Search Results (99)

This study is one of the first comprehensive assessments of soil carbon dynamics on the Black Sea coast of Russia, focusing on the role of soils in the terrestrial carbon cycle and the greenhouse gas balance of sub-Mediterranean ecosystems. Our integrated approach combined soil classification with the analysis of the distribution of organic and inorganic carbon, as well as the measurement of microbial biomass and respiration. Soil respiration components, including substrate-induced respiration (SIR) and basal respiration (BR), as well as greenhouse gas (carbon dioxide (CO₂) and methane (CH₄)) dynamics, were evaluated using a combination of laboratory and field measurements. Our results revealed significant differences between natural Rendzic Leptosols and terraced Skeletic Rendzic Leptosols (Technic and Transportic types). The latter contained higher organic carbon stocks (up to 25 kg m⁻²) associated with buried humus horizons, whereas the former were dominated by inorganic carbon accumulation. Microbial biomass carbon (MBC) ranged from 113 to 1119 µg C g⁻¹ of soil and decreased with depth. Basal respiration averaged 0.39 ± 0.30 µg C–CO₂ g⁻¹ h⁻¹. CO₂ emissions were strongly correlated with soil temperature (r = 0.65, p < 0.05) and negatively correlated with soil moisture, reflecting the predominant influence of abiotic factors. Seasonal chamber observations confirmed that these soils consistently function as CH₄ sinks, with negative CH₄ fluxes recorded across all seasons. Thus, Rendzic Leptosols on the Black Sea coast serve as significant CO₂ sources and stable CH₄ sinks simultaneously, and anthropogenic terracing enhances their potential for organic carbon sequestration. These findings refine our understanding of the carbon balance in sub-Mediterranean forest soils and highlight their dual role in greenhouse gas dynamics under changing climate conditions. Full article

To ensure the quality and efficient access of the population to plant-derived resources, research on the sustainable cultivation of medicinal species is of great importance, and the present study aimed to evaluate the influence of poultry litter-based organic fertilization and seasonality on plant growth, soil health (quality), and secondary metabolism of Cuphea carthagenensis. Plants were cultivated during the summer and autumn/winter seasons in a randomized design with five poultry litter application rates (0, 10, 20, 30, and 40 t ha⁻¹) and three replications per plot field (1 × 2 m). The parameters evaluated included soil health, plant biomass, nutrient content, extract yield from the aerial parts, and chemical composition. In the summer, soil bioindicators (microbial biomass carbon and basal respiration) increased with the addition of poultry litter, although plant biomass was not affected by the season. Plant nutrient levels, particularly N and P, increased under poultry litter application rates of 30 t ha⁻¹ and higher. Under these conditions, the highest extract yield from the aerial parts was obtained at a rate of 40 t ha⁻¹. During autumn/winter, poultry litter increased significantly soil microbial biomass carbon, plant biomass, and N and P contents, resulting in an 11.07% increase in extract yield at a rate of 20 t ha⁻¹. Phytochemical analysis of the extracts identified 29 compounds, predominantly quercetin derivatives. Overall, the findings demonstrate that the sustainable cultivation of C. carthagenensis under organic fertilization enhances soil health, plant biomass, and extract yield. These findings highlight the potential of organic nutrient management as a promising strategy for advancing sustainable medicinal plant production and meeting societal demands for natural bioactive resources. Full article

The diversification of cover crops grown in soils with granulometric variability may potentially enhance microbial community and enzyme activities. Thus, the main goal was to evaluate the effect of autumn/winter cover crop sequences and cash crops in spring/summer on soil microbial biomass and enzyme activities. The experiment was conducted in open-field microplots (10 m × 1 m × 0.7 m), containing soils from B horizon of five Oxisols with granulometric variability and clay content ranging from 17 to 80 dag kg⁻¹. The treatments were three cover crops and a winter fallow with a completely randomized experimental design with three replicates. Soil samples from the 0–10 cm layer were collected to analyze soil microbial biomass of carbon and nitrogen, enzyme activities of the acid phosphatase, arylsulfatase, urease, and fluorescein diacetate hydrolysis. The number of nodules in soybean roots was average 63 ± 14.42 nodules per plant and dry mass of nodules was 169 ± 13.74 mg plant⁻¹. Soybean nodulation and N uptake ensured the supply of nitrogen to the soybean plants with 331 ± 82 mg plant⁻¹. Overall, diversified autumn/winter cover crop sequences provide plant residue, containing nutrients, and different carbon/nitrogen, which alters microbial biomass, the ratio of C_mic/N_mic, basal respiration, and soil enzyme activities within each Oxisol with different particle size distribution. Full article

