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Rainforests provide vital ecosystem services that are underpinned by plant-soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests. [ABSTRACT FROM AUTHOR]

At present, soil contaminated with arsenic (As) and antimony (Sb) is escalating at an alarming rate, which is harmful to human health. In this study, Fe- and Mn-modified activated carbon (AC) and biochar (BC) were prepared and compared for the remediation of As- and Sb-contaminated soil. The effects on the speciation of As and Sb, soil pH, organic matter (SOM), and enzyme activity with various dosages and remediation times were investigated. The results showed that on the whole, the best stabilization effect of As and Sb was achieved with 3% FeMnBC. Furthermore, with increases in time and dosage, the immobilization effect on As and Sb was more significant. Fe/Mn-modified AC and BC enhanced soil pH, with 3% MnAC being particularly effective; 3% AC and 3% FeMnAC demonstrated the most pronounced enhancement in SOM. The modified carbon materials exhibited a dramatic increase in enzymatic activity. In particular, urease activity showed an increasing trend, and catalase activity first decreased and then increased over 30 days. Among the treatments, 3% MnAC showed the most significant enhancements in catalase and urease activities, whereas 1% FeMnBC had the most pronounced effect on increasing sucrase activity. This study provides theoretical support for the remediation of soil co-contaminated with As and Sb by Fe/Mn-modified AC and BC. [ABSTRACT FROM AUTHOR]

Fritillaria cirrhosa, an endangered medicinal plant in the Qinghai-Tibet Plateau, is facing resource scarcity. Artificial cultivation has been employed to address this issue, but problems related to continuous cultivation hinder successful transplantation. Imbalanced microbial communities are considered a potential cause, yet the overall changes in the microbial community under continuous cropping systems remain poorly understood. Here, we investigated the effects of varying durations of continuous cropping on the bacterial and fungal communities, as well as enzymatic activities, in the rhizospheric soil of F. cirrhosa. Our findings revealed that continuous cropping of F. cirrhosa resulted in soil acidification, nutrient imbalances, and increased enzyme activity. Specifically, after 10 years of continuous cropping, there was a notable shift in the abundance and diversity (e.g., Chao1 index) of soil bacteria and fungi. Moreover, microbial composition analyses revealed a significant accumulation of harmful microorganisms associated with soil-borne diseases (e.g., Luteimonas, Parastagonospora, Pseudogymnoascus) in successively cropped soils, in contrast to the significant reduction of beneficial microorganisms (e.g., Sphingomonas, Lysobacter, Cladosporium) that promote plant growth and development and protect against diseases such as Fusarium sp.These changes led to decreased connectivity and stability within the soil microbial community. Structural equation modeling and redundancy analysis revealed that alkaline hydrolytic nitrogen and available phosphorus directly influenced soil pH, which was identified as the primary driver of soil microbial community changes and subsequently contributed to soil health deterioration. Overall, our results highlight that soil acidification and imbalanced rhizosphere microbial communities are the primary challenges associated with continuous cropping of F. cirrhosa. These findings establish a theoretical foundation for standardized cultivation practices of F. cirrhosa and the bioremediation of continuously cultivated soils. [ABSTRACT FROM AUTHOR]

The vermiremediation potential of Eudrilus eugeniae was assessed in heavy metals (HMs) contaminated soil in a microcosm experiment. In detail, efficacy of E. eugeniae was investigated in terms of reduction in HMs content, enhancement in the soil enzyme activities, synergistic correlation between the HMs and enzyme activities and bioaccumulation of HMs in the earthworm's biomass. Moreover, a seed germination assay was also conducted to assess the HMs toxicity in soil after remediation. The results showed that Eudrilus eugeniae was capable of decreasing the Cu, Zn, Mn, Cr, and Ni contents in the soil by 17.56–26.30% after 90 days of experimental trial. Introduction of E. eugeniae increased cellulase, amylase, polyphenol oxidase, peroxidase, urease, dehydrogenase, and catalase activities by 30.3–80.95% compared to controls. Earthworm addition led to a 12.98% increase in G-Mean and 2.89% increase in T-QSI values, indicating significant soil health improvement. PCA revealed the negative impact of HMs on synergistic enzyme activities during vermiremediation. HMs content in earthworm biomass increased 13-fold. Seed germination assay confirmed HMs reduction by the end of the experiment. Thus, this study demonstrated the interconnected changes in the soil enzyme activities during vermiremediation of HMs from crude oil polluted soil. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have distributed in agricultural soil. However, the effects of MPs on the growth of tobacco remain unclear. In this study, a pot experiment was conducted to evaluate the effects of linear low-density polyethylene (LLDPE) MPs at four different concentrations (0 mg·kg-1 as control, 10 mg·kg-1, 100 mg·kg-1, and 1000 mg·kg-1) on soil enzyme activity, physiological characteristics, and tobacco growth. The results showed that compared with the control, the treatments of 100 and 1000 mg·kg-1 significantly inhibited the activities of soil catalase (S-CAT) and soil sucrase (S-SC). Compared with the control, the 1000 mg·kg-1 treatment significantly altered root morphology, inhibited tobacco growth, and water content, resulting in a significant decrease in chlorophyll a content, catalase (CAT) and superoxide dismutase (SOD) activities in tobacco leaves, thereby incited a significant increase in malondialdehyde (MDA) content and peroxidase (POD) activity. Interestingly, the 10 mg·kg-1 treatment stimulated the activity of soil urease (S-UE) and root biomass. Overall, this study highlights the significant impact of MPs on soil enzymes, oxidative damage to tobacco, and inhibition of tobacco growth and development. It emphasizes the environmental risks of MPs pollution in soil, particularly for commercial crops like tobacco, and provides insights for controlling MPs abundance in the environment. Further research is needed to investigate the underlying mechanisms of MPs' effects on metabolism and genes in the soil-tobacco-microbial system. [ABSTRACT FROM AUTHOR]

Soil contamination by heavy metals (HM) from pesticides poses a serious environmental threat, affecting sustainability and agricultural productivity. Soil enzymes are essential for biochemical reactions such as organic matter decomposition and nutrient cycling and are vital for maintaining soil health. However, the effects of HM on soil enzyme activity are not yet well understood. This study examined the impact of HM contamination on enzymatic stoichiometry in regions with intensive pesticide use. We selected flower cultivation areas with 5 years (CA1) and 10 years (CA2) of pesticide exposure and a native forest area (NFA) as a reference during the dry and rainy seasons. We measured Cd, Cu, Mn, Pb, and Zn levels and employed ecological risk indices to assess contamination levels. We also analyzed enzyme activities (arylsulfatase, β-glucosidase, acid phosphatase, urease) and enzymatic stoichiometry. CA2 exhibited the highest concentrations of Cd, Cu, and Mn in both periods, while Zn was highest in both CA1 and CA2. CA2 had higher values for all indices, indicating significant contamination. Compared with NFA, arylsulfatase activity was lower in cultivated areas during both periods, suggesting decreased soil quality. We found negative correlations between Cu, Mn, Zn, and arylsulfatase, as well as a reduction in urease with Cd; these elements also increased microbial C limitation. Our findings show that continuous pesticide input increases HM levels and that enzyme activity and stoichiometry are effective bioindicator of soil contamination. This study underscores the urgent need for guidelines to protect soils from prolonged HM buildup. [ABSTRACT FROM AUTHOR]

Proper crop rotation determines soil fecundity, which is pertinent for successor crops. With this problem in mind, a study was performed to evaluate the interference of spring wheat (Triticum aestivum L. subsp. aestivum), winter wheat (T. aestivum L. subsp. aestivum), maize (Zea mays L.), and winter rape (Brassica napus L.) as forecrops on the increase in faba bean (Vicia faba L.) and the biochemical and physicochemical properties of the soil. Tests with faba bean were performed in pots in the vegetation hall. The pots were filled with soil from under the abovementioned four plant species, and faba bean was grown. Soil unsown with faba bean was also tested to measure the rhizosphere effect. At the beginning of the experiment, and after its completion, enzymatic and physicochemical analyses of the soil were performed. On the 120th day of the study, faba bean was harvested and biometry was performed. The forecrop substantially influenced the biometric features of the faba bean and the biochemical activity of the soil. Faba beans grown in soil under spring wheat and winter wheat had the highest seed yield, while those grown in soil under the winter rape had the lowest yield. The geometric mean of the enzyme activity index was only significantly positively correlated with the number of faba bean seeds and the soil pH, as well as with the seed dry matter yield and the faba bean plant height. Faba bean cultivation increased the soil biochemical activity. The values of the biochemical and physicochemical parameters of the unsown soil were lower compared to the soil sown with faba bean. The conducted research can help to estimate the changes occurring in arable soils and maintain their stability thanks to the use of appropriate bioindicators, which are the soil enzymes. Moreover, the use of a diversified crop rotation in soil cultivation can provide a lot of information about its function, which can ultimately be used for planning the plant rotation, leading to the improvement of the soil structure and fertility, as well as its protection. [ABSTRACT FROM AUTHOR]

