Soil Enzyme Activities Research Articles

Positive impacts of compost and biochar from orange peel waste on Phaseolus vulgaris physio-biochemistry and productivity and soil properties under salinity stress

ABSTRACT Bioconversion of organic orange peel wastes into compost (OPC) or biochar (OPB) can help overcome the effects of soil salinity and maintain agricultural productivity. Effect of 1.0% OPC or 1.0% OPB as soil amendments on soil properties and performance of Phaseolus vulgaris plants under two salinity levels [5.60 dS m−1 (S-1) and 9.60 dS m−1 (S-2)] versus control [1.60 dS m−1 (S-0)] was investigated. Compared to the control, S-1 and S-2 increased soil sodium ion (Na+) content, while reducing soil organic matter (OM), macro- and micro-nutrients, cation exchange capacity (CEC), and enzyme (urease, acid phosphatase, and alkaline phosphatase) activities, reflecting decreased plant growth and yield. Under S-1 or S-2, OPC application exceeded OPB application, but both considerably enhanced soil OM content, nutrients, CEC, and enzyme activities. These positive results reflected decreased leaf electrolyte leakage and increased leaf-relative water content, pigments, nutrients, K+/Na+ ratio, antioxidant activity, plant growth, and yield. The beneficial impacts of 1.0% OPC were more pronounced under S-2 than S-1 or S-0. In conclusion, adding 1.0% OPC to saline soil (ECe of about 5–10 dS m−1) could mitigate the influences of soil salinity to improve Phaseolus vulgaris growth, physio-biochemistry, and yield.

Effects of a Novel Tripyrasulfone Herbicide on Key Soil Enzyme Activities in Paddy Rice Soil

Weeds significantly impact paddy yields, and herbicides offer a cost-effective, rapid, and efficient solution compared to manual weeding, ensuring agricultural productivity. Tripyrasulfone, a novel 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor developed by Qingdao Kingagroot Chemicals Co., Ltd., has demonstrated high efficacy when applied post-emergence, causing characteristic foliar bleaching in susceptible weed species, distinct from conventional acetolactate synthase, acetyl-CoA carboxylase, and synthetic auxin herbicides. This study investigates the impact of tripyrasulfone on the activity of key soil enzymes (urease (UE), acid phosphatase (ACP), sucrase (SC), catalase (CAT), and dehydrogenase (DHA)) in paddy soils from Jilin Province and Shandong Province. Different doses of tripyrasulfone (0.1, 1.0, and 2.5 mg kg−1) were applied, and the enzymatic activities were measured. Results indicated that tripyrasulfone initially inhibited UE and ACP activities before activating them. On the 20th day after treatment, UE activity had returned to control levels, whereas ACP activity remained significantly higher, showing long-lasting activation. SC and CAT activities were inhibited but gradually recovered to control levels. Furthermore, DHA activity was activated with a sustained effect, remaining significantly higher than the control group even 20 days after treatment. Overall, the impact of tripyrasulfone on soil enzyme activities diminished over time, suggesting that tripyrasulfone posed minimal long-term ecological risk to soil health.

The Impact of Grafting with Different Rootstocks on Eggplant (Solanum melongena L.) Growth and Its Rhizosphere Soil Microecology

This study investigated the effects of grafting on eggplant growth, yield, and disease resistance, with a focus on microbial dynamics in the rhizosphere. Eggplant scions were grafted onto rootstocks of wild eggplant and tomato, with self-rooted eggplants serving as controls. Greenhouse experiments were conducted over an eight-month growing period, using standard field practices such as film mulching and integrated water–fertilizer management. High-throughput sequencing was used to analyze the biological properties and microbial community of the rhizosphere soil. Results showed that plants grafted onto ‘Huimei Zhenba’ and ‘Torvum’ rootstocks yielded up to 36.89% more than self-rooted controls, achieving yields of 4619.59 kg and 4399.73 kg per 667 m², respectively. The disease incidence of bacterial wilt was reduced to as low as 3.33% in the ‘Huimei Zhenba’ treatment, compared to 55.56% in non-grafted controls. Additionally, grafted plants exhibited increased stem diameter and chlorophyll content, with the TL/HM combination reaching 54.23 ± 3.17 SPAD units. The enhanced microbial biomass of carbon, nitrogen, and phosphorus, particularly in the TL/HM treatment (377.59 mg/kg, 28.31 mg/kg, and 36.30 mg/kg, respectively), supports a more nutrient-rich rhizosphere environment. Moreover, soil enzyme activities, such as β-glucosidase and phosphatase, were significantly higher in grafted plants, enhancing nutrient cycling and potentially increasing resistance to pathogens. Overall, grafted eggplants demonstrated enhanced soil microbial biomass, enzyme activity, and a more diverse microbial community, which are critical factors contributing to the improved yield and disease resistance observed in grafted crops.

