Substrate-induced Respiration Research Articles

Organic Management and Intercropping of Fruit Perennials Increase Soil Microbial Diversity and Activity in Arid Zone Orchard Cropping Systems

Organic farming encourages soil management practices that can improve soil health and fertility by increasing soil organic matter inputs and system sustainability. This study evaluated the effect of three years of continuous organic farming and intercropping orchard treatments on soil microbial diversity, microbial enumeration, respiration, soil fertility and fruit yields. Organic management resulted in higher soil organic matter content, Olsen P, and water holding capacity, but did not affect soil pH, electrical conductivity (EC), K, or Na levels. Growth parameters measured on all fruit trees were not significantly different among treatments. The enumeration of bacteria was significantly higher in organic plots when compared to conventionally managed plots. Soil respiration and substrate-induced respiration were significantly higher in the organic diverse plots in comparison to both conventional systems. The genomic analysis of prokaryotes (16S rRNA) and eukaryotes/fungi (ITS) revealed a significantly higher number of taxa, Shannon H index, and Equitability index in the organic systems for both prokaryotes and eukaryotes, in comparison to conventional farming, all of which are indicators of system sustainability. The relative abundance of Operational Taxonomic Units (OTUs) previously reported as diazotrophs, denitrifiers, or involved in the sulfur cycle, as well as Arbuscular Mychorrizae Fungi (AMF)/glomeromycotan, were highest in the organically managed soils than in the conventional plots. A multivariate correlation network clustering revealed that the microbial communities within the organic and conventional soils had strong dissimilarities regarding soil microbial niches. Our work provides evidence that organic management can be used for increasing soil microbial diversity and soil health, leading to higher levels of sustainability in fruit orchard systems.

Are Changes Occurring in Bacterial Taxa Community and Diversity with the Utilization of Different Substrates within SIR Measurements?

This research explores how the availability of substrates affects the regulation of soil microbial communities and the taxonomical composition of bacteria. The goal is to understand the impact of organic matter and substrate availability and quality on the diversity of soil bacteria. The study observed gradual changes in bacterial diversity in response to the addition of different substrate-induced respiration (SIR) substrates. Understanding the structure, dynamics, and functions of soil microbial communities is essential for assessing soil quality in sustainable agriculture. The preference for carbon sources among bacterial phyla is largely influenced by their life history and trophic strategies. Bacterial phyla like Proteobacteria, Bacteroidetes, and Actinobacteria, which thrive in nutrient-rich environments, preferentially utilize glucose. On the other hand, oligotrophic bacterial phyla such as Acidobacteria or Chloroflexi, which are found in lower numbers, have a lower ability to utilize labile C. The main difference between the two lies in their substrate utilization strategies. Understanding these distinct strategies is crucial for uncovering the bacterial functional traits involved in soil organic carbon turnover. Additionally, adding organic matter can promote the growth of copiotrophic bacteria, thus enhancing soil fertility.

Labile not stable SOC fractions constitute the manageable drivers of soil health advances in carbon farming

The assessment of soil health and the determination of carbon stability in soils are current challenges that have gained momentum through initiatives at national as well as international scales. However, inferring universally valid soil health parameters that are directly linked to carbon permanence remains challenging. Our aim was to evaluate the potential of simultaneous thermal analysis (STA) for an improved monitoring of soil health advances in the context of carbon farming strategies. For this purpose, an on-farm comparison of soil health in ten conservation agricultural systems with adjacent conventional farms was performed based on STA and thermal measures were related to key biological and physical indicators for monitoring soil functions. Using an autocorrelation-based approach, we identified independent thermal indicators, revealing that carbon farming efforts predominantly increased labile soil organic matter fractions in the range of 300–400 °C, while thermally more recalcitrant fractions did not respond to farming system transformation. Similarly, most soil health indicators revealed highest correlation with temperature ranges of mass loss of labile organic matter fractions. The relation of STA with commonly used soil health indicators was highest for soil organic carbon (SOC, r=0.971) and total nitrogen (TN, r=0.981). However, also inference on microbial activity parameters such as dimethylsulfoxid reduction, microbial biomass carbon and substrate-induced respiration could be demonstrated with r>0.663. The results thus highlight key temperature ranges of organic matter stability for future soil monitoring tasks of climate change mitigation potentials of carbon farming and related advances in soil health.