Fungicides play a role in managing plant diseases but raise concerns about environmental impact, emphasizing the need to understand and minimize their effects on non-target ecosystems. Flutriafol is a fungicide used to combat fungal diseases in crops. It has two enantiomers that exhibit different levels of efficacy and environmental impact. This study focuses on evaluating the effects of different doses of flutriafol on soil microorganism populations and enzyme activity and the possible specificity of enantiomer interactions with soil enzymes by combining experimental and computational approaches. The effects of different doses of flutriafol on the population of microorganism and on the activity of soil enzymes were experimentally assessed. Molecular docking of the enantiomers with soil enzymes was used to assess the possible stereoselectivity of the interactions. Regardless of the dose used (normal dose recommended by the manufacturer for cereal crops, half this dose, and double dose), flutriafol had no significant impact on soil microbial communities or on catalase activity. The half dose of flutriafol produced increases in the activity of dehydrogenases (8%), phosphatases (26%), and urease (33%) during the first 7 days of incubation. Molecular docking showed that both enantiomers were able to bind to the active sites of dehydrogenases and phosphatases. The average value of the interaction energy observed for (R)-flutriafol with dehydrogenases was −7.85 kcal/mol, compared to −7.45 kcal/mol for the interaction of (S)-flutriafol with these enzymes. Similarly, the interaction energy obtained for the interaction of (R)-flutriafol with phosphatase was −9.16 kcal/mol, compared to −9.04 kcal/mol for the interaction of (S)-flutriafol with this enzyme. This study confirms the need to implement optimized application practices when using flutriafol by considering the enantiomer that is most effective on the target organism and less toxic to non-target ecosystems. [ABSTRACT FROM AUTHOR]

The studies showed the effectiveness of green-synthesized SiO2NPs in mitigating the toxicity of Arsenic. Density Functional Theory (DFT) is a computational method used to determine electronic structure, energy gap, and toxicity prediction. Experimentally, silicon nanoparticles of 0 (S0) and 100% v/v (S100) were applied to the surface of the soil. 150 mL of Arsenic trioxide was applied twice at a rate of 0 (As0) and 3.2 g/mL (As3.2) at an interval of three weeks. Green synthesized SiO2NPs possessed a higher chemical potential (µ) and electrophilicity index; consequently, charges could be transferred and easily polarized. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the green synthesized SiO2NPs enable them to donate electrons and complex with arsenic, reducing their bioavailability and toxicity. Evidence from the studies further showed that SiO2NPs had buffered the soil acidity and electric conductivity, posing a high binding site and reactivity with exchangeable cations and micronutrients due to their smaller energy gap. Furthermore, the catalytic activities of the soil enzymes dehydrogenase (DHA) and peroxidase (POD) were greatly increased, which enhanced the electrostatic interaction between the SiO2NPs and As. [ABSTRACT FROM AUTHOR]

Soil acidification is a global environmental problem with significant impacts on agricultural production, environmental protection, and ecosystem health. Soil acidification is widespread in China, affecting crop yields, agricultural product quality, and biodiversity. Since the 1980s, much work has been done on acidic soils in China, but it is controversial whether excessive nitrogen fertilizer application can lead to soil acidification mechanisms. To address the above issues, we conducted a meta-analysis of 115 published papers to integrate and analyze the effects of N fertilizer application on soil acidification and biological properties from 1980 to 2024. We also quantified the effect of nitrogen fertilization on soil acidification and biological changes under different climatic conditions. The results showed that under long-term application of nitrogen fertilizers in China from 1980 to 2024, soil pH decreased by an average of 15.27%, and the activities of soil urease, nitrate reductase, nitrite reductase, catalase, glutamate dehydrogenase, and glutamate synthetase decreased by an average of 9.82–22.37%. The soil microbial community richness (Chao1 index) increased by 6.53%, but the community diversity (Shannon index) decreased by 15.42%. Among the dominant soil microorganisms, the relative abundance of bacteria decreased by an average of 9.67–29.38% and the abundance of gene expression of nifH, amoA-AOA, amoA-AOB, and qnorB decreased by 9.92–19.83%. In addition, we found that the mean annual temperature and rainfall impacted soil acidification via their effect on soil microbial diversity and community composition. This study provides a scientific basis for an in-depth understanding of the spatial and temporal variation of soil acidification and biological properties in China. [ABSTRACT FROM AUTHOR]

The soil microbiota is a key component of agroecosystems, and understanding its traits is crucial for effective agronomic management. Among beneficial microorganisms, arbuscular mycorrhizal fungi (AMFs) are mutually associated with grapevine (Vitis vinifera L.), enhancing the ability of this cropping system to adapt to soil conditions and bolstering its resistance and resilience against abiotic stresses, particularly drought, by promoting root growth and enhancing the roots' absorption surface. The objective of this on-field study was to determine AMF species richness and diversity along with their relation to soil chemical, physical, and biological characteristics in two adjacent organic vineyards in Central Italy. The two tested vineyards of the autochthonous cv. Aleatico differed by the presence of grafted (Vitis berlandieri × V. riparia rootstock; AL-420) or own-rooted (ungrafted V. vinifera L.; AL-ORV) vines. To this aim, soil and root samples were collected and geo-referenced. Analysis of the AMF species colonizing roots of both AL-ORV and AL-420 revealed the presence of four species: Scutellospora alterata, Paraglomus laccatum, Acaulospora laevis, and A. baetica, with S. alterata being the most frequent. Mycorrhization parameters were higher in the roots of grafted plants compared to ungrafted ones. A high beta-glucosidase (BG):N-acetylglusosaminidase (NAG) ratio in two tested vineyards indicated that microbes utilized more cellulose than chitin and peptidoglycan as dominant C resources. A negative correlation between mycorrhization rate (MyCP) and BG was observed, likely because AMFs form mutualistic relationships with plants, depending on the host plant for carbon. Results revealed a positive correlation between the degree of mycorrhizal association and the species involved, with the presence of copper and nickel among metals. Negative correlations were found concerning soil clay content along with beta-glucosidase. In conclusion, the grapevine root system was characterized by a differential symbiotic relationship with AMF species, whose development is influenced by the root genotype, soil texture, and biochemistry. Specifically, the increased frequency of AMFs in relation to copper content strengthens the evidence of their role in maintaining a vine's production capacity in the event of soil contamination by this element. [ABSTRACT FROM AUTHOR]

Abstract Fritillaria cirrhosa, an endangered medicinal plant in the Qinghai-Tibet Plateau, is facing resource scarcity. Artificial cultivation has been employed to address this issue, but problems related to continuous cultivation hinder successful transplantation. Imbalanced microbial communities are considered a potential cause, yet the overall changes in the microbial community under continuous cropping systems remain poorly understood. Here, we investigated the effects of varying durations of continuous cropping on the bacterial and fungal communities, as well as enzymatic activities, in the rhizospheric soil of F. cirrhosa. Our findings revealed that continuous cropping of F. cirrhosa resulted in soil acidification, nutrient imbalances, and increased enzyme activity. Specifically, after 10 years of continuous cropping, there was a notable shift in the abundance and diversity (e.g., Chao1 index) of soil bacteria and fungi. Moreover, microbial composition analyses revealed a significant accumulation of harmful microorganisms associated with soil-borne diseases (e.g., Luteimonas, Parastagonospora, Pseudogymnoascus) in successively cropped soils, in contrast to the significant reduction of beneficial microorganisms (e.g., Sphingomonas, Lysobacter, Cladosporium) that promote plant growth and development and protect against diseases such as Fusarium sp.These changes led to decreased connectivity and stability within the soil microbial community. Structural equation modeling and redundancy analysis revealed that alkaline hydrolytic nitrogen and available phosphorus directly influenced soil pH, which was identified as the primary driver of soil microbial community changes and subsequently contributed to soil health deterioration. Overall, our results highlight that soil acidification and imbalanced rhizosphere microbial communities are the primary challenges associated with continuous cropping of F. cirrhosa. These findings establish a theoretical foundation for standardized cultivation practices of F. cirrhosa and the bioremediation of continuously cultivated soils.

