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Despite the essential role of nitrogen fertilizers in achieving high crop yields, current application practices often exhibit low efficiency. Optimizing nitrogen (N) fertilization in agriculture is, therefore, critical for enhancing crop productivity while ensuring sustainable food production. This study investigates the effects of nitrification inhibitors (Nis) such as Dimethyl Pyrazole Phosphate (DMPP) and Dimethyl Pyrazole Fulvic Acid (DMPFA), plant growth-promoting bacteria inoculation, and phosphorus (P) application on the soil-plant-microbe system in maize. DMPFA is an organic nitrification inhibitor that combines DMP and fulvic acid for the benefits of both compounds as a chelator. A comprehensive rhizobox experiment was conducted, employing varying levels of P, inoculant types, and Nis, to analyze the influence of these factors on various soil properties, maize fitness, and phenotypic traits, including root architecture and exudate profile. Additionally, the experiment examined the effects of treatments on the bacterial and fungal communities within the rhizosphere and maize roots. Our results showed that the use of Nis improved plant nutrition and biomass. For example, the use of DMPFA as a nitrification inhibitor significantly improved phosphorus use efficiency by up to 29%, increased P content to 37%, and raised P concentration in the shoot by 26%, compared to traditional ammonium treatments. The microbial communities inhabiting maize rhizosphere and roots were also highly influenced by the different treatments. Among them, the N treatment was the major driver in shaping bacterial and fungal communities in both plant compartments. Notably, Nis reduced significantly the abundance of bacterial groups involved in the nitrification process. Moreover, we observed that each experimental treatment employed in this investigation could select, promote, or reduce specific groups of beneficial or detrimental soil microorganisms. Overall, our results highlight the intricate interplay between soil amendments, microbial communities, and plant nutrient dynamics, suggesting that Nis, particularly DMPFA, could be pivotal in bolstering agricultural sustainability by optimizing nutrient utilization. [ABSTRACT FROM AUTHOR]

Soil residual herbicides are often applied at cover crop termination to extend the period of weed control and reduce the selection pressure for herbicide resistance. Previous studies indicate that one of the benefits of cover crop use is the increase in the activity of enzymes in the soil. Some enzymes are also responsible for breaking down herbicide molecules. The biodegradation of herbicides in the soil is a natural process that leads to a reduction in the concentration of the parent compound overtime. Although cover crop use can result in the increased activity of soil enzymes, to date, there is no evidence that such increased activity also leads to a reduced persistence of residual herbicides in the soil. However, cover crop use does alter the fate of residual herbicides by interception, with some studies reporting more than 90% interception. Without rainfall or irrigation during the days following its application, the herbicide remains on the plant surface and is ineffective as a weed control tool. Following the integrated weed management approach, the combination of cover crop and soil residual herbicides is a promising alternative to delay the development of new herbicide resistance cases. However, more research is needed to understand the impact of biomass accumulation on residual herbicide fate and to determine the best strategies to improve herbicide placement on cover cropping system. This paper reviews the impact of cover crop use on soil microbial activity and the further degradation of soil residual herbicides as well as the fate of residual herbicides when applied at cover crop termination. [ABSTRACT FROM AUTHOR]

Despite the essential role of nitrogen fertilizers in achieving high crop yields, current application practices often exhibit low efficiency. Optimizing nitrogen (N) fertilization in agriculture is, therefore, critical for enhancing crop productivity while ensuring sustainable food production. This study investigates the effects of nitrification inhibitors (Nis) such as Dimethyl Pyrazole Phosphate (DMPP) and Dimethyl Pyrazole Fulvic Acid (DMPFA), plant growth-promoting bacteria inoculation, and phosphorus (P) application on the soil-plant-microbe system in maize. DMPFA is an organic nitrification inhibitor that combines DMP and fulvic acid for the benefits of both compounds as a chelator. A comprehensive rhizobox experiment was conducted, employing varying levels of P, inoculant types, and Nis, to analyze the influence of these factors on various soil properties, maize fitness, and phenotypic traits, including root architecture and exudate profile. Additionally, the experiment examined the effects of treatments on the bacterial and fungal communities within the rhizosphere and maize roots. Our results showed that the use of Nis improved plant nutrition and biomass. For example, the use of DMPFA as a nitrification inhibitor significantly improved phosphorus use efficiency by up to 29%, increased P content to 37%, and raised P concentration in the shoot by 26%, compared to traditional ammonium treatments. The microbial communities inhabiting maize rhizosphere and roots were also highly influenced by the different treatments. Among them, the N treatment was the major driver in shaping bacterial and fungal communities in both plant compartments. Notably, Nis reduced significantly the abundance of bacterial groups involved in the nitrification process. Moreover, we observed that each experimental treatment employed in this investigation could select, promote, or reduce specific groups of beneficial or detrimental soil microorganisms. Overall, our results highlight the intricate interplay between soil amendments, microbial communities, and plant nutrient dynamics, suggesting that Nis, particularly DMPFA, could be pivotal in bolstering agricultural sustainability by optimizing nutrient utilization. [ABSTRACT FROM AUTHOR]

The effect of secondary succession of abandoned agricultural lands on soil properties and soil microbial community is still poorly understood due to a complexity of interacting environmental factors. A significant area of agricultural lands has become abandoned in the central part of Latvia due to non-ideal agrotechnical conditions caused by soil and topography, resulting in natural colonization of trees. The aim of the study was to compare physicochemical parameters and microbial activity in soil adjacent to Norway spruce (Picea abies (L.) H.Karst.) trunks under the crown and on grassland outside the tree canopy, 15 years after the tree colonization. The redundancy analysis showed that bulk density, total nitrogen, total carbon, and exchangeable cations (Mg2+, K+, Ca2+, Mn2+) were positively related to substrate-induced respiration, fluorescein diacetate hydrolysis, and urease activity in sandy soil. However, positive correlations were found between urease activity and bulk density, exchangeable cations (Al3+, Fe2+, Mn2+) in loamy sand soil, while negative correlations were observed with pHBaCl2, total carbon, total nitrogen, CECe, bulk density, and exchangeable cations (K+, Ca2+). Significant differences were observed among the sampling sites (trunk and grassland), soil types (sandy Podzols and loamy sand Stagnosols), and depths (0–10 cm and 11–20 cm). Specifically, higher levels of potential ammonium oxidation and dehydrogenase activity, as well as concentrations of exchangeable cations (K+, Mn2+), were observed near the spruce trunk in sandy soil. In contrast, fluorescein diacetate hydrolysis activity, CECe, and exchangeable cations (Mg2+, Ca2+) showed higher levels in loamy sand soil. The observed spatial differences showed that secondary succession of agricultural lands with spruce affects physicochemical properties of soil and microbial activity, even in a relatively short period of time. Thus, we assume that these changes will be even more pronounced in the future, as the field transforms from grassland to forest. [ABSTRACT FROM AUTHOR]

Abstract The agronomic use of compost and biochar as soil amendments may exhibit contrasting results in terms of soil fertility and plant nutrition. The effects of the biennial application of biochar, compost and a blend of compost:biochar (90:10; % dw:dw) on the agronomical performance of an organically managed and well established 25-year-old olive orchard was assessed 5 years after the initial application. The agronomical evaluation was based on the assessment of the soil physical, chemical, and biological characteristics, and the assessment of the soil fertility by both crop production and nutritional status of the orchard, and the bioassay with olive plantlets. Biochar mainly benefited the physical properties (bulk density, total porosity, aeration, water retention capacity) of soil, especially in the top 0–5 cm. Compost and its blend with biochar improved microbial activity, soil nutritional status (increasing the content of soluble organic C, N, and P) and favoured the formation of aggregates in soil. The bioassay conducted with young plantlets confirmed the enhanced soil fertility status in the three amended treatments, particularly in the case of biochar and its blend with compost. However, this effect was not significantly observed in the adult plants after 5 years of application, reflecting the slow response of adult olive trees to changes in fertilization. Based on these results, alongside the desirable long-residence time of biochar in soil and the ready availability of compost, the blend of biochar with compost assayed in this study is defined as a valid strategy for preparing high quality soil organic amendments.

