Variation In Soil pH Research Articles

Assessing the Spatial Distribution, Condition, and Intensity of Soil Acidity for Informed Management Decisions in the Semen Aari District of Ari Zone, Southwestern Ethiopia

Soil acidity poses a significant challenge to agricultural productivity in Ethiopia's highlands, particularly affecting the Semen Ari district in the Ari zone. The common practice of applying agricultural lime to mitigate soil acidity is hampered by a lack of detailed information on the extent, severity, and spatial distribution of acidic soils. This study aims to determine how soil acidity varies spatially by identifying and mapping the specific geographic patterns of soil acidity levels in the Semen Ari district. Seventy-one composite soil samples from the 0–20 cm layer were geo-referenced and analyzed. Using statistical analysis and ArcGIS software for spatial interpolation through ordinary kriging, soil pH ranged from 3.29 to 5.68, classifying 99% of the soils as strongly acidic. The root mean squared error (RMSE) of the interpolation was 0.30. Soil pH showed a significant negative correlation with exchangeable acidity but a non-significant negative correlation with organic carbon and total nitrogen. The results highlight the need for targeted soil management strategies, such as appropriate lime application rates and the cultivation of acid-tolerant crops, to enhance crop yields. Further research is recommended to include comprehensive soil property datasets to better understand the factors influencing soil pH variability, thus supporting more precise management of acidic soils in the region. The generated high-resolution soil acidity map serves as a valuable tool for agricultural planning and decision-making.

Mapping and Assessment of Within-field Spatial Variability of Soil pH, Electrical Conductivity, and Particle Size Distribution to Delineate Management Zones

Mapping and Assessment of Within-field Spatial Variability of Soil pH, Electrical Conductivity, and Particle Size Distribution to Delineate Management Zones

A transformation and auxiliary extraction of Cr during electrokinetic removal of Cr-contaminated multilayer composite soil chamber.

Multilayer composite soil chamber was proposed to extract the Cr of contaminated site soil and insight into transformation of Cr fractionation associated with valence states. The variations of current, soil pH and moisture content were explored, as well as the migration of Cr fractionation and redistribution of Cr. Results indicated that duration of half peak current could be used to adjust treatment time and it varied among different composite ways. Moreover, extraction efficiency of Cr in soil near cathode was relatively higher and reached 60% when citric acid was used. Citric acid could promote the transformation between different Cr fractionations or different valence states. It could also improve the desorption of Cr, and could prevent excessive fluctuations of moisture content at the same time. Cr redistributed acrossed the soil chamber after extraction. When deionized water was used, Cr(VI) significantly migrated toward anode mainly in the form of exchangeable fractionation (EXC) while Fe-Mn oxides fractionation (Fe-Mn) which may be in the form of cationic Cr(III) hydroxides migrated toward cathode. When using citric acid, fractionations that were difficult to migrate of Cr, especially for Fe-Mn in site soils could be activated and became EXC and carbonate fractionation (CAR), then migrated to the anode or cathode. The migration of exchangeable Cr(III) was dramatically enhanced. But the use of citric acid could cause Cr(VI) transformation to Cr(III) near anode. In addition, during the migration process, EXC could go back to Fe-Mn again or transform to residue fractionation (RES).

Calibrated SoilOptix ® estimates of soil pH and exchangeable cations in three agricultural fields in western Canada – implications for managing spatially variable soil acidity

Spatial variability in soil pH is a major contributor to within-field variations in soil fertility and crop productivity. An improved understanding of the spatial variability of soil pH within agricultural fields is required to determine liming requirements for precision farming. This study with the use of proximal sensors, firstly assessed the spatial pattern of soil pH and how it can be used to determine site-specific, spatially variable lime requirements. Secondly, the effects of soil pH on soil concentrations of nitrate nitrogen (N03-N), phosphorus (P), potassium (K), sulfur (SO4-S), calcium (Ca), magnesium (Mg), soil organic matter (SOM), aluminum (Al), and manganese (Mn) were assessed in three study fields in central Alberta, Canada. Soil pH varied between 4.5 and 7.5 across all field sites. The field-scale coefficient of variation (CV %) for soil pH, Al and Mn ranged between 4.39 and 7.50 %, 7.33–13.72 %, and 7.33–13.72 % across the three sites. The other soil properties showed low, moderate, and high variability, with field-scale CVs ranging between 6.39 and 17.70 % for SOM and 24.33–91.39 % for SO4-S. Soil pH exhibited positive correlations with both Ca and Mg, across all fields. Negative correlations were observed between soil pH and Al across all fields. A principal component analysis (PCA) was performed for all soil parameters and two principal components accounted for 50 %, 54.9 %, and 76.8 % of the total variance in field 1, field 2, and field 3, respectively. Geostatistical semivariance indicated a strong spatial dependence of all chemical parameters across fields. Large regions within a field were strongly acidic (pH < 5.5) and required lime applications ranging from 0 to 6 t ha−1. We conclude that proximal soil sensors can be calibrated to soil properties, enabling variable rate lime recommendations on spatially variable fields for the management of soil acidity.