Organic manure amendments into the rainfed agricultural soil could change the carbon saturation deficit. This study was conducted in the central Himalayan region of India to assess the impact of varying quantities of farmyard manure (FYM) and vermicompost (VC) on changes of soil carbon saturation deficit in the rainfed agricultural system. The experimental plots with three replications and three different amendment rates, such as 15, 30, and 60 Mg ha−1 of FYM and VC were used on the traditional paddy-wheat-finger millet-fallow cropping system. The soil amended with FYM and VC showed significant (p <.05) variations in the soil carbon content, nitrogen content, total microbial activity, β-glucosidase activity, and acid phosphatase activity with an increasing rate of both the manures in each cropping season. The mean soil carbon saturation deficit values varied from 25 to 36% and 19 to 28% in the first year cropping and second year cropping seasons, respectively. Our results demonstrate that the VC amendment was better than FYM for the accumulation of more carbon content in the rainfed agricultural soils of Himalaya, whereas the organic manure amendment rates must be considered for climate change impact mitigation action policy in the future. [ABSTRACT FROM AUTHOR]

Plant growth promoting rhizobacteria (PGPR) have evolved to thrive in challenging environments and provide the plants with defense against the harmful impacts of the environmental stressors. The present study aimed to isolate, screen, and identify PGPB obtained from the rhizosphere soil of some field crops at different sites in Ismailia, Egypt. Isolation process was carried out from drought-suffered locations to obtain efficient promising strains adapted to carry out vital processes under an irrigation water shortage. Eight bacterial isolates were selected and identified by phenotypic properties, and were subjected to screening procedures to assess their growth capabilities and evaluate their potential as PGPB. The screening process involved investigating various PGPB features, such as phosphate solubilization, formation of indole-3-acetic acid (IAA), ammonia, and hydrogen cyanide (HCN) production. Among the eight isolates, two isolates only (MW3 and AB3) gave positive results for all the tested plant growth promoting traits. The promising isolates were identified by sequencing of their16S rRNA as Arthrobacter globiformis (MW3) and Micrococcus luteus (AB3). A field trial was conducted to evaluate the activity of the two PGPB and their mixture to act as biofertilizers for maize under deficit irrigation 0.75 from crop evapotranspiration (ETc). All tested inoculants significantly increased yield components of maize, NPK uptake by plants, availability of N and P in soil, activity of some soil enzymes, and total bacterial counts compared to the un-inoculated control. Utilization of stress adapting PGPR showed great potential in overcoming the challenges of sustainable agriculture under environmental stress conditions.

Abstract Two potent greenhouse gases that are mostly found in agricultural soils are methane and nitrous oxide. Therefore, we investigated the effect of different moisture regimes on microbial stoichiometry, enzymatic activity, and greenhouse gas emissions in long-term paddy soils. The treatments included a control (CK; no addition), chemical fertilizer (NPK), and NPK + cattle manure (NPKM) and two moisture regimes such as 60% water-filled pore spaces (WFPS) and flooding. The results revealed that 60% water-filled pore spaces (WFPS) emit higher amounts of N2O than flooded soil, while in the case of CH4 the flooded soil emits more CH4 emission compared to 60% WFPS. At 60% WFPS higher N2O flux values were recorded for control, NPK, and NPKM which are 2.3, 3.1, and 3.5 µg kg−1, respectively. In flooded soil, the CH4 flux emission was higher, and the NPKM treatment recorded the maximum CH4 emissions (3.8 µg kg−1) followed by NPK (3.2 µg kg−1) and CK (1.7 µg kg−1). The dissolved organic carbon (DOC) was increased by 15–27% under all flooded treatments as compared to 60% WPFS treatments. The microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased in the flooded treatments by 8–12%, 14–21%, and 4–22%, respectively when compared to 60% WFPS. The urease enzyme was influenced by moisture conditions, and significantly increased by 42–54% in flooded soil compared with 60% WFPS while having little effect on the β-glucosidase (BG) and acid phosphatase (AcP) enzymes. Moreover DOC, MBC, and pH showed a significant positive relationship with cumulative CH4, while DOC showed a significant relationship with cumulative N2O. In the random forest model, soil moisture, MBC, DOC, pH, and enzymatic activities were the most important factors for GHG emissions. The PLS-PM analysis showed that soil properties and enzymes possessed significantly directly impacted on CH4 and N2O emissions, while SMB had indirect positive effect on CH4 and N2O emissions.

Abstract Fertilizers application are widely used to get a higher yield in agricultural fields. Nutrient management can be improved by cultivating leguminous species in order to obtain a better understanding of the mechanisms that increase the amount of available phosphorus (P) and potassium (K) through fertilizer treatments. A pot experiment was conducted to identify the leguminous species (i.e., chickpea and pea) under various fertilizer treatments. Experimental design is as follows: T0 (control: no fertilizer was applied), T1: P applied at the level of (90 kg ha−1), T2: (K applied at the level of 90 kg ha−1), and T3: (PK applied both at 90 kg ha−1). All fertilizer treatments significantly (p

Two potent greenhouse gases that are mostly found in agricultural soils are methane and nitrous oxide. Therefore, we investigated the effect of different moisture regimes on microbial stoichiometry, enzymatic activity, and greenhouse gas emissions in long-term paddy soils. The treatments included a control (CK; no addition), chemical fertilizer (NPK), and NPK + cattle manure (NPKM) and two moisture regimes such as 60% water-filled pore spaces (WFPS) and flooding. The results revealed that 60% water-filled pore spaces (WFPS) emit higher amounts of N2O than flooded soil, while in the case of CH4 the flooded soil emits more CH4 emission compared to 60% WFPS. At 60% WFPS higher N2O flux values were recorded for control, NPK, and NPKM which are 2.3, 3.1, and 3.5 µg kg−1, respectively. In flooded soil, the CH4 flux emission was higher, and the NPKM treatment recorded the maximum CH4 emissions (3.8 µg kg−1) followed by NPK (3.2 µg kg−1) and CK (1.7 µg kg−1). The dissolved organic carbon (DOC) was increased by 15–27% under all flooded treatments as compared to 60% WPFS treatments. The microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased in the flooded treatments by 8–12%, 14–21%, and 4–22%, respectively when compared to 60% WFPS. The urease enzyme was influenced by moisture conditions, and significantly increased by 42–54% in flooded soil compared with 60% WFPS while having little effect on the β-glucosidase (BG) and acid phosphatase (AcP) enzymes. Moreover DOC, MBC, and pH showed a significant positive relationship with cumulative CH4, while DOC showed a significant relationship with cumulative N2O. In the random forest model, soil moisture, MBC, DOC, pH, and enzymatic activities were the most important factors for GHG emissions. The PLS-PM analysis showed that soil properties and enzymes possessed significantly directly impacted on CH4 and N2O emissions, while SMB had indirect positive effect on CH4 and N2O emissions. [ABSTRACT FROM AUTHOR]

Background and aims: Root exudation is a key process for plant nutrient acquisition, but the controls on root exudation and its relationship to soil C and N processes in agroecosystems are unclear. We hypothesized that root exudation rates would be related to root morphological traits, N fertilization, and soil moisture. We also anticipated that root exudation would be correlated with bulk soil enzyme activity. Methods: Root exudation, root traits, and bulk soil extracellular enzyme activity were assessed in maize (Zea mays L.), soybean (Glycine max (L.) Merr.), biomass sorghum (Sorghum bicolor (L.) Moench), giant miscanthus (Miscanthus × giganteus), and switchgrass (Panicum virgatum L.). Measurements were taken in situ during two growing seasons with contrasting precipitation regimes, and N fertilization rate was varied in sorghum during one year. Results: Specific root exudation (per unit root surface area) was negatively related to root diameter and was generally higher in annuals than perennials. Sorghum N fertilization did not affect root exudation rates, and soil moisture regime had no effect on annual root exudation rates within maize, sorghum, and miscanthus. Specific root exudation was negatively related to bulk soil C- and N-degrading soil enzyme activities. Conclusion: Intrinsic plant characteristics appeared more important than environmental variables in controlling in situ root exudation rates. The relationships between root diameter, root exudation, and soil C and N processes link root morphological traits to soil functions and demonstrate the potential tradeoffs among plant nutrient acquisition strategies in agroecosystems. [ABSTRACT FROM AUTHOR]

High salinity levels exert detrimental effects on plant growth and development by disturbing photosynthesis, water relations, and nutrient absorption. Different soil amendments are used to alleviate the adverse effects of soil salinity on plant growth and development. This study investigated the impact of cottonseed meal (CSM) application as soil amendment on soil enzymes, macro- and micro-nutrients, and phenol and sugar content in cotton plants grown on normal and saline soil. Three different CSM levels, i.e. 0 (CK), 40 and 80 Mg ha-1 were included in the study. Soil amendment with CSM significantly increased soil enzyme activities, organic carbon, and available nutrients, and improved soil structure. Soil amendment with 40 Mg ha-1 CSM improved dehydrogenase and urease enzyme activities by 15.38 and 40.51%, whereas amendment with 80 Mg ha-1 improved the activities of these enzymes by 15.29 and 21.47%, respectively. However, the activity of catalase enzyme was decreased by 32.18 and 48.28% under 40 and 80 Mg ha-1 CSM amendment, respectively. Soil amendment with 40 Mg ha-1 CSM to increased N, K, Ca, and Mg content by 65.90, 52.29, 5.71, 15.79%, and decreased Na content by 28.85%, whereas 80 Mg ha-1 increased these nutrients by 87.12, 53.63, 10.60, 40.63% and decreased Na content by 4.19%. Similarly, application of 40 Mg ha-1 CSM significantly increased B and Mn content in plants by 7.12, 8.6% on saline soil and by 1.13, and 10.09% on normal soil. Likewise, while 80 Mg ha-1 CSM application increased the B and Mn content by 1.84, and 9.46% on saline soil and 4.0, and 8.94% on normal soil. The application of 80 Mg ha-1 CSM improved total sugar content by 45.5% in saline soil and 3.97% in normal soil. The total phenol content of the plants was improved by 17.25% in saline soil and 2.9% in normal soil. It is concluded that CSM can be used alone or in combination with other organic amendments, such as compost and poultry manure, to alleviate the adverse effects of soil salinity on soil enzymes and nutrient uptake by plants. [ABSTRACT FROM AUTHOR]