Soil pH is crucial to soil health, influencing nutrient availability, microbial activity, and plant growth. This review aims to assess the adaptability of soil pH under changing soil conditions by analyzing natural and human factors. Information was gathered from various sources, including peer-reviewed articles, field studies, and recent advances in soil science. The study explores how natural factors such as parent material, climate, and vegetation establish baseline soil pH, while human activities such as intensive farming and land-use changes further modify it, often leading to soil acidification or alkalinization. Traditional management methods like lime application, organic amendments, and crop rotation are reviewed for their effectiveness in stabilizing soil pH and their limitations under varying soil conditions. The review also explores modern technological innovations like precision agriculture, which uses soil sensors and variable rate technology for targeted pH management, and biological approaches, such as microbial inoculants, to enhance nutrient cycling and organic matter decomposition. Integrating these traditional and contemporary approaches is essential for sustainable soil pH management and long-term productivity. The findings highlight the need for a holistic approach that combines historical knowledge with emerging technologies to promote sustainable agricultural practices and environmental conservation. [ABSTRACT FROM AUTHOR]

The agronomic use of compost and biochar as soil amendments may exhibit contrasting results in terms of soil fertility and plant nutrition. The effects of the biennial application of biochar, compost and a blend of compost:biochar (90:10; % dw:dw) on the agronomical performance of an organically managed and well established 25-year-old olive orchard was assessed 5 years after the initial application. The agronomical evaluation was based on the assessment of the soil physical, chemical, and biological characteristics, and the assessment of the soil fertility by both crop production and nutritional status of the orchard, and the bioassay with olive plantlets. Biochar mainly benefited the physical properties (bulk density, total porosity, aeration, water retention capacity) of soil, especially in the top 0–5 cm. Compost and its blend with biochar improved microbial activity, soil nutritional status (increasing the content of soluble organic C, N, and P) and favoured the formation of aggregates in soil. The bioassay conducted with young plantlets confirmed the enhanced soil fertility status in the three amended treatments, particularly in the case of biochar and its blend with compost. However, this effect was not significantly observed in the adult plants after 5 years of application, reflecting the slow response of adult olive trees to changes in fertilization. Based on these results, alongside the desirable long-residence time of biochar in soil and the ready availability of compost, the blend of biochar with compost assayed in this study is defined as a valid strategy for preparing high quality soil organic amendments. [ABSTRACT FROM AUTHOR]

In this work, three wheat crops were planted successively under semi-arid climatic conditions; we wished to evaluate the positive and negative effects of the addition of sewage sludge (SS) on plants and soils under the conditions encountered during conventional agricultural management. SS was added to the first two crops at doses equivalent to 170 kg N/ha, and the third crop was left untreated. The soils were sampled initially and at the end of each cultivation period. At the end of the third crop's cultivation period, the heavy metal and organic pollutant contents of grain and straw were analyzed, as well as the presence of Escherichia coli and Salmonella. The amended soils showed a higher N content, greater microbial respiration, and greater dehydrogenase and phosphatase activity than the control. The amended plants showed higher N, Ca, and K contents than the control. Yields were 11% and 16% higher in the SS-amended soils than in the control in the experiments involving the second and third crop, respectively. No problems related to salinity or the heavy metal content were observed in both the soil and plant. However, nitrate content increased in the amended soils compared to the control. Among the persistent organic compounds, only linear alkyl benzene sulphonates and polycyclic aromatic hydrocarbons increased with the addition of SS, but such differences from the control disappeared gradually. No problematic coliform content or presence of Salmonella spp. was detected in the soil or plant. We can thus conclude that SS of adequate quality can be recycled in agricultural soils, but adequate monitoring of the receiving soil is crucial. [ABSTRACT FROM AUTHOR]

The use of artificial fertilizers follows the intensification of agricultural production as a consequence of population growth, which leads to soil depletion, loss of organic matter, and pollution of the environment and production. This can be overcome by increasing the use of organic fertilizers in agriculture. In the present study, we investigated the effect of using vermicompost, biochar, mineral fertilizer, a combination of vermicompost and mineral fertilizer, and an untreated control on alluvial-meadow soil on the development of fodder winter barley Hordeum vulgare L., Zemela cultivar. We used a randomized complete block design of four replications per treatment. Barley grain yield, number of plants, and soil and microbiological parameters were studied. We found statistically proven highest grain yield and grain protein values when applying vermicompost alone, followed by the combined treatment and mineral fertilizer. The total organic carbon was increased by 70.2% in the case of vermicompost and by 44% in the case of combined treatment, both compared to the control. Thus, soil microbiome activity and enzyme activities were higher in vermicompost treatment, where the activity of β-glucosidase was 29.4% higher in respect to the control, 37.5% to the mineral fertilizer, and 24.5% to the combined treatments. In conclusion, our study found the best overall performance of vermicompost compared to the rest of the soil amendments. [ABSTRACT FROM AUTHOR]

Despite the essential role of nitrogen fertilizers in achieving high crop yields, current application practices often exhibit low efficiency. Optimizing nitrogen (N) fertilization in agriculture is, therefore, critical for enhancing crop productivity while ensuring sustainable food production. This study investigates the effects of nitrification inhibitors (Nis) such as Dimethyl Pyrazole Phosphate (DMPP) and Dimethyl Pyrazole Fulvic Acid (DMPFA), plant growth-promoting bacteria inoculation, and phosphorus (P) application on the soil-plant-microbe system in maize. DMPFA is an organic nitrification inhibitor that combines DMP and fulvic acid for the benefits of both compounds as a chelator. A comprehensive rhizobox experiment was conducted, employing varying levels of P, inoculant types, and Nis, to analyze the influence of these factors on various soil properties, maize fitness, and phenotypic traits, including root architecture and exudate profile. Additionally, the experiment examined the effects of treatments on the bacterial and fungal communities within the rhizosphere and maize roots. Our results showed that the use of Nis improved plant nutrition and biomass. For example, the use of DMPFA as a nitrification inhibitor significantly improved phosphorus use efficiency by up to 29%, increased P content to 37%, and raised P concentration in the shoot by 26%, compared to traditional ammonium treatments. The microbial communities inhabiting maize rhizosphere and roots were also highly influenced by the different treatments. Among them, the N treatment was the major driver in shaping bacterial and fungal communities in both plant compartments. Notably, Nis reduced significantly the abundance of bacterial groups involved in the nitrification process. Moreover, we observed that each experimental treatment employed in this investigation could select, promote, or reduce specific groups of beneficial or detrimental soil microorganisms. Overall, our results highlight the intricate interplay between soil amendments, microbial communities, and plant nutrient dynamics, suggesting that Nis, particularly DMPFA, could be pivotal in bolstering agricultural sustainability by optimizing nutrient utilization.

Abstract Background The use of rock powders in soil has emerged as a nature-based technology to improve soil properties relevant to crop development and for atmospheric carbon dioxide removal (CDR) via enhanced rock weathering (ERW). Although modeling this process is crucial, the soil microbiome has been identified as the main reason why several experimental and field results do not fit the geochemical and kinetic theoretical models. Here, the hypothesis that the bacterial community structure is modulated by the application of different silicate rock powders was tested. One phonolite, three basalt variations and one granite, as well as KCl treatments, were applied to a Ferralsol cultivated with Brachiaria in short-term pedogeochemical experiments and assessed after 1 (1M), 4 (4M) and 8 (8M) months. Results The main changes in soil bacterial structure were observed at 8M and found to be modulated according to rock type, with petrochemistry and mineralogy acting as the main drivers. The content of microbial biomass carbon tended to decrease over time in the Control and KCl treatments, especially at 4M, while the rock treatments showed constant behavior. The sampling time and treatment affected the richness and diversity indices. The Si, Ca and Fe from mafic minerals were the main chemical elements related to the soil bacterial changes at 8M. Conclusions The type (acidity) of silicate rock powder modulated the soil bacterial community (SBC) in a pot experiment with tropical soil. The specificity of the SBC for each rock type increased with time until the end of the experiment at 8 months (8M). The carbon content in the microbial biomass was lower in the rock powder treatments in the first month (1 M) than in the control and KCl treatments and was equal to or higher than that in the 8 M treatment. This result illustrates the challenge of modeling rock powder dissolution in soil since the soil medium is not inert but changes concurrently with the dissolution of the rock. Graphical Abstract

The applicability of ionic liquids has grown exponentially over the last few decades. This growth is due to the easy modification of these compounds formed by ions, through the proper choice of both moieties, and the possibility of introducing functional groups into their cations and anions. However, studies of their toxicity and effects on the environment remain scarce. This study analyses firstly the response to adding different concentrations of choline dihydrogen phosphate to the germination of seeds of eight plant species. It also examines the microbial population and the respiration of two soils with contrasting organic matter contents. Seeds were incubated in a Petri dish in a Phytotron with a photoperiod of 16 h under light at 24 °C and 8 h in darkness at 16 °C. The activity of microbial populations of untreated and treated soils was analysed by isothermal microcalorimetry at 25 °C. Basal soil respiration kinetics were measured at optimal moisture (80% of field water retention capacity) and temperature (25 °C) over 10 days. The results indicate that this compound has diverse effects on the different endpoints. Nevertheless, this compound can be classified as non-toxic considering its effects on seeds and on soil, at least in the medium- to long-term. [ABSTRACT FROM AUTHOR]