Influence of soil pH and organic carbon content on the bioaccessibility of lead and copper in four spiked soils

Exploration of the association between heavy metal bioaccessibility (BAc) and soil properties is essential for rationalization of risk assessment and remediation of contaminated soil; however, the high complexity of soil systems often yield conflicting outcomes. To avoid erroneous conclusions, individual comparisons of soil properties is essential. Herein, we determined the changes in the BAc of Pb and Cu with the variation in soil pH and SOC content using Unified Bioaccessibility Research Group of Europe method, and validated these findings with in vivo mouse bioassays. Results indicated that the BAc of Pb and Cu in gastric and intestinal phases decreased by 1.76%–3.92% and 0.90%–3.27%, and by 0.41%–6.01% and 0.67%–1.59%, respectively, with every unit increase in soil pH. Furthermore, with every 1% increase in the absolute content of SOC, the BAc of Pb and Cu decreased by 4.04%–13.94% and 4.01%–34.7%, and by 8.98%–30.15% and 9.58%–20.03%, respectively. The in vivo bioassays results confirmed decrease in Pb concentrations in the liver, kidney, and blood of mice with the increase in Ferralosol pH and SOC content. These findings revealed that the health risks associated with accidental exposures to Pb- and Cu-contaminated soils with high pH and SOC level were relatively low, and the consistent in vivo and in vitro results for the BAc of Pb and Cu suggest the requirement for a swift and simple approach for assessing the risks of heavy metal contaminated soils. Thus, this study enhanced our understanding of the variations in risk assessments with soil properties of Pb- and Cu-contaminated soils, highlighting the role of soil characteristics in health risk assessment and remediation of contaminated soils.

Microenvironment heterogeneity affected by anthropogenic wildfire-perturbed soil mediates bacterial community in Pinus tabulaeformis forests.

In recent years, the frequency and intensity of anthropogenic wildfires have drastically increased, significantly altering terrestrial ecosystems worldwide. These fires not only devastate vegetative cover but also impact soil environments and microbial communities, affecting ecosystem structure and function. The extent to which fire severity, soil depth, and their interaction influence these effects remains unclear, particularly in Pinus tabulaeformis forests. This study investigated the impact of wildfire intensity and soil stratification on soil physicochemical properties and microbial diversity within P. tabulaeformis forests in North China. Soil samples were collected from different fire severity zones (Control, Light, Moderate, High) and depths (topsoil: 0-10 cm; subsoil: 10-20 cm). Analyses included measurements of soil pH, organic carbon (SOC), total nitrogen (TN), and other nutrients. Microbial diversity was assessed using 16S rRNA gene sequencing. Our findings revealed significant variations in soil pH, SOC, TN, and other nutrients with fire severity and soil depth, profoundly affecting microbial community composition and diversity. Soil pH emerged as a critical determinant, closely linked to microbial α-diversity and community structure. We found that fire severity significantly altered soil pH (p = 0.001), pointing to noteworthy changes in acidity linked to varying severity levels. Topsoil microbial communities primarily differentiated between burned and unburned conditions, whereas subsoil layers showed more pronounced effects of fire severity on microbial structures. Analysis of bacterial phyla across different fire severity levels and soil depths revealed significant shifts in microbial communities. Proteobacteria consistently dominated across all conditions, indicating strong resilience, while Acidobacteriota and Actinobacteriota showed increased abundances in high-severity and light/moderate-severity areas, respectively. Verrucomicrobiota were more prevalent in control samples and decreased significantly in fire-impacted soils. Chloroflexi and Bacteroidota displayed increased abundance in moderate and high-severity areas, respectively. Correlation analyses illustrated significant relationships between soil environmental factors and dominant bacterial phyla. Soil organic carbon (SOC) showed positive correlations with total nitrogen (TN) and alkaline hydrolysable nitrogen (AN). Soil pH exhibited a negative correlation with multiple soil environmental factors. Soil pH and available phosphorus (AP) significantly influenced the abundance of the phylum Myxococcota. Soil water content (WC) significantly affected the abundances of Acidobacteriota and Actinobacteriota. Additionally, ammonium nitrogen (NH4 +-N) and nitrate nitrogen (NO3 --N) jointly and significantly impacted the abundance of the phylum Chloroflexi. This study highlights the significant long-term effects of anthropogenic wildfires on soil microenvironment heterogeneity and bacterial community structure in P. tabulaeformis forests in North China, 6 years post-fire. Our findings demonstrate that fire severity significantly influences soil pH, which in turn affects soil nutrient dynamics and enhances microbial diversity. We observed notable shifts in the abundance of dominant bacterial phyla, emphasizing the critical role of soil pH and nutrient availability in shaping microbial communities. The results underscore the importance of soil stratification, as different soil layers showed varying responses to fire severity, highlighting the need for tailored management strategies. Future research should focus on long-term monitoring to further elucidate the temporal dynamics of soil microbial recovery and nutrient cycling following wildfires. Studies investigating the roles of specific microbial taxa in ecosystem resilience and their functional contributions under varying fire regimes will provide deeper insights. Additionally, exploring soil amendments and management practices aimed at optimizing pH and nutrient availability could enhance post-fire recovery processes, supporting sustainable ecosystem recovery and resilience.