Soil pH and Nutrient Content Sustain Variability of Soil Bacterial Community Structure and Activity after Forest Clear-Cutting

Clear-cutting is the most robust intervention in a forest ecosystem, causing marked changes in ecosystem processes. Although the effects of forest harvesting have been widely investigated, comparative studies can provide vital supplementary information concerning specific fields, including changes in soil microbiota structure and functioning. Our study examined the soil bacterial community composition, diversity, and activity of a mixed pedunculate oak stand over three years after clear-cutting based on 16S rRNA sequencing and substrate-induced respiration data. In addition, we conducted a yearly comparison with a control oak stand already in the regeneration phase. According to our results, the forest harvest caused only limited changes in the diversity, structure, and activity of the soil bacterial community of the oak stand, suggesting that soil parameters influence the soil bacterial community structure and functioning more significantly than the cessation of forest cover.

Biogeographic and co-occurrence network differentiation of fungal communities in warm-temperate montane soils

Studying the biogeographic patterns of fungal communities across altitudinal and soil depth gradients is essential for understanding how environmental variations shape the diversity and functionality of these complex ecological assemblages. Here, we evaluated the response and assembly patterns of fungal communities to altitude and soil depth, and the co-occurrence patterns influencing soil fungal metabolic preferences on Dongling Mountain. We observed significant variations in fungal β-diversity, driven by elevation and soil depth, with climatic parameters (MAT and MAP) and nutrient concentrations (TOC, TP, and TN) serving as prominent influencers. Additionally, we found that the multiple substrate-induced respiration rate of fungi degrading various carbon substrates was diminished in high-altitude and subsurface soils compared to low-altitude and surface soils. Stochastic processes play a more important role in controlling fungal community assembly than deterministic processes, with dispersal limitation emerging as the main driver of community assembly. While greater network complexity was evident in the topsoil compared to the subsoil, both layers harbored altitude-sensitive OTUs (asOTUs) that belonging to distinct modules. Moreover, fungal groups sensitive to the same altitude exhibited similar metabolic preferences. The asOTUs designated for lower altitude areas favored unstable carbon substrates (glucose and sucrose), while those designated as higher altitude areas exhibited a preference for recalcitrant carbon (xylan and lignin). This evidence suggests that soil fungal communities respond to environmental changes by trading off their life strategies and metabolic characteristics.

Soil Parameters and Forest Structure Commonly Form the Microbiome Composition and Activity of Topsoil Layers in Planted Forests.

Soil bacterial communities play a remarkable role in nutrient cycling, significantly affecting soil organic material content, soil fertility, and, in an indirect way, plant succession processes. Conversely, vegetation type influences microbial soil life. The present study compared the bacterial microbiome composition, diversity and catabolic activity profile of topsoil samples collected under three different forest types (a twice-coppiced black locust stand, a young, naturally reforested, and a middle-aged mixed pedunculate oak stand) planted on former arable land in the early 20th century. Diversity indices determined during 16S ribosomal RNA sequencing-based metagenome analysis indicated that the black locust stand had the highest soil bacterial community diversity. At the phylum level, Acidobacteriota, Actinobacteriota, Proteobacteria, Verrucomicrobiota, Bacteroidota, and Gemmatimonadota were the most abundant taxa in the forest soils. Concerning soil parameters, redundancy analysis revealed that pH had the highest impact on bacterial community structure and pH, and soil organic carbon content on the samples' respiration patterns. As for catabolic activity, the recently clearcut oak forest showed the lowest substrate-induced respiration, and citrate was the main driver for the inter-stand variability of microbial activity. Our results confirm that soil parameters and forest type influence the composition and functioning of the soil bacterial microbiome.

