Soil Enzyme Activities Research Articles

Eucalyptus and Native Broadleaf Mixed Cultures Boost Soil Multifunctionality by Regulating Soil Fertility and Fungal Community Dynamics.

The growing recognition of mixed Eucalyptus and native broadleaf plantations as a means of offsetting the detrimental impacts of pure Eucalyptus plantations on soil fertility and the wider ecological environment is accompanied by a clear and undeniable positive impact on forest ecosystem functions. Nevertheless, the question of how mixed Eucalyptus and native broadleaf plantations enhance soil multifunctionality (SMF) and the mechanisms driving soil fungal communities remains unanswered. In this study, three types of mixed Eucalyptus and native broadleaf plantations were selected and compared with neighboring evergreen broadleaf forests and pure Eucalyptus plantations. SMF was quantified using 20 parameters related to soil nutrient cycling. Partial least squares path modeling (PLS-PM) was employed to identify the key drivers regulating SMF. The findings of this study indicate that mixed Eucalyptus and native broadleaf plantations significantly enhance SMF. Mixed Eucalyptus and native broadleaf plantations led to improvements in soil properties (7.60-52.22%), enzyme activities (10.13-275.51%), and fungal community diversity (1.54-29.5%) to varying degrees compared with pure Eucalyptus plantations. Additionally, the mixed plantations exhibit enhanced connectivity and complexity in fungal co-occurrence networks. The PLS-PM results reveal that soil properties, fungal diversity, and co-occurrence network complexity directly and positively drive changes in SMF. Furthermore, soil properties exert an indirect influence on SMF through their impact on fungal diversity, species composition, and network complexity. The findings of this study highlight the significant role of mixed Eucalyptus and native broadleaf plantations in enhancing SMF through improved soil properties, fungal diversity, and co-occurrence network complexity. This indicates that incorporating native broadleaf species into Eucalyptus plantations can effectively mitigate the negative impacts of monoculture plantations on soil health and ecosystem functionality. In conclusion, our study contributes to the understanding of how mixed plantations influence SMF, offering new insights into the optimization of forest management and ecological restoration strategies in artificial forest ecosystems.

Development of root rot in Zanthoxylum bungeanum is closely linked to changes in soil microbial communities, enzyme activities, and physicochemical factors

Due to the emergence of root rot (RR), it can cause harm to the health of Zanthoxylum bungeanum (Z. bungeanum) plants. However, the reason for this is not clear, and further research is needed. We selected healthy and RR-affected 6-year-old Z. bungeanum trees (infected for 1 year), collected their rhizosphere and bulk soils, and analyzed soil microbial communities, enzyme activities, and physicochemical properties. When the plants were diseased, soil water content (SWC), available potassium (AK), organic matter (OM) contents, β-1,4-glucosidase (β-G) activity, and fungal Shannon index significantly decreased, while bacterial Shannon index significantly increased in the rhizosphere soil. Soil total nitrogen (TN), SWC, AK, OM contents, and β-G and N-acetyl-glucosamine (NAG) activity significantly reduced, while fungal Simpson index significantly increased in the bulk soil. There were significant differences in the bacterial communities of bulk and rhizosphere soil. However, there were no obvious differences in the fungal communities. Pearson's correlation analysis showed that changes in soil microbial communities were significantly correlated with changes in the contents of TN, AK, OM, and SWC, as well as the activities of β-G and NAG. In summary, changes in soil AK, OM, SWC, and TN resulted in changes in microbial community composition, as well as changes in β-G and NAG activities, and these alterations may lead to RR in Z. bungeanum.

Understanding the interaction between soil ORP and enzyme activity: How does wetland type affect constructed wetland performance for the advanced treatment of swine wastewater?