Spatial heterogeneity of soil moisture caused by drainage and its effects on cadmium variation in rice grain within individual fields

Paddy drainage is the critical period for rice grain to accumulate cadmium (Cd), however, its roles on spatial heterogeneity of grain Cd within individual fields are still unknown. Herein, field plot experiments were conducted to study the spatial variations of rice Cd under continuous and intermittent (drainage at the tillering or grain-filling or both stages) flooding conditions. The spatial heterogeneity of soil moisture and key factors involved in Cd mobilization during drainages were further investigated to explain grain Cd variation. Rice grain Cd levels under continuous flooding ranged from 0.16 to 0.22 mg kg−1 among nine sampling sites within an individual field. Tillering drainage slightly increased grain Cd levels (0.19–0.31 mg kg−1) with little change in spatial variation. However, grain-filling drainage greatly increased grain Cd range to 0.33–0.95 mg kg−1, with a huge spatial variation observed among replicated sites. During two drainage periods, soil moisture decreased variously in different monitoring sites; greater variation (mean values ranged from 0.14 to 0.27 m3 m−3) was observed during grain-filling drainage. Accordingly, 2.9–3.3-fold variation in soil Eh and 0.55–0.67-unit variation in soil pH were observed among those sites. In the soil with low moisture, ferrous fractions such as ferrous sulfide (FeS) were prone to be oxidized to ferric fractions; meanwhile, the followed generation of hydroxyl radicals involved in Cd remobilization was enhanced. Consequently, soil dissolved Cd changed from 2.97 to 8.92 μg L−1 among different sampling sites during grain-filling drainage; thus, large variation was observed in grain Cd levels. The findings suggest that grain-filling drainage is the main process controlling spatial variation of grain Cd, which should be paid more attention in paddy Cd evaluation.

Effect of three-year amendment measures on coastal saline-alkali soil conditions during the growing season

Seawater intrusion and fluctuations in the water table in coastal areas lead to seasonal variations in soil salinity and pH, which greatly limit the development of coastal protection forests. In a three-year field study, the impact of five soil amendment measures were evaluated on soil conditions in coastal areas. Amendments included biochar, biochar with arbuscular mycorrhizal fungi (AMF), straw with AMF, straw alone, and AMF alone, compared to a control (CK) with no additive. Results indicated that combinations of straw, biochar, and AMF reduced soil pH across various layers and seasons, with electrical conductivity mainly decreasing in spring. During the summer, at the 0-20 cm soil depth, microbial biomass carbon notably increased due to these mixtures. Additionally, AMF alone and biochar with AMF significantly improved enzyme activities in the 0-40 cm layer in spring, while in fall, AMF alone notably increased nutrient availability in the same layer. Linear regression analysis revealed a negative correlation between electrical conductivity, microbial biomass carbon, enzyme activity, and nutrient availability with pH. The biochar–AMF mixture emerged as the most effective soil amendment, suggesting that using it in conjunction with seasonal management could optimize soil health and promote silviculture in coastal regions.