Microbial Biomass and Rhizosphere Soil Properties in Response to Heavy Metal-Contaminated Flooding

Mining and metallurgy are the main sources of soil contamination with harmful metals, posing a significant threat to human health and ecosystems. River floodplains in the vicinity of metal mines or industrial plants are often subject to flooding with sediments containing heavy metals, which can be harmful to the soil ecosystem. This study aimed to investigate the microbial properties of the soil at a metal-contaminated site and to determine the significant relationships between the biological and chemical properties of the soil. The study site was located near the village of Gyöngyösoroszi, in the Mátra mountain region of Northwest Hungary. A phytoremediation experiment was conducted in a metal-polluted floodplain using willow and corn plantations. The soil basal respiration, substrate-induced respiration, soil microbial biomass carbon (MBC), acid phosphatase activities, and soil chemical properties were measured. The soil of the contaminated sites had significantly higher levels of As, Pb, Zn, Cu, Cd, and Ca, whereas the unpolluted sites had significantly higher levels of phosphorus and potassium. The substrate-induced respiration showed a positive correlation with MBC and negative correlations with the metabolic quotient (qCO2). The soil plasticity index and phosphorus showed a positive correlation with MBC, whereas salinity and the presence of Cd, Pb, Zn, As, and Cu showed a negative correlation. Acid phosphomonoesterase activity negatively correlated with the plant-available phosphorus content and MBC, but was positively correlated with the contents of toxic elements, including cadmium, lead, zinc, arsenic, and copper. This study found a significant correlation between the qCO2 and the toxic element content. This suggests that an enhanced metabolic quotient (qCO2), together with a decreased MBC/SOC ratio, could be used to indicate the harmful effect of soil contamination by heavy metals in floodplain soils.

Biochar pH reduction using elemental sulfur and biological activation using compost or vermicompost

This study aimed to improve biochar’s quality for arid land applications by using elemental sulfur as a pH reducer agent co-applied with compost or vermicompost as biological activators. Biochar pH was decreased by the addition of elemental sulfur, with the highest reduction from 8.1 to 7.2 occurring when co-amended with vermicompost. Elemental sulfur increased the water-soluble concentrations of calcium, magnesium, and many other elements, and stimulated substrate-induced respiration, especially when co-amended with vermicompost. The bacterial diversity community structure were significantly affected by all treatments. The Shannon index significantly increased in response to compost and sulfur treatments, while the vermicompost treatments showed higher microbial evenness and equitability diversity indices. Multivariate analyses indicated that elemental sulfur oxidation was associated with specific sulfur-oxidizing bacterial clusters. Integrating biochar with sulfur and (vermi)compost was found to be a promising sustainable technology for managing excessive biochar alkalinity, increasing its fertility and potential for application in aridlands.

Effect of tire wear particle accumulation on nitrogen removal and greenhouse gases abatement in bioretention systems: Soil characteristics, microbial community, and functional genes

Tire wear particles (TWPs), as predominant microplastics (MPs) in road runoff, can be captured and retained by bioretention systems (BRS). This study aimed to investigate the effect of TWPs accumulation on nitrogen processes, focusing on soil characteristics, microbial community, and functional genes. Two groups of lab-scale bioretention columns containing TWPs (0 and 100 mg g−1) were established. The removal efficiencies of NH4+-N and TN in BRS significantly decreased by 7.60%–24.79% and 1.98%–11.09%, respectively, during the 101 days of TWPs exposure. Interestingly, the emission fluxes of N2O and CO2 were significantly decreased, while the emission flux of CH4 was substantially increased. Furthermore, prolonged TWPs exposure significantly influenced the contents of soil organic matter (increased by 27.07%) and NH4+-N (decreased by 42.15%) in the planting layer. TWPs exposure also significantly increased dehydrogenase activity and substrate-induced respiration rate, thereby promoting microbial metabolism. Microbial sequencing results revealed that TWPs decreased the relative abundance of nitrifying bacteria (Nitrospira and Nitrosomonas) and denitrifying bacteria (Dechloromonas and Thauera), reducing the nitrification rate by 42.24%. PICRUSt2 analysis further indicated that TWPs changed the relative abundance of functional genes related to nitrogen and enzyme-coding genes.