Constructed wetlands (CWs) are widely used for the advanced treatment of swine wastewater. Wetland type is the most critical parameter for engineering applications; therefore, the performance of horizontal/vertical subsurface flow CWs (HSFCWs and VSFCWs) was explored over one year of operation. The effects of five antibiotics (40 μg/L each), copper (Cu, 1.0 mg/L), and their combination on CW performance and soil oxidation–reduction potential (ORP) and enzyme activity were investigated. The annual removal efficiencies of HSFCWs and VSFCWs for total organic carbon (TOC), nitrogen, and phosphorus were 72.03 %–84.49 % and 87.15 %–90.72 %, for antibiotics were 91.35 %–99.52 % and 87.33 %–99.57 %, and for Cu were 97.37 %–97.44 % and 95.52 %–96.85 %, respectively. The CWs removed antibiotics through substrate adsorption, plant absorption, and biodegradation. Total antibiotic residues in HSFCW and VSFCW soils ranged from 6.29 to 17.31 and 24.57 to 589.07 μg/kg, respectively, and enrofloxacin and roxithromycin posed medium and high risks in VSFCW non-rhizosphere soil. The amount of residual antibiotics in Phragmites australis parts was in the order of fibrous roots > rhizomes > aboveground. ORP and enzyme activities were greater in rhizosphere soil than in non-rhizosphere soil and greater in the VSFCWs than in the HSFCWs. CW performance and soil enzyme activities decreased under the stress of antibiotics and coexistence of antibiotics and Cu. These findings advance our knowledge of CW design, elucidate the unique advantages of CWs, and offer efficient operation strategies for swine wastewater advanced treatment, helping researchers recognize the adverse effects of antibiotics on CWs.

Global perspective of ecological risk of plastic pollution on soil microbial communities.

The impacts of plastic pollution on soil ecosystems have emerged as a significant global environmental concern. The progress in understanding how plastic pollution affects soil microbial communities and ecological functions is essential for addressing this issue effectively. A bibliometric analysis was conducted on the literature from the Web of Science Core Collection database to offer valuable insights into the dynamics and trends in this field. To date, the effects of plastic residues on soil enzymatic activities, microbial biomass, respiration rate, community diversity and functions have been examined, whereas the effects of plastic pollution on soil microbes are still controversial. To include a comprehensive examination of the combined effects of plastic residue properties (Type, element composition, size and age), soil properties (soil texture, pH) at environmentally relevant concentrations with various exposure durations under field conditions in future studies is crucial for a holistic understanding of the impact of plastic pollution on soil ecosystems. Risk assessment of plastic pollution, particularly for nanoplasctics, from the perspective of soil food web and ecosystem multifunctioning is also needed. By addressing critical knowledge gaps, scholars can play a pivotal role in developing strategies to mitigate the ecological risks posed by plastic pollution on soil microorganisms.

Phosphogypsum with Rice Cultivation Driven Saline-Alkali Soil Remediation Alters the Microbial Community Structure.

The improvement of saline-alkali land plays a key role in ensuring food security and promoting agricultural development. Saline soils modifies the response of the soil microbial community, but research is still limited. The effects of applying phosphogypsum with rice cultivation (PRC) on soil physicochemical properties and bacterial community in soda saline-alkali paddy fields in Songnen Plain, China were studied. The results showed that the PRC significantly improved the physicochemical properties of soil, significantly reduced the salinity, increased the utilization efficiency of carbon, nitrogen, and phosphorus, and significantly increased the activities of urease and phosphatase. The activities of urease and phosphatase were significantly correlated with the contents of total organic carbon and total carbon. A redundancy analysis showed that pH, AP, ESP, HCO3-, and Na+ were dominant factors in determining the bacterial community structure. The results showed that PRC could improve soil quality and enhance the ecosystem functionality of soda saline-alkali paddy fields by increasing nutrient content, stimulating soil enzyme activity, and regulating bacterial community improvement. After many years of PRC, the soda-alkali soil paddy field still develops continuously and healthily, which will provide a new idea for sustainable land use management and agricultural development.