Biochar is a promising pyrolysed carbon-enriched soil amendment and has excellent properties for agriculture production and to remediate environmental pollution. A set of reviews were conducted on biochar production by pyrolysis process from various waste biomass which has drawn extensive interest due to the low cost of production with several benefits. As many potential technologies have been developed, there are still several knowledge gaps that have been identified for some key points to contribute a comprehensive study towards soil fertility, nutrient and water retention, soil microbial activity, plant growth and yield, pollution remediation, mitigation of greenhouse gas emission and an improvement in the farmer's economy to achieve maximum profit by adopting environmentally friendly technique "pyrolysis". Therefore, this review explored a detailed study on food waste biochar production by the pyrolysis process and its impact on different applications as an amendment. Slow pyrolysis process at low and medium temperatures is a potential amendment for agriculture production and soil and water remediation by enhancing biochar properties like carbon, BET surface area, cation exchange capacity, zeta potential, and nutrient content, etc. with minimum ash content. The biochar enhances soil water and nutrient retention capacity, crop yield, and improved microbial community at different soil quality. Additionally, food waste to biochar is a realistic adsorbent and economical carbon sequester to mitigate GHG emissions. This review conducted a brief assessment of the knowledge gaps and future research directions for researchers, encouraging investigators, stakeholders, and policymakers to make the best possible decision for food waste valorization. Highlights: • Valorization of food waste to biochar is a promising amendment for agriculture and soil–water remediation. • Lower and medium pyrolysis temperatures qualitatively changed all aspects of biochar properties. • Biochar improves soil fertility, microbial activity, soil water and nutrient retention capacity, and plants growth. • Biochar is a good carbon sequestrator to mitigate greenhouse gas and a bioeconomy product for the farmer's community and policymakers. [ABSTRACT FROM AUTHOR]

Background: The use of rock powders in soil has emerged as a nature-based technology to improve soil properties relevant to crop development and for atmospheric carbon dioxide removal (CDR) via enhanced rock weathering (ERW). Although modeling this process is crucial, the soil microbiome has been identified as the main reason why several experimental and field results do not fit the geochemical and kinetic theoretical models. Here, the hypothesis that the bacterial community structure is modulated by the application of different silicate rock powders was tested. One phonolite, three basalt variations and one granite, as well as KCl treatments, were applied to a Ferralsol cultivated with Brachiaria in short-term pedogeochemical experiments and assessed after 1 (1M), 4 (4M) and 8 (8M) months. Results: The main changes in soil bacterial structure were observed at 8M and found to be modulated according to rock type, with petrochemistry and mineralogy acting as the main drivers. The content of microbial biomass carbon tended to decrease over time in the Control and KCl treatments, especially at 4M, while the rock treatments showed constant behavior. The sampling time and treatment affected the richness and diversity indices. The Si, Ca and Fe from mafic minerals were the main chemical elements related to the soil bacterial changes at 8M. Conclusions: The type (acidity) of silicate rock powder modulated the soil bacterial community (SBC) in a pot experiment with tropical soil. The specificity of the SBC for each rock type increased with time until the end of the experiment at 8 months (8M). The carbon content in the microbial biomass was lower in the rock powder treatments in the first month (1 M) than in the control and KCl treatments and was equal to or higher than that in the 8 M treatment. This result illustrates the challenge of modeling rock powder dissolution in soil since the soil medium is not inert but changes concurrently with the dissolution of the rock. [ABSTRACT FROM AUTHOR]

Introduction: With the continuous changes in climate patterns due to global warming, drought has become an important limiting factor in the development of terrestrial ecosystems. However, a comprehensive understanding of the impact of drought on soil microbial activity at a global scale is lacking. Methods: In this study, we aimed to examine the effects of drought on soil microbial biomass (carbon [MBC], nitrogen [MBN], and phosphorus [MBP]) and enzyme activity (b-1, 4-glucosidase [BG]; b-D-cellobiosidase [CBH]; b-1, 4-Nacetylglucosaminidase [NAG]; L-leucine aminopeptidase [LAP]; and acid phosphatase [AP]). Additionally, we conducted a meta-analysis to determine the degree to which these effects are regulated by vegetation type, drought intensity, drought duration, and mean annual temperature (MAT). Result and discussion: Our results showed that drought significantly decreased the MBC, MBN, and MBP and the activity levels of BG and AP by 22.7%, 21.2%, 21.6%, 26.8%, and 16.1%, respectively. In terms of vegetation type, drought mainly affected the MBC and MBN in croplands and grasslands. Furthermore, the response ratio of BG, CBH, NAG, and LAP were negatively correlated with drought intensity, whereas MBN and MBP and the activity levels of BG and CBH were negatively correlated with drought duration. Additionally, the response ratio of BG and NAG were negatively correlated with MAT. In conclusion, drought significantly reduced soil microbial biomass and enzyme activity on a global scale. Our results highlight the strong impact of drought on soil microbial biomass and carbon- and phosphorus-acquiring enzyme activity. [ABSTRACT FROM AUTHOR]

Over the last decades, Pinus taeda L. plantations in southern Brazil showed a great increase in average production. However, the gains in productivity obtained by genetic selection and breeding have nowadays stabilized. Research on edaphic factors and silvicultural practices is currently performed with the aim of both increasing the productivity of P. taeda plantations and maintaining the soil quality. To this end, soil microbiological attributes are considered better indicators of soil quality as they are more sensitive than chemical and physical ones. In this study, we aimed to evaluate the relationship between microbial activity and the physical and chemical parameters of different soil types under young Pinus taeda plantations at five different sites in southern Brazil. Soil samples were collected at depths of 0-5 and 5-10 cm. The soil microbiological attributes evaluated were: potentially mineralizable nitrogen (PMN), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial basal respiration (MBR), and metabolic quotient (qCO2). We also evaluated some physical and chemical soil parameters. Sites with the highest values of C, clay, and nutrients in the soil, showed higher values for the soil microbiological attributes, compared to the other study sites. The previous management with minimal tillage in some sites seems to positively affect soil quality. The MCB and MBR showed better sensitivity in indicating differences between sites and showed a good relationship with clay content, C/N ratio, K, and pH. These results suggest that site-specific characteristics such as soil type or forest management influence soil microbiological attributes in Pinus taeda plantations during initial growth in southern Brazil.

Soil residual herbicides are often applied at cover crop termination to extend the period of weed control and reduce the selection pressure for herbicide resistance. Previous studies indicate that one of the benefits of cover crop use is the increase in the activity of enzymes in the soil. Some enzymes are also responsible for breaking down herbicide molecules. The biodegradation of herbicides in the soil is a natural process that leads to a reduction in the concentration of the parent compound overtime. Although cover crop use can result in the increased activity of soil enzymes, to date, there is no evidence that such increased activity also leads to a reduced persistence of residual herbicides in the soil. However, cover crop use does alter the fate of residual herbicides by interception, with some studies reporting more than 90% interception. Without rainfall or irrigation during the days following its application, the herbicide remains on the plant surface and is ineffective as a weed control tool. Following the integrated weed management approach, the combination of cover crop and soil residual herbicides is a promising alternative to delay the development of new herbicide resistance cases. However, more research is needed to understand the impact of biomass accumulation on residual herbicide fate and to determine the best strategies to improve herbicide placement on cover cropping system. This paper reviews the impact of cover crop use on soil microbial activity and the further degradation of soil residual herbicides as well as the fate of residual herbicides when applied at cover crop termination.