Nitrogen addition alleviates the negative effects of reduction in precipitation on soil multifunctionality in a typical steppe

The increasing frequency of drought events and nitrogen deposition have fundamentally changed soil microbial functions in terrestrial ecosystems. However, most studies have mainly concentrated on the impact of a single environmental factor on ecosystem functions; how drought and nitrogen enrichment interactively affect soil multifunctionality remains largely unknown. In this study, the effects of different drought scenarios [intense drought (ID), chronic drought (CD), and reduced rainfall frequency (RF)] and nitrogen addition on soil microbial biomass, and soil multifunctionality (determined using soil enzyme activity) were examined in the fourth year of a field manipulative experiment conducted in a typical steppe in northern China. The results demonstrated that both ID and CD significantly reduced soil multifunctionality, microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN). The CD treatment also decreased the ratio of MBC to MBN, while RF had less impacts on soil multifunctionality and the biomass of soil microbes. In contrast, nitrogen addition enhanced soil multifunctionality, MBC and MBN. Structural equation modeling analysis demonstrated that drought decreased soil multifunctionality directly and indirectly by reducing MBN and soil water content, whereas nitrogen addition increased soil multifunctionality mainly by increasing MBN and soil inorganic nitrogen. This study provides the first experimental evidence of the opposing impacts of reduction in precipitation and nitrogen enrichment on soil microbial biomass and soil multifunctionality in a semiarid typical steppe, and suggests that nitrogen fertilization could be an effective measure to alleviate the negative effects of climate drought on soil functions in nitrogen- and water-limited grassland ecosystems.

Effects of different microplastic types on soil physicochemical properties, enzyme activities, and bacterial communities

Global concern continues to mount regarding the accumulation of microplastics (MPs) in soil. However, little is known about how various types of MPs influence the properties of soil ecosystems. Here, we evaluated the effects of six different types of MPs, including low-density polyethylene (LDPE), polyamide (PA), polystyrene (PS), polyhydroxy-alkanoates (PHA), polybutadiene styrene (PBS), and polylactide (PLA), on soil physicochemical properties, enzyme activities, and microbial communities. At the end of a 230-day soil incubation, we observed significant changes in soil moisture content, soil organic carbon, pH, NH4+-N, NO3--N, and available phosphorus. The addition of MPs had a significant influence on the activities of soil β-glucosidase, acid phosphatase, urease, and fluorescein diacetate hydrolase, with effects varying with MP type. Results of 16S rRNA gene high throughput sequencing showed that MP exposure had little effect on soil microbial alpha diversity, but that PHA contamination significantly reduced ACE, Chao1, and Shannon index values. MP contamination also altered soil microbial community composition. In particular, the relative abundance of Firmicutes increased significantly while the relative abundance of Actinobacteriota, Proteobacteria (especially the nitrogen-fixing rhizobia), and Acidobacteriota decreased following exposure to PHA. Redundancy analysis showed that acid phosphatase and pH were the two main environmental factors affecting bacterial community structure at the phylum and order levels. Furthermore, Tax4Fun2 analysis found that MP treatment disrupted fundamental bacterial metabolic pathways. Our findings indicate that different types of MPs can affect soil fertility, bacterial community structure, and function in various ways, and highlight that biodegradable MPs may alter soil bacterial communities more than conventional MPs.