The differences in soil water content across the soil profiles produce changes in soil microbial and enzymatic properties, which play a major role in the transformation of soil organic matter. Permanent water saturation contributes to the formation of gleyic/stagnic horizons which have reducing conditions, this leads to a depletion in soil oxygen and changes in soil properties. To assess the effect of water content, we compared soil properties in the gleyic/stagnic horizons to the oxidative layers, which occurred at the same/similar depth in other profiles. The enzymatic activity and the number of microbial groups were assessed in eight soil profiles located in central Poland. The studied properties responded differently to the water content. As expected, nitrate-reductase activity and the nitrate content were significantly higher in gleyic/stagnic than in oxidative conditions, while the opposite trend was found for phenol oxidase, urease, N -acetyl-glucosaminidase activity and the fungi number. No clear response in the total bacteria and facultative anaerobic bacteria (Bfa) count toward oxidation-reduction conditions was found. The dehydrogenases did not have a higher activity in the gleyic/stagnic as compared to the oxidative horizons and did not correlate significantly with the Bfa count. Differences in enzyme activities may be caused by the fact that the variation in frequency and duration of the reducing conditions in the soils may be insufficient to affect the short-term dynamics of these enzymes. The higher activity of some hydrolases in the reducing horizons may also be associated with the greater carbon and nitrogen content in these horizons. [ABSTRACT FROM AUTHOR]

Water stress detrimentally affects soil quality and crop development. The coupled of biochar and compost tea could be a promising strategy for improving soil quality, crop development as well as the productivity of rice plants. Our investigation was performed in split block design to appraise the impact of coupling addition of biochar with compost tea for mitigating the increasing of irrigation intervals (6 days (I1), 9 days (I2), and 12 days (I3)) in rice (Oryza sativa L. Giza 179) during 2022 and 2023 seasons. It was found that the coupled addition of biochar and Compost tea further improved exchangeable sodium percentage and soil enzymes than sole application. In addition, no difference significance was found between irrigation periods every 6 days (I1) and 9 days (I2) and coupled treatment. Consequently, the coupled application enhanced physiological attributes (RWC relative water content and gssto matal conductance) while decrement proline content due to the increased activity of antioxidant enzymes (CAT catalase, Ascorbate peroxidase (APX, and POD peroxidase). Accordingly, the greatest findings were obtained with the integrative use of biochar and compost tea. In conclusion, the integrated application of biochar and Compost tea might be promising efforts for reinforcing soil, physiological characteristics and productivity of rice under environmental stressors conditions. [ABSTRACT FROM AUTHOR]

Background: Cowpea (Vigna unguiculata L.) an important and commonly grown kharif pulse crop in India for vegetable, grain, forage and green manuring. Considering the adverse effects of chemical fertilizers, bio-inoculants should be encouraged as natural nutrient source. Methods: Three indigenous bio-inoculants viz., Rhizobium sp., Bacillus megaterium and Glomus mosseae were evaluated in a field experiment which was conducted during kharif season 2020 to study the influence of bioinoculants on growth and yield of cowpea. The experiment was laid out in randomized block design (RCBD) with ten treatments replicated thrice. Result: The application of microbial consortia significantly influenced the number of pods bearing branches, number of nodules, fresh weight of nodules, chlorophyll content, plant nitrogen and phosphorus content and microbial activities in the cowpea rhizosphere. The present study concluded that combined application of bio-inoculants (Rhizobium, PSB, AM fungi) can save 25 per cent of recommended dose of fertilizer by sustaining the crop yield and improving the soil health. [ABSTRACT FROM AUTHOR]

Phosphorus and zinc are important nutrient elements of concern in upland rice production. To determine the suitable combination of phosphorus, nanoparticles (NPs), and bio-fertilizer application as an alternative nutrient management approach in upland rice cultivation, a Polyvinyl Chloride (PVC) column experiment was conducted under controlled conditions in 2015. The treatments consisted of three phosphorus levels, two foliar sprays of NPs (ZnO and TiO2), and PSB seed treatment. The results indicated that the combined application of P (50 kg ha−1), ZnO NPs (500 ppm), and PSB seed treatment (20 g kg−1) improved the root system architecture traits of rice (total root length: 3.73–6.74%, diameter: 8.57–22.22%, and volume: 3.40–3.70%) at depths of 0–30 cm and 30–60 cm, compared to higher P + TiO2 NPs + no PSB. Consequently, this combination led to an enhancement in photosynthetic leaf area (by 3.3%), tiller numbers (by 7%), and dry matter production (by 35.5%). The favorable root growth resulting from the application of higher P and PSB enhanced zinc uptake by rice grains (by 38.44%) and straw (by 26.99%). Furthermore, the supplemental application of PSB improved the activity of soil enzymes such as dehydrogenase and phosphatase. As a result, maximum phosphorus use efficiency (PUE; 31.5%) was achieved through the combined application of P (50 kg ha−1) × ZnO NPs × PSB. In conclusion, this study demonstrated the beneficial effects of an integrated approach involving phosphorus, PSB, and metal oxides (ZnO NPs) as a fertilizer management strategy to enhance the total biomass and PUE of upland rice. [ABSTRACT FROM AUTHOR]

Rocky desertification is a devastating process in Karst areas of Southwest China and induces serious fragmentation in ecosystems. Therefore, vegetation restoration and the scientific evaluation of soil quality are key restorative strategies in these areas. In this study, a natural closed forest and a disturbed forest with three restoration models, including an evergreen broad-leaved forest, mixed forest, and deciduous forest, were investigated in Huanjiang County. More than nineteen soil properties (including physical, chemical, and biotic properties) were analyzed across treatments, and principal component analyses (PCA) were combined with a minimum data set (MDS) applied to evaluate the soil quality. Our study sought to identify a vegetation restoration model to improve the soil quality in this area. We demonstrated that soil physical and chemical properties, microbial biomass, and enzyme activities significantly differed across all of the models. Soil water content, capillary porosity, total porosity, organic carbon, total phosphorus, available phosphorus, and urease activity were high in the mixed forest, leading to better physical soil properties. Also, relatively high soil total nitrogen, total potassium, available nitrogen, available potassium, microbial biomass C and N, catalase, sucrose, and alkaline phosphatase levels were observed in the deciduous broad-leaved forest, resulting in improved soil chemical properties. Based on the minimum data set (MDS) method, six indicators, including non-capillary porosity, organic carbon, total phosphorus, pH, microbial biomass nitrogen, and urease activity, were selected to evaluate the soil quality across the models. Our data showed that, among the five models, the deciduous broad-leaved forest had the highest soil quality index (0.618), followed by the mixed forest (0.593). Stepwise regression analysis showed that soil organic carbon explained 79.9% of the variations in the soil quality indices, suggesting it was a major factor affecting the soil quality. Thus, vegetation restoration models mainly comprised of native tree species effectively improved the soil quality in Karst rocky desertification areas, with deciduous broad-leaved forests displaying the best effects, followed by mixed forests. [ABSTRACT FROM AUTHOR]

An incubation study investigated the decomposition patterns, microbial activities, soil aggregates distribution, and soil organic carbon (SOC) contents, using four crop residues; wheat (Triticum aestivum L.), rice (Oryza sativa L.), cotton (Gossypium hirsutum L.), and maize (Zea mays L.), at low and high rates (10 and 20 g kg-1). An average increase of about 35% in cumulative C-CO2 emissions and 26% in soil microbial biomass carbon (MBC) was observed at high residue rates as compared to low rates. A positiv e and strong correlation (0.96) was found between C-CO2 emissions and MBC, and the effect of residue quality on decomposition was found to be less at high rates. The relative reduction in C-CO2 emissions by adding rice residues may be due to their high silica content. Differences in extracellular enzyme activities (EEA) with different residues indicated the effect of residue quality on microbial activities. Cotton residues increased β-glucosidase and chitinase activities by 41 and 38%, respectively, at high rates than at low rates. High maize residues also markedly increased chitinase activity by 41%, implying higher N cycling and fungal prevalence. Acid phosphatase activity was found to increase by about 25 to 32% with high rice and wheat residues, respecti vely. Higher EEA at high residues input likely reflected the microbial nutritional limitations. Crop residues raised SOC content from 0.7 under control to 1.0% at low residues input but not at high input. Increased macro-aggregates fraction at high residues input may be attributed to higher microbial activities. In summary, high residues input can minimize residue biochemical quality's effect on decomposition, with no further increase in SOC content. While a positive effect on the soil MBC, but not on the SOC content, was observed at high residue input, suggesting moderation in the additions of organic amendments is key for SOC buildup. Crop residues, added at 10 g kg-1, may help maintain a positive SOC balance in the arid agroecosystems by moderating higher microbial activities and soil respiration. [ABSTRACT FROM AUTHOR]

