) in it, which can affect the binding–chelation of heavy metals, limiting their availability to plants. The conducted studies determined the effect of adding organic matter (high peat, brown coal and wheat straw) to mineral soil on nickel detoxification in radish, its yield, nitrogen management and chloroplast pigments. The studies were conducted for three years in a greenhouse in a container system. The tested substrates were contaminated with nickel in the amount of 50, 75 and 100 mg dm⁻³. It was found that introducing organic matter into mineral soil can affect the reduction as well as the increase in nickel content in edible parts of radish. The type of organic material introduced into mineral soil as a source of organic matter has a significant impact on nickel content in radish. It was shown that nitrate reductase activity (NR) depends to a large extent on the substrate in which the plants are grown as well as on the applied dose of nickel. A similar relationship was demonstrated in the case of changes in the level of chloroplast pigments (chlorophyll a, chlorophyll b and carotenoids). Full article

Background/Objectives: Timbe (Acaciella angustissima) is a legume recognized for its environmental benefits, such as soil restoration, wildlife nutrition, and the presence of biologically active compounds. This study investigates the antioxidant, pharmacological, and antimicrobial properties of Timbe. Methods: The total phenolic content, flavonoids, and condensed tannins from Timbe flowers, seeds, and pods were quantified, and their antioxidant activity was evaluated using the DPPH and ABTS assays. Enzymatic activities were assessed through α-amylase, α-glucosidase, and ACE-I inhibition, and antimicrobial properties were tested against various bacterial strains. Results: The pods and flowers exhibited higher antioxidant capacities compared to seeds, effectively neutralizing free radicals. Flavonoids and condensed tannins showed positive correlations with antioxidant activity and the inhibition of α-amylase and α-glucosidase, suggesting the potential benefits of these metabolites in blood glucose control. Timbe also demonstrated ACE-I inhibition, particularly the flowers. Regarding antimicrobial activity, the pods displayed moderate inhibition against E. coli, K. pneumoniae, and S. aureus. Conclusions: The results indicate that different parts of Timbe (flowers, seeds, and pods) possess significant therapeutic potential for preventing and treating metabolic disorders and bacterial infections. Full article

Considering the global competition to increase food productivity due to the increasing population growth, the use of chemical pesticides has become the quick solution, but by increasing awareness about the serious dangers of wasteful chemicals in various areas of life, it has become necessary to move immediately, albeit gradually, towards safe biological treatments. From this point of view, the use of biochar is one of the trends in reducing soil pollution with chemical pesticides. Therefore, the main objectives of this work are (i) to assess if the application of three pesticides based on imidacloprid, methyl thiophanate, and glyphosate has detectable adverse consequences on soil organisms’ activity and (ii) to evaluate if the addition of biochar modifies the effects of these chemicals. An agricultural soil was amended with different doses of biochar. The treated soil received realistic amounts of currently used pesticides. Samples were stored at 21 °C and 50% WHC (water holding capacity) for a period of 28 days under dark conditions. Oxygen consumption was measured for 12 consecutive hours after the addition of 2.5 g glucose kg⁻¹ as a stimulant for soil organisms. Biomass C was estimated from the difference between the amount of C in 0.5 M K₂SO₄ extracts of CHCl₃ fumigated soil and the extractable C in non-fumigated samples. Specific respiration was computed as the amount of O₂ consumed per unit of Biomass Carbon. The results of this work proved that the tested biochar could modulate the effects produced by the agrochemicals on soil biomass. Full article

Chloroderivatives of phenoxyacetic acid are a group of compounds commonly used as plant protection products. Differences in the molecular structure of these compounds are related to varying substitution and the number of chlorine atoms in the aromatic ring. Different molecular structures may affect the activity of these compounds, their physicochemical properties, as well as their toxicity and biological effects. A group of 6 chemical compounds derived from phenoxyacetic acid was tested. The molecular structure was analysed using spectroscopic methods (FTIR, FTRaman, UV-VIS, ¹HNMR, ¹³CNMR) and quantum chemical computational methods (DFT). The reactivity of the tested compounds was determined using DFT calculations and experimentally in reaction with a hydroxyl radical. The electronic charge distribution of NBO, CHelpG and ESP was analysed and aromaticity indices were calculated for theoretically modeled structures and structures examined by X-ray diffraction (data obtained from the CSD database). Phenoxyacetic acid derivatives were tested for antimicrobial activity on soil bacterial strains. Cytotoxicity tests were performed on normal human skin fibroblasts (BJ CRL-2522) and the human prostate cancer cell line (DU-145 HTB-81). The purpose of this study was to investigate the relationship between the molecular structure of phenoxyacetic acid derivatives and their reactivity and biological activity. Full article