Stochastic Processes Dominate the Assembly of Soil Bacterial Communities of Land Use Patterns in Lesser Khingan Mountains, Northeast China

To meet the demands of a growing population, natural wetlands are being converted to arable land, significantly impacting soil biodiversity. This study investigated the effects of land use changes on bacterial communities in wetland, arable land, and forest soils in the Lesser Khingan Mountains using Illumina MiSeq 16S rRNA sequencing. Soil physicochemical properties and enzyme activities were measured using standard methods, while microbial diversity was assessed through sequencing analysis. Our findings revealed that forest soils had significantly higher levels of total potassium (2.62 g·kg−1), electrical conductivity (8.22 mS·cm−1), urease (0.18 mg·g−1·d−1), and nitrate reductase (0.13 mg·g−1·d−1), attributed to rich organic matter and active microbial communities. Conversely, arable soils showed lower total potassium (1.94 g·kg−1), reduced electrical conductivity, and suppressed enzyme activities due to frequent tilling and fertilization. Wetland soils exhibited the lowest values primarily due to water saturation, which limits organic matter decomposition and microbial activity. Land use changes notably reduced microbial diversity, with conversion from forest to arable land leading to habitat loss. Forest soils supported higher abundances of Proteobacteria (37.59%) and Actinobacteriota (34.73%), while arable soils favored nitrogen-fixing bacteria. Wetlands were characterized by chemoheterotrophic and anaerobic bacteria. Overall, these findings underscore the profound influence of land use on soil microbial communities and their functional roles, highlighting the need for sustainable management practices.

Dynamics of major plant nutrients and enzymatic activities in soil influenced by application of biochar and organic waste.

The concentration of salt ions influences the availability and plant nutrients dynamics in the soil. Proper management of these ions can enhance food grain production, helping to feed the growing population. In this experiment, nine fertility combinations were followed to enhance the soil organic carbon and reduce the salt toxicity and monitor the plant nutrient availability. An incubation experiment was conducted for the period of one year with different organic soil amendments in combinations including biochar (BC), pressmud (PM), and farm yard manure (FYM) as follow: T1-control, T2-RDF, T3-FYM (10 t/ha), T4-PM (10 t/ha), T5-BC (10 t/ha), T6-FYM (5 t/ha) + PM (5 t/ha), T7-FYM (5 t/ha) + BC (5 t/ha), T8-PM (5 t/ha) + BC (5 t/ha), T9-FYM (5 t/ha) + BC (2.5 t/ha) + PM (2.5 t/ha). Results showed that addition of organic substance (10 t/ha) significantly (p < 0.05) affected soil pH and electric conductivity. Plant nutrient availability (N, K, and S) was also influenced by application of organic substance (10 t/ha). Organic C and available N were recorded the highest in the treatment T7 (FYM-5 t/ha + BC -5 t/ha); whereas, the highest available K and S were observed in treatment T5 (BC-10 t/ha). The microbial soil fertility indicators (alkaline phosphatases, arylsulphatase, dehydrogenase activity and microbial biomass carbon) were measured the highest in FYM (5 t/ha) + BC (5 t/ha) applied treatment. In conclusion, application of organic substance 10 t/ha (biochar alone or with FYM) improved the plant nutrient availability and soil microbial activities in saline soil. It could be a suitable option for enhancing the soil fertility in saline soils.

Synergistic effects of SAP and PGPR on physiological characteristics of leaves and soil enzyme activities in the rhizosphere of poplar seedlings under drought stress

Super absorbent polymers (SAP) provide moisture conditions that allow plant growth-promoting rhizobacteria (PGPR) to enter the soil for acclimatization and strain propagation. However, the effects of SAP co-applied with PGPR on the physiological characteristics of leaves and rhizosphere soil enzyme activities of poplar seedlings are not well understood. Here, a pot experiment using one-year-old poplar seedlings with five treatments, normal watering, drought stress (DR), drought stress + SAP (DR+SAP), drought stress + Priestia megaterium (DR +PGPR) and drought stress + SAP + P. megaterium (DR+S+P), was performed to analyze the contents of non-enzymatic antioxidants, osmotic regulators and hormones in leaves, as well as rhizosphere soil enzyme activities. Compared with normal watering, the DR treatment significantly decreased the contents of dehydroascorbate (DHA; 19.08%), reduced glutathione (GSH; 14.18%), oxidized glutathione, soluble protein (26.84%), indoleacetic acid (IAA; 9.47%), gibberellin (GA) and zeatin (ZT), the IAA/abscisic acid (ABA), GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (34.67%) ratios in leaves, and the urease and sucrase activities in the rhizosphere soil. Additionally, it significantly increased the soluble sugar, proline and ABA contents in leaves. However, in comparison with the DR treatment, the DR+S+P treatment significantly increased the DHA (29.63%), GSH (15.13%), oxidized glutathione, soluble protein (29.15%), IAA (12.55%) and GA contents, the IAA/ABA, GA/ABA, ZT/ABA and (IAA+GA+ZT)/ABA (46.85%) ratios in leaves, and the urease, sucrose and catalase activities in rhizosphere soil to different degrees. The soluble sugar, proline and ABA contents markedly reduced in comparison to the DR treatment. The effects of the DR+SAP and DR+PGPR treatments were generally weaker than those of the DR+S+P treatment. Thus, under drought-stress conditions, the simultaneous addition of SAP and P. megaterium enhanced the drought adaptive capacities of poplar seedlings by regulating the non-enzymatic antioxidants, osmotic regulators, and endogenous hormone content and balance in poplar seedling leaves, as well as by improving the rhizosphere soil enzyme activities.