Plant growth-promoting rhizobacteria (PGPR) can ameliorate soil fertility and boost crop yields. This paper reports a study of the effect of PGPR inoculation on Medicago sativa plants. Sixteen indigenous PGPR were isolated and screened for PGP traits. Their influence was assessed on the growth of M. sativa plants, root colonisation by arbuscular mycorrhizal fungi (AMF), and soil enzyme activities (SEA). The bacterial isolates showed interesting PGP traits. They increased the plant's shoot and root dry weights, AM colonisation, and SEA. Two bacteria assigned to Pseudomonas koreensis and Alcaligenes faecalis were selected as effective inoculants for M. sativa plants. These PGPR may represent suitable candidates as bio-enhancers and biofertilizers in sustainable agricultural systems. [ABSTRACT FROM AUTHOR]

The enormous soil carbon pool stored by mangroves depends upon microbial respiratory activities and enzymes associated with carbon breakdown in soils. Our hypothesis is that increased microbial activity leads to elevated carbon breakdown. To prove this, we measured microbial respiratory and enzyme activity for nitrogen, phosphorus, and carbon cycle in soil from three coastal ecosystems: mangroves, restinga, and Atlantic forest. The multivariate ordination analysis showed that each treatment had distinct soil microbial activity according to the soil layer and seasons. Our results suggest that the Atlantic forest ecosystem had the highest respiration activity (i.e., CO2-C release), dehydrogenase, phosphatase, protease, and urease activities, while mangroves and sandy coastal plains (called restinga) had lower respiration and enzyme activity. Therefore, soil microbial respiratory activity variation was influenced by soil microbial activity in the most superficial layer in coastal soil ecosystems. The agreement between dehydrogenase activity and CO2-C respiration measurements suggests that microbial activity is an efficient indicator of carbon breakdown. Our findings also indicate that the vegetation type in the different ecosystems contribute to stimulate the soil microbiota increasing both its microbial activity and carbon storage. These issues should be considered for the conservation policies to promote effective protection of vital coastal ecosystems in Brazil. Understanding the coastal ecosystem-induced nutrient shifts in microbial communities is important because they can lead to lagged and multiplicative effects on carbon storage. Taken together, our results illustrate the identification of keystone (organic carbon and microbial activity) as an indicator to offer evidence-providing tools to achieve more ecologically efficient managing practices. [ABSTRACT FROM AUTHOR]

Few studies have been reported on the effect of planting years on fruit quality and soil of pear trees. In this study, four planting years (T5, T20, T30, and T40) of Cuiguan pears were used to analyze fruit quality, rhizosphere soil enzymes, and microbial diversity of pear trees, and their correlations. The results showed that the content of sucrose, reducing sugar and ascorbic acid in Cuiguan Pear showed a tendency of increasing and then decreasing with the increase of planting years, in which the highest content was found in 20- and 30-year-old fruits, and the highest content of total acid was found in 5-year-old fruits. Rhizosphere soil enzyme activities varied with planting year, with the highest protease activity in 20-year-old soil, phosphatase and urease in 30-year-old soil, polyphenol oxidase in 5-year-old soil, and sucrase in 40-year-old soil. The microbial diversity index and the number of OTUs showed an increasing and decreasing trend with the increase of planting years. Among the top 11 bacteria in pear rhizosphere soil average relative abundance, with Bradyrhizobium decreasing in relative abundance at the peak pear fruiting stages (T20 and T30), while Acidothermus showed an increasing trend in relative abundance with increasing planting years. RDA analysis showed that there were differences in the microbial community structure of pear trees at different planting years, and that both sucrose and reducing sugar contents in pears were positively correlated with T20 and T30, ascorbic acid content was positively correlated with T40, whereas the total acid content was positively correlated with T5, and that T20 was positively correlated with soil protease and phosphate mono esterase activities, and that T30 was positively correlated with polyphenol oxidase and urease activities, whereas T40 was positively correlated with sucrase activity. In summary, with the increase of planting years, changes in soil microbial community structure and soil enzyme activity have a significant impact on pear quality formation, and the results of the study provide a theoretical basis for scientific management of pear orchards. [ABSTRACT FROM AUTHOR]

Objectives: To slow down the chemical fixation of phosphate fertilizer, reduce the risk of active phosphorus leaching, stimulate the inherent phosphorus resource activity of soil, and improve phosphorus supply capacity. Methods: This study utilized a combination of field experiments and indoor chemical analysis. Six types of exogenous organic matter (fulvic acid, biochar, compound microbial fertilizer, high-energy microbial inoculum, pig manure-vermicompost, cow manure-vermicompost) were added based on conventional fertilization. The experiment was conducted under the wheat-maize rotation system in the Huang-Huai-Hai region. Results: Compared with control (CK) without exogenous organic matter (EOM), all the other treatments with EOM had an enhancing effect on the available phosphorus of the cultivated soil. During the maize harvest, the combined application of biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of available phosphorus in 0–20 cm soil by 45.87–56.59% compared with CK. The combined application of fulvic acid, biochar, pig manure-vermicompost and cow manure-vermicompost treatment significantly increased the content of Ca2-P in 0–20 cm soil by 34.04–65.14%. The content of Ca10-P in each treatment with EOM exhibited a lower level compared to CK. EOM could slow down the fixation of phosphorus to some degree. Correlation analysis revealed significant associations between Ca2-P, Ca8-P, Al-P, Fe-P, neutral phosphatase activity, acid phosphatase activity, and the available phosphorus content in the soil. The combined application of fulvic acid, biochar, and cow manure-vermicompost could enhance the activity of neutral and acid phosphatase in topsoil to a certain extent, thereby facilitating the conversion of phosphorus into highly available Ca2-P. EOM could enhance the soil phosphorus availability and decelerate the conversion of soil phosphorus into O-P and Ca10-P forms with low availability. Among all treatments, biochar exhibited the most pronounced efficiency in mitigating phosphorus leaching downward. Conclusions: All the EOMs had the potential to enhance the conversion of phosphorus into soluble phosphorus (Ca2-P), thereby mitigating the chemical fixation of soil phosphorus and ameliorating non-point source pollution caused by phosphorus. EOM enhanced the activity of neutral and acid phosphatase, which was beneficial to the conversion of organic phosphorus to inorganic phosphorus and increasing the content of available phosphorus. All EOMs had good effects on the retention of soil effective phosphorus, among which biochar had the best effect on retaining effective phosphorus in the tillage layer and blocking phosphorus leaching downward. [ABSTRACT FROM AUTHOR]

Aviation mutagenesis is a breeding method for the rapid selection of superior plant varieties. In this study, rhizosphere soil chemical indexes, soil enzyme activities, and soil metabolites were measured in Dahongpao tea trees with aviation mutagenesis (TM) and without aviation mutagenesis (CK). The main soil metabolites distinguishing TM and CK and their relationships with soil chemical indexes and soil enzyme activities were analyzed and obtained. The results showed that there was no significant change in the rhizosphere soils' pH of TM tea trees compared to CK (p = 0.91), while all other chemical indexes of TM were significantly higher than CK (p < 0.05). In addition, the activities of enzymes related to soil nutrient cycling such as urease, protease, sucrase, acid phosphatase and cellulase, and enzymes related to soil antioxidants such as superoxide dismutase, catalase, peroxidase, and polyphenol oxidase were significantly increased (p < 0.05) in the rhizosphere soils of TM tea trees compared to CK. Soil metabolite analysis showed that the main soil metabolites distinguishing CK from TM were carbohydrates, nitrogen compounds, and amines. Of these, carbohydrates and nitrogen compounds were significantly positively correlated with soil chemical indexes and soil enzymes, whereas amine was significantly negatively correlated with soil chemical indexes such as organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus; amine showed significant negative correlation with soil enzymes such as catalase, peroxidase, polyphenol oxidase, and urease. It can be seen that aviation mutagenesis is conducive to improving the ability of tea tree rhizosphere aggregation and transformation of soil nutrients, increasing the total amount of soil nutrients and the content of available nutrients, which is more conducive to promoting the uptake of nutrients by the tea tree, and thus promoting the growth of the tea tree. [ABSTRACT FROM AUTHOR]