Study in a long-term laboratory experiment of the potential susceptibility to mineralization of organic matter in post-agrogenic light gray soils

Relevance. Since 2021, work has begun in Russia to assess the fertility of unused arable land and its involvement in agricultural circulation. Changes in the farming system of post-agrogenic soils can lead to uncontrolled mineralization of newly formed soil organic matter (SOM) under fallow vegetation and significant CO2 emissions into the atmosphere. Studies of the nature of SOM accumulation under fallow vegetation and assessment of its potential susceptibility to mineralization are relevant, since they can become the basis for the development of agrotechnical methods for returning unused lands to arable circulation with the maximum preservation of their fertility.Methods. In a long-term laboratory incubation experiment, we studied the dynamics of changes in the intensity of basal (BR) and substrate-induced respiration (SIR) in postagrogenic soils to assess the potential susceptibility to SOM mineralization with a change in land use. Layered samples (0–10 and 10–20 cm) were used from the old arable horizons of two fallow plots with different humus conditions. The results of the incubation experiment were compared with the results of assessing the quantitative content and qualitative composition of SOM.Results. In the 0–10 cm layer, the respiration rates are higher than in the 10–20 cm layer. The results of the assessment of the respiration intensity are consistent with the assessment of the qualitative composition of SOM. The accumulation of SOM occurs mainly in the upper part of postagrogenic soils due to mobile easily oxidized organic compounds of a fulvic nature. When developing agrotechnical methods for returning fallow lands to arable circulation, it is necessary to focus primarily on basic processing technologies that ensure maximum preservation of potentially easily mineralized material accumulated in the upper layer.

Dynamic of carbon pools in the postagrogenic ecosystems of the southern taiga

The aim of the study was to assess the nature of changes in the main carbon pools of ecosystems during post-agrogenic vegetation restoration for different agricultural lands. Location and time of the study. The research was carried out in the Kostroma region. The objects are chronosequences, representing overgrown arable land, hayfield, hayfield-pasture and a well-fertilized private garden. Methods. The biomass of forest stand was calculated allometrically; the biomass of living ground plant cover was calculated using the method of cuttings (aboveground) and monoliths (underground). Soil organic carbon content was determined by dichromate digestion, and soil microbial biomass was assessed by substrate-induced respiration. Results. During succession in arable lands and hayfields, an increase in ecosystem carbon reserves was revealed due to the growth of woody phytomass, the share of carbon reserves growing from 0–10 to 65–78% over 40–50 years. When fertilized vegetable gardens become overgrown within 35 years, there was no regeneration of the tree stand. The upper horizons of arable soils contained 0,83–1,05% organic carbon, whreas the soil of the hay and the hay-pasture meadows contained 2,25% and 3,97%, respectively, and the soil of a vegetable garden contained 4,89%. When arable land is overgrown, carbon reserves in the old arable layer increased from 2,0–2,6 to 3,0–5,0 kg C/m2; when the hay meadow is overgrown, soil organic carbon stock decreased from 5,2 to 4,8 kg C/m2; in the hayfield-pasture, it decreased by 3,8 times; in the vegetable gardens, the carbon stock (10 kg C/m2) remained virtually unchanged for 35 years. Conclusions. When reforesting arable lands, as well as hayfields in the absence of livestock grazing, ecosystem carbon reserves increased 4–7 times with a decrease in the soil carbon share. The direction and nature of the carbon pools dynamics is determined by the soil humus state at the beginning of succession and, as a consequence, the type of use.

