Soil pH Research Articles

Soil nutrients and pH modulate carbon dynamics in particulate and mineral-associated organic matter during restoration of a Tibetan alpine grassland

Soil nutrients and pH modulate carbon dynamics in particulate and mineral-associated organic matter during restoration of a Tibetan alpine grassland

Effect of anaerobic digested sludge biochar on soil quality improvement: An insight into mechanisms, microbial composition, and toxicity risk assessment.

Biochar is widely acknowledged for its remarkable impact on soil conditioning. However, the influence of different sources of biochar, particularly anaerobic digested sludge biochar (ADBC) derived from anaerobic digested sludge and biochar derived from waste activated sludge, on alkaline soil remains largely unexplored. To address this knowledge gap, a comprehensive field experiment was conducted over a period of 180 days to investigate the effects of ADBC on slightly alkaline soil. This study evaluated various aspects, including soil properties, nutrient content, microbial composition, and soil toxicity. The results demonstrated significant improvements in the quality of alkaline soil following the application of ADBC. Notably, soil pH decreased from 8.24 to 7.5, while conductivity increased from 56.7μs/cm to 249.0μs/cm, total organic carbon from 13.5g/kg to 19.9g/kg, available nitrogen from 45.5g/kg to 237.5g/kg, and available phosphorus from 549.5g/kg to 1396.7g/kg. Moreover, ADBC substantially increased the relative abundance of functional bacteria associated with nutrient cycling, such as Proteobacteria, Actinobacteriota, and Bacteroidota. Conversely, the assessment of biotoxicity revealed a decrease in toxicity with increasing preparation temperature and particle size. These findings highlight the promising potential of ADBC for improving the key properties of alkaline and nutrient-poor soils crucial for overall soil productivity.

Effects of combined applications of S-nZVI and organic amendments on cadmium and arsenic accumulation in rice: Possible mechanisms and potential impacts on soil health

In situ remediation of cadmium (Cd) and arsenic (As) (Cd&As) contaminated soil using iron-based materials has been extensively investigated. Simultaneous immobilizing Cd&As with iron-based materials while maintaining soil health poses a significant challenge. This study examined the effects of sepiolite-supported nanoscale zero-valent iron (S-nZVI) combined with organic amendments (RS: Rice straw; PM: Pig manure) on Cd&As uptake by rice and soil quality. Grain Cd (0.134mgkg-1) and inorganic As (iAs) (0.099mgkg-1) levels in S-nZVI+PM treatment were reduced by 78.95% and 68.69% compared to CK (P<0.05), and decreased by 52.62% and 17.50% compared to S-nZVI treatment (P<0.05), significantly lower than the Chinese Food Safety Standard (<0.20mgkg-1). The elevated soil pH, increased amorphous iron (Feox), and PM complexation co-contributed to Cd immobilization in S-nZVI+PM treatment; concurrently, the higher Feox maintained lower available As levels in paddy soil. In addition, S-nZVI+PM improved soil fertility, functional enzyme activity, soil bacterial community diversity, and increased brown rice yield. However, S-nZVI+RS facilitated the reductive dissolution of Fe(oxy)(hydro) oxides and As methylation in paddy soil, significantly increasing the total As and organic As content in grains by 113.13% and 236.79%, respectively, compared to S-nZVI treatment. Caution should be exercised in the application of S-nZVI+RS in As-contaminated paddy soil. S-nZVI+PM proved more effective in immobilizing Cd&As and provided greater benefits to soil quality compared to S-nZVI+RS. Overall, S-nZVI+PM represents an eco-friendly approach for alleviating Cd&As accumulation in rice grains while concurrently improving soil health.