Analysis of Physicochemical Properties, Enzyme Activity, Microbial Diversity in Rhizosphere Soil of Coconut (Cocos nucifera L.) Under Organic and Chemical Fertilizers, Irrigation Conditions

The application of chemical fertilizers and organic fertilizers, as well as irrigation, is an important agricultural practice that can increase crop yields and affect soil biogeochemical cycles. This study conducted coconut field experiments to investigate the effects of conventional fertilization (NCF), optimized fertilization (MCF), conventional fertilization + organic fertilizer (NOF), optimized fertilization + organic fertilizer (MOF), conventional fertilization + organic fertilizer + irrigation (NOFW), and optimized fertilization + organic fertilizer + irrigation (MOFW) treatments on soil physicochemical properties, soil enzyme activity, bacterial and fungal community structure and diversity, and compared the controls (CK, non-fertilizer and non-irrigation). The results showed that MOFW significantly increased soil electrical conductivity (EC), organic matter (OM), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), available calcium (ACa), and available magnesium (AMg) levels. At the same time, it also significantly enhanced the activities of soil catalase (CE), polyphenol oxidase (POE), sucrase (SE), urease (UE), acid protease (APE), and acid phosphatase (APPE) (p &lt; 0.05). The PCA analysis of soil microorganisms in the coconut rhizosphere soil showed indicated significant changes in bacteria and fungi community structure under fertilization treatments. The fertilization application leaded to an increase in the relative abundance and diversity of bacteria, but a decrease in fungi. Acidobacteriota, Proteobacteria, and Actinobacterota were the dominant bacterial phyla, and Ascomycota, Basidiomycota, Rozellomycota, and Mortierellomycota were the significant fungal phyla. Compared with CK, MOFW significantly increased the abundance of Acidobacteriota, Proteobacteria, Basidiomycota, and Mortierellomycota. Redundancy analysis (CCA) and Mantel test further revealed that pH, EC, OM, and AP were the main soil fertility factors driving changes in microbial communities. CE, SE, UE, APE, APPE were significantly correlated with microbial communities. Compared with NOFW, MOFW has a lower proportion of N, P, and K fertilizers in its fertilizer composition. The results indicated that MOFW can better improve the nutrient and enzyme status of the soil, which is a promising method for maintaining the balance of soil microorganisms in coconut orchards, and accordingly, reducing chemical fertilizers within a certain range can not only ensure consistency with conventional fertilizers, but also effectively improve soil conditions.

Effects of plant litter diversity on soil enzyme activity and microbial community composition in a Mongolian pine plantation

Effects of plant litter diversity on soil enzyme activity and microbial community composition in a Mongolian pine plantation

Optimizing Irrigation Scheduling to Enhance Nutrient Uptake and Soil Microbial Activity in Linseed Cultivation (Linum usitatissimum L.)