Contrasting mechanisms of nutrient mobilization in rhizosphere hotspots driven by straw and biochar amendment

Straw return strategies are widely used green management practices that can alter soil organic matter transformation and dynamics through changes in microbial community structure and functions. How the exogenous input of organic materials of contrasting qualities affects the composition of dominant taxa, growth, and microbial functional properties related to nutrient acquisition in space remains unclear. In this study, we investigated the hotsopts and kinetics of C- and N-acquiring hydrolases, microbial growth, and bacterial community structure in maize rhizosphere hotspots after the addition of straw and straw-derived biochar using soil zymography, substrate-induced respiration and high-throughput sequencing. Compared with no amendment and maize straw-derived biochar, straw addition increased the growing biomass and microbial specific growth rate by 1.2–1.6 and 1.7–2.0-fold, respectively, indicating the relative dominance of fast-growing r-strategists. This corresponds to an increased relative abundance of the keystone taxa Firmicutes and their gene copies encoding β-1,4-glucosidase (BG) and β-N-acetylglucosaminidase (NAG). The potential activity and affinity (Vmax and Km) of BG increased 2.2 and 1.8 times, respectively, and those of NAG increased 4.0 and 2.0 times, respectively. In contrast, the relative abundance of Actinobacteria belonging to K-strategists increased in the biochar-amended soil. This resulted in slower growth and retarded enzymatic activity than the straw return treatment. Biochar enhanced the root biomass by 31% and increased the rhizosphere hotspot extents of BG and NAG by 26% and 47%, respectively. The highest robustness and modularity of the co-occurrence network indicated a more stable network with biochar input. In summary, the addition of straw accelerated rhizosphere nutrient cycling by triggering microbial growth, especially fast-growth r-strategists (Firmicutes), and synthesizing a large number of enzymes. In contrast, the addition of biochar increased rhizosphere nutrient mobilization by expanding the extent of rhizosphere hotspots to mobilize nutrients from a larger soil volume. This suggests that there are different strategies for nutrient mobilization in the rhizosphere with contrasting exogenous C addition.

Non-native and native tree species plantations and seasonality could have substantial impacts on the diversity of indigenous soil fauna in a semi-arid forest ecosystem.

The temporal and spatial dynamics of soil fauna in many terrestrial ecosystems are still not fully understood, while soil fauna is one of the most critical characteristics in assessing soil quality. Therefore, the effects of native [Quercus brantii (QP) and Amygdalus scoparia (AMP)] and non-native [Cupressus arizonica (CUP) and Pinus eldarica (PIN)] plantations and natural trees [Quercus brantii coppice trees (QNC), standard (QNS), and Amygdalus scoparia (AMN)] on diversity and abundance of macro- and mesofauna were done in the semi-arid forest of Zagros, Iran. Samples were collected beneath the canopy of woody species and the outer edge of the canopy in spring and summer seasons. For this purpose, soil samples [(7 samples per woody species + control) × 2 seasons × 3 replicates] were taken from 0 to 20 cm depths. Each soil sample was a mix of three soil cores. For the macrofauna, 15 species belonging to four families (in spring) and 17 species in nine families (in summer) were collected and identified. For the soil mesofauna, 14 species belonging to 14 families (in spring) and 13 species in 13 different families (in summer) were identified, respectively. The fauna diversity indices under the canopy of studied species were higher in summer season than in spring. The result showed that the macrofauna diversity was affected by tree species, while mesofauna was affected by seasonal changes. Macrofauna biodiversity was higher under the canopy of PIN and CUP than other trees. Principle component analysis showed that the diversity of the macrofauna was higher under the canopy of PIN and CUP, and influenced by soil characteristic properties, soil properties did not influence them. Yet the diversity of the mesofauna was affected by soil characteristics and was higher in areas with higher organic carbon, nitrogen, substrate-induced respiration, basal respiration, microbial carbon biomass, and alkaline phosphatase. In addition, mesofauna biodiversity had a significant positive correlation with the soil quality index (SQI). SQI was higher under the canopy of natural stands, especially the QNS. Conservation of native species (QNS, QNC, and AMN) and plantation with native deciduous species (QP and AMP) seem to moderate environmental conditions and increase soil macro- and mesofauna diversity and SQI.