Arctic warming is expected to alter permafrost landscapes and shift tundra ecosystems from greenhouse gas sinks to sources. We quantified plant biomass and necromass, carbon stocks, and microbial activity across five Low-Arctic tundra sites in the Yana–Indigirka Lowland (Chokurdakh, NE Siberia) during the 2024 growing season. Above- and below-ground plant biomass was measured by harvest adjacent to 50 × 50 m permanent plots; total C and N were determined by dry combustion on an elemental analyzer. Total organic carbon (TOC) stocks were calculated by horizon from TOC (%), bulk density, and thickness. Microbial basal respiration (BR), substrate-induced respiration (SIR), microbial biomass C (MBC), and the metabolic quotient (qCO₂) were assessed in litter/organic (O), peat (T), and mineral gley horizons. Mean above-ground biomass was 15.8 ± 1.5 t ha⁻¹; total living biomass averaged 43.1 ± 1.6 t ha⁻¹. Below-ground biomass exceeded above-ground by 1.73×. Carbon in above-ground, below-ground, and necromass pools averaged 7.8, 12.2, and 12.5 t C ha⁻¹, respectively. Surface organic horizons dominated ecosystem C storage: litter–peat stocks ranged from 234 to 449 t C ha⁻¹, whereas 0–30 cm mineral layers held 18–50 t C ha⁻¹; total (surface + 0–30 cm) stocks spanned 258–511 t C ha⁻¹ among sites. Key contributors to biomass and C storage were deciduous shrubs (Salix pulchra, Betula nana), bryophytes (notably Aulacomnium palustre), and the graminoids (Eriophorum vaginatum). BR and MBC were highest in O and T horizons (BR up to 21.9 μg C g⁻¹ h⁻¹; MBC up to 70,628 μg C g⁻¹) and declined sharply in mineral soil; qCO₂ decreased from O to mineral horizons, indicating more efficient C use at depth. These in situ data show that Low-Arctic tundra C stocks are concentrated in surface organic layers while microbial communities remain responsive to warming, implying high sensitivity of carbon turnover to thaw and hydrologic change. The dataset supports model parameterization and remote sensing of shrub–tussock tundra carbon dynamics. Full article

Wildfires can significantly alter soil physicochemical conditions and microbial communities in forest ecosystems. This study aimed to characterize the culturable soil fungal community and evaluate biological activity in Banco Totumo Bijibana, a protected dry tropical forest in Atlántico, Colombia, affected by a wildfire in 2014. Twenty soil samples were collected for microbiological (10 cm depth) and physicochemical (30 cm) analysis. Basal respiration was measured using Stotzky’s method, nitrogen mineralization via Rawls’ method, and fungal diversity through culture-based identification and colony-forming unit (CFU) counts. Diversity was assessed using Simpson, Shannon–Weaver, and ACE indices. The soils presented low organic matter (0.70%) and nitrogen content (0.035%), with reduced biological activity as indicated by basal respiration (0.12 kg C ha⁻¹ d⁻¹) and mineralized nitrogen (5.61 kg ha⁻¹). Four fungal morphotypes, likely from the genus Aspergillus, were identified. Simpson index indicated moderate dominance, while Shannon–Weaver values reflected low diversity. Correlation analysis showed Aspergillus-3 was positively associated with moisture, whereas Aspergillus-4 correlated negatively with pH and sand content. The species accumulation curve reached an asymptote, suggesting an adequate sampling effort. Although no control site was included, the findings provide a baseline characterization of post-fire soil microbial structure and function in a dry tropical ecosystem. Full article