Facilitating effects of plant extracts on soil health and replanted Panax ginseng growth in recession soil.

Plant extracts have been shown to be effective agricultural strategies for improving soil fertility and quality, and promoting plant growth in soil degradation remediation. The application of plant extracts improves the material cycle of soil microecology, such as the decomposition of nitrogen, phosphorus, and potassium, while increasing plant resistance. However, there is currently no experiment to demonstrate whether plant extracts have a promoting effect on the growth of ginseng and the mechanism of action. Pot experiments were carried out to investigate the effects of extracts, namely Rubia cordifolia (RC), Schisandra chinensis (SC), and Euphorbia humifusa (EH) on soil properties, enzyme activities, and plant physiological characteristics were evaluated. Results showed that compared with CK, plant extract-related treatments increased soil Organic carbon (OC), Available nitrogen (AN), Available phosphorus (AP) contents, and Soil urease activity. (S-UE), Soil sucrase activity (Soil sucrase), Soil acid phosphatase activity. (S-ACP). Meanwhile, plant extract-related treatments significantly increased plant physiological properties and TP (Total protein) content, and decreased the content of MDA (malondialdehyde) by 15.70% -36.59% and PRO (proline) by 30.13% -148.44%. Furthermore, plant extract-related treatments also significantly promote plant growth and reduce plant incidence, the fresh weight of ginseng increased by 27.80% -52.08%, ginseng root activity increased by 45.13% -90.07%, and ginseng incidence rate decreased by 20.00% -46.67%. Through correlation analysis between fresh weight of ginseng and root parameters and soil index, fresh weight is significantly positively correlated with root diameter, fiber root number, root activity, total protein (TP), catalytic activity (CAT) and superoxide dismutase activity (SOD), H, soil urea activity (S-UE), soil sucrose activity (S-SC), soil acid phosphate activity (S-ACP), and soil laccase activity (SL); The fresh weight was significantly negatively correlated with incidence rate, disease severity index, and malondialdehyde content (MDA). In summary, plant extract-related treatments improve soil quality and promote ginseng growth, further enhancing soil health and plant disease resistance. These findings provide new insights into ginseng cultivation and soil health management and highlight a new approach that can be applied to a wider range of agricultural practices and environmental sustainability.

Effects of biochar application on soil properties and the growth of Melissa officinalis L. under salt stress

Soil salinization is one of the world's most seriously ecological issues. The application of biochar may enhance the properties of the soil and lessen the harm that salt stress causes to plants. In this study, we used the cuttings of Melissa officinalis as experimental materials. The method of pot experiment was used to explore to explore the effects of different concentrations of biochar (0, 10 %, and 20 % w/w) on soil properties and plant physiological characteristics under salt stress (0, 0.20 %, and 0.60 % NaCl+Na2SO4). The results indicate that the physicochemical properties of soil and the plant growth were decreased impacted with increasing salinity level, and these negative impacts were decreased traits were improved with the application of biochar. It was discovered that the application of biochar could increase the soil water holding capacity, total porosity, available P and K content, and soil enzyme activity while also decreasing the soil bulk density under salt stress. Biochar addition promoted the accumulation of plant biomass and the acquisition of nutrients, and reduced Na content in plants. With the addition of biochar, malondialdehyde (MDA) content and electrolyte leakage displayed a significant decrease under salt stress. A reduction in the osmotic substances and secondary metabolite accumulation in the leaves was also evident. The presented results reveal that biochar can contribute to protect M. officinalis against salt stress by alleviating the oxidative stress. Among the test samples, the 20 % biochar application had the best performance, suggesting that this is an advantageous method for improving soil properties and lessening the harm caused by salt stress on M. officinalis.