Effects of agricultural plastic films on crop growth and soil health in tobacco fields: A comparative study

In recent years, the impact of microplastics on soil microorganisms and crop growth has gained significant attention. However, the effects of agricultural plastic films on crop growth and soil health in tobacco fields are not clear. In our study, we conducted field experiments to investigate the effects of six types of agricultural film treatments on soil fertility, soil microbial community, and plant growth. Compositions of study treatments were as follows: T1: farmhouse film; T2: photodegradation film; T3: black film (6 μm); T4: black film (8 μm); T5: transparent film (6 μm); T6: transparent film (8 μm). Our results showed that photodegradable film treatment was beneficial for promoting crop growth and root development. The fresh stem biomass, dry root biomass, and dry stem biomass were significantly increased by 14.58 %, 68.70 %, and 18.27 %, respectively, under the T2 treatment, when compared to the T1 treatment. In addition, our results showed that photodegradation film treatment maintained soil pH value, compared with other agricultural film treatments. The application of photodegradation film treatment offered advantageous effects in the preservation of soil moisture and temperature. In addition, the diversity of soil microorganisms improved with photodegradable film. Compared to T1 treatment, the number of OTUs of bacteria and fungi improved by 1.94–7.64 % and 7.39–30.08 % under other treatments, respectively. Furthermore, our study showed that pH emerged as the paramount environmental determinant. The number of subnetworks treated with photodegradable film significantly increased, indicating a more complex and stable functional diversity of soil microbial communities. Additionally, compared to bacteria, fungal communities exhibited greater adaptability and stability. The results of this study support the view that photodegradable film can be employed, as it can to enhance crop yield, improve soil quality, maintain a favorable ecological environment, and mitigate the adverse environmental impact of microplastics.

Synergistic Impacts of Bismuth Ferrite and Graphitic Carbon Nitride Nanomaterials on Soil Properties: A Path Toward Enhance Soil Properties

ABSTRACT The use of nanostructured materials in soil sustainability is advancing in recent time. The aim of this research is to investigate the impact of synthesized nanostructured photocatalysts, including metal-free graphitic carbon nitride (g-C3N4), bismuth ferrite (BiFeO3), magnesium-doped bismuth ferrite (Bi0.7Mg0.3FeO3), and a heterojunction of g-C3N4/BiFeO3, on various soil properties. Photocatalysts were synthesized using pyrolysis, sol–gel, and coprecipitation methods and were systematically characterized using powdered X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. Soil samples for the experiment were collected, prepared, and were subjected to different catalyst treatments and exposure to sunlight durations. Experiment was conducted following a completely randomized design with three repetitions. Results revealed that the photocatalysts significantly altered some of the soil properties. The study found that the photocatalysts significantly influenced soil pH (from 6.91 in control to 6.44 in BiFeO3) and exchangeable acidity on a short-term (from 1.42 cmolkg−1 in 0 h to 0.82 cmolkg−1 in 500 h) after application. Notably, g-C3N4 demonstrated nitrogen fixation potential (9.1 gkg−1 compared to 1.8 gkg−1 in control), significantly increasing total nitrogen levels in the soil and demonstrated the highest cation exchange capacity (7.23 cmolkg−1 compared to 6.71 cmolkg−1 in control). In conclusion, the novelty of these findings provide important insights into the potential of synthesized nanostructured photocatalysts in the modification of soil properties. It highlights the importance of exposure time and catalyst levels in accomplishing desired modifications in soil characteristics, offering a basis for further investigations into agricultural and soil remediation applications of these photocatalytic nanostructured materials.

The heterogeneity of Pinus yunnanensis plantation growth was driven by soil microbial characteristics in different slope aspects