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

Although the benefits of rational grazing by polygastric animals are well known, little is understood about how chicken grazing affects soil biological health and its capacity to store organic matter. This study aimed to assess the impact of long-term free-range chicken grazing in an olive grove on the soil chemical and biochemical properties, including the total organic carbon (TOC), total nitrogen (TN), microbial biomass (Cmic), basal respiration, and microbial community structure, as well as the soil’s capability to stock organic carbon and total nitrogen. A field experiment was conducted in an olive grove grazed by chickens for over 20 years, with the animal load decreasing with distance from the poultry houses. At 20 m, where the chicken density was highest, the soils showed reduced OC and TN contents and a decline in fungal biomass. This was mainly due to the loss of both aboveground vegetation and root biomass from intensive grazing. At 50 m, where grazing pressure was lower, the soil OC, TN, and microbial community size and activity were similar to those in a control, ungrazed area. These findings suggest that high chicken density can negatively affect soil health, while moderate grazing allows for the recovery of vegetation and soil organic matter. Rational management of free-range chicken grazing, particularly through the control of chicken density or managing grazing time and frequency, is therefore recommended to preserve soil functions and fertility. Full article

This study investigated carbon dynamics in a peach orchard subjected to three treatments with a mixed compost amendment (MCA, 35% organic content): a control with no amendment (A0), a full dose (A1, 10 t ha⁻¹), and a half dose (A2, 5 t ha⁻¹). The sustainability of MCA was assessed in terms of (i) potential and (ii) actual soil respiration, (iii) soil carbon and physical properties and (iv) fruit quality and yield. Carbon dioxide (CO₂) emissions were measured both in the laboratory, by incubating soil samples without root removal, and in the field using static chambers. Observations spanned three growing seasons (2021–2023). A correlation was found between actual and potential soil respiration, with emission peaks occurring near the time of MCA application. Cumulative actual CO₂ emissions amounted to 5.6, 12.0 and 9.4 t CO₂ ha⁻¹ for A0, A1 and A2, respectively. MCA application (i) increased microbial respiration, (ii) reduced soil physical characteristics, such as bulk density and water-filled pore space, and (iii) slightly improved fruit quality, although the yield was not significantly affected. Furthermore, the MCA enhanced soil organic carbon and total nitrogen content compared to the control. These results suggest that high organic content amendments, such as MCA, could represent a strategy to maintain or increase soil organic matter in a sustainable way, although MCA does not improve carbon emission efficiency. Full article

Rain gardens are efficient nature-based solutions (NBSs) for the sustainable management of surface run-off in urban areas. The functionality of a rain garden in an urban environment depends on the resistance of plant and soil components to anthropogenic stressors. In temperate climates, the negative effects of de-icing chemicals applied in wintertime are one of the major anthropogenic stressors for the rain gardens’ ecosystem. The research aimed to study the effect of a NaCl-based de-icer in the mesocosm experiment, where materials of soil mixtures (seven parts by volume of quartz or carbonate sand and three parts by volume of loam or peat), plants (Hemerocallis hybrida), de-icer dose (529 mg L⁻¹ for Cl⁻ and 472 mg L⁻¹ for Na⁺ concentrations), and irrigation period simulated typical conditions for the Moscow city—the largest world megapolis with permanent snow cover during the wintertime. For all soil mixtures, a short-term negative impact of salinization on soil health included a decrease in microbial biomass (4–7-times) and basal respiration (2–3.6-times). After six months, soil health indicators recovered by 80–90% in the peat and carbonate sand mixture, whereas the negative effects on the quartz sand and loam mixtures remained irreversible (1.3 and 3 times lower than the control, respectively). The chlorophyll content of the plants on all soil mixtures was reduced compared to the control plants (37.1 ± 4.1 vs. 39.9 ± 1.2 SPAD units). The worst plat condition was observed for soil mixtures based on quartz sand. In this variant, the negative effect of salinization coincided with low nutrient content. In our results, the ash content was up to three times less compared to the initial state, as well as to the other materials. Plants grown in mixtures based on loam were more resistant to salinization due to higher nutrient content than peat. Overall, based on soil Na uptake, plant biomass, and recovery of soil microbiota, soil mixtures based on peat, loam, and carbonate sand will be the most resistant to NaCl-based de-icers and could be recommended for the creation of rain gardens in cities with permanent snow cover in winter. Full article