Spatial and Temporal Variations of Soil pH in Farmland in Xinjiang, China over the Past Decade

Soil pH is crucial for the quality of the farmland and crop growth. The objective of this study is to analyze the spatial and temporal variations of farmland soil pH in Xinjiang (XJ), and to provide a scientific basis for soil improvement and agricultural production optimization. Based on soil pH data from XJ farmland in two periods, 2008~2010 and 2019~2021, geostatistical methods and kriging spatial interpolation techniques were employed to analyze the spatiotemporal changes in soil pH and to investigate the relationship between relevant influencing factors and pH over more than a decade. The results indicate that the spatiotemporal distribution of soil pH in XJ farmlands is uneven. Between 2019 and 2021, the average soil pH was 8.11, generally being on the higher side, with a coefficient of variation (CV) of 3.85%, indicating minimal spatial variability. In the farmland soil of Southern Xinjiang (S-XJ), the average pH value was 8.17, significantly higher than that of Northern Xinjiang (N-XJ), which was 8.10, demonstrating a spatial pattern of “higher in the south, lower in the north”. Over the past decade, soil pH in XJ has significantly increased from 8.11 to 8.13, with a 0.05 unit increase in the north and a 0.01 unit increase in the south (p &lt; 0.05). Regionally, Altay saw the largest increase of 0.22 units, while Bortala Mongol Autonomous Prefecture (Bortala) experienced the most significant decrease, dropping by 0.59 units. Furthermore, this study found that factors such as topography, nutrients, and irrigation methods all have certain influences on the spatial distribution of soil pH in XJ farmland, while variations in climate factors and fertilization levels may affect its long-term temporal changes. These research findings will provide new insights for adjusting and updating agricultural management measures related to soil pH regulation in XJ.

Relationship Between Fine Root Biomass and Soil Physico-chemical Properties of Grassland Ecosystem in Bhadrapur Municipality of Jhapa district, Eastern Nepal

This study investigated the distribution of fine root biomass and various soil properties in a grassland ecosystem within Bhadrapur Municipality, Nepal. Soil samples were systematically collected from randomly selected blocks in undisturbed, disturbed, and roadside areas during the late rainy season. Analyses included soil texture, moisture content, temperature, pH, and quantification of fine root biomass (FRB; &lt;5 mm diameter) within the top 15 cm soil depth. Results showed the mean FRB was significantly higher in undisturbed areas (7.77 t/ha) compared to disturbed (7.053 t/ha) and roadside (1.76 t/ha) areas. Across all sites, FRB exhibited a positive correlation with soil moisture content. Soil pH was slightly more acidic in undisturbed versus disturbed and roadside areas. Soil temperature demonstrated a positive correlation with FRB in undisturbed and roadside areas but a negative correlation in disturbed areas. Additionally, FRB negatively correlated with sand content in disturbed and roadside areas. The findings highlight how soil moisture is a key driver of fine root proliferation in this grassland ecosystem. Variations in soil texture, pH, and temperature between sites reveal their influence on root growth dynamics. Understanding these root-soil interactions has implications for sustainable grassland management, biodiversity conservation, and ecosystem resilience under changing environmental conditions.

Soil pH, developmental stages and geographical origin differently influence the root metabolomic diversity and root-related microbial diversity of Echium vulgare from native habitats.

Improved understanding of the complex interaction between plant metabolism, environmental conditions and the plant-associated microbiome requires an interdisciplinary approach: Our hypothesis in our multiomics study posited that several environmental and biotic factors have modulating effects on the microbiome and metabolome of the roots of wild Echium vulgare plants. Furthermore, we postulated reciprocal interactions between the root metabolome and microbiome. We investigated the metabolic content, the genetic variability, and the prokaryotic microbiome in the root systems of wild E. vulgare plants at rosette and flowering stages across six distinct locations. We incorporated the assessment of soil microbiomes and the measurement of selected soil chemical composition factors. Two distinct genetic clusters were determined based on microsatellite analysis without a consistent alignment with the geographical proximity between the locations. The microbial diversity of both the roots of E. vulgare and the surrounding bulk soil exhibited significant divergence across locations, varying soil pH characteristics, and within the identified plant genetic clusters. Notably, acidophilic bacteria were characteristic inhabitants of both soil and roots under acidic soil conditions, emphasizing the close interconnectedness between these compartments. The metabolome of E. vulgare significantly differed between root samples from different developmental stages, geographical locations, and soil pH levels. The developmental stage was the dominant driver of metabolome changes, with significantly higher concentrations of sugars, pyrrolizidine alkaloids, and some of their precursors in rosette stage plant roots. Our study featured the complex dynamics between soil pH, plant development, geographical locations, plant genetics, plant metabolome and microbiome, shedding light on existing knowledge gaps.