The slope aspect is an important environmental factor, which can indirectly change the acceptable solar radiation of forests. However, the mechanism of how this aspect changes the underground ecosystem and thus affects the growth of aboveground trees is not clear. In this study, Pinus yunnanensis plantation was taken as the research object, and the effects of soil and microbial characteristics on tree growth under different slope aspects and soil depths were systematically analyzed. The tree height (H) and ground diameter (GD) on the sunny slope were 7.64% and 8.69% higher than those on the shady slope. The soil pH, alkaline hydrolyzable nitrogen (AHN), available phosphorous (AP), available potassium (AK), total nitrogen (TN), total phosphorous (TP), and total potassium (TK) were significantly different between the different slope aspects. With the increase in soil depth, the content of organic matter (OM), AHN, AP, and AK decreased. There were significant differences in soil microbial diversity and community structure between the different slope aspects, but there was no significant difference among different soil depths. The abundance of Proteobacteria on a sunny slope was lower than that on a shady slope, and the richness of Firmicutes and Planctomycetota was higher than that in a shady slope. With the increase of soil depth, the richness of Proteobacteria increased, and the richness of Firmicutes and Planctomycetota decreased. The structural equation model showed that the influence of soil bacteria and fungi on soil characteristics was much greater than that on tree growth, and the influence of soil characteristics on tree growth was much greater than that of soil microorganisms. The slope aspect caused the difference of soil microorganisms, further affected the soil characteristics and led to the heterogeneity of aboveground forest growth. The insights gleaned from this study hold the potential to inform the formulation of customized management strategies, thereby enhancing resource utilization efficiency and fostering the vitality of forest ecosystems. Furthermore, this research offers theoretical underpinning for the targeted cultivation of coniferous plantations.

Effect of Peanut Intercropping on Arsenic Uptake and Remediation Efficiency of Plants in Arsenic-Contaminated Soil

Phytoremediation is an economically viable and environmentally friendly technique among various arsenic-contaminated soil remediation technologies. Field plot experiments were conducted to investigate the effects of peanut intercropping with sunflower, lucerne, and jute on the growth and development of intercropped crops and the efficiency of arsenic (As) remediation in polluted soil within the intercropping system. The results indicate that intercropping peanuts with other crops can enhance the biomass and yield of the crops. The land equivalent ratios (LER) of the three intercropping patterns were 1.03, 1.70, and 1.17, respectively. The intercropping pattern also influences the absorption and accumulation of As in crops. Total arsenic accumulation in peanuts intercropped with jute reached 493 μg·plant−1, which was significantly higher by 29.5% compared to peanut monoculture. Additionally, the translocation factor (TF) and bioaccumulation factor (BCF) of peanut seeds were significantly higher in peanut-jute intercropping compared to other treatments, but the As content of peanut seeds in all treatments complied with national food safety standards (GB2762-2022, 0.5 mg·kg−1). Intercropping of peanuts altered the pH and Eh values of rhizosphere soil, further influencing the percentage content of various forms of As in the soil, and reducing the mobility and effectiveness of As. The metal removal equivalent ratios (MRER) for the three intercropping patterns were 1.30, 2.11, and 1.26, respectively. The intercropping of peanuts and lucerne resulted in an MRER of 2.11. It indicates that peanut intercropping has a significant promotion and high restoration efficiency on the growth and development of lucerne. Therefore, among the three patterns, the peanut intercropping lucerne pattern has the best effect in applying to contaminated soil, and can better realize the integration of economic and ecological benefits.