Linseed crop cultivated under residual moisture and water scarcity conditions in rabi season. To improve the productivity of linseed irrigation water is applied at different stages of crop. So, to optimize the irrigation scheduling and enhance the nutrient uptake and soil microbial activity, this experiment was conducted at Main Agriculture Research Station, University of Agricultural Sciences, Raichur (which comes under North Eastern Dry zone of Karnataka) (India) during rabi 2023-24. The experiment was carried out with Randomized Complete Block Design (RCBD) with five treatments and four replications. The results revealed that, pre sowing irrigation fb three irrigations at vegetative stage (30-35 DAS), flowering stage (40-45 DAS) and capsule development stage (60-65 DAS) (T4) recorded significantly higher nutrient uptake by linseed crop (46.07, 19.87 and 39.83 NPK kg ha-1). The rainfed condition treatment (T5) recorded significantly lower nutrient uptake by the crop (19.35, 8.15 and 18.40 NPK kg ha-1). Among the different treatments, pre sowing irrigation fb three irrigations at vegetative stage (30-35 DAS), flowering stage (40-45 DAS) and capsule development stage (60-65 DAS) recorded significantly higher soil microbial population of bacteria (16.1 X 106 cfu g-1 of soil), fungi (13.8 X 104 cfu g-1 of soil) and actinomycetes (6.8 X 103 cfu g-1 of soil) as compared to other treatments. The soil enzymatic activity was significantly influenced by scheduling of irrigation at different growth stages in linseed. At harvest among the different treatments, pre sowing irrigation fb three irrigations at vegetative stage (30-35 DAS), flowering stage (40-45 DAS) and capsule development stage (60-65 DAS) recorded significantly higher dehydrogenase, urease and alkaline phosphatase activity (18.63 μg TPF g-1 soil day-1, 22.5 μg NH4-N g-1 soil hr-1 and 14.4 µg PNP g-1 soil hr-1, respectively).

Improvement of Saline–Alkali Soil and Straw Degradation Efficiency in Cold and Arid Areas Using Klebsiella sp. and Pseudomonas sp.

Corn straw is an important renewable resource, which could improve the quality of saline–alkali cultivated land. However, the slow decomposition of crop residues in cold, arid, and saline–alkali soils can lead to serious resource waste and ecological crises. The use of beneficial microorganisms with degradation functions could solve these problems. In this study, three types of saline–alkali soil with low, medium, and high salinity levels were used in the straw-returning experiment. The experiment was conducted with four treatments: GF2 (Klebsiella sp.), GF7 (Pseudomonas sp.), GF2+GF7, and CK (control without bacteria). Microbial characteristics, straw degradation efficiency, element release rate, and soil factors were compared, and random forest linear regression and partial least squares path modeling analysis methods were utilized. The results indicated that the degradation of bacterial metabolites, the efficiency of corn stover degradation, the efficiency of component degradation, and the release rates of elements (C, N, P, and K) initially increased and then decreased with the increase in salinity. At the maximum value of moderately saline–alkali soil, the effect of GF2+GF7 treatment was significantly better than that of other treatments (p &lt; 0.05). Given the interactive effects of saline–alkali soil and microbial factors, the application of exogenous degrading bacteria could significantly increase soil enzyme activity and soil available nutrients, as well as regulate the salt–alkali ion balance in soil. The cation exchange capacity (9.13%, p &lt; 0.01) was the primary driving force for the degradation rate of straw in saline–alkali soil with different degrees of salinization under the influence of exogenous degrading bacteria. Straw decomposition directly affected the soil chemical properties and indirectly affected soil enzyme activity. The results of this study would provide new strategies and insights into the utilization of microbial resources to promote straw degradation.

Nitrogen induced soil carbon gains are resistant to loss after the cessation of excess nitrogen inputs

Nitrogen (N) deposition has increased soil carbon (C) storage across eastern US temperate forests by reducing microbial decomposition. However, the fate of these N-induced soil C gains are uncertain given strong declines in N-deposition rates and rising soil temperatures. As N deposition has reduced soil pH and plant C investments into the rhizosphere, we compared the extent to which removing limitations to microbial decomposition by increasing soil pH, adding artificial root exudates, or elevating soil temperature would increase microbial decomposition in soils that have and have not received excess N inputs. We hypothesized that alleviating these microbial decomposition limitations would prime soil C losses from soils that have received excess N inputs. To test this hypothesis, we conducted a soil microcosm experiment where we compared microbial respiration, microbial biomass, and soil enzyme activity in soils from an unfertilized watershed and a previously N-fertilized watershed 4 years after the end of a 30-year N deposition experiment at the Fernow Experimental Forest in West Virginia. In both watersheds, we found that removing pH, plant carbon, or temperature limitations to decomposition stimulated microbial respiration. However, microbial decomposition and soil C losses were consistently lower in the previously N-fertilized watershed across all treatments. This response, coupled with a lack of differences in microbial biomass between watersheds and treatments, suggests that long-term N fertilization has fundamentally altered soil microbial communities and has led to a sustained impairment of the ability of the microbial community to decompose soil organic matter. Collectively, our results indicate that the legacy effect of N deposition on microbial communities may influence the persistence of soil C stocks in the face of global change.