Two plots (10 ha each) of Triticum aestivum L. wheat crop were analysed, one with a phosphorus‐solubilizing bioinoculant (bioinput) and another without the bioinput (control). Traditional physical–chemical variables and four enzymes were analysed: arylsulfatase (AS), β‐glucosidase (β‐G), acid phosphatase (AP), and N‐acetyl‐β‐d‐glucosaminidase (NAG). These variables were considered by Hierarchical Cluster Analysis (HCA) and partial least squares‐discriminant analysis (PLS‐DA). The HCA separated 100% correctly the control and bioinput samples along the wheat phenological stages (Feekes‐Large scale). The PLS‐DA model was constructed with seven latent variables and obtained 100% accuracy, explaining a variance of 97.05% in calibration and 93.13% in cross‐validation. The control soil had a productivity of 57.8 bags per hectare, while the soil with bioinput had a productivity of 60.8 bags per hectare. Furthermore, soil with the bioinput presented higher concentrations of the enzymes AS, β‐G, and AP in the final phenological stages. [ABSTRACT FROM AUTHOR]

The current study investigates the impact of biosurfactant (sophorolipids, SL) concentrations (0.1 to 1 g kg−1) on the removal of cadmium (29 mg kg−1) from soil using Bidens pilosa. The results showed that increasing concentrations of SL increased the plant biomass. The dry weight of plants was 0.87 g, 0.77 g, 0.65 g, 0.85 g, 0.91 g, 0.92 g, 1.06 g in control, SL0 (No SL), SL1 (0.1 g kg−1), SL2 (0.25 g kg−1), SL3 (0.5 g kg−1), SL4 (0.75 g kg−1), and SL5 (1 g kg−1), respectively. It was observed that root length was higher in SL augmented soil in comparison to treatments without SL. It was also found that, with increasing the SL concentration, total chlorophyll and proline concentrations increased as well. The SL2 treatment had the highest Cd accumulation (76.33 µg pot−1) in the plant. Therefore, SL at 0.25 g kg−1 was considered the most effective concentration for the phytoextraction of Cd from soil. Soil enzyme activities, i.e., alkaline phosphatase, dehydrogenase, and urease activity, increased with the increase in SL concentration. The results of this study concluded that SL promotes the removal of Cd from soil and supports plant growth as well as enzymatic activities in soil. [ABSTRACT FROM AUTHOR]

Fresh-cut leafy vegetables are produced in Southern Italy in very intensive crop systems under tunnel greenhouses in which continuous cropping has triggered soil organic carbon (SOC) depletion and the risk of degradation of soil fertility. A two-year trial of soil organic amendment was carried out on a private farm producing baby-leaf crops on a very poor OC soil (<1%). Biowaste compost, two types of olive pomace composts and buffalo manure were compared to evaluate their ability to recover a positive SOC balance and sustain crop growth and yield. The effects on soil health and crop system were studied by measuring different aspects such as SOC stock change and SOC sequestration rate, soil microbial biomass and nine enzyme activities, yields of rocket and concentration of nitrates in leaves. Soil amendments were distributed once a year at doses of 15 and 30 Mg ha−1 as fresh matter without integration of mineral fertilizers. In our study, the SOC stock improved in the amended soils in a range of 4–6 Mg ha−1, except for dose 30 of buffalo manure, with the highest values where biowaste compost was applied. Our data showed an increase in biological parameters in all the amended soils with respect to Control. In soil amended with olive pomace, however, compost mineralization rates likely did not match crops' nutrient needs so the yields of rocket were lower than with the biowaste compost and buffalo manure. Biowaste compost showed the best results as it balanced the best C conversion efficiency, the higher increment of SOC and yields of rocket. [ABSTRACT FROM AUTHOR]

Conventional fertilization practices can lead to many ecological problems, such as nutrient imbalance, soil acidity, and reduced soil fertility, in natural rubber plantations. To address these challenges, a field investigation was strategically carried out to substitute inorganic fertilizer with organic fertilizer, consisting of six treatments: no fertilization (CK), inorganic fertilizer (NPK), 25% replacement of inorganic through organic (25% manure (M)), 50% replacement of inorganic through organic (50% manure (M)), 75% replacement of inorganic through organic (75% manure (M)), and 100% organic fertilizer (100% manure). The soil physicochemical properties (soil organic carbon (SOC), total nitrogen (TN), mineral nitrogen (N), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N)), C:N, pH, and the carbon- and nitrogen-converting enzymes β-1,4-glucosidase (BG), N-acetylglucosaminidase (NAG) and L-leucine aminopeptidase (LAP) were all determined. The partial substitution of inorganic fertilizer with organic fertilizer (i.e., 75% M at surface soil layer) showed higher SOC (14.52 g·kg−1), TN (1.06 g·kg−1), N (20.07 mg·kg−1), C:N (14.63), NH4+-N (10.63 mg·kg−1), and NO3−-N (11.06 mg·kg−1) than NPK and CK. This increase in physicochemical properties after partial replacement of inorganic with organic fertilizer resulted from higher carbon and nitrogen enzyme activities (BG (143.17·nmol·g−1·h−1), NAG (153.96 nmol·g−1·h−1), and LAP (153.48 nmol·g−1·h−1)) compared to NPK and CK. Further, the Pearson correlation and redundancy analysis (RDA) analyses confirmed a significant positive correlation between SOC, N, and soil enzymes. This study presents a new strategy for assessing the impact of partially replacing inorganic fertilizer with organic fertilizer in rubber plantations in tropical regions, mainly by modifying the soil nutrient composition. [ABSTRACT FROM AUTHOR]

Rainforests provide vital ecosystem services that are underpinned by plant–soil interactions. The forests of Borneo are globally important reservoirs of biodiversity and carbon, but a significant proportion of the forest that remains after large-scale agricultural conversion has been extensively modified due to timber harvest. We have limited understanding of how selective logging affects ecosystem functions including biogeochemical cycles driven by soil microbes. In this study, we sampled soil from logging gaps and co-located intact lowland dipterocarp rainforest in Borneo. We characterised soil bacterial and fungal communities and physicochemical properties and determined soil functioning in terms of enzyme activity, nutrient supply rates, and microbial heterotrophic respiration. Soil microbial biomass, alpha diversity, and most soil properties and functions were resistant to logging. However, we found logging significantly shifted soil bacterial and fungal community composition, reduced the abundance of ectomycorrhizal fungi, increased the abundance of arbuscular mycorrhizal fungi, and reduced soil inorganic phosphorous concentration and nitrate supply rate, suggesting some downregulation of nutrient cycling. Within gaps, canopy openness was negatively related to ectomycorrhizal abundance and phosphomonoesterase activity and positively related to ammonium supply rate, suggesting control on soil phosphorus and nitrogen cycles via functional shifts in fungal communities. We found some evidence for reduced soil heterotrophic respiration with greater logging disturbance. Overall, our results demonstrate that while many soil microbial community attributes, soil properties, and functions may be resistant to selective logging, logging can significantly impact the composition and abundance of key soil microbial groups linked to the regulation of vital nutrient and carbon cycles in tropical forests.

Abstract Our investigation revealed that alterations in sulphur (S) pools are predominantly governed by soil organic carbon (SOC), soil nitrogen (N), microbial biomass, and soil enzyme activities in sandy clay loam (Vertic Ustropept) soil. We employed ten sets of nutrient management techniques, ranging from suboptimal (50% RDF) to super-optimal doses (150% RDF), including NPK + Zn, NP, N alone, S-free NPK fertilizers, NPK + FYM, and control treatments, to examine the interrelation of S with SOC characteristics. Fourier-transform infrared (FT-IR) spectroscopy was utilized to analyze the functional groups present in SOC characterization across four treatments: 100% NPK, 150% NPK, NPK + FYM, and absolute control plots. Principal component analysis (PCA) was then applied to assess 29 minimal datasets, aiming to pinpoint specific soil characteristics influencing S transformation. In an Inceptisol, the application of fertilizers (100% RDF) in conjunction with 10 t ha−1 of FYM resulted in an increase of S pools from the surface to the subsurface stratum (OS > HSS > SO4 2−–S > WSS), along with an increase in soil N and SOC. FT-IR spectroscopy identified cellulose and thiocyanate functional groups in all four plots, with a pronounced presence of carbohydrate—protein polyphenol, sulfoxide (S=O), and nitrate groups specifically observed in the INM plot. The PCA findings indicated that the primary factors influencing soil quality and crop productivity (r2 of 0.69) are SOC, SMBC, SMBN, SMBS, and the enzyme activity of URE, DHA, and AS. According to the study, the combined application of fertilizer and FYM (10 t ha−1) together exert a positive impact on sulphur transformation, SOC accumulation, and maize yield in sandy clay loam soil.