УРОЖАЙНОСТЬ ЯРОВОГО ЯЧМЕНЯ В ЗАВИСИМОСТИ ОТ НОРМ ВЫСЕВА И СРОКОВ ПОСЕВА В УСЛОВИЯХ РЕСПУБЛИКИ ТЫВА

Experimental data for 2019–2021 are presented. to study the effect of seeding rates and sowing dates on the yield of spring barley in the conditions of the Republic of Tyva. The object of the study was the varieties of spring barley Biom and Olenek, approved for use in the East Siberian Region. The Acha variety served as the standard. The studies were carried out on the boghara of the forest-steppe zone at the experimental site of the Tuva Research Institute of Agriculture. The soil is dark chestnut light loam, with a neutral soil reaction pH 7.0. The moisture supply regime for the studied years was favorable, the temperature regime had lower values, compared with long-term ones. The results of the experimental work revealed that the optimal sowing time for spring barley in the conditions of rainfed agriculture falls on the last ten days of May. It has been established that the best seeding rate for spring barley varieties, providing a high weight of 1000 grains, grain weight per ear and yield, is the rate of 4.5 million germinating grains per ha. Varieties Olenek and Biom in 2021 were higher than the standard by 0.59 and 0.65 g, respectively, in terms of grain weight per ear in the second term at a seeding rate of 4.5 million. In terms of the weight of 1000 grains, on average over three years, Biom was higher than the standard in the first and second terms at a rate of 3.5 million per 3.7–4.27 g, and also at a rate of 4.5 million per 3.86–5.86 g respectively. The Biom variety had a high yield in 2021 in the second term with a seeding rate of 4.5 million germinating grains above the standard by 3.31 t/ha.

Current Status of Pulsatilla patens in Latvia—Population Size, Demographic and Seed Viability Indicators, Soil Parameters and Their Relationships

Pulsatilla patens (L.) Mill. (Eastern pasque flower) is classified as a highly endangered and declining species in Europe. The present research assessed the current status of P. patens in Latvia by collecting data on its distribution in historical places, Natura 2000 territories, and other areas, largely covering the entire country. We aimed to analyze the relationships between P. patens populations size, demographic indicators, and soil parameters, in order to gain knowledge on the impact of local ecological factors and optimal growth conditions, which are important for conservation and potential reintroduction. Although P. patens was not detected in more than a third of the surveyed 624 locations, more than 18 thousand individuals were recorded. Our results indicate that optimal growth conditions for P. patens occurred near highways, forest roads, and paths, that is, in places with reduced competition from other species and improved lighting conditions. The seed viability ranging from 22% to 62% can be considered potentially sufficient for the continuation of the species if enough flowering plants and moss-free spaces for germination are maintained. Although P. patens tolerates a broad soil pH range, in Latvia this species mainly grows in acidic sandy soils with an average pHKCl of 4.07. The soil parameters that most strongly positively correlated with P. patens regional population size and performance included higher soil pH level and plant available nutrient content, particularly P, K, Ca, Mg, Mn and B. Increased soil P and Mn levels significantly enhanced flowering, while high organic matter content could be associated with reduced population sizes. Despite its still large current population, long-term risks remain without active management. Conservation measures, such as creating open soil areas, where vegetation is removed and shading is reduced, are necessary to mitigate population decline.

Soil constraints and recommendations for improving major farming in Vinh Long province, Vietnam

This study aims to assess the potential of soil and its constraints for production to meet economic needs and diversify types of crop models of Vinh Long province in the Vietnamese Mekong Delta region. Identifying the main constraints of the soil is the basis for reasonable land arrangement and proposing measures to maintain and improve the soil characteristics suitable for each crop type and purpose of use. The study used survey methods, interviewed farmers about the current farming situation and collected soil samples to analyze physical and chemical properties. Research results show that in Vinh Long, for three main crops, namely rice, fruit trees (grapefruit trees) and sweet potatoes, the primary constraints are a potential and active acid sulfate and low pH soil. In addition, Al toxicity causes phosphorus fixation, the exchangeable K content is low and the organic matter is only moderate. These limitations have affected crop productivity, especially for fruit trees. The research results also recommended improving soil properties suitable for the cultivation of major crops, including controlling the water level so as not to oxidize the sulfidic material to active acid sulfate soils, draining the water at the beginning of the season rain to leach the toxicity in the soil and need to fertilize with nitrogen, phosphorus and potassium supplements for a long time, divided into several times of application.