Alteration of soil pH induced by submerging/drainage and application of peanut straw biochar and its impact on Cd(II) availability in an acidic soil to indica-japonica rice varieties

The effects of soil pH variations induced by submergence/drainage and biochar application on soil cadmium (Cd) availability to different rice (Oryza sativa L.) varieties are not well understood. This study aims to investigate the possible reasons for available Cd(II) reduction in paddy soil as influenced by biochar and to determine Cd(II) absorption and translocation rates in different parts of various rice varieties. A pot experiment in a greenhouse using four japonica and four indica rice varieties was conducted in Cd(II) contaminated paddy soil with peanut straw biochar. The results indicated that the submerging led to an increase in soil pH due to the consumption of protons (H+) by the reduction reactions of iron/manganese (Fe/Mn) oxides and sulfate (SO42−) and thus the decrease in soil available Cd(II) contents. However, the drainage decreased soil pH due to the release of protons during the oxidation of Fe2+, Mn2+, and S2− and thus the increase in soil available Cd(II) contents. Application of the biochar increased soil pH during soil submerging and inhibited the decline in soil pH during soil drainage, and thus decreased soil available Cd(II) contents under both submerging and drainage conditions. The indica rice varieties absorbed more Cd(II) in their roots and accumulated higher amounts of Cd(II) in their shoots and grains than the japonica rice varieties. The Cd(II) sensitive varieties exhibited a greater absorption and translocation rate of Cd(II) compared to the tolerant varieties of both indica and japonica rice. Biochar inhibited the absorption and accumulation of Cd(II) in the rice varieties, which ultimately lowered the Cd(II) contents in rice grains below the national food safety limit (0.2 mg kg−1). Overall, planting japonica rice varieties in Cd(II) polluted paddy soils combined with the use of biochar can effectively reduce Cd(II) content in rice grains which protects human health against Cd(II) toxicity.

Effect of Soil pH Variation on Peanut Plant Growth

This research investigates the qualitative effects of soil pH variation on peanut plant growth, aiming to provide insights into the complex interactions between soil properties and plant responses in agricultural ecosystems. Through semi-structured interviews with ten informants, supplemented by insights synthesized from prior research and theoretical frameworks, the study explores perceived relationships, implications for soil health and nutrient availability, challenges, opportunities, and practical implications for peanut production. Key findings highlight the critical influence of soil pH on peanut growth and productivity, with deviations from optimal pH levels affecting nutrient availability, root health, and overall plant vigor. Participants underscore the importance of targeted soil management practices, including lime application, organic matter incorporation, and crop rotation, in optimizing soil pH and supporting resilient peanut production systems. The study identifies challenges in soil pH management, such as limited accessibility of soil testing services and inadequate farmer knowledge, while also highlighting opportunities for innovation and improvement. The insights gleaned from the study contribute to advancing knowledge in agricultural sciences and inform evidence-based soil management practices for sustainable peanut production.

Continuous cropping system altered soil microbial communities and nutrient cycles.

Understanding the response of microbial communities and their potential functions is essential for sustainability of agroecosystems under long-term continuous cropping. However, limited research has focused on investigating the interaction between soil physicochemical factors and microbial community dynamics in agroecosystems under long-term continuous cropping. This study probed into the physicochemical properties, metabolites, and microbial diversity of tobacco rhizosphere soils cropped continuously for 0, 5, and 20 years. The relative abundance of bacterial genera associated with nutrient cycling (e.g., Sphingomonas) increased while potential plant pathogenic fungi and beneficial microorganisms showed synergistic increases with the duration of continuous cropping. Variations in soil pH, alkeline nitrogen (AN) content, and soil organic carbon (SOC) content drove the shifts in soil microbial composition. Metabolites such as palmitic acid, 3-hydroxypropionic acid, stearic acid, and hippuric acid may play a key role in soil acidification. Those results enhance our ability to predict shifts in soil microbial community structure associated with anthropogenic continuous cropping, which can have long-term implications for crop production.