Management of soft rot in pakchoi (Brassica chinensis L.) using polyphenols from pineapple peel waste

Soft rot is one of the most susceptible soil-borne diseases of pakchoi (Brassica chinensis L.), severely hindering its industrial development. The research aimed to evaluate the application effect of polyphenols extracted from pineapple peel waste in improving the rhizosphere soil environment of pakchoi infected by soft rot and promoting plant health and growth. We found that using pineapple peel polyphenols (PPPs) at 4 mg/mL concentration (P1 treatment) significantly improved soil quality, reduced pakchoi disease incidence, and effectively promoted pakchoi growth. Compared with the control group (CK), the P1 treatment led to a marked 79.97 % reduction in diseased pakchoi leaves. Meanwhile, the rhizosphere soil structure showed reduced diseased genera and increased beneficial bacterial phyla, along with boosted soil enzyme activities. Furthermore, P1 treatment improved key growth parameters of pakchoi, including neck thickness (62.07 %), plant height (57.43 %), fresh weight (154.52 %), dry weight (121.88 %), maximum leaf length (47.28 %), width (30.98 %), and total chlorophyll content (50.11 %). The application of PPPs has shown significant effects in enhancing the ecological environment of the diseased soil and reducing the incidence of soft rot disease of pakchoi and has great potential in increasing the yield of pakchoi. This study offers an eco-friendly and sustainable approach for the valorization of PPPs and the management of soil-borne diseases, which holds profound implications for enhancing crop quality, soil health, and human well-being.

Effects of Nitrogen Forms on Soil Enzyme Activities in a Saline-Alkaline Grassland.

Global climate change and agricultural practices have increased atmospheric nitrogen (N) deposition, significantly affecting the nitrogen cycling process in grasslands. The impact of different N forms on key soil enzyme activities involved in N nitrification, particularly in the saline-alkali grasslands of the Hexi Corridor, using natural grassland as a control (CK) and adding three N treatments: inorganic N (IN), organic N (ON) and a mixed N treatment (MN, with a 4:6 ratio of organic to inorganic N). Our study assessed the effects of these N forms on soil properties and enzyme activities crucial for N cycling. The findings indicate that different N forms significantly enhance soil mineral N content, with ON treatment leading to the highest increases in nitrate and ammonium content 92.44% and 35.6%, respectively, compared to CK. Both IN and ON treatments significantly boosted soil nitrate reductase and urease activities (p < 0.05), while MN treatment decreased nitrate reductase activity, with ON treatment showing the greatest sensitivity to enzyme activity changes. Soil pH slightly increased with N addition, but soil nitrite reductase activity remained relatively unchanged (0.372-0.385 mg g-1). Correlation analysis revealed that soil mineral N content and pH are key regulators of enzyme activities in saline-alkaline grasslands. These results suggest that different N forms should be considered in nutrient cycling models, with organic N addition potentially enhancing soil N conversion and mitigating nutrient limitations in grassland ecosystems.

Changes in Soil Bacterial and Fungal Community Composition and Functional Groups During the Artificial Restoration of Degraded Grassland of "Black-Soil Mountain".

About 35% of grassland in Sanjiangyuan area of China has degenerated into black-soil mountain. Artificial grassland is considered to be an effective measure to alleviate the severely degraded grassland in the alpine region of the three rivers and has been widely used. However, the pattern, potential function, and changes of carbon and nitrogen contents of soil microorganisms in degraded grassland in Heimushan by planting artificial grassland are still unclear. In this study, mixed-sown artificial alpine grassland (AG) was the focus of our study, whereas degraded black-soil mountain grassland (BG) and natural alpine grassland (NG) served as controls. Illumina 16S and ITS gene sequence analyses were used to analyze the community structure of the soil bacteria and fungi. The functional groups of NG, AG, and BG were predicted using the FAPROTAX and FUNGuild databases. In addition, the levels of soil carbon, nitrogen, and soil enzyme activities were evaluated. The results indicated a significant increase in the aboveground biomass of BG due to the planting artificial grassland. Moreover, the contents of total carbon (TC), total nitrogen (TN), ammonium nitrogen ( ), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and leucine aminopeptidase (LAP) increased in the soil. Planting artificial grasslands changed the composition of bacterial and fungal communities. Among these, the bacterial community was more sensitive to planting artificial grasslands. The relative abundance of bacterial functional groups involved in carbon and nitrogen cycling changed significantly, suggesting that bacteria may play a role in regulating nutrient cycling during artificial grassland planting. Soil TC, TN, LAP, and affected the microbial community structure related to carbon and nitrogen. and β-1,4-glucosidase were carbon and nitrogen factors, respectively, that affected functional changes in fungi. These results indicate that planting artificial grasslands can effectively enhance the productivity of degraded black-soil mountain and regulate soil microbial communities and soil physical and chemical properties.