Biochar is increasingly being recognized as an effective soil amendment to enhance plant health and improve soil quality, but the complex relationships among biochar, plant resistance, and the soil microbial community are not clear. In this study, biochar derived from an invasive plant (Solidago canadensis L.) was used to investigate its impacts on bacterial wilt control, soil quality, and microbial regulation. The results reveal that the invasive plant biochar application significantly reduced the abundance of Ralstonia solanacearum in the soil (16.8–32.9%) and wilt disease index (14.0–49.2%) and promoted tomato growth. The biochar treatment increased the soil organic carbon, nutrient availability, soil chitinase, and sucrase activities under pathogen inoculation. The biochar did not influence the soil bacterial community diversity, but significantly increased the relative abundance of beneficial organisms, such as Bacillus and Sphingomonas. Biochar application increased the number of nodes, edges, and the average degree of soil microbial symbiotic network, thereby enhancing the stability and complexity of the bacterial community. These findings suggest that the invasive plant biochar produces win–win effects on plant–soil systems by suppressing soilborne wilt disease, enhancing the stability of the soil microbial community network, and promoting resource utilization, indicating its good potential in sustainable soil management. [ABSTRACT FROM AUTHOR]

Cave ecosystems, which represent a very specific environment for living organisms, are largely influenced by the external environment. These systems are among the most vulnerable ecosystems because they are extremely sensitive to any environmental changes. The main aim of this study was to analyse the biological and chemical indices of soil samples collected in the Karst region. Soil organic carbon, total nitrogen content, soil pH, activity of selected soil enzymes (FDA, ß-glucosidase, urease, phosphatases), and content of risk elements were determined at nine sites around Ponická Cave. Enzymatic activity reduces its function under the influence of inappropriate agricultural activity as well as the high content of risk elements. Ponická Cave is characterized by a close hydrological connection with the earth's surface, thus representing a very vulnerable habitat, which deserves more attention in the protection of natural elements of the landscape. Very high concentration of toxic elements (As, Cd, Co, Cu, Fe, Mn, Pb and Zn) was recognized on localities that are close to the cave entry, which in higher concentrations cause contamination of underground ecosystems. The results showed that risk elements have an impact on important soil parameters, such as the enzymatic activity of the microbial population and chemical properties. In view of the risks associated with water erosion and rainwater runoff from non-karst lands, agricultural activity in these soils should be completely excluded. [ABSTRACT FROM AUTHOR]

The use of artificial fertilizers follows the intensification of agricultural production as a consequence of population growth, which leads to soil depletion, loss of organic matter, and pollution of the environment and production. This can be overcome by increasing the use of organic fertilizers in agriculture. In the present study, we investigated the effect of using vermicompost, biochar, mineral fertilizer, a combination of vermicompost and mineral fertilizer, and an untreated control on alluvial-meadow soil on the development of fodder winter barley Hordeum vulgare L., Zemela cultivar. We used a randomized complete block design of four replications per treatment. Barley grain yield, number of plants, and soil and microbiological parameters were studied. We found statistically proven highest grain yield and grain protein values when applying vermicompost alone, followed by the combined treatment and mineral fertilizer. The total organic carbon was increased by 70.2% in the case of vermicompost and by 44% in the case of combined treatment, both compared to the control. Thus, soil microbiome activity and enzyme activities were higher in vermicompost treatment, where the activity of β-glucosidase was 29.4% higher in respect to the control, 37.5% to the mineral fertilizer, and 24.5% to the combined treatments. In conclusion, our study found the best overall performance of vermicompost compared to the rest of the soil amendments.

Abstract Introduction Despite their potential benefits, it is not well understood how the application of biostimulants influences soil biological properties and their microbial communities in field conditions. In this study, we aimed to evaluate the impacts of biostimulants on soil biological and physicochemical properties relevant to soil health. Materials and Methods To achieve this, we conducted a field study to investigate the effects of two types of commercially available biostimulants, Universal Natural Plant food (UNP) and Converte Seed Primer (CSP), on microbial activity, bacterial and fungal abundance, community structure and diversity, and soil chemical and physical properties across two depths (0–10 and 10–20 cm) from five sites under either wheat or pasture cultivation. Results Our findings suggest that application of UNP stimulated microbial activity by 40.1% in surface (0–10 cm) and 36.4% in deeper (10–20 cm) soil, but was dependant on site. Effects were generally greater in grasslands compared with arable soils. At sites where UNP stimulated microbial respiration, substrate‐induced respiration was also stimulated in surface soils and was associated with increased soil moisture content and higher total carbon and nitrogen. At the one site where UNP was combined with CSP, soil enzymes associated with carbon and nitrogen cycling were stimulated in UNP and UNP + CSP treatments. Total bacterial and fungal abundance and their alpha diversity did not respond to biostimulant treatment. However, microbial indicator communities were identified that responded positively to UNP and CSP addition across the two depths. Bacterial indicator species included Elsterales, Propionibacteriales, Solibacterales, Candatus, Reyranellales and Sphingomonadales, but differed between depths. For the fungal indicator species Filobasidiales (Basidiomycota) and Pleosporales (Ascomycota) were strong responders and common across both depths. Conclusion Overall, our results suggest some positive effects of biostimulants on soil biological and physicochemical properties. Further long‐term studies should be conducted to evaluate the effects of biostimulants on crop yield and farm resilience.

In this work, three wheat crops were planted successively under semi-arid climatic conditions; we wished to evaluate the positive and negative effects of the addition of sewage sludge (SS) on plants and soils under the conditions encountered during conventional agricultural management. SS was added to the first two crops at doses equivalent to 170 kg N/ha, and the third crop was left untreated. The soils were sampled initially and at the end of each cultivation period. At the end of the third crop’s cultivation period, the heavy metal and organic pollutant contents of grain and straw were analyzed, as well as the presence of Escherichia coli and Salmonella. The amended soils showed a higher N content, greater microbial respiration, and greater dehydrogenase and phosphatase activity than the control. The amended plants showed higher N, Ca, and K contents than the control. Yields were 11% and 16% higher in the SS-amended soils than in the control in the experiments involving the second and third crop, respectively. No problems related to salinity or the heavy metal content were observed in both the soil and plant. However, nitrate content increased in the amended soils compared to the control. Among the persistent organic compounds, only linear alkyl benzene sulphonates and polycyclic aromatic hydrocarbons increased with the addition of SS, but such differences from the control disappeared gradually. No problematic coliform content or presence of Salmonella spp. was detected in the soil or plant. We can thus conclude that SS of adequate quality can be recycled in agricultural soils, but adequate monitoring of the receiving soil is crucial.

The applicability of ionic liquids has grown exponentially over the last few decades. This growth is due to the easy modification of these compounds formed by ions, through the proper choice of both moieties, and the possibility of introducing functional groups into their cations and anions. However, studies of their toxicity and effects on the environment remain scarce. This study analyses firstly the response to adding different concentrations of choline dihydrogen phosphate to the germination of seeds of eight plant species. It also examines the microbial population and the respiration of two soils with contrasting organic matter contents. Seeds were incubated in a Petri dish in a Phytotron with a photoperiod of 16 h under light at 24 °C and 8 h in darkness at 16 °C. The activity of microbial populations of untreated and treated soils was analysed by isothermal microcalorimetry at 25 °C. Basal soil respiration kinetics were measured at optimal moisture (80% of field water retention capacity) and temperature (25 °C) over 10 days. The results indicate that this compound has diverse effects on the different endpoints. Nevertheless, this compound can be classified as non-toxic considering its effects on seeds and on soil, at least in the medium- to long-term.

Soil proteinase and proteinase-producing microbial community are closely associated with soil fertility and soil health. Sea rice has been planted in the coastal beach of Jiaozhou Bay, China, in an effort to transform saline-alkali soil into arable land. However, the knowledge regarding the bacterial degradation of organic nitrogen in sea rice soils is limited. This study aims to investigate the physicochemical characteristics and enzymatic activities of the sea rice soils, as well as the microbial communities by both the Illumina sequencing-based culture-independent technology and culture-dependent methods. Sea rice soils exhibited a lower salinity and higher organic matter content and proteinase activity, as well as an increase in both the richness and diversity of the proteinase-producing bacterial community, compared to the adjacent non-rice soils. The Proteobacteria phylum and the Gammaproteobacteria class were dominant in sea rice soils, showing higher abundance than in the reference soils. The Planococcus genus and Bacillus-like bacterial communities were abundant in the cultivable proteinase-producing bacteria isolated from sea rice soils. Furthermore, a significant proportion of the extracellular proteinase produced by the isolated soil bacteria consisted of serine proteinases and metalloproteinases. These findings provided new insights into the degradation of soil organic nitrogen in coastal agricultural regions. [ABSTRACT FROM AUTHOR]