Increases in the soil ammonia oxidizing phylotypes and their rechange due to long-term irrigation with wastewater.

Wastewater irrigation is a common practice for agricultural systems in arid and semiarid zones, which can help to overcome water scarcity and contribute with nutrient inputs. Ammonia-oxidizing bacteria (AOB) and archaea (AOA) are key in the transformation of NH4+-N in soil and can be affected by variations in soil pH, EC, N and C content, or accumulation of pollutants, derived from wastewater irrigation. The objective of this study was to determine the changes in the ammonia oxidizing communities in agricultural soils irrigated with wastewater for different periods of time (25, 50, and 100 years), and in rainfed soils (never irrigated). The amoA gene encoding for the catalytic subunit of the ammonia monooxygenase was used as molecular reporter; it was quantified by qPCR and sequenced by high throughput sequencing, and changes in the community composition were associated with the soil physicochemical characteristics. Soils irrigated with wastewater showed up to five times more the abundance of ammonia oxidizers (based on 16S rRNA gene relative abundance and amoA gene copies) than those under rainfed agriculture. While the amoA-AOA: amoA-AOB ratio decreased from 9.8 in rainfed soils to 1.6 in soils irrigated for 100 years, indicating a favoring environment for AOB rather than AOA. Further, the community structure of both AOA and AOB changed during wastewater irrigation compared to rainfed soils, mainly due to the abundance variation of certain phylotypes. Finally, the significant correlation between soil pH and the ammonia oxidizing community structure was confirmed, mainly for AOB; being the main environmental driver of the ammonia oxidizer community. Also, a calculated toxicity index based on metals concentrations showed a correlation with AOB communities, while the content of carbon and nitrogen was more associated with AOA communities. The results indicate that wastewater irrigation influence ammonia oxidizers communities, manly by the changes in the physicochemical environment.

Influence and Mechanism Study of Soil Moisture on the Stability of Arsenic-Bearing Ferrihydrite in Surface Soil Vertical Profiles

Ferrihydrite is usually used as a remedy for arsenic (As)-contaminated soil due to its strong affinity and large specific surface area. However, its noncrystalline phase makes it unstable in long-term applications in the soil. In this study, a soil incubation experiment was designed using the diffusive gradient in thin film (DGT) technique and spectral techniques to investigate the fate of As-bearing ferrihydrite [As(V)-Fh] after long-term incubation at different soil water holding capacities (SWHCs). After As(V)-Fh (0.05 and 0.005 As/Fe molar ratio) was incubated in soil for 360 days, both DGT-derived labile As and Fe were released at 70% SWHC and 120% SWHC into the soil (at a vertical depth of 12 cm). The concentrations of DGT-As and DGT-Fe increased with incubation time and were greater at 120% SWHC. The results of X-ray diffraction (XRD) and scanning electron microscopy (SEM) showed that As(V)-Fh gradually transformed into hematite and goethite after 360 days of incubation. Goethite was mainly found in the 120% SWHC treatment after 180 days. Hematite and goethite formation rates were greater in the 120% SWHC treatment and in the bottom soil layer. Mechanistic analysis based on X-ray photoelectron spectroscopy (XPS) revealed that the variation in soil pH and the formation of Fe(II) (under flooded water conditions) are the two key factors promoting the formation of hematite (dehydrogenation and dehydration) and goethite (As(V)-Fh dissociation and reorganization). The As release mainly occurred due to the loss of adsorption sites. Thus, it is recommended that ferrihydrite be applied in paddy–dry rotations or dry-field patterns to effectively avoid the loss of As(V)-Fh in long-term-saturated soil.

Digital Mapping of Soil pH and Electrical Conductivity Using Geostatistics and Machine Learning

This study investigates the spatial variability of soil pH and electrical conductivity (EC) in Suryapet district of Southern Telangana Zone through various digital soil mapping approaches. The 202 surface (0-15cm) soil samples were collected and analysed for pH and EC. The analysed data was further divided into calibration set and validation set in the ratio of 75:25. The geostatistical techniques like Ordinary Kriging, Inverse Distance Weighting (IDW) and Regression Kriging and data mining technique like random forest technique were used to predict the spatial distribution of pH and EC (dSm-1) over the study area. The accuracy of these methods was assessed using validation data set by calculating RMSE, ME and R2 values. The results showed that among all the approaches, random forest (RF) technique performed better with lower RMSE, ME and higher R2 values for spatial prediction of soil pH (RMSE=0.014, ME=0.28 and R2=0.81) and EC (RMSE=0.134, ME=0.022 and R2=0.73). The RF predicted maps show that the pH of soils varied from neutral (6.5-7.5) to slightly alkaline (7.5-8.5) and the soils of Suryapet district were considered as non-saline (EC: 0-2 dSm-1). The findings of the current study shows that among digital soil mapping techniques, random forest model can be an effective tool for assessing spatial variability of soil pH and EC for further studies.