The Marine-Origin Exopolysaccharide-Producing Bacteria Micrococcus Antarcticus HZ Inhibits Pb Uptake in Pakchoi (Brassica chinensis L.) and Affects Rhizosphere Microbial Communities.

Exopolysaccharides (EPSs) produced by microorganisms play an important role in biotolerance and reducing heavy metal (HM) contamination by limiting the migration of HMs into plants. However, research on the application of EPS-producing marine bacteria for soil heavy metal remediation remains limited, particularly regarding their mechanisms of HM immobilization in soil and impact on plant growth. In this study, the EPS-producing marine bacterium Micrococcus antarcticus HZ was investigated for its ability to immobilize Pb and produce EPSs in soil filtrate. The effects on the growth quality and biomass of pakchoi (Brassica chinensis L.), as well as bacterial communities in inter-root soil contaminated with Pb, were also investigated. The results indicated that HZ could reduce the Pb concentration in the soil filtrate, achieving a removal rate of 43.25-63.5%. The EPS content and pH levels increased in the presence of Pb. Pot experiments showed that adding HZ significantly increased the biomass of pakchoi (9.45-14.69%), vitamin C (Vc) (9.69-12.92%), and soluble protein content (22.58-49.7%). HZ reduced the Pb content in the roots (17.52-47.48%) and leaves (edible tissues) (43.82-52.83%) of pakchoi. HZ increased soil enzyme activities (alkaline phosphatase, dehydrogenase, and urease), and the contents of ammonium nitrogen and nitrate nitrogen. Additionally, HZ also increased the relative abundance of beneficial bacteria (e.g., Proteobacteria, Cyanobacteria, and Chlorobacteria) in the inter-root soil, which have prophylactic and heavy-metal fixation functions. In summary, HZ reduces effective Pb content in edible tissues, roots, and inter-root soil by regulating inter-root soil microbial community structure, increasing soil pH, nitrogen content, and soil enzyme activity, and altering dominant phylum abundance.

Micro-plastics in soil environment: A review

Environmental scientists and other stakeholders have paid serious attention to soil pollution by microplastics in the last ten years. In soils, the microplastic particles act as a vector for the toxic persistent organic pollutants and potentially toxic metals that are easily sorbed by plants and enter the food chain. Microplastics are emerging as persistent terrestrial pollutants due to mismanagement and indiscriminate use. Microplastic contaminants affect the physicochemical characteristics of the soil as well as the feeding patterns of the soil biota. Sewage sludge, bio waste compost additions, plastic mulching, wastewater irrigation, landfill leachate, and air deposition are the causes of microplastics in soils. The amount of microplastics particles per kilogram of soil ranged from zero to thirteen thousand pieces. There are 523 times as many microplastic particles in the soil as there are in the ocean. Plant growth and seed germination are slowed down by the microplastic in the soil. Microplastics also affect the soil's enzymatic activities. The environmental sources of microplastic include plastic pellets, city dust, abrasion of road markings, tires, synthetic textiles, personal care products, and cosmetics. Human consumption through food can have a variety of harmful effects, including cytotoxicity, immunotoxicity, pulmonary toxicity, and reproductive toxicity. The current study describes the origins, distribution, and effects of microplastics on plants, soil biota, and human health in the soil environment. Bangladesh J. Nuclear Agric, 38(1): 1-19, 2024

Response of earthworm enzyme activity and gut microbial functional diversity to carbendazim in the manured soil.