The responses of dominant species to plant–soil feedback (PSF) are well established; however, the changes in the PSF of companion species remain unclear. This study aims to assess the direction and intensity of PSF, determine the main factors influencing it, and interpret the ecological significance of PSF in companion species within the context of grassland community succession. Three typical companion species, namely Artemisia sacrorum, Artemisia capillaris, and Artemisia giraldii, were planted in soils at three grassland community succession stages (early, middle, and late) on the Loess Plateau. Our results indicate that during both plant growth periods, the shoot biomass of A. sacrorum, A. capillaris, and A. giraldii in early- and late-stage soils was higher than that in the middle-stage soil, suggesting consistent growth of the three companion species during the two growth periods. However, plant growth simultaneously led to a reduction in soil nutrient content and microbial biomass, resulting in an overall decrease in the biomass of the three species, indicating a negative PSF effect in companion species. In conclusion, the negative PSF observed in all three associated species explains the temporary dominance of companion species during succession. This study enhances our understanding of the mechanisms driving PSF in community succession. [ABSTRACT FROM AUTHOR]

The patterns of soil physicochemical properties at large-scales such as buffer zone have been extensively studied, while at fine-scales of vegetation buffer strips (represent a trade-off between economic and ecology benefits of land) and the relationship with vegetation biodiversity are yet to be deepened. This study focused on the discrepancy between soil physicochemical properties (categorizing as soil properties, soil texture, soil stoichiometric ratio, soil microbial activity) and vegetation biodiversity indices in the buffer strips of newly constructed Chushandian reservoir, China. The results showed that the woodland buffer strips had higher soil microbial activity and carbon sequestration capacity than grassland and abandoned cropland. Soil physicochemical properties at 0 m in the reservoir buffer strips with three land use types were more influenced by the overlying water. Distance from watercourse is an important factor affecting soil properties in the reservoir buffer strips with different land use types, mainly mediated by affecting the vegetation biodiversity indices. The width of the existing grassland and abandoned cropland (20 m) is not enough for ecological restoration and should be appropriately widened. Finally, we suggest that the restoration of reservoir buffer strips should be set with flexible width according to the previous land use types. [ABSTRACT FROM AUTHOR]

IntroductionThe incidence of drought periods and its continuity in arid and semi-arid areas is considered one of the factors affecting soil microbial population and activity and soil water content, and thus affect soil fertility and nutrient availability. Implementation of the straw checkerboard barrier technique in these areas as a cheap, effective, and easy technology has an important role in reviving soil microbial communities and desertification control. In the present study, the effect of the straw checkerboard barriers technique on moisture retention, soil microbial population and their CO2 production was investigated.Materials and MethodsThis research was carried out in a semi-arid region prone to wind erosion with damaged soil communities, in which the straw checkered barrier technique was established to control wind erosion. For this purpose, 5 t.ha-1 of rice (Oryza sativa L.) straws were arranged in 1 m × 1 m checkerboard patterns in January 2018. This research was carried out in a part of the “ Margh” meadow the south of Shahrekord, the capital of Chaharmahal and Bakhtiari province (50° 50 ́E, 32° 17 ́N). Then the effect of this technique on soil microbial properties, including respiration and soil microbial biomass as well as moisture retention and aggregate stability, were considered. The same area was also dedicated for control as bare ground. Several straw squares were randomly selected, and the trend of changes in microbial respiration and soil moisture in the border of barriers, the center of barriers, and bare ground were measured in several stages. Also in the fourth stage of microbial respiration determination, microbial biomass, and aggregate stability were measured too. Microbial respiration and soil moisture data were analyzed based on a split-plot experiment in time in a randomized complete block design, and microbial biomass data and weight and geometric mean particle diameter were analyzed based on a randomized complete block design.Results and DiscussionThe results indicate that soil water content at the borders of the barriers significantly increased compared to the center of the barriers and the bare ground by 10.91% and 18.56%, respectively. Soil water content at the borders of the barriers was maintained for a longer time compared to the bare ground, but the decreasing trend of soil moisture in the bare ground was steeper over time, reaching the lowest position compared to the others. This can be attributed to the reduction of wind speed and shading of straws on the soil surface, creating a safer microclimate near the soil surface. The addition of rice straw in the form of checkered barriers to the soil significantly increased carbon mineralization compared to the bare ground in all measurement stages. In the first stage, the amount of CO2-C produced at the borders and center of the barriers increased by 37.76% and 14.69%, respectively, compared to the bare ground. On July 5th, CO2-C production decreased significantly. From July 15th to October 28th, the trend of carbon mineralization at the borders and center of the barriers and bare ground showed a steady state with lower values for the bare ground. Residue incorporation in soils may increase C mineralization and have a positive priming effect for accelerating soil organic carbon (SOC) decomposition. The establishment of straw checkerboard barriers alleviated the effects of moisture deficiency on soil microbial activity and increased carbon mineralization. The higher rates of microbial respiration in the barriers indicate the efficiency of the straws added to the soil and the better adjustment of drought conditions in the soil. The highest soil microbial biomass and aggregate stability were observed at the borders of the barriers, which was significantly different from the bare ground. The return of residues to the soil increased aggregate stability, which may be due to the improvement of organic matter and soil porosity.ConclusionThe results of this study indicate that the implementation of straw checkerboard barriers improved the soil's biological properties, moisture content and aggregates stability and can provide a better microclimate for plant establishment and growth, which may lead to higher conservation of natural resources and sustainable production.

A study was undertaken in the Vaishali district of Bihar, India, in 2020 to assess the effect of various agroforestry systems (AFS) on the distribution of different pools of soil organic carbon (fraction I - very labile, fraction II - labile, fraction III - less labile and fraction IV - non-labile), carbon stocking and soil microbial activity. The mean (0-45 cm) total organic carbon (TOC) in different AFS ranged from 5.55 to 6.64 Mg C ha-1, with the highest under poplar-based AFS (PB-AFS). Across the AFS studied, the C stocks (0-45 cm) varied from 36.24 (mango-based AFS) to 41.43 Mg C ha-1 (PB-AFS). Overall, the magnitude of C fractions showed the order: fraction I > fraction IV > fraction III > fraction II. Significantly higher soil microbial biomass carbon was recorded under PB-AFS (219.36 μg g-1) in 0-15 cm depth. Basal respiration was also the highest under PB-AFS (0.54 μg CO2-C g-1 h-1), followed by TB-AFS (0.50 μg CO2-C g-1 h-1) in 0-15 cm depth. Principal component analysis result showed that PC 1 and PC 2 represented about 97% of the total variation. TOC and active carbon pool had the maximum loading in PC 1, while microbial metabolic quotient and bulk density had the maximum value in PC 2. [ABSTRACT FROM AUTHOR]

Purpose: Improving crop yields by increasing fertilizer-use-efficiency is essential to minimizing agriculture's environmental impact. Water-dispersible carbon nanomaterials (CNM) have emerged as an innovative material to improve crop yields by increasing nutrient utilization and enhancing crop physiological processes. However, the optimum dose of CNM, performance on crop growth, and impact on soil biochemical properties remain poorly understood. Methods: A greenhouse pot experiment (55 days) was conducted to evaluate the effect of three CNM rates, applied basally as a soil drench amendment, on the growth of two lettuce varieties and soil biochemical properties. We compared three CNM rates (200, 400 & 800 mg kg−1; C200F, C400F & C800F) along with a negative control (C0F0; no fertilizer or CNM) and a positive control (C0F; fertilizer at recommended doses like CNM treatments, no CNM applied). Results: We found that nitrogen (N), phosphorus and potassium (K) accumulation by lettuce and availability in soil were enhanced with CNM application, with 31% (C200F) and 34% (C400F) increases in shoot N accumulation compared to C0F, and K accumulation peaking at C800F (230% increase over C0F). Compared to C0F, soil microbial biomass carbon was 67–180% (C200F) or 42–150% (CF400) higher, phosphatase enzyme activity was 29–32% higher with C200F, and urease enzyme activity was 37–38% higher at C400F, indicating greater soil biological activity at lower application rates. Conclusion: Overall, CNM (200–400 mgkg−1 soil) promoted lettuce growth, enhanced soil fertility and soil biological activity, elucidating that water-dispersible CNM can be an alternative soil amendment to improve crop growth and soil biochemical quality. [ABSTRACT FROM AUTHOR]

IntroductionWith the continuous changes in climate patterns due to global warming, drought has become an important limiting factor in the development of terrestrial ecosystems. However, a comprehensive understanding of the impact of drought on soil microbial activity at a global scale is lacking.MethodsIn this study, we aimed to examine the effects of drought on soil microbial biomass (carbon [MBC], nitrogen [MBN], and phosphorus [MBP]) and enzyme activity (β-1, 4-glucosidase [BG]; β-D-cellobiosidase [CBH]; β-1, 4-N-acetylglucosaminidase [NAG]; L-leucine aminopeptidase [LAP]; and acid phosphatase [AP]). Additionally, we conducted a meta-analysis to determine the degree to which these effects are regulated by vegetation type, drought intensity, drought duration, and mean annual temperature (MAT).Result and discussionOur results showed that drought significantly decreased the MBC, MBN, and MBP and the activity levels of BG and AP by 22.7%, 21.2%, 21.6%, 26.8%, and 16.1%, respectively. In terms of vegetation type, drought mainly affected the MBC and MBN in croplands and grasslands. Furthermore, the response ratio of BG, CBH, NAG, and LAP were negatively correlated with drought intensity, whereas MBN and MBP and the activity levels of BG and CBH were negatively correlated with drought duration. Additionally, the response ratio of BG and NAG were negatively correlated with MAT. In conclusion, drought significantly reduced soil microbial biomass and enzyme activity on a global scale. Our results highlight the strong impact of drought on soil microbial biomass and carbon- and phosphorus-acquiring enzyme activity.