Variations of Soil Organic Matter and Nutrients in Diverse Hilly Soils of Bandarban, Bangladesh

Functioning and positive interactions in an ecosystem depend on physical and chemical features of soil, along with nutrient status. These soil nutrients are vital for the growth and development of plants, playing a crucial role in various essential functions. The current study investigates the dynamic changes in soil nutrient patterns across different land use scenarios and soil depths at Bandarban Sadar Upazila, Chittagong Hill Tracts, Bangladesh. The research focuses on how soil nutrient levels are distributed in two soil depths (0-15 cm and 15-30 cm) among three different land use practices, such as forest land, agricultural land and barren land. About 90 soil samples from the study area were collected using a stratified random sampling design. The analysis reveals significant variations in soil pH, organic matter (OM), total nitrogen (TN), phosphorus (P), potassium (K), and sulfur (S) levels among these land use types and soil depths. The findings revealed that agricultural land typically exhibited higher levels of soil S content and pH, in contrast to forested areas where OM, TN, P, and K levels were comparatively more abundant. Again, barren land showed a relatively higher pH and S content than agricultural land and forest land. Additionally, the topsoil (0-15 cm) generally showed higher nutrient content than the deeper soil layer (15-30 cm). The investigation uncovered significant positive correlations of OM with soil nutrients such as TN, P, K &amp; S, indicating mutual influences on their availability. Overall, the research outcomes emphasize the importance of sustainable land management practices to maintain soil fertility and optimize soil productivity in this ecologically significant region.

Stochastic processes dominated the soil bacterial community assemblages along an altitudinal gradient in boreal forests

Soil bacteria, as integral components of the soil microbial community, play pivotal roles in biogeochemical cycles and ecosystem functions in boreal forests. The altitudinal patterns of soil bacteria have been widely reported, but their community assembly is uncertain. Here, we investigated the soil bacterial community attributes (diversity, taxonomic and functional composition, and bacterial interactions) and ecological processes associated with community assembly on Mt. Oakley in the northern Greater Khingan Mountains via Illumina MiSeq sequencing and functional annotation tools. The alpha diversity indices of the soil bacteria exhibited a progressively decreasing trend with increasing altitude across seasons. The relative abundance of the dominant bacterial taxa was more sensitive to altitude than to season. More complex (more nodes and links) bacterial interactions were detected at the lowest and highest altitudinal sites, as well as in September. The variations in the taxonomic and functional compositions of the soil bacteria induced by altitude were mainly driven by the variations in soil pH and extracellular enzyme activities. Stochastic (dispersal limitation and drift) processes largely controlled the soil bacterial community assemblages across spatiotemporal scales. The community assemblages of soil bacteria were affected by altitude-induced changes in the taxonomic composition and functional groups. Collectively, our results have significant implications for understanding bacterial biogeography and community assembly mechanisms along altitudinal gradients in boreal forest ecosystems.

Organik ve kimyasal gübre ile kullanılmak üzere mikroorganizma izolasyon ve karakterizasyonu