Maize-Straw Biochar Enhances Soil Properties and Grain Yield of Foxtail Millet in a Newly Reclaimed Land

Large-scale land reclamation has become common in northwestern China; however, low soil fertility and poor soil water-holding capacity limit agricultural production on these reclaimed lands, requiring increased fertilizer and irrigation inputs. Biochar, produced from agricultural waste, has shown potential in improving soil quality and water-holding capacity. In this two-year field study (2021 and 2022), we investigated the effects of biochar produced from maize straw on soil properties and grain yield of foxtail millet grown on newly reclaimed land. Three biochar treatments (3000, 4500, and 6000 kg ha−1) were compared to a control (CK) with no biochar application. Biochar application resulted in increased soil organic matter, total phosphorus, total nitrogen, soil enzyme activity, and soil organic acid content. It also significantly decreased soil pH and bulk density. Compared with the CK, biochar increased available nitrogen from 29.7% to 108% in 2021 and 37.0% to 88.4% in 2022. Similarly, biochar increased available phosphorus from 64.7% to 143% in 2021 and 41.9% to 96.5% in 2022. Grain yields ranged from 3092 to 4753 kg ha−1. Biochar treatments increased grain yield compared to the CK, ranging from 12.2% to 24.6% in 2021 and 27.1% to 53.7% in 2022. Correlation analysis revealed that soil pH was negatively related to soil oxalic acid content, phosphorus content, and sucrase activity. Available nitrogen and phosphorus contents were negatively related to soil bulk density and positively related to catalase activity. Soil water content was negatively correlated with soil bulk density and positively correlated with organic matter. In conclusion, biochar improved the rhizosphere soil pH and the effectiveness of soil fertility in the newly reclaimed soil, resulting in an enhanced grain yield of foxtail millet.

Synergistic impact of tank mixing pendimethalin and pyroxasulfone on soil enzymatic and microbial dynamics.

A field experiment was carried out during the Rabi 2022-23 at Punjab Agricultural University, Ludhiana to evaluate the effect of pyroxasulfone and pendimethalin on soil enzymatic and microbial activities when applied individually or as a tank mix combination. The experiment employed a factorial randomized complete block design in triplicate encompassing 16 treatments. Control soils exhibited a continuous increase in enzymatic and microbial activities over time. In herbicide-treated plots, a highly dose-dependent lag phase was observed in all enzymatic and microbial activities which gets shorter or disappear at higher application rates. Following the initial lag phase, inhibition in enzymatic and microbial activities was observed with higher inhibition in tank mix combination (90.7 to 99.1% up to 90days after herbicide application (DAA) followed by pendimethalin (77.3 to 92.9% up to 90 DAA) and pyroxasulfone (30.3 to 76.2% up to 45 DAA). After initial inhibition, enzymatic and microbial activities increased at harvest. Principal component analysis (PCA) revealed that dehydrogenase activity among soil enzymes and bacteria among microbial populations were more sensitive to studied herbicides. Based on the values of the Integrated Biomarker Response (IBRv2), pendimethalin had a greater impact on soil activities than pyroxasulfone, and their combined application exhibited a synergistic effect.