Introduction and GoalThe rangeland ecosystems of arid and semi-arid regions play the most important role in the distribution and density of vegetation in these areas due to the specific environmental conditions governing the soil, which is the bridge between living and non-living parts of ecosystems. Soil enzymes play important biochemical roles in the decomposition of organic matter at all stages in the soil system. These enzymes play an important role in the stability of the soil structure, the decomposition and formation of organic matter, the cycle of elements and the activity of soil microorganisms. Environmental stresses, such as drought, have negative impact on plant growth and soil microorganism's activity. Therefore, evaluating the effect of flood spreading on soil quality indicators can be a useful step in improving knowledge in this field. Therefore, this research was conducted during 2018 and 2019 to investigate the effect of flood spreading, plant types and characteristics on biological soil in the Kowsar floodplains located in Gareh-Bygone, Fasa.Materials and MethodsSampling of the soil around the roots of Artemisia sieberi Besser, Dendrostellera lessertii (Wikstr) Van Tiegh. and Heliantemum lippii (L) Pers, in two situations: with flood spreading and without flood spreading (control area) in spring and autumn from a depth of 0-20 cm and in three repetitions. After ensuring the normality and homogeneity of the variance of the data by the Shapiro–Wilk and Levene tests, the data were analyzed using the two-way variance method and mean comparison were made using Duncan's test at the 1% and 5% level and using the R software.Results and DiscussionThe results of soil fertility characteristics showed that there was no significant difference in the amount of phosphorus and potassium in the three pasture species studied under flood spreading and the control areas. However, the amount of carbon and nitrogen in all studied species was significantly higher in the flood spreading area (containing 0.3% organic matter) than the control area (with 0.15% organic matter). In addition, the results of this research indicated that the highest activity of acid phosphatase enzyme was observed in the rhizosphere of D. lessertii species and in the spring season, and on the contrary the lowest activity was observed in the rhizosphere of H. lippii species under the flood spreading condition. Alkaline phosphatase activity in all species was significantly higher in spring than in autumn season. The highest activity of this enzyme was observed for A. sieberi in the spring season with an average of 186 (µg p-nitrophenol g-1 soil h-1) in the flood spreading area and the lowest level was observed for H. lippii in the control area with an average of 57 (µg p-nitrophenol g-1 soil h-1) in the autumn season. In general, the level of phosphatase enzyme activity for the A. sieberi species in the spring season was approximately 89% higher in the flood spreading area than in the control area. The dehydrogenase enzyme activity was higher in spring than in autumn. Also, the highest activity of this enzyme was observed in the spring season for the D. lessertii species with an average of 8.5 (µg TPFg-1 soil 24 h-1 ) in the control area, and the lowest level was observed in the autumn season for the A. sieberi species in the flood spreading area with an average amount of triphenol formazan was 1 (µg TPFg-1 soil 24 h-1 ) .In other words, the amount of dehydrogenase enzyme activity in the spring season was approximately 66% higher than that in the fall season in both areas (control and flood spreading). The results of this research showed that the activity of urease enzyme under flood spreading conditions in both seasons (autumn and spring), with an average of 270 and 300 (µg N/g.dm.2h) is more than the control area with an average of 173 and 250 (µg N/g.dm.2h). Also, the soil quality indices in all three studied species in the two (control and flood spreading) areas have a significant difference, so that the flood spreading operation has upgraded the value of these indices for the H. lippii species and the A. sieberi, while which has reduced the soil quality index of D. lessertii.Conclusions and SuggestionsThe results of this research showed that the flood spreading system is a desirable method for improving soil organic carbon, and its efficiency increases with the plant planting. The increase in moisture and the amount of organic matter in the flood spreading area can be a reason for increasing the activity of enzymes in the flood spreading area, so that in both autumn and spring, the activity of soil enzymes is more in the region. Considering the important role of organic matter in improving biological indicators and soil quality and health, the restoration of floodplains with native species can play an important role in providing these conditions. In addition, it is recommended that these tests be repeated with more samples and in different areas and the nitrogen, carbon, sulfur and phosphorus cycles and its relationship with the activity of other soil enzymes related to this cycle should be investigated.

To avoid soil degradation, adapt to climate change and comply with the Sustainable Development goals 2030 (UN General Assembly), establishing the quality/fertility of the agricultural soils of the Mediterranean region and evaluate how these evolve with time is mandatory. This enables adequate management practices to be implemented. The Mediterranean calcareous region has received little attention in this sense, in spite its soil particularities. So, 24 different representative calcareous agricultural soils of the Mediterranean region, including the main management strategies of agricultural soils (rainfed and irrigated), were sampled from the island of Mallorca; and their physical, chemical and biological properties determined. The values obtained for most of the soil characteristics allowed to establish an initial approach to the reference values for the type of calcareous agricultural soils considered, and to clearly distinguish the effect of rainfed or irrigation management practices on soils properties and dynamics. Some enzyme activities were not stimulated by the irrigation conditions assayed or they were only in dry conditions, suggesting optimum enzyme activities could be obtained when alternating dry and humid soil conditions. Soil organic carbon, calcium carbonate and active lime revealed of significant importance in the collection of soils. Finally, the results obtained clearly indicate the heterogeneity of the region and its implications on the different soil characteristics. Therefore, this study could serve as a starting point to adequately establish the quality (fertility) for Mediterranean calcareous agricultural soils and their reference values by conducting further research in this region and including more type of soils.

Our investigation revealed that alterations in sulphur (S) pools are predominantly governed by soil organic carbon (SOC), soil nitrogen (N), microbial biomass, and soil enzyme activities in sandy clay loam (Vertic Ustropept) soil. We employed ten sets of nutrient management techniques, ranging from suboptimal (50% RDF) to super-optimal doses (150% RDF), including NPK + Zn, NP, N alone, S-free NPK fertilizers, NPK + FYM, and control treatments, to examine the interrelation of S with SOC characteristics. Fourier-transform infrared (FT-IR) spectroscopy was utilized to analyze the functional groups present in SOC characterization across four treatments: 100% NPK, 150% NPK, NPK + FYM, and absolute control plots. Principal component analysis (PCA) was then applied to assess 29 minimal datasets, aiming to pinpoint specific soil characteristics influencing S transformation. In an Inceptisol, the application of fertilizers (100% RDF) in conjunction with 10 t ha−1 of FYM resulted in an increase of S pools from the surface to the subsurface stratum (OS > HSS > SO42−–S > WSS), along with an increase in soil N and SOC. FT-IR spectroscopy identified cellulose and thiocyanate functional groups in all four plots, with a pronounced presence of carbohydrate—protein polyphenol, sulfoxide (S=O), and nitrate groups specifically observed in the INM plot. The PCA findings indicated that the primary factors influencing soil quality and crop productivity (r2 of 0.69) are SOC, SMBC, SMBN, SMBS, and the enzyme activity of URE, DHA, and AS. According to the study, the combined application of fertilizer and FYM (10 t ha−1) together exert a positive impact on sulphur transformation, SOC accumulation, and maize yield in sandy clay loam soil. [ABSTRACT FROM AUTHOR]

Soil salinization is a common form of land degradation in coastal regions. The Yellow River Delta is a typical coastal saline‐alkali soils distribution region, with saline‐alkali soils accounting for nearly half of the total area of the region. In view of the lack of fresh water in the region, the use of brackish water and biochar made from agricultural waste to improve coastal saline‐alkali soils has a good application prospect, but there are fewer studies on this at present. To explore water conservation, fertilization, and yield enhancement solutions appropriate for saline‐alkali soils in the Yellow River Delta region, this study focused on investigating the impact of biochar addition on the fertility, enzyme activity, and winter wheat yield in saline‐alkali soils under brackish water irrigation conditions. The research was conducted through outdoor potting experiments, utilizing a local moderately saline‐alkali soil as the subject of study. The study design established three different irrigation water mineralization levels (0, 2, and 4 g L−1) during the research. Two types of biochar, wheat straw biochar (WB) and corn straw biochar (CB) were used with four different applications (0, 5, 10, and 20 t ha−1). There were 21 treatments; each replicated three times. The research findings indicated that brackish water irrigation adversely affected soil fertility and soil alkaline phosphatase activity and soil sucrase activity but increased soil urease activity and soil peroxidase activity. In contrast, biochar application improved soil fertility and enzyme activities. The soil fertility and enzyme activities of K2Y10 treatment was higher than that of CK (fresh water, no biochar application) except for soil total nitrogen, which increased by 5.5%–71.2%. While brackish water irrigation decreased winter wheat yield. Biochar application increased winter wheat yield, with the K2Y10 treatment showing the highest yield under brackish water irrigation conditions, and increased by 17.7% compared to CK. In conclusion, the study recommends a combination of water‐saving measures, fertilizer cultivation, and yield increase strategies to improve saline‐alkali soils in the Yellow River Delta region effectively. Specifically, irrigating with 2 g L−1 brackish water and application 10 t ha−1 of CB demonstrated greater efficacy in addressing the challenges of saline‐alkali soils in the region. [ABSTRACT FROM AUTHOR]