Soil biological activity after a sixty-year fertilization practice in a wheat-maize crop rotation.

This study aimed to survey the long-term effects of fertilization practices on the functional diversity of the soil microbiota. A 60-year fertilization experiment with mineral fertilizers, farmyard manure and combined treatments was sampled in two consecutive years in maize (Zea mays L.) and wheat (Triticum aestivum L.). Soil chemical properties, plant growth and physiological parameters were measured. The MicroRespTM method was applied to assess the community level physiological profiles (CLPPs) of the rhizosphere soil, and the arbuscular mycorrhizal fungal (AMF) colonization of the roots was determined. Samples were taken in the early vegetative stages, at flowering, and at harvest in both years. The measured parameters were analysed using multifactorial ANOVA to determine treatment effects, crop-dependent differences, and seasonality. PCA analysis was performed on the data matrix to reveal more complex correspondences, and Pearson's product-moment correlation was used to confirm relationships between some of the measured soil and plant parameters. Fertilization treatments caused long-term changes in some biological parameters such as: MicroRespTM parameters, citrate utilization, total substrate-induced respiration value, and the ratio of utilization of amino acids and sugars. The rate of AMF colonization responded mainly to the plant nutrition status and the plant requirements, suggesting a plant-mediated effect in the case of mycorrhiza. Mineral nitrogen fertilization and soil acidification were found to be the main factors affecting the catabolic activity of soil microbiota, while AMF colonization responded to the balance of plant nutrition.

Evaluation of Direction and Mechanisms of Biochar Application Effect on Substrate-Induced Soil Respiration in a Long-Term Laboratory Experiment

In a laboratory experiment, the effect of biochar (BC) on substrate-induced respiration (SIR) of soils was studied. In the experiment, 10 samples of BC obtained from woody and herbaceous materials in two modes of pyrolysis were used. The SIR intensity was determined after 3 days, 3 and 6 months of incubation. During short-term incubation, no effect of BC on SIR was observed. The exception was the corn-based BU application, which saw a 34.6% increase in SIR. Аfter incubation for 3 months, a significant increase in SIR was found (from 30.4 to 54.8%) for five BCs were added. When incubated for 6 months, a significant increase in SID (from 30.4 to 65.9%) was observed when eight BCs were applied. Lasso regression and 23 measures of BC properties were used as potential predictors to evaluate BC properties that affect SIR. It was found that during a three-day incubation, the following properties of BС have a positive effect on SIR: the content of oxidizable organic matter (OM), exchangeable calcium, and pH of the aqueous suspension, and a weak negative effect on the content of exchangeable sodium. When incubated for 3 months there is a positive effect of oxidized OM, and after 6 months – ash content. Since only a positive statistically significant effect of BC on SIR was observed in the experiments, the authors conclude that in order to objectively assess the effectiveness of their use for CO2 sequestration in soils, balance calculations are necessary, in which, along with the amount of stable carbon introduced into soils with BC, a potential increase in CO2 emissions from soils due to the activation of soil saprophytic microbiota.