The effect of pesticide pollution on environmental microorganisms in soil has become the focus of widespread concern in society today. The response of earthworm gut and surrounding soil microbial functional diversity and enzyme activity to carbendazim (CBD) was studied in a soil-earthworm ecosystem amended with manure. In the experiment, CBD was added to the manured soil (MS). Meanwhile, the pesticide treatment without manure and the control treatment without pesticides were also set up. The activities of catalase (CAT) and acetylcholinesterase (AChE) were measured to evaluate the toxicity of CBD. The Biolog method was used to assess the functional diversity of the microbial community. In the 2 mg/kg CBD treatment, earthworm AChE activity decreased significantly in the MS after 14 d, which occurred earlier than in the un-manured soil (NS). The changes of earthworm CAT activity in the pesticide treatments showed a trend of initially increasing and then maintaining at a high activity level. However, the CAT activities at 28 d in the manured soils were clearly lower than that at 7 d for both the CBD treatments, while they remained stable in the control treatments. The carbon source utilization, Simpson index, Shannon index, and McIntosh index of soil microorganisms in the MS treatments were significantly higher than those in the NS treatments. The overall activity of earthworm gut microorganisms in the MS treated with 2 mg/kg CBD was higher than that in the control. Also, CBD treatment (2 mg/kg) increased significantly the Simpson index and McIntosh index of earthworm gut microorganisms. The results indicated that the enzyme activities in the manured soils increased before 7 d for the pesticide treatments. Furthermore, exposure to CBD at a high concentration in the MS not only led to the earlier inhibition of earthworm enzyme activity but also significantly improved the overall activity of earthworm gut microorganisms and microbial functional diversity. This study revealed the ecotoxicological effects of earthworms in response to pesticide stress following the use of organic fertilizers under facility environmental conditions, which can provide a theoretical basis for the remediation of pesticide pollution in soil in the future.

Responses of microbial communities to the addition of different types of microplastics in agricultural soils

A 90-day soil incubation study was performed to investigate impacts of four types (PE, PP, PVC and PET) of microplastics (MPs) on the physicochemical properties, nutrient contents, enzyme activities, and microbial community structure and diversity of agricultural soils. Effects of the four microplastic types and addition ratios on the microbiology of the agricultural soils were significant. With the addition of MPs, there was a positive correlation between physicochemical properties, nutrients (AN, AP, AK) and enzyme activities (CAT, Urease, ACP, SUC), which were all decreased to some extent. Overall PE and PVC surfaces were the roughest and had the greatest impact on soil physicochemical properties, nutrients and enzyme activities. The changes in soil microbial α-diversity were not significant (P > 0.05), but, PP and PVC led to an increase in community diversity and abundance. Clearly, the four types of the MPs reduced the physicochemical properties, nutrient content, enzyme activity and microbial community, and thus significantly affected the microbiology of the farmland soils.

Global hierarchical meta-analysis to identify the factors for controlling effects of antibiotics on soil microbiota

It is widely known that antibiotics can affect the structure and function of soil microbial communities, but the specific degree of impact and controlled factors on different indicators remain inconclusive. We conducted a multiple hierarchical mixed effects meta-analysis on 2564 observations that were extracted from 60 publications, to comprehensively assess the impact of antibiotics on soil microbiota. The results showed that antibiotics had significant negative effects on soil microbial biomass, α-diversity and soil enzyme activity. Under neutral initial soil, when soil was derived from agricultural land or had a fine-textured, the negative impacts of antibiotics on soil microbial community were exacerbated. Both single and mixed additions of antibiotics had significant inhibitory effects on soil microbial enzyme activities. The Random Forest model predicted the following key moderators involved in the effects of antibiotics on the soil microbiome, and antibiotics type, soil texture were key moderators on the severity of soil microbial biomass changes. Soil texture, temperature and single or combined application constitute of antibiotics were the main drivers of effects on soil enzyme activities. The reported results can be helpful to assess the ecological risk of antibiotics in a soil environment and provides a scientific basis for the rational of antibiotics use in the soil environment.