Oat and Forage Pea Mixed Sowing Improves Soil Chemical Fertility and Fresh and Dry Mass Yield in Light Saline–Alkali Land: Preliminary Results

Saline–alkali land is widely distributed worldwide, and poses significant challenges to agricultural productivity and ecological restoration, particularly in the Qaidam Basin. This study investigates the effects of intercropping and mixed sowing systems of oats (Avena sativa L.) and forage peas (Pisum sativum L.) on hay yield and soil chemical fertility in mildly saline–alkali soils of the Qaidam Basin. Through a comprehensive analysis of hay yield, soil chemical properties, and enzyme activities under different sowing methods (mixed sowing, intercropping, and monoculture) and row spacings (30, 25, 20 and 15 cm), an optimal planting pattern was identified. The 25 cm intercropping treatment produced the highest amount of fresh biomass (2242 kg hm⁻1), with an increase ranging from 3.17% to 70.44% compared to other treatments. Additionally, this treatment led to significant reductions in soil pH and electrical conductivity (by 3.87–8.31% and 5.13–6.05%, respectively), while enhancing organic matter content and enzyme activities. The intercropping system also demonstrated higher ammonium nitrogen and available phosphorus contents compared to the mixed sowing system. Structural equation modeling revealed that row spacing indirectly influenced both hay yield and enzyme activities, with the 25 cm row spacing proving to be the most effective. A comprehensive evaluation using the TOPSIS model further affirmed that the 25 cm intercropping system significantly enhanced hay yield, soil chemical properties, and enzyme activities, making it the most suitable planting pattern for sustainable land management in the study area. Therefore, the 25 cm intercropping model not only optimizes hay yield, but also improves soil quality and ecological functions in saline–alkali land, offering valuable insights and practical recommendations for the sustainable use of saline–alkali land in the Qaidam Basin.

Edaphic factors mediate the response of nitrogen cycling and related enzymatic activities and functional genes to heavy metals: A review.

Soil nitrogen (N) transformations control N availability and plant production and pose environmental concerns when N is lost, raising issues such as soil acidification, water contamination, and climate change. Former studies suggested that soil N cycling is chiefly regulated by microbial activity; however, emerging evidence indicates that this regulation is disrupted by heavy metal (HM) contamination, which alters microbial communities and enzyme functions critical to N transformations. Environmental factors like soil organic carbon, soil texture, water content, temperature, soil pH, N fertilization, and redox status play significant roles in modulating the response of soil N cycling to HM contamination. This review examines how different HMs affect soil N processes, including N fixation, mineralization, nitrification, denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and immobilization, as well as microbial activities and functional genes related to soil N transformations. The review additionally outlines the impact of HMs on environmental degradation, including the risk of soil N losses (e.g., leaching, runoff, and gaseous emissions) and depletion of soil fertility, thus threatening the sustainability of the ecosystem. The effect of edaphic factors and fertilization on soil N cycling response to HM contamination was also examined. The effect of phytoremediation, a sustainable approach to remediate HM polluted soils, on N cycling was also reviewed. Thus, this review underscores the importance of increasing research and innovative strategies to combat HM pollution's effects to enhance soil health, boost crop yields, and protect soil stability and productivity.

Mitigating cadmium contamination in soil using Biochar, sulfur-modified Biochar, and other organic amendments

Biochar is a novel approach to remediating heavy metal-contaminated soil. Using various organic amendments like phyllosilicate-minerals (PSM), compost, biochar (BC) and sulfur-modified biochar (SMB), demonstrates superior adsorption capacity and stability compared to unmodified biochar (BC). The adsorption mechanisms of SMB are identified for its potential to increase soil-pH and reduce available cadmium (Cd). The study reveals the potential of BC and SMB in immobilizing Cd in contaminated soil. SMB demonstrated the highest adsorption capacity for Cd, followed by BC, PSM, and compost, with capacities ranging from 7.47 to 17.67 mg g−1. Both BC and SMB exhibit high adsorption capacities (12.82 and 17.67 mg g−1, respectively) and low desorption percentages (4.46–6.23%) at ion strengths of 0.01 to 0.1 mol-L−1 and pH levels ranging from 5 to 7. SMB showed a higher adsorption capacity (17.67 mg g−1) and lower desorption percentage (4.46–6.23%) compared to BC. The adsorption mechanism involves surface-precipitation, ion exchange, and the formation of Cd(OH)2 and CdCO3 precipitates, as well as interactions between Cd and organic sulfur, leading to more stable-Cd and CdHS+ compounds. Adding 1% SMB increased soil pH and significantly reduced available Cd, demonstrating its potential for pollutant remediation. The study underscores the promise of SMB in providing a sustainable solution for Cd-contaminated soil remediation.