The Effect of Mineral Fertilizers on Soil Respiration in Urban Lawns

Application of mineral fertilizers to regulate microbial respiration and carbon dioxide emissions from urban lawn soils was evaluated due to the need to develop technologies for reducing CO2 emissions and for increasing the C-absorption capacity of natural and anthropogenic ecosystems. The studies were performed in the Botanical Garden of Moscow State University on Leninskie Hills in a small-plot experiment with the fractional application of four types of complex fertilizers (NPKS 27 : 6 : 6 : 2, NPKS 21 : 10 : 10 : 2, NPK 15 : 15 : 15 and NPK 18:18:18 + 3 MgO + trace elements (TE)) at the doses of 60 and 120 kg N/ha during the growing season. We studied the basal respiration (BR) of soils, carbon content of microbial biomass (Cmic) by substrate-induced respiration, and the CO2 emission from soils by the method of closed static chambers. Cmic in soil of the control plot in the summer period was 1300–1450 µg/g. Application of NPKS 21 : 10 : 10 : 2 and NPK 18 : 18 : 18 + 3 MgO + TE at a low dose increased Cmic by 12–35% within the first two weeks, and then it dropped. All types of fertilizers applied for a short period of time increased BR of soils and CO2 emission maximum on the sixth day. After two weeks and onwards, their growth decreased or their intensity dropped to the control values (500 mg CO2 m2/h–1 and 1.5 μg C–CO2 g/h, respectively) and lower. The lowest intensity of CO2 emission, a rise in basal respiration, and an increase in microbial biomass were recorded after the application of fertilizer NPKS 21 : 10 : 10 : 2. The change in the functioning of the soil microbial community detected by the maximal qCO2 was the greatest in case of NPKS 27 : 6 : 6 : 2 application. The dynamics of CO2 emission from the soils of the small-plot experiment from April to October correlated with the soil temperature (rS = 0.66, p < 0.05, n = 135). Emissions of CO2 were minimal for the plot with NPKS 21 : 10 : 10 : 2 in all periods of the study.

THE EFFECT OF MINERAL FERTILIZERS ON SOIL RESPIRATION IN URBAN LAWNS

Due to the need to develop technologies for reducing carbon dioxide emissions and increasing the C-absorption capacity of natural and anthropogenic ecosystems, the possibility of using mineral fertilizers to regulate microbial respiration and CO2 emissions from urban lawn soils was evaluated. The studies were carried out on the territory of the Botanical Garden of Moscow State University on the Lenin Hills in a small-plot experiment with the fractional application of four types of complex fertilizers (NPKS 27:6:6:2, NPKS 21:10:10:2, NPK 15:15:15 and NPK 18:18:18 + 3 MgO + trace elements (TE)) at doses of 60 and 120 kg N ha-1 during the growing season. The carbon content of microbial biomass (Cmic) using substrate-induced respiration was studied, the basal respiration (BR) of soils was estimated, and the emission of CO2 from soils using closed static chambers was determined. Тhe Cmic content in the soil of the control plot in the summer period varied within 1300–1450 μg·g-1. The application of NPKS 21:10:10:2 and NPK 18:18:18 + 3 MgO + TE at a low dose increased the Cmic content by 12–35% for two weeks, then it de-creased. The application of all fertilizers for a short period increased basal respiration of soils and CO2 emission, maximum on the 6th day. Aft er two weeks, the increase in the intensity of BR and CO2 emission decreased or it reached the control values (1,5 μg C-CO2·g-1·h-1 and 500 mg·CO2 ·m-2·h-1 respectively) or less. In the short term, the lowest intensity of CO2 emission and a surge in basal respiration, along with an increase in microbial biomass, were observed with the addition of fertilizer NPKS 21:10:10:2. The greatest change in the functioning of the soil microbial community, revealed by the maximum qCO2, occurred with the introduction of NPKS 27:6:6:2. Th e dy-namics of CO2 emission from the soils of the small-plot experiment from April to October correlated with the soil temperature (rS = 0.66, p&lt;0.05, n=135). In all periods of the study, the minimum CO2 emissions were noted for the plot with NPKS 21:10:10:2 fertilizer.