Monilinia spp., which causes brown rot, is one of the most damaging pathogens in stone fruits. Researchers are exploring epiphytic and endophytic microorganisms with the potential to suppress pathogens, control pathogenic microorganisms, and/or promote plant growth. In this study, microorganisms with antagonistic activity against three Monilinia species were isolated from plum orchard soil and plum fruits. Antagonism tests in vitro showed strong antagonistic properties of six strains of bacteria and two yeast-like fungi against M. fructigena, M. fructicola, and M. laxa, with growth inhibition from 45.5 to 84.6%. The antagonists were identified and characterized at the genetic level using whole genome sequencing (WGS). Genes involved in antibiotic resistance, virulence, secondary metabolite synthesis, and plant growth promotion were identified and characterized through genome mapping, gene prediction, and annotation. None of the microorganisms studied were predicted to be pathogenic to humans. The results of this study indicate that the bacteria Bacillus pumilus, B. velezensis, two strains of Lysinibacillus agricola, Pseudomonas chlororaphis isolated from stone fruit orchard soil, and the yeast-like fungus Aureobasidium pullulans, isolated from plums, are promising candidates for the biological control of Monilinia spp. Full article

Mushrooms play an important role in ecosystem sustainability and are highly valued in medicine and human nutrition. Using AAS and biochemical methods of analysis, the antioxidant status and mineral composition of seven mushroom species (Armillaria mellea, Xeromocus illudens, Leccinum aurantiacum, Leccinum scrabum, Lactarium pubescens, Rusula vesca, and Lycoperpon molle Pers.) gathered near the Pechenganikel smelting plant in the Pasvik Nature Reserve of the Murmansk region were evaluated. The concentrations of Ni and Cu in the fruiting bodies of mushrooms were in the ranges of 0.43–39.7 and 7.9–45.9 mg kg⁻¹ d.w., respectively. An unusually high biological concentration factor (BCF) for Ni, Cu, and Zn levels in mushrooms grown in soils with a low amount of these elements indicates the low suitability of the mentioned parameter for mushroom characteristics in territories with an uneven distribution of elements in soil. On the other hand, selenium (Se) showed high BCF levels, exceeding 1, for all mushrooms tested, with the highest values associated with L. saccatum (5.17) and the lowest values with A. mellea (1.36). A significant excess (3.4) of the Recommended Daily Allowance (RDA) level per 30 g of dry mushrooms was recorded for Ni in Russula vesca gathered 6 km from the Ni/Cu smelting plant, and 1.3 excess of the RDA was recorded in L. scrabum grown in the vicinity of the Shuonyoka waterfall. No RDA excess was revealed for Cu. Positive correlations between Se, polyphenol content, and total antioxidant activity (AOA) (r = 0.915–0.926; p < 0.001) and a negative correlation between Cu–Se and Cu–AOA in Leccinum species indicate the important role of antioxidant defense and Se, particularly in Arctic mushroom growth and survival, providing a specific protection of mushrooms against Cu toxicity. Full article

Global challenges such as soil degradation and water scarcity necessitate sustainable agricultural practices, particularly in regions where saline water is increasingly used for irrigation. This study investigates the effects of four compost treatments, including surface-applied mulch compost (MC), Johnson–Su biologically active compost incorporated into soil (JCI), mulch compost incorporated into soil (MCI), and no compost as control (NC), on soil fertility, microbial activity, and Capsicum annuum (chili pepper) growth. Greenhouse experiments were conducted using soil from two different sites (New Mexico State University’s (NMSU) agricultural research plots and agricultural field-testing site at the Brackish Groundwater National Desalination Research Facility (BGNDRF) in Alamogordo, New Mexico) and two irrigation water salinities (brackish at ~3000 µS/cm and agricultural at ~800 µS/cm). The Johnson–Su compost treatment demonstrated superior performance, due to its high soil organic matter (41.5%), nitrate (NO₃⁻) content (82.5 mg/kg), and phosphorus availability (193.1 mg/kg). In the JCI-treated soils, microbial biomass increased by 40%, and total microbial carbon reached 64.69 g/m² as compared to 64.7 g/m² in the NC. Plant growth parameters, including chlorophyll content, root length, and wet biomass, improved substantially with JCI. For instance, JCI increased plant height by 20% and wet biomass by 30% compared to NC treatments. The JCI treatment also effectively mitigated soil salinity, reducing Na⁺ accumulation by 60% and Cl⁻ by 70% while enhancing water retention and soil structure. Principal Component Analysis (PCA) revealed a distinct clustering of JCI treatments, demonstrating its ability to increase nutrient retention and minimize salinity stress. These results indicate that biologically active properties, such as fungi-rich compost, are critical to providing an effective, environmentally resilient approach for enhancing soil fertility and supporting sustainable crop production under brackish groundwater irrigation, particularly in regions facing freshwater scarcity. Full article