Microbiomes-Plant Interactions and K-Humate Application for Salinity Stress Mitigation and Yield Enhancement in Wheat and Faba Bean in Egypt’s Northeastern Delta

Salinity, resulting from climate change and excessive mineral fertilization, burdens farmers and negatively impacts soil and water ecosystems in the Northeastern Nile Delta. Organic and biological approaches are crucial for addressing these issues. This study examined the effects of individual and combined inoculations with cyanobacteria, yeast, and Arbuscular Mycorrhizal Fungi (AMF), with or without K-Humate and reducing Nitrogen, phosphorus and potassium (NPK) mineral fertilizers application rates to crop quality of wheat and faba bean. In preliminary laboratory experiments, the interactive effects of these microbiomes on plant antioxidant and soil enzyme production were examined under salinity stress. Results showed that co-inoculation, especially with K-Humate, yielded superior outcomes compared to individual inoculations. These findings were validated by a field trial conducted in saline-alkaline soil in the Northeastern Nile Delta region. All biological treatments 25% of recommended doses, and enhancing salinity tolerance, increasing yield, and improving enhanced rhizosphere microbial activity, including soil enzyme activity, AMF colonization, spore density, and the total numbers of bacteria, cyanobacteria, and yeast. These effects were further amplified by K-Humate and were more pronounced with combined inoculations than with individual ones, leading to improved soil fertility and significant increases in both crop quantity and quality compared to control treatments. The triple treatment, combining cyanobacteria, yeast, and mycorrhizae in the presence of K-Humate while reducing the mineral NPK rate by 75%, achieved superior increases in the productivity of wheat grains and faba bean seeds, reaching 54.72% and 128.92%, respectively, compared to the 100% NPK mineral control. This treatment also significantly improved crop quality, with notable increases in nitrogen, potassium, phosphorus, and protein percentages in wheat grains and faba bean seeds. Microbiomes-interaction increased potassium uptake over sodium, enhancing the plant’s potassium/sodium ratio and improving salt stress tolerance. This approach reduces reliance on costly mineral fertilizers, enabling bio-organic farming in marginal lands, optimizing resource utilization, and preserving natural resources.

Биологическая активность горных почв Западного Кавказа после сведения леса

A study of a set of indicators characterizing the ecological state of forest soils in the mountains of the North-Western Caucasus under broad-leaved and mixed forests has been conducted. The aim of the study has been to assess changes in the biological activity of soils of different genesis after deforestation. The objects of the study have been rendzina, gray forest and gray forest-steppe soils of forest and disturbed ecosystems of the Republic of Adugeya at altitudes from 500 to 1635 m above sea level. Logging plots of different ages (from 10 to 40 years old) after deforestation have been considered. The analyzed indicators have included: the content of total and active carbon, the activity of soil enzymes (catalase, invertase, dehydrogenase, urease, phosphatase), the number of bacteria, as well as an integral index of the biological properties of the soil. The correlation of these indicators with hydrothermal conditions, density of soil structure, penetration resistance, medium reaction, hydrolytic acidity, total absorbed bases and other soil parameters has been evaluated. The level of biological activity of soils in logging areas in the low mountains of Adygea depends on the relief and the timing of restoration after deforestation. Even after several decades of restoration of woody vegetation on the slopes of 12–15° there is no complete return of biological activity to the values of Greyic Phaeozem Eutric of the background forest area. 40 years after logging, the integral index of biological properties of gray forest soil is still 17 % lower than in the control plot. The biological activity of post-forest soils can change in three main directions. On steep slopes, with severe disturbance of the soil and vegetation cover due to the operation of heavy machinery, the integral index of the biological properties of soils decreases by 25–40 % or more without a tendency to recovery. At an average level of disturbance in plots with slight slopes, after an initial decrease, the soils are restored to control values. Restorative successions with intensive development of herbaceous flora and the turf process with slight disturbance can lead to an increase in biological activity above the control values in just 2–3 years. Comprehensive biodiognostic studies using an integral index of the biological state of the soil have revealed, in general, increased stability of low-mountain terrain soils (gray forest and forest-steppe) compared to the soils of the middle mountains of Adygea (rendzina soils). The main degradation factor that reduces the biological activity of soils disturbed by logging is erosion.