Isolation and Characterization of Microorganisms for Use with Manure and Chemical Fertilizers&#x0D; Levent Değirmenci1, Özge Kaygusuz İzgördü2, Cihan Darcan3&#x0D; ORCID: 0000-0001-6608-0398; 0000-0002-3652-4266; 0000-0003-0205-3774&#x0D; 1 Corresponding author: Department of Chemical Engineering, Bilecik Şeyh Edebali University, 11210, Bilecik/Turkey Tel: +90 228 2141548, e-mail: levent.degirmenci@bilecik.edu.tr &#x0D; 2 Biotechnology Application and Research Center, Bilecik Şeyh Edebali University, 11210, Bilecik, Turkey 3 3Department of Molecular Biology and Genetics, Bilecik Şeyh Edebali University, 11210, Bilecik, Turkey&#x0D; &#x0D; Abstract&#x0D; A microbial consortium with the ability to utilize nitrogen of certain chemical fertilizers were established via a series of tests. Results indicated four strains, 3 of which were identified as Bacillus cereus sp and an Alcaligenes faecalis sp. which was the only non-Bacillus member of the consortium. The members of the consortium showed no antagonistic activity against each other implying their successful utilization as components of a commercial fertilizer.&#x0D; Keywords: IAA, siderophore, Bacillus spp., nitrogen fixation, ammonia/nitrite oxidation, MALDI-TOF MS&#x0D; &#x0D; Organik ve Kimyasal Gübre ,le Kullanılmak Üzere Mikroorganizma İzolasyon ve Karakterizasyonu&#x0D; &#x0D; Özet &#x0D; Farklı kimyasal gübrelerin içeriğinde yer alan azotu bitkinin kullanımına sunabilen mikroorganizma karışımı bir dizi testler sonucunda elde edilmiştir. Sonuçların değerlendirilmesiyle mikroorganizma karışımına üç Bacillus Cereus sp. suşu ile karışımın Bacillus sp. olmayan tek üyesi Alcaligenes faecalis sp. seçilmiştir. Mikroorganizma karışımında yer alan suşların birbirlerine karşı antagonistik etki göstermediği dolayısıyla karışımın mikrobiyal gübre olarak ticarileştirilmesinin mümkün olduğu da elde edilen sonuçlar arasındadır. &#x0D; Anahtar Kelimeler: IAA, siderophore, Bacillus spp. azot fiksasyonu, amonyum/nitrit oksidasyonu, MALDI-TOF MS&#x0D; 1. Introduction &#x0D; Chemical fertilizer is gaining an increasing attention and its harmful effects on environment possesses a serious threat [2]. Heavy metal accumulation is another problem during utilization of chemical fertilizers [2].The variation of soil pH, another problem encountered due to excessive fertilizer utilization, has negative impact on phosphorus uptake [3]. Plant growth promoting bacteria when added to soil, operate via certain mechanisms facilitating acquisition of already existing resources in soil [4]. Siderophore producing bacteria also acts as biocontrol agent capable of decreasing phytopathogen population in the flora [4–7].&#x0D; Certain procedures were developed and/or modified in the present study to obtain a microbial consortium which would act as an enhancer during plant growth. &#x0D; 2. Materials and Method&#x0D; &#x0D; 2.1. Semi-selective isolation procedure as starting-point&#x0D; &#x0D; Semi-selective isolation procedures were conducted according to [12]. &#x0D; 2.2. Standard tests applied to determine the potential of isolates as PGPB.&#x0D; &#x0D; Nitrogen fixation ability, IAA production, phosphate solubility siderophore production were conducted according to [13-18]. &#x0D; 2.3. Specified tests to determine nitrogen evaluation potential of PGP isolates&#x0D; &#x0D; Nitrogen evaluation potential was determined according to [19]. &#x0D; 2.4. Biochemical tests conducted to determine Bacillus sp. in accordance with MALDI-TOF MS analyses evaluated for validation. &#x0D; &#x0D; Biochemical tests were evaluated based on positive results for both caseinase activity and starch hydrolysis [20-22].&#x0D; MALDI-TOF MS analyses applied for selected strains and an isolate with positive activity towards siderophore production.&#x0D; 3. Results &#x0D; IAA production, Nitrogen fixation performance, Ammonifier selection, phosphate solubility, siderophore production ability, urea degradation, ammonium oxidation and nitrite oxidation abilities of strains were evaluated to establish a microbial consortium. &#x0D; 4. Conclusion and discussion&#x0D; • Media selection could serve as a selection criterion to assemble a certain group of microorganisms.&#x0D; • Tests conducted for isolates could be diversified to establish a consortium with modified properties.&#x0D; • Test procedures could be modified to facilitate establishment of microbial consortium.&#x0D; • Strains with different properties could serve as members of consortium which was the case in our study. &#x0D; • Identification in species level was possible to a certain extent. MALDI-TOF MS analysis presented a brief idea on strains and similar results would have been obtained in the case of applying its costlier alternatives. Hence a relatively simpler procedure is concluded to be better for initial investigation.&#x0D; • Evaluation of results led to investigation of certain prospects including determination of physicotolerant activity of strains and management of Fusarium wilt disease as the topics of future investigations.