The widespread worldwide use of antibiotics leads to significant diffuse pollution of the environment, but the understanding of the effects of many important antibiotics on plants is still limited. This study aimed to gain insight into the impact of ampicillin (AMP) and ciprofloxacin (CIP) on the bioactive compounds, antioxidant capacity, and elemental content of lettuce (Lactuca sativa L.). The lettuce was grown in a climate chamber under controlled conditions of light and temperature, in soil with contaminated antibiotics of different concentrations (7.5 mg kg⁻¹—AMP I; 15 mg kg⁻¹—AMP II; 30 mg kg⁻¹—AMP III; 5 mg kg⁻¹—CIP I; 10 mg kg⁻¹—CIP II; and 20 mg kg⁻¹—CIP III). The results obtained for the plants grown in the presence of antibiotics were compared with the control plants. Changing the growth conditions influenced the composition of the biologically active compounds and the content of elements selected in this study. Thus, it was observed that the plants grown with antibiotics exhibited a double increase in polyphenolic content, especially at higher treatment levels, but also a significant decrease in assimilatory pigments (up to 70.19%), 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical-bleaching activity (up to 83.80%), and elemental contents compared to the control plants. Multivariate analysis was used to gain insight into similarities and differences between treatments and the association of the tested variables following the applied treatments, indicating a coping mechanism of the plants against the antibiotic treatments. Full article

Biological control is considered one of the most important methods for preventing and controlling the worldwide fungal disease gray mold, caused by Botrytis cinerea. Among the various agents used in biological control, actinomycetes represent a significant group of microorganisms that offer valuable resources for biocontrol strategies. In this study, a total of 132 actinomycetes, belonging to four genera (Streptomyces, Kitasatospora, Amycolatopsis, and Nocardia), were isolated from soil. Among the five media tested, ISP-2 and GS NO.1 media were found to be highly suitable for isolating actinomycetes. It is worth mentioning that the strain TCS21-117 displayed significant inhibitory effects against Botrytis cinerea and nine other pathogenic fungi. The strain TCS21-117 was identified as Streptomyces roietensis by its morphological characteristics and phylogenetic analysis of the 16S rRNA gene. The optimum culture conditions for the strain TCS21-117 were a potato dextrose broth medium at an initial pH of 8.0, a liquid volume of 125 mL in a 250 mL flask, 180 r·min⁻¹ at 28 °C, and an inoculum size of 1% for 7 days. Under these conditions, the inhibition rate against Botrytis cinerea was 93.31%, a significant increase (31.98%) as compared to the control. Notably, the antifungal compounds produced by the strain TCS21-117 exhibited strong stability across a range of temperatures, pH levels, and durations of storage and UV irradiation. This study showed that the Streptomyces roietensis strain TCS21-117 had strong inhibitory activity against Botrytis cinerea under optimized fermentation conditions, enriching the microbial resources for gray mold control. Full article

Land use change is associated with both higher fossil fuel usage and global cement production, significantly impacting environmental sustainability. Cement dust emission is the third-largest source of anthropogenic CO₂ emissions, right behind fossil fuel usage due to intense agricultural practices like aggressive tillage management. This study’s aim is to determine cement dust emissions impacts on various tillage management methods and the formation of cement dust-affected CO₂ emissions, soil pH, soil organic matter content, total nitrogen content, available phosphorus, CaCO₃ content, bacteria and fungi populations, and enzyme activities. The target of this study is to evaluate how cement dust emissions impact the soil properties and sustainability of different tillage practices. Composite soils from wheat–sugar beet (potato)–fallow cropping sequences under conventional tillage (CT) and no-till (NT) management were collected (0–30 cm depth) with three replications at varying distances from a cement factory (1, 2, 4, 6, 8, and 10 km). To find differences among individual treatments and distances, a two-way ANOVA was employed along with Duncan’s LSD test comparing the various effects of tillage techniques. The associations between soil chemical and biological properties and CO₂ fluxes under the impact of cement dust were examined using Pearson’s correlation analysis. There were notable relationships between soil microbial population, enzyme activities, pH, CaCO₃, and CO₂ fluxes. The sampling distance from the cement plant had a substantial correlation with soil organic carbon, urease activity, pH, CaCO₃, and bacterial populations. According to the study, different tillage methods (CT and NT) affected the diversity and abundance of microorganisms within the soil ecosystem. CT was more beneficial for the microbial population and for sustainable management. Full article