Effect of zeolite application on soil enzyme activity of potted sandy soil cultivated with Swiss chard and cabbage

A zeolite pot experiment was conducted at the Agricultural Research Council Infruitec-Nietvoorbij in Stellenbosch, South Africa, under greenhouse conditions. The experiment aimed to investigate the impact of zeolite application on soil enzyme activities in sandy soils cultivated with Swiss chard (Beta vulgaris Var. cicla) and cabbage (Brassica oleracea Var. capitata L.) over two years (2018-2019). Different zeolite-to-soil ratios (0:1, 1:9, 2:8, and 3:7 w/w) were used, with each pot containing 12 kg of soil. The experiment involved 72 pots for each vegetable, arranged in a randomized complete block design (RCBD). Soil enzyme activities, including acid phosphatase, β-glucosidase, and urease, as well as soil chemical properties (pH, total plant-available nitrogen, organic carbon, and phosphorus), were analyzed. Key findings indicate that the effect of zeolite application on enzyme activities varied between the vegetable species. Zeolite application significantly increased (P

Response of β-glucosidase enzyme activity of soil to biochar applications in a crop rotation at Blacksea agroecosystem

The use of biochar has emerged a potentially effective approach to improve soil function and promote crop performance. However, the specific impact of biochar on β-glucosidase enzyme activity (BGA) within crop rotation systems in the Black Sea agroecosystem requires further investigation. This study was conducted to determine the effects of rice husk biochar (RHB) and poultry manure biochar (PMB) on BGA in soils. Six biochar doses (0-control, 10, 20, 30, 40 and 50 t ha-1) were applied at the beginning of two wheat-cabbage red pepper rotation periods. The mean BGA at second rotation (73.71 µg pNP g-1) was significantly lower compared to the BGA of the first period (93.39 µg pNP g-1). The BGA value in control (94.51 µg pNP g-1) decreased with increasing biochar application doses (76.05 µg pNP g-1, 50 t ha-1) treatment. The mean BGA value in PMB treatment was slightly higher than that of RHB, but it was not statistically different between two biochar types. However, the decrease in BGA value (25.0%) in the highest RHB dose compared to control was more than two-fold compared to the decrease in PMB application (12.1%). The difference in carbon/nitrogen ratio between RHB and PMB can be attributed to the variation in BGA values observed at the application of same biochar doses. The decrease in BGA over the course of the two rotation cycles implies that biochar may have a long-term influence on soil carbon cycling.

Effects of Trichoderma harzianum Fertilizer on Growth and Rhizosphere Microbial Community of Continuous Cropping Lagenaria siceraria

This study analyzed the effects of Trichoderma harzianum fertilizer on the growth of continuous cropping Lagenaria siceraria and the physical and chemical properties of rhizosphere soil and microbial community structure, using Illumina Miseq (PE300) high-throughput sequencing technology along with physiological and biochemical detection. The results indicated that after applying T. harzianum fertilizer, the growth of L. siceraria was significantly promoted, with increases in plant height, fresh weight, and dry weight of 21.42%, 24.5%, and 4.5%, respectively. The pH of the rhizosphere soil decreased from 7.78 to 7.51, while the electrical conductivity (EC), the available phosphorus (AP), the available potassium (AK), and the total nitrogen (TN) were markedly higher compared to the CC group and increased by 13.95%, 22.54%, 21.37%, and 16.41%, respectively. The activities of catalase and sucrase in the rhizosphere increased by 18.33% and 61.47%, and the content of Soil Organic Carbon (SOC) elevated by 27.39%, which indicated that T. harzianum fertilizer could enhance soil enzyme activity and promotes the transformation of organic matter. Among them, the relative abundance of beneficial bacteria such as Pseudomonas increased, while the relative abundance of harmful fungi such as Fusarium and Podosphaera decreased significantly. This study clarified that T. harzianum fertilizer promoted the growth of continuously planted L. siceraria plants by improving soil physical and chemical properties and microbial community structure and was an effective microbial agent to alleviate the adverse effects of continuous cropping of L. siceraria.