Soil biological activity and macroinvertebrate diversity are key indicators of ecosystem function in tropical landscapes. This study evaluates the effects of different land-use systems—Amazonian Chakra agroforestry (timber-based and fruit-based), cocoa monoculture, and tropical rainforest—on soil microbial respiration, enzymatic activity, and macroinvertebrate diversity in the Ecuadorian Amazon. Forest soils exhibited the highest edaphic respiration (240 ± 64.3 mg CO₂ m² ha⁻¹, p = 0.034), while agroforestry systems maintained intermediate biological activity, surpassing monocultures in microbial diversity and enzymatic function. The soil organic matter (SOM) content at a 10 cm depth was significantly higher in monocultures (19.8 ± 3.88%) than in agroforestry and forest soils (p = 0.006); however, the enzymatic activity showed greater functional responses in agroforestry and forest systems. The relationship between recorded CO₂ respiration (REC_CO₂) and basal respiration (RBC_CO₂) exhibited a non-linear trend, as revealed by LOWESS smoothing, suggesting that microbial respiration dynamics are influenced by substrate availability and enzymatic thresholds beyond simple linear predictions. These findings underscore the potential of agroforestry as a sustainable land-use strategy that enhances soil biodiversity, carbon sequestration and nutrient cycling. Implementing optimized agroforestry practices can contribute to long-term soil conservation and ecosystem resilience in tropical agroecosystems. Full article

Iron ore extraction can lead to significant environmental degradation, particularly due to the generation of tailings during the beneficiation process. This issue was highlighted by the B1 dam collapse in Brumadinho, Brazil, in 2019. Therefore, the study and monitoring of affected areas is essential to assess soil quality throughout the rehabilitation process, whether through natural recovery or active rehabilitation practices. Microbial indicators can serve as valuable tools to track the recovery of these areas, given their high sensitivity and rapid response to environmental changes. The aim of this study was to evaluate soil microbial indicators, such as enzyme activity, microbial biomass carbon, microbial basal respiration and microbial diversity, and to select microbial approaches for monitoring the area affected by mining tailings in Brumadinho. The results indicated that the reference area initially outperformed the affected area on all evaluated bioindicators, highlighting environmental stress in the affected zone. Over the course of the study, the two areas began to show greater similarity, suggesting a natural recovery of the soil together with the return of natural vegetation. Indicators such as microbial carbon biomass went from values close to 50 mg of C Kg of soil⁻¹ in the affected area, to around 200, statistically equal to the reference. qCO₂ also varied in the affected area to values statistically equal to those of the reference over time, variated in the first collection to 0.25 mg of C-CO₂ mg of C⁻¹ h⁻¹ in the affected area against 0.1 in the reference area; in the last collection, both areas presented values close to 0.2. Enzymatic activity had superior values in the reference area about the affected area, being urease, and arylsulfatase more sensitive to show differences between areas over time. The metataxonomic data again revealed indicator species for each environment, including genera such as Bacillus, Mycobacterium, Acidibacter, and Burkholderia representative of the reference, and the genera Ramlibacter, Sinomonas, Psedarthrobacter, and Knoellia indicators of the affected area. By the end of this study, the applicability of microbial indicators for monitoring soil microbiota and its ecosystem services was successfully demonstrated. In addition, specific microbial indicators were proposed for monitoring areas affected by iron mining tailings. Full article