Biochar is increasingly being recognized as an effective soil amendment to enhance plant health and improve soil quality, but the complex relationships among biochar, plant resistance, and the soil microbial community are not clear. In this study, biochar derived from an invasive plant (Solidago canadensis L.) was used to investigate its impacts on bacterial wilt control, soil quality, and microbial regulation. The results reveal that the invasive plant biochar application significantly reduced the abundance of Ralstonia solanacearum in the soil (16.8–32.9%) and wilt disease index (14.0–49.2%) and promoted tomato growth. The biochar treatment increased the soil organic carbon, nutrient availability, soil chitinase, and sucrase activities under pathogen inoculation. The biochar did not influence the soil bacterial community diversity, but significantly increased the relative abundance of beneficial organisms, such as Bacillus and Sphingomonas. Biochar application increased the number of nodes, edges, and the average degree of soil microbial symbiotic network, thereby enhancing the stability and complexity of the bacterial community. These findings suggest that the invasive plant biochar produces win–win effects on plant–soil systems by suppressing soilborne wilt disease, enhancing the stability of the soil microbial community network, and promoting resource utilization, indicating its good potential in sustainable soil management.

Aflatoxins (AFs) are fungal secondary metabolites frequently detected in soil that exhibit in vitro toxicity to certain soil microorganisms. However, microbial responses at different levels and in complex systems such as the soil environment have not been systematically studied. Therefore, we investigated multiple microbial responses in two different soils (sandy loam and clay) to aflatoxin B1 (AFB1) at environmentally relevant concentrations (0.5–500 µg kg−1) during a 28-day incubation. General microbial parameters for biomass (microbial biomass carbon and ergosterol), activity (glucose-induced and basal respiration), and catabolic functionality (substrate utilization patterns) were assessed. We observed minor and transient effects in both soils. In sandy loam, we found negative effects on activity and catabolic functionality with increased metabolic quotient, while clay soil exhibited stimulation for the same parameters, suggesting a hormetic effect due to reduced bioavailability through sorption onto clay minerals. Our results indicate that AFB1 does not pose a threat to general microbial indicators under the test conditions in soils without previous AF contamination. Given the toxic potential of AFs to specific microorganisms, further studies should investigate responses at higher taxonomic and functional levels in natural environments of aflatoxigenic fungi, such as tropical soils, and including additional physicochemical stressors. [ABSTRACT FROM AUTHOR]

Soil microorganisms are critical biological indicators for evaluating soil health and play a vital role in carbon (C)-climate feedback. In recent years, the accuracy of models in terms of predicting soil C pools has been improved by considering the involvement of microbes in the decomposition process in ecosystem models, but the parameter values of these models have been assumed by researchers without combining observed data with the models and without calibrating the microbial decomposition models. Here, we conducted an observational experiment from April 2021 to July 2022 in the Ziwuling Mountains, Loess Plateau, China, to explore the main influencing factors of soil respiration (RS) and determine which parameters can be incorporated into microbial decomposition models. The results showed that the RS rate is significantly correlated with soil temperature (TS) and moisture (MS), indicating that TS increases soil C loss. We attributed the non-significant correlation between RS and soil microbial biomass carbon (MBC) to variations in microbial use efficiency, which mitigated ecosystem C loss by reducing the ability of microorganisms to decompose organic resources at high temperatures. The structural equation modeling (SEM) results demonstrated that TS, microbial biomass, and enzyme activity are crucial factors affecting soil microbial activity. Our study revealed the relations between TS, microbial biomass, enzyme activity, and RS, which had important scientific implications for constructing microbial decomposition models that predict soil microbial activity under climate change in the future. To better understand the relationship between soil dynamics and C emissions, it will be necessary to incorporate climate data as well as RS and microbial parameters into microbial decomposition models, which will be important for soil conservation and reducing soil C loss in the Loess Plateau. [ABSTRACT FROM AUTHOR]

While numerous studies focus on the ecosystem effects of invasive mammals, few explore the causal mechanisms of such effects. Wild boar is one of the most widely introduced invasive mammal species in the world. By overturning extensive areas of vegetation and soil to feed on belowground resources, wild boar alter the soil food web and thus many microbial-mediated soil processes. Here, we take advantage of a long-term, 8-year, wild boar exclosure experiment across three plant community types in Patagonia, Argentina to explore how wild boar impact soil communities and their potential function. Previous work in this experimental system found that wild boar significantly impacted litter decomposition in the field, but it remained unclear if this effect was mediated through changes in abiotic or biotic soil properties. To explore both the abiotic and biotic drivers of decomposition, we measured soil moisture, soil temperature, soil bulk density, and soil respiration as well as soil micro-arthropod richness and abundance, earthworm abundance, and microbial biomass inside and outside of 10 exclosures in each of three plant community types. To assess potential microbial activity, we measured potential decomposition rates, substrate-induced respiration, and soil microbial enzyme activity. Rooting decreased soil moisture by 18% across plant communities, and soil respiration by 30% in Nothofagus and Austrocedrus forests. Additionally, rooting decreased soil micro-arthropod richness and abundance by ~ 80% in shrublands. However, rooting had no effect on soil potential microbial activity. Together, our results suggest that changes in both abiotic and biotic soil factors likely mediate observed wild boar impact on decomposition rates. Overall, we show that wild boar rooting alters soil functioning, but the pathway of impact varies by plant community, suggesting that wild boar impacts on native ecosystems can be difficult to predict. [ABSTRACT FROM AUTHOR]

The effects of inoculations with a N2-fixing cyanobacterium (Anabaena cylindrica) on nutrient and microbial dynamics of an arable Mollisol were studied under simulated high intensity rainfall. Inoculated and non-inoculated pots (controls) were incubated for 14 days and then subjected to three rain events in 1 week, followed by three weekly events for a total of six events. Soil samples at three depth layers (0–1, 5–6, and 10–11 cm) were taken at four time points: 1 day after inoculation, 14 days after inoculation, after rain 1, and after rain 6. Soil chlorophyll a (Chla), soluble fractions of N (SolN) and organic C (SolC), microbial biomass C (MBC) and N (MBN), microbial activity (FDA hydrolysis), and soil respiration (CO2 efflux) were determined. Results revealed depth-related changes in Chla, SolC, SolN, MBC, MBN, and FDA hydrolysis with greater effects at the surface layer (0–1 cm). Soil respiration varied with soil moisture and increased in inoculated treatments. After all rain simulations (49 days after inoculation), higher SolC, MBC, MBN, and FDA hydrolysis in surface soil of inoculated treatments indicated positive changes that persisted after consecutive rains. These findings suggest that cyanobacterial soil amendments might enhance soil quality and resiliency in agricultural soils exposed to high intensity rainfall. [ABSTRACT FROM AUTHOR]