The roles of nanoparticle-enriched biochars in improving soil enzyme activities and nutrient uptake by basil plants under arsenic toxicity

Enriched biochar with improved properties and functionality can play a significant role in providing sustainable solutions for mitigating heavy metal contamination in soil. In this experiment, the effects of solid and enriched biochars (potassium-enriched biochar (BC-K), magnesium-enriched biochar (BC-Mg), both individually and combined) were examined on soil microbial and enzyme activities, as well as nutrient uptake by basil plants cultivated in a soil with three levels of arsenic (nontoxic, 50 mg As kg−1 soil, and 100 mg As kg−1 soil). Biochar-related treatments, increased soil organic matter (65–76%), while decreased availability of arsenic (6–55%) in the soil. The microbial biomass carbon (by about 123%) and soil basal respiration (by about 256%), and soil enzymatic activities (β-glucosidase, urease, alkaline phosphatase, and dehydrogenase) were enhanced by enriched biochars under arsenic toxicity. The solid and particularly enriched biochars decreased arsenic content and improved nitrogen and phosphorus contents of roots and shoots, root length, root activity, and root and shoot biomass in basil plants. Therefore, it is conceivable to suggest that enriched biochars are superior treatments for improving nutrient absorption rates and basil growth under arsenic toxicity through decreasing arsenic mobility and increasing soil microbial activities.

Response of soil nitrogen mineralization, nitrification and denitrification to milk vetch (Astragalus sinicus L.) application in a paddy field

We conducted incubation experiments with a paddy soil collected from a long-term field experiment to explore the effect of Chinese milk vetch (Astragalus sinicus L., CMV) application on potential nitrogen (N) denitrification (PDA), nitrification (PNA), mineralization (PNM), soil chemical properties, microbial communities, enzyme activities, yields and nutrient uptake of rice under different fertilization treatments. Five treatments were included: no chemical fertilizers (C0), chemical fertilizers (C100), Chinese milk vetch (M), CMV combined with 100% chemical fertilizers (MC100) and with 80% chemical fertilizers (MC80). Results showed that the M, MC100, and MC80 treatments significantly increased PNM and PNA compared with the C100 treatment (P &lt; 0.05). Meanwhile, the CMV application significantly increased total N, microbial biomass N, and carbon (C) concentrations, the abundances of the bacterial phylum Actinobacteria, and the genera Bradyrhizobium, Mycobacterium, Streptomyces and Reyranella, N-acetyl-glucosaminidase (NAG) activity, yields and N nutrient uptake of rice grain compared with the C100 treatment (P &lt; 0.05). Correlation analyses indicated that grain yield and N uptake of rice, soil total N, microbial biomass C and N, the bacterial phylum Actinobacteria, the genera Bradyrhizobium, Mycobacterium, Streptomyces, Reyranella, and NAG were significantly correlated with PNM under different fertilization regimes, while microbial biomass C and N, Actinobacteria, Bradyrhizobium, and Reyranella were positively related to PNA (P &lt; 0.05). Together, the application of CMV alone or in combination with chemical fertilizers can improve soil properties and rice growth, which may accelerate N mineralization and nitrification in this soil.

Antibacterial Activity of Ocimum Basilicum L. and Thymus Vulgaris L. Extracts against Escherichia coli as a future method for decontamination and deodorization of compost-like mixtures

Ocimum basilicum L. and Thymus vulgaris L. are natural plant sources of antimicrobial activity, which is essential to determine their qualities as biological agents against pathogenic microorganisms. The aim of the study is the analysis of the antibacterial activity of plant extracts of basil and thyme against Escherichia coli for their subsequent application in agricultural practice as additives for decontamination and deodorization of compost-like mixtures. Plant extracts from roots, stems, leaves and whole plants of basil and thyme were obtained by various methods: decoction, tincture, medicinal vinegar, medicinal wine and medicinal oil. Agar diffusion method was used to determine the antimicrobial activity of the extracts against Escherichia coli. The analyzed essential oil cultures increase the microbiological and enzymatic activity of soils. Basil extracts showed stronger antimicrobial activity against Escherichia coli than thyme extracts, differing for individual plant parts - roots variants showed higher antimicrobial activity compared to variants with leaves, stems and whole plant. In general, a lower antimicrobial activity of the plant extracts was found in the medicated wine and tincture variants (except for roots tincture), compared to the decoction, medicated vinegar and medicated oil variants. The antibacterial activity of the stem extracts depended significantly, and that of the root, leaf and whole plant extracts moderately, on the biogenicity of the soils. The analyzed essential oil cultures can be applied for decontamination (against Escherichia coli) and deodorization of compost-like mixtures. The use of basil and thyme extracts decontaminated composts from E. coli content in a repeated 4-month application.