Agricultural practices significantly impact soil properties and ecological functions, highlighting the importance of comprehensive soil health assessments. Traditionally, these assessments have focused on physical and chemical indicators, often neglecting microbiological properties. This review explores the potential of microbiological indicators in evaluating the effects of agricultural practices on soil ecological functions, emphasizing their significance and addressing challenges associated with their application. A key advantage of microbiological indicators is their high sensitivity and rapid response to environmental changes. These indicators can be grouped into three categories: microbial biomass and abundance, microbial taxonomic composition and diversity, and microbial activity. Among these, microbial biomass carbon, basal respiration, and decomposition rates are considered the most reliable and interpretable indicators. Microbial taxonomic composition and diversity remain limited in their diagnostic and predictive capabilities due to challenges in interpretation. Integrating microbiological indicators offers a more holistic understanding of the interactions between agricultural practices and soil health, enhancing our ability to monitor, manage, and preserve soil ecosystems. To facilitate their adoption in agricultural production and land management, further efforts are needed to improve the interpretability of these indicators and to establish standardized criteria for soil health assessment. Full article

Plant biostimulants have been the subject of intense interest in recent years. The aim of this study was to assess, during the years 2021–2022, the effect of mineral nitrogen (N) fertilizer, experimental (PGPB) and commercial (G) microbial biostimulants, and humic substance product (A) on the soil microbial communities, and yield of strawberries, under field conditions. Dehydrogenase activity was significantly affected by nitrogen fertilization, but an increase occurred in the treatment N+G. The treatments N+G, N+G+A, and N+PGPB+A increased FDA hydrolysis, and phosphatase activity. All plant biostimulants increased basal as well as substrate-induced respiration. Culturable bacteria (total counts, dormant forms, actinomycetes) were not clearly affected by treatment. Based on 16S rRNA analysis, bacterial community composition was different in N+PGPB+A and N+G+A treatments. The number of cultivable fungi was significantly lower in N+PGPB and N+PGPB+A treatments. The genus of fungi Pilidium, a potential phytopathogen of strawberries, was present in the second year, but in these treatments, it was absent. In the second year, strawberry yield was shown to be 95% higher in the N+PGPB+A treatment than in the control. Microbial biostimulants in combination with humic substances represent a potential solution in increasing strawberry production. Full article

Organic matter has a very important function in soil, without which, soil formation processes cannot take place properly. It can be divided and classified based on several aspects; the most general division is between the living and non-living parts of organic matter. The results presented in this paper specifically refer to the living microbial part of organic matter. This research was carried out in the years 2021–2024 in the South Bohemia region located in the Czech Republic. Two types of land use (four permanent grassland areas, two forest areas) were evaluated. Based on laboratory soil analyses, some significant dependencies were found. For example, in grasslands with statistically identical pH, there was a dependence (p-value 0.05) between soil organic carbon (SOC), carbon of microbial biomass (MBC) and microbial basal respiration (MBR). Additionally, coniferous forest experimental locations had a lower pH, which, in turn, slowed the activity of microorganisms and promoted the accumulation of SOC in the soil. The results from this experiment support the current knowledge of organic matter and are important for a better understanding of the soil organic matter cycle. Full article

Vineyards are distinctive agroecosystems heavily influenced by local natural factors and traditional management practices, with significant implications for the quality and quantity of grape production. This study investigated the ecological impact of copper-containing fungicides on the accumulation and distribution of copper, manganese, chromium, and cobalt in the upper soil horizons of vineyards of varying ages in the Fruška Gora region, Serbia. The results indicated a marked difference in total copper content across vineyards, with the oldest vineyard exhibiting levels 6.9 times above the regulatory limit. Factor analysis delineated a strong correlation between copper accumulation and vineyard age while also highlighting the influence of landscape morphology on the spatial distribution of heavy metals. The findings suggest that copper accumulation is primarily related to agricultural practices, particularly the duration of fungicide application, while the distribution of other heavy metals is more closely associated with topographic features. The novelty of our research lies in the fact that we have shown that the assessment of copper accumulation in soil in vineyard ecosystems should take into account not only viticultural practices but also the history of land use and the landscape characteristics of the area. Full article