The effects of elevated atmospheric carbon dioxide concentration (e[CO 2 ]) and temperature (e°T) on various traits of oat (Avena sativa L.) varieties using open-top chambers (OTC) were investigated. A simulated environment was created for the experiment i.e., ambient temperature and CO 2 (a°T + a[CO 2 ]); elevated temperature (3 °C > ambient temperature) (e°T); elevated CO 2 (550 ± 50 ppm) (e[CO 2 ]); and a combination of ambient temperature with elevated CO 2 (a°T + e[CO 2 ]), for accessing the effect of e°T and e[CO 2 ] on oats. a°T + e[CO 2 ] increased plant height to 121 cm compared to 114 cm in a°T + a[CO 2 ] and 111 cm in e°T + e[CO 2 ]. Seed weight was highest in a°T + e[CO 2 ] (3.09 g) compared to 2.53 g in a°T + a[CO 2 ] and 2.60 g in e°T + e[CO 2 ]. Leaf number and tillers were significantly higher in a°T + e[CO 2 ] (61.4 leaves, 10 tillers) than in a°T + a[CO 2 ] (27.6 leaves, 5.6 tillers) and e°T + e[CO 2 ] (44.3 leaves, 6.93 tillers). Chlorophyll content was highest in a°T + e[CO 2 ] (5.13 mg/g) compared to 3.61 mg/g in a°T + a[CO 2 ] and 1.47 mg/g in e°T + e[CO 2 ]. In contrast, germination rate was best in a°T + a[CO 2 ] (81.6 %) compared to e°T + e[CO 2 ] (60.3 %) and a°T + e[CO 2 ] (63.1 %). Malondialdehyde (MDA), a stress marker, was significantly higher in e°T + e[CO 2 ] (1.35 nmol/g) compared to a°T + a[CO 2 ] (0.299 nmol/g). Membrane stability index (MSI) was lowest in e°T + e[CO2] (13.2) compared to 20.9 in a°T + a[CO 2 ], indicating greater stress under e°T + e[CO 2 ]. Starch content in a°T + e[CO 2 ] (14.6 %) was more than double that of a°T + a[CO 2 ] (7.09 %). Microbial activity also showed significant differences. Dehydrogenase was highest in e°T + e[CO 2 ] (13.86 µg/g/day) compared to a°T + a[CO 2 ] (8.80) and a°T + e[CO 2 ] (12.62). Total bacterial count (TBC) increased in e°T + e[CO 2 ] (72) compared to a°T + a[CO 2 ] (61). Similarly, phosphate-solubilizing bacteria (PSB) and fungi (PSF) were highest in e°T + e[CO 2 ] (PSB: 104.5, PSF: 8.5) compared to a°T + a[CO 2 ] (PSB: 75.0, PSF: 4.0). Rhizobium and Azotobacter counts were elevated in a°T + e[CO 2 ] (95 and 94) compared to a°T + a[CO 2 ] (72.5 and 42.0), showing a strong positive impact of e[CO 2 ] on microbial populations. Specific oat varieties such as JHO-2000–4 and JHO-99–2 performed best under these conditions, showing higher yields and better stress tolerance. While e[CO 2 ] offers substantial benefits to oat plant growth and soil microbial activity, the additional stress from e°T complicates these benefits. [Display omitted] • e[CO 2 ] enhanced photosynthesis, growth, and yield in oat plants. • Elevated temperature and e[CO 2 ] improved microbial activity and soil enzyme functions. • Combined stress of e[CO 2 ] and temperature caused mixed outcomes in oat traits. • Specific oat varieties showed higher yields and better stress tolerance under stress. • Study aids in developing climate-resilient oat varieties for sustainable agriculture. [ABSTRACT FROM AUTHOR]

Despite growing interest in soil microbial resource limitation (MRL), the impacts of clipping-and-burning on bacterial resource acquisition and its soil carbon, nitrogen, and phosphorous stoichiometry (C:N:P) remain unclear, yet are critical for nutrient cycling and SOC accumulation in vegetation restoration. We examined the soil C:N:P and eco-enzymatic stoichiometry, bacterial life-history strategies, and bacterial resource limitation under the influence of clipping-and-burning management practices: high-intensity fire (HIF), low-intensity fire (LIF), clipping-and-fire (CF), clipping (CP), and an undisturbed control (CK) in a Karst site in southwest China. The results showed that SOC, TN, and TP in HIF and LIF were significantly (p < 0.05) reduced (by 64%, 97%, and 99%) compared to CK. However, soil C:N, C:P, and N:P ratios were surprisingly higher (18.1, 56, and 3.08) in CF than in CK. The ratios of soil microbial biomass carbon (MBC) and nitrogen (MBN) were higher (4.8) under clipping. In contrast, their ratios with microbial biomass phosphorus (MBP) were observed to be higher (22.3 and 6.4) under high-intensity fire compared to CK. Moreover, results show that there is a higher percentage of species linked with oligotroph bacteria of Rickettsiales in CF treatments than CK. Soil bacterial communities in CF treatments exhibited co-limitation by C and P, whereas N limitation was more pronounced under low-intensity fire conditions. In conclusion, the evidence links MRL to soil C:N:P stoichiometry, underscoring the critical role of oligotrophic bacteria in mediating soil nutrient dynamics under clipping-and-burning disturbances. These findings improve our understanding of MRL over the Karst region under clipping-and-burning treatments, shedding light on its relationship with soil C:N:P, eco-enzymatic stoichiometry, and bacterial life-history strategies. • Fire and clipping alter soil microbial communities and nutrient dynamics. • Oligotrophic bacteria dominate in nutrient-limited conditions. • Fire and clipping cause shifts in microbial life history, inducing C-N-P stoichiometry. • Oligotrophic bacteria contribute to SOM stabilization under fire and clipping. [ABSTRACT FROM AUTHOR]

• Forested areas are crucial for carbon reserves in Atlantic Forest. • Soil biological attributes are affected by seasonality and plant cover. • Mycorrhizal attributes are sensitive indicators of soil quality and land use. The objective of this study was to determine the biochemical and microbiological attributes in areas with different vegetation covers (mature forest, secondary forest, and sugar cane monoculture) and seasonal changes, and to compare the sensitivity of these attributes types (mycorrhizal, enzymatic, and carbon attributes) in response to changes in vegetation cover and season. Soil samplings were conducted over two years (one per semester, during the dry and wet periods of 2007 and 2008) in three types of areas: (I) mature forest; (II) secondary forest; and (III) sugar cane crop. The enzymatic activity of fluorescein diacetate, dehydrogenase, saccharase, basal carbon respiration, the carbon content of microbial biomass, the microbial coefficient, total and easily extracted glomalin soil-related proteins, mycorrhizal colonization, the number of glomerospores, total organic carbon, fulvic and humic acid content, and the fulvic/humic acid ratio were analyzed. In general, mycorrhizal parameters were more sensitive in distinguishing areas with different types of vegetation cover. Additionally, carbon stocks in areas of mature and secondary forest were higher compared to areas cultivated with sugar cane. The study reveals that mycorrhizal properties, such as root colonization and GRSP fractions, are more sensitive indicators of soil health than soil C attributes, providing a cost-effective alternative for evaluating soil health in the Atlantic Forest. The confirmed hypothesis supports the effectiveness of microbiological activity and C dynamics in discerning significant changes between sugar cane cultivation and forested areas. The study underscores the vital role of conserving forested areas, serving as crucial carbon reservoirs, and emphasizes the potential for enhanced sustainability through conservation practices and rapid soil function recovery in secondary forests within the Atlantic Forest. [ABSTRACT FROM AUTHOR]

EL-FAME (ester-linked fatty acid methyl ester), PLFA (phospholipid fatty acid), and qPCR (quantitative PCR) of ribosomal genes are three of the most common methods used to quantify soil microbial communities due to their versatility. The reliability of these three methods has not been simultaneously compared in situations of rapid (in the frame of days and weeks) changes in soil microbial abundances. For this purpose, we (i) incubated badland, cropland, and forest soils with nutrients or antibiotics for 2, 7, 14, and 28 days, (ii) quantified total, bacterial, and fungal abundances through EL-FAME, PLFA, and qPCR methods, and (iii) measured soil basal respiration (as indicator of living biomass). The general dynamic patterns of the three soil microbial fractions in response to soil addition of nutrients and antibiotics were captured by the three methods, which led to strong and positive associations between the abundances of total microorganisms, bacteria, and fungi measured by the three procedures. However, these relationships were stronger between the EL-FAME and PLFA results. Further, soil basal respiration was associated to a higher extent with total, bacterial, and fungal abundances captured by EL-FAME and PLFA analyses than with those measured by qPCR, which suggests that the first two methods are most closely related to the soil living microbial community. In general, dynamics in the abundance of total and bacterial communities were better captured than those of fungi by the three methods. The PLFA analysis seems to perform better than the EL-FAME method in forest soil and in detecting the small antibiotic-induced decreases in microbial abundances. Since the EL-FAME method is cheaper and allows a much faster processing of samples than the PLFA method, and the reliability of both methods is similar in detecting rapid changes of soil microbial abundances, choosing EL-FAME over PLFA may be advantageous in most cases. • EL-FAME, PLFA, and qPCR were compared for change detection in microbial abundances. • The general microbial dynamic patterns were captured by the three methods. • EL-FAME and PLFA data were associated to a higher extent than qPCR results. • EL-FAME and PLFA results correlated better with soil basal respiration than qPCR. • EL-FAME is much faster and as reliable as PLFA, its selection is advantageous. [ABSTRACT FROM AUTHOR]