Plants are often exposed to multiple stresses, including heavy metals (HM) and drought, which limit the plant growth and productivity. Though biochar or plant growth-promoting rhizobacteria (PGPR) have been widely used for alleviating HM or drought stress in plants, the study of the effects of combined treatment with biochar and PGPR under simultaneous HM and drought stress is limited. This study investigated individual and combined effects of groundnut shell biochar (GS-BC) and PGPR Bacillus pseudomycoides strain ARN7 on Zea mays growth, physiology, and HM accumulation, along with their impact on soil enzymes under HM (Ni and Zn), drought, or HM+drought stress. It was observed that even under HM+drought stress, Z. mays growth, total chlorophyll, proteins, phenolics, and relative water contents were increased in response to combined GS-BC and ARN7 treatment. Furthermore, the combined treatment positively influenced plant superoxide dismutase, ascorbate peroxidase, and catalase activities, while reducing electrolyte leakage and phenolics, malondialdehyde, and proline under HM, drought, or HM+drought stress. Interestingly, the combined GS-BC and ARN7 treatment decreased HM accumulation and the bioaccumulation factor in Z. mays, highlighting that the combined treatment is suitable for improving HM phytostabilization. Additionally, GS-BC increased soil enzymatic activities and ARN7 colonization irrespective of HM and drought stress. As far as we know, this study is the first to illustrate that combined biochar and PGPR treatment could lessen the adverse effects of both HM and drought, suggesting that such treatment can be used in water-deficient HM-contaminated areas to improve plant growth and reduce HM accumulation in plants. [ABSTRACT FROM AUTHOR]

Soil enzyme activities are closely associated with soil organic carbon (SOC) or microbial biomass carbon (MBC). High correlation between SOC and MBC masks their individual effects on enzyme activities. Expressing soil enzymes activity relative to soil organic carbon (SOC) or Microbial Biomass Carbon (MBC) would normalize the differences in SOC/MBC. A long term subtropical rice-wheat system was selected to study the variation in soil-specific enzyme activity (per unit SOC and MBC) in soil aggregates under integrated nutrient management. Soil organic carbon, microbial biomass carbon and the enzyme activities like acid phosphatase (ACP), alkaline phosphatase (AKP), dehydrogenase (DHA), fluorescien diacetate hydrolysing capacity (FDA) and urease were measured in three aggregate size fractions viz., >2000, 2000–250 and <250 µm. Integrated nutrient management practices significantly increased the specific enzyme activities expressed in relation to SOC and MBC. Aggregate size fractions of 2000–250 µm size exhibited higher specific enzyme activities, when expressed in terms of SOC. Enzyme activity (per unit MBC) in aggregates also followed the same pattern with an exception to dehydrogenase activity which was almost uniform across all the aggregates size fractions. Aggregates of larger size do not always possess higher enzymes activity; even smaller macroaggregates were able to retain stable extracellular enzyme activity per unit of SOC or MBC. This study opens an alley to express soil enzymatic activities relative to SOC or MBC level in the soils, rather than expressing absolute activities. [ABSTRACT FROM AUTHOR]

In the present study, biological indicators were used to assess the impact of applying spent mushroom substrate and manure on the soil environment. The use of spent mushroom substrate had a varied effect on the microorganisms. Stimulation was recorded in the abundance of copiotrophic bacteria and fungi, but only in the first year of the study. In the case of cellulolytic bacteria, this effect was visible only in single plots. Similar observations were also noted regarding the relative DNA content (in relation to the control), which increased for both bacteria and fungi after applying spent mushroom substrate. In the soil fertilized with spent mushroom substrate, a decrease in DNA concentration was observed, but only in the first and second year. For enzymatic activity, the use of spent mushroom substrate alone proved to be more favorable, but this effect was again observed only in the first year of the study. The application of manure caused similar changes as observed with the use of spent mushroom substrate. These observations indicate a similar impact of spent mushroom substrate and manure on the parameters tested. The research presented suggests the use of both classical methods and methods based on the analysis of DNA extracted from soil to study the impact of spent mushroom substrate on the activity of soil microbial populations. [ABSTRACT FROM AUTHOR]

Biochar is a beneficial substance for sequestering organic carbon in soil. Application of fresh biochar (FB) to the soil leads to an increase in soil organic carbon (SOC). However, the effects of aged biochar on SOC stabilization in acidic soils are unclear. A 90‐day incubation study was assessed to evaluate the impact of adding rice straw biochar on acid soil. The study aimed to assess the alterations in carbon fractions, enzyme activity and bacterial communities in soil. We used different ageing processes (water‐washed biochar [WB] and H2O2 oxidation biochar [OXB]) at a rate of 2%, with control at 0% of biochar. The results indicated that aged biochar reduced CO2 efflux and increased microbial biomass carbon (MBC), reducing the microbial metabolic quotient (qCO2). The SOC and its fractions increased with ageing relative to the FB treatment. Compared with the FB treatment, the carbon pool management index (CPMI) also increased with the OXB application. Additionally, the application of OXB stimulated the soil enzymes involved in carbon cycling, specifically β‐1,4‐glucosidase (βG), β‐1,4‐xylosidase (βX) and cellobiohydrolase (CBH) relative to the FB and WB treatments. Moreover, biochar applications improved the structure and functions of the bacterial population in soil with high acidity. Proteobacteria, Acidobacteria, Actinobacteria and Chloroflexi were the most prevalent species in all treatments, as shown by their relative abundances. The redundancy analysis revealed that the DOC (dissolved organic carbon) and MBC significantly impacted on the microbial community. Furthermore, adding OXB altered the Bacterial community involved in the C cycle by affecting SOC. These findings help us learn more about how applying fresh or aged rice straw biochar changes different carbon fractions and microbial communities in soil. It may serve as an instance for studying the provision of soil organic carbon after applying biochar in acidic soil. [ABSTRACT FROM AUTHOR]

Management practices and soil environmental variables influence microbiological properties and may cause inaccuracies in the interpretation of the results of these bioindicators. This study evaluated the sensitivity of seven microbiological properties to soil management and environmental variables of a Rhodic Ferralsol from a subtropical region of Brazil. The experimental area was cultivated with crotalaria and corn, followed by a fallow period. Samples were collected monthly for a year to determine soil enzyme activities and heterotrophic bacteria and fungi counts. Soil respiration was evaluated directly in the field. Total hydrolytic activity, cellulases, proteases, dehydrogenases and soil respiration were sensitive to management. Moreover, soil respiration was sensitive to fluctuations in soil temperature (r = 0.75) and pre-sampling precipitation (r = 0.54). Dehydrogenase activity was sensitive to soil moisture (r = 0.72) and total microorganisms (r = 0.61). The bacterial (5.69 ± 0.37 log10 CFU g soil−1) and fungal (3.99 ± 0.42 log10 CFU g soil−1) counts showed low sensitivity to soil management and environmental variables. The seven microbiological properties evaluated responded differently to the management and environmental variables. This information must be considered when using soil quality bioindicators to avoid errors in interpreting results. [ABSTRACT FROM AUTHOR]

This study aimed to determine the suitable reclamation ways of post‐mining magnesite. It was hypothesized that adding amendments and planting would decrease pH, increasing the nutrient availability and enhancing the soil microbial activity. Treatments included 200 g gypsum, 2 kg goat manure, and 200 g sulfur per square meter. Cedar (Cedrus libani A. Rich.), black locust (Robinia pseudoacacia L.), black pine (Pinus nigra J.F. Arnold), and sainfoin (Onobrychis sativa L.) were planted. Before and after the treatments, samples were taken from each experimental unit and analyzed. Analysis of the data indicated that the pH had decreased by 0.6 and 0.5 units on the gypsum + sulfur‐ and gypsum + manure‐treated experimental units, respectively, compared to the other treated plots. In addition, using manure significantly increased the organic matter N, P, and K content, by 3‐fold, 2.5‐fold, 7.5‐fold, and 2.5‐fold, respectively, and enhanced microorganism activity. The sulfur + manure treatment increased microbial C and N approximately twofold. Because the manure, sulfur, and gypsum treatments improved the tailings conditions for plant growth, the use of these amendments for mine tailing reclamation was strongly recommended. Across all treatments, cedar and black pine demonstrated 83 and 77% survival rates for the first 3 years of afforestation, respectively. For the same period, the black locust survival rate was 35% lower than that of the other species. The gypsum + manure application increased seedling height growth by about 20% for all three species compared to the other treatments. [ABSTRACT FROM AUTHOR]