Exploring the Influence of Diverse Viticultural Systems on Soil Health Metrics in the Northern Black Sea Region

The present study investigates the functionalecological status of typical light clay soils in vineyards in the southern region of Crimea, using both traditional (including fallow soils) and organic land-use systems. This analysis was carried out by examining agrochemical indicators, microbial respiratory activity, microbial biomass, and the ecological status of the microbial community. In organic vineyard soils, the mean substrate-induced respiration, microbial biomass carbon and the ratio of microbial biomass to organic carbon were found to be 2.8, 4.0, and 4.1 times higher, respectively, compared to conventional farm soils. On the contrary, the microbial metabolic coefficient was 1.4 times lower, signifying more favorable conditions for the functioning of the soil microbiota. The increased mobile sulfur content in organic vineyard soils (18.3 mg kg−1 vs. 8.0 mg kg−1 in traditional farms) and inadequate mobile phosphorus supply in some farms present potential risks. The suboptimal functional state of the microbiome in fallow soils previously under traditional plant protection necessitates comprehensive ecotoxicological analyses before development. Assessing the soil functional ecological status through an ecophysiological evaluation of the microbiome is vital for understanding ampelocenosis soils and making informed decisions on vineyard management practices.

Interactive effect of biochar and urea addition increases plant growth and rhizosphere microbial activity and decreases N2O emissions

Simultaneous addition of biochar with applied N fertilizer was proposed as useful way how to improve soil fertility and reduce negative effects of nitrogen fertilization. A hypothesis that added N decreases root growth and soil microbial activity and increases N2O emissions while addition of biochar has opposite effect was tested. We further hypothesized that increased microbial activity in biochar-amended soil stimulates growth of subsequently cultivated plants.The supposed interactive effect of biochar and N-fertilizer was studied in pot experiment with cultivation of lettuce in soil amended with urea, biochar and their combination. In each pot, yield of plant biomass was determined and basal respiration, substrate-induced respiration and content of mineral N were determined in soil samples. Soil with roots decomposing after lettuce harvest was also analyzed and subsequently used for the cultivation of wheat plants.Emissions of N2O were measured following N application and measurement continued after harvest. Contrary to the hypothesis, N fertilization stimulated the growth of not only aboveground but also belowground plant biomass. Biochar increased growth of roots in agreement with the hypothesis. The effect of treatments on microbial biomass and respiration was relatively weak in the rhizosphere of growing plants. However, when roots were decomposed, lower Nmin and higher microbial biomass were observed in biochar amended soils. Biochar amendment significantly stimulated the yield of subsequently cultivated wheat. At the beginning of the experiment, N2O emissions were higher in biochar-amended soil. However, at the later phase of the experiment, cumulative emissions were lower in biochar-amended soils. Results suggest that biochar supports more efficient N utilization by plants and increases soil fertility. Biochar also decreases N losses through N2O emissions, even with simultaneous N fertilization.

Humate-Coated Urea as a Tool to Decrease Nitrogen Losses in Soil

Processes of N transformation in soil as affected by application of the three kinds of urea fertilizers, conventional urea (U), humate-coated urea (U_HA), and urea treated with the urease inhibitor NBPT (U_UI), are examined in a model laboratory experiment. Effects of urea fertilizers on soil chemical (content of water-extractable N-NH4 and N-NO3), and microbiological properties (rate of actual and potential N2O emission, basal and substrate-induced respiration, microbial biomass C, emission of ethylene) are focused to answer the following questions: (i) whether humate-coated urea has the ability to decrease N losses in soil; and (ii) how it affects soil biological activity comparable to synthetic urease inhibitor. The results showed that U_HA demonstrated advantages comparable to U in its ability to decrease N losses in soil: it increased N-NH4 content by 35%, reduced nitrate content by 9%, and decreased N2O emissions by 50%. U_HA promoted basal soil respiration by 10% and the specific activity of the soil microbial community by 7%, providing the highest metabolic quotient qCO2. Comparably to NBPT-treated U, U_HA mainly shows intermediate results between U-UI and conventional U. Considering the low cost of raw humates, U-HA can be regarded as a promising tool to decrease N losses in soils.