Appropriately using phosphorus (P) for the fertilization of sugarcane is critical to achieving high productivity because it is one of the most limiting nutrients in agricultural cropping systems. Thus, the objective of this research was to evaluate the morphological, biochemical, and yield responses of sugarcane, and the soil microbial–chemical properties, under the use of organomineral fertilizer (OF) associated or not with Bacillus velezensis strain UFV 3918 (B) combined with mono ammonium phosphate (MAP) doses. The experimental design used was completely randomized, consisting of eight treatments [Control (3/3 MAP); OF (without MAP); OF + 1/3 MAP; OF + 2/3 MAP; OF + 3/3 MAP; B + OF + 1/3 MAP; B + OF + 2/3 MAP; B + OF + 3/3 MAP] and four replicates. B + OF + 1/3 MAP provided increases in accumulated soil basal respiration (11.9%), carbon of microbial biomass (35.9%), fluorescein diacetate (12.7%), arylsulfatase (25.5%), and acid phosphatase (10.1%) activity compared to the control, which implied in higher shoot and total biomass. These results present a potential strategy for sugarcane fertilization, using bacteria in combination with OF to improve P nutrition and growth in sugarcane with reduced economic and environmental impact. [ABSTRACT FROM AUTHOR]

In vineyards, the under-vine area is managed to control vegetation growth and to reduce the competing effect of growing plants on vines and fruit development. Applied under-vine management methods are the application of herbicides, soil tillage or the growth of spontaneous vegetation or cover crops. These methods affect pedo-climatic conditions differentially as well as the soil biota and have, therefore, consequences on soil functions and ecosystem services. In the presented case study, the effects of five under-vine management methods on the activity of soil hydrolytic enzymes, the soil water content, vine photosynthetic activity, shoot pruning weight, grape yield and quality are investigated in a vineyard in Lower Austria over three consecutive seasons. Thereby, we hypothesise that a permanent under-vine vegetation cover, either mowed or without mowing, supports the soil microbial communities and soil functions in a way to enhance water and nutrients availability for vines which partly compensates for the competition of the growing vegetation. Our results confirm effects on the soil water balance, more specifically, a reduced soil water content in 11 -20 cm soil depths induced by a permanent vegetation cover as compared to herbicide application or soil tillage. Further consequences of permanent vegetation below vines were lower shoot pruning weights and lower berry weights, while total soluble solids and titratable acidity were not affected. The vine's photosynthetic activity, as well as the soil water content, were partly affected by treatments dependent on the precipitation ahead of the measurement. In parallel, the soil microbial activity was significantly enhanced by a permanent vegetation cover below the vines as compared to herbicide application, a trend which increased with the years of the project. In conclusion, permanent under-vine vegetation strongly promoted soil microbial activity without strong effects on shoot pruning weight, grape yield and quality. In the next step, a functional proof is necessary to characterise the interaction between soil microbial activity, soil water balance and vine nutrition and water status by using sensors for continuous measurements.

Soil proteinase and proteinase-producing microbial community are closely associated with soil fertility and soil health. Sea rice has been planted in the coastal beach of Jiaozhou Bay, China, in an effort to transform saline-alkali soil into arable land. However, the knowledge regarding the bacterial degradation of organic nitrogen in sea rice soils is limited. This study aims to investigate the physicochemical characteristics and enzymatic activities of the sea rice soils, as well as the microbial communities by both the Illumina sequencing-based culture-independent technology and culture-dependent methods. Sea rice soils exhibited a lower salinity and higher organic matter content and proteinase activity, as well as an increase in both the richness and diversity of the proteinase-producing bacterial community, compared to the adjacent non-rice soils. The Proteobacteria phylum and the Gammaproteobacteria class were dominant in sea rice soils, showing higher abundance than in the reference soils. The Planococcus genus and Bacillus-like bacterial communities were abundant in the cultivable proteinase-producing bacteria isolated from sea rice soils. Furthermore, a significant proportion of the extracellular proteinase produced by the isolated soil bacteria consisted of serine proteinases and metalloproteinases. These findings provided new insights into the degradation of soil organic nitrogen in coastal agricultural regions.

Cadmium (Cd) pollution has led to a serious deterioration in soil quality, plant growth, and human health. Therefore, restoration of soil quality is imperative. Phytoremediation is inexpensive and yields acceptable outcomes. Phytoremediation involves interaction between plant physiology and microbial activity and has been widely used in the remediation of Cd-contaminated soil. In the present study, Lolium perenne L. (perennial ryegrass) was planted in Cd-spiked soil and indole-3-acetic acid (IAA) was used to explore the physiological and biochemical characteristics of ryegrass as well as soil enzyme activity to remove Cd. The present study provides a theoretical basis for the phytoremediation of Cd-contaminated soil. The study investigated the effect of 30-mg/kg Cd-spiked soil on ryegrass (C) and 30-mg/kg Cd-spiked soil on ryegrass treated with 10-mg/kg IAA (CI) compared with uncontaminated soil and ryegrass as the control. At the end of the experiment, the ryegrass biomass, total chlorophyll, superoxide dismutase (SOD) activity, and soil invertase activity in C group were decreased by 33.7%, 23.0%, 29.7%, and 18.3%, respectively, whereas the peroxidase (POD) activity and soil basal respiration increased by 17.1% and 87.9%, respectively, compared with the control. In the CI group, the biomass of ryegrass, chlorophyll content, SOD activity, sucrase activity, fluorescein diacetate (FDA) hydrolase activity, and Cd removal rates increased by 14.5%, 19.9%, 24.3%, 12.1%, 20.4%, and 15.1%, respectively, whereas the POD activity, soil basal respiration, and Cd residues in the soil declined by 8.0%, 15.0%, and 17.0%, respectively, compared with the C group. Therefore, exposure to exogenous IAA alleviated the Cd stress on ryegrass and soil microorganisms and improved Cd absorption by ryegrass from the contaminated soil. [ABSTRACT FROM AUTHOR]

Belowground responses are critical in understanding how plants cope with the predicted increase in drought intensity and frequency in the Mediterranean region, because plant root systems compete with each other and interact with soil microbial communities under limiting water availability. However, the combined responses of plant roots and soil microorganisms to drought are not well understood. Using an experimental approach, we addressed the question of how recurrent drought and different combinations of two individuals from three common Mediterranean plant species (Quercus coccifera, Cistus albidus, and Brachypodium retusum) affect root characteristics and soil microbial activity. We hypothesized that drought effects on root characteristics and associated soil microbial communities are stronger when plant individuals of the same species compete for limiting water compared to inter-specific competition. Root morphological traits were more affected by the species identity of the neighbor individual than by recurrent severe drought, particularly in B. retusum, which may in part explain the higher survival previously observed for this species. On the other hand, drought and plant composition had little effect on root-associated soil microbes’ ability to use a wide range of different carbon substrates. Overall, our results did not confirm stronger effects of intra- compared to interspecific competition on the root and microbial responses, but showed strong species identity effects.

Drought has the most significant impact on arid grassland ecosystems. Managed grazing, including the timing and intensity of defoliation, may interact with drought to differentially affect processes related to soil organic matter decomposition. Extracellular enzyme activity (EEA) provides integrated measure of soil microbial activity which affects nutrient cycling. This study examined EEAs in response to five defoliation regimes and drought at seven grasslands across temperate grasslands of Canada. All sites were dominated by perennial grasses and forbs, but differed in plant species, climate, and soils. Soil samples were analyzed for five EEAs involved in carbon (C), nitrogen (N) and phosphorus (P) cycling. Drought reduced activity of enzymes involved in C cycling, β-glucosidase and β-cellobiosidase by 16 and 17%, respectively, P cycling (acid phosphatase) by 11%, and N cycling (N-acetyl-β-glucosaminidase) by 12%. β-xylosidase showed close association with, and was not affected by drought, suggesting a reduction in C turnover under future drought. β-glucosidase activity was reduced by intermediate defoliation relative to both control and heavy. Acid phosphatase and N-acetyl-β-glucosaminidase were affected by three-way interaction of drought, defoliation and mean growing season precipitation, highlighting the complex mechanism underlying EEA responses. Findings suggest that EEA was affected by drought, but defoliation effects were largely dependent upon drought and local climate. • Drought reduced activity of enzymes involved in C and N cycling, except β-xylosidase. • Effects of defoliation on extracellular enzyme activity were contingent upon drought. • β-xylosidase showed a positive association with drought. [ABSTRACT FROM AUTHOR]