Effects of different nutrient supply options on system productivity, nitrogen use efficiency and soil enzyme activities in maize - wheat cropping system cropping system

The field experiments were conducted during during kharif and the following rabi seasons of 2011-12 and 2012-13 with five different treatments in maize (Zea mays L.) and wheat (Triticum aestivum (L.) emend Fiori &amp; Paol.) cropping systems. Application of 50% RDF + 50% RDN recorded maximum WEY of maize (3.23 and 4.58 t/ha) and system productivity (8.20 and 9.03) over rest of the treatments, but remained statistically similar with other treatments except control during 2011-12 and 2012-13, respectively. The highest ANUE (5.07 and 15.36 kg grain yield increase/kg N applied) of maize crop was recorded at 50% RDF + 25% RDN + BF, followed by 50% RDF + 25% RDN during both the years. The highest ANUE (17.64 and 17.18 kg grain yield increase/kg N applied) of wheat crop were recorded from 37.5% RDF + 37.5% RDN + BF during both the years, respectively. Application of 50% RDF + 50% RDN to maize resulted in increased the value of MBC (18.0 and 18.4%), DH (22.9 and 18.6%), alkaline phosphatase (33.3 and 29.6%) and urease (37.1 and 37.8%) over control during 2011 and 2012, respectively. An increased value of MBC (38 and 34.6%), DH (29.2 and 29.8%), alkaline phosphatase (37.2 and 34.9%) and urease (30.1 and 25.6%) was recorded with the application of 37.5% RDF + 37.5% RDN + BF to wheat over control during both the years, respectively. Bangladesh J. Bot. 53(3): 429-438, 2024 (September)

Ectomycorrhizal fungi and the nitrogen economy of Nothofagus in southern Patagonia.

Subantarctic Nothofagus forests are the southernmost forests in the world, with negligible atmospheric nitrogen (N) deposition. Most paradigms about the role of ectomycorrhizal (ECM) fungi in N cycling and plant N uptake at high latitudes have been tested in boreal coniferous forests, while in the southern hemisphere, ECM hosts are primarily angiosperms. Using ITS1 meta-barcoding, we characterized ECM and saprotrophic fungal communities in evergreen and deciduous Nothofagus forests forming monodominant and mixed stands in the archipelago of Tierra del Fuego (Chile and Argentina). We assessed the N economy of Nothofagus by correlating host species with fungal relative abundances, edaphic variables, net N mineralization, microbial biomass N and the activity of eight extracellular soil enzymes activities. The N economy of deciduous N. pumilio forests was strikingly similar to boreal coniferous forests, with the lowest inorganic N availability and net N mineralization, in correlation to higher relative abundances of ECM fungi with enzymatic capacity for organic N mobilization (genus Cortinarius). In contrast, the N economy of evergreen N. betuloides forests was predominantly inorganic and correlated with ECM lineages from the family Clavulinaceae, in acidic soils with poor drainage. Grassy understory vegetation in deciduous N. antarctica forests likely promoted saprotrophic fungi (i.e., genus Mortierella) in correlation with higher activities of carbon-degrading enzymes. Differences between Nothofagus hosts did not persist in mixed forests, illustrating the range of soil fertility of these ECM angiosperms and the underlying effects of soil and climate on Nothofagus distribution and N cycling in southern Patagonia.