Effect of sludge-based biochar on the stabilization of Cd in soil: experimental and theoretical studies

Soil heavy metal contamination and sludge disposal have become globally environmental issues problems of great concern. Utilizing sludge pyrolysis to produce biochar for remediating heavy metal-contaminated soil is an effective strategy to solve these two environmental problems. In this study, municipal sewage sludge and papermaking sludge were used as feedstock to prepare co-pyrolyzed biochar, which was then applied to reduce the toxicity of Cd in soil. The results indicated that the application of co-pyrolyzed biochar significantly increased soil pH, CEC, and enzyme activity, while decreasing the content of available Cd in the soil. Following the application of 3% co-pyrolyzed biochar, the proportion of acid-soluble Cd in the soil decreased to below 46%, as the biochar facilitated the conversion of leachable acid-soluble Cd to stable oxidizable and residual forms through precipitation and complexation. The DFT computational results indicate that the aromatics in co-pyrolyzed biochar can adsorb Cd ions through cation-π interactions, while carboxyl, hydroxyl, aldehyde, and amide groups can provide more electrons for the adsorption of Cd ions, resulting in stronger adsorption capacities. The study findings provide a feasible solution for the resourceful treatment of sludge and the remediation of heavy metal-contaminated soil.

Assessment of land suitability and crop water requirements for irrigated sugarcane in the Kuraz Irrigation Scheme, Lower Omo Basin, Ethiopia

ABSTRACT Assessing land suitability is crucial for sustainable agricultural production. This study focuses on evaluating the suitability of land for irrigated sugarcane cultivation and determining crop water requirements within the Kuraz Irrigation Scheme in Ethiopia. A combination of geographic information system (GIS) and analytical hierarchy process (AHP) tools was used to classify land suitability and support decision-making by considering factors such as soil pH, texture, temperature, rainfall, land use-land cover, and slope. The AquaCrop model was utilized to simulate current and future scenarios for biomass, canopy cover, yield, maximum evapotranspiration, and water productivity of sugarcane crops. The model was calibrated for irrigated sugarcane during the 2015–2016 crop season, revealing that the majority of the study area is highly suitable for sugarcane cultivation. Specifically, 28% of the area was classified as highly suitable, 38% as moderately suitable, 21% as marginally suitable, and 13% as unsuitable. These findings highlight the potential for expanding sugarcane cultivation to boost yields and profitability. However, the study also underscores the need to consider potential environmental impacts, such as water usage and soil degradation from agricultural expansion. Additionally, social factors, including labor practices and the possible displacement of local communities, must be taken into account when expanding sugarcane cultivation.

Long-term transfer of 137Cs in sensitive agricultural environments after the Chornobyl fallout in Sweden.

In this study, the long-term transfer of 137Cs from soil to grass on Swedish farms and fields, heavily contaminated after the 1986 radioactive fallout, was investigated. The study spans over 8-14 years, beginning in June 1986, and covers various soil types and agricultural practices. The transfer of 137Cs from soil to grass was highly variable, with transfer factors ranging from 1.0×10-5 to 0.357m2kg-1. Higher values were observed on fields with sandy loam, loamy sand, and organic soils, and lower values on fields with a high clay content. The transfer of 137Cs to grass generally exhibited an exponential decline across the majority of fields over the years. The rate of decrease was most pronounced in clay loam and silty loam soils, while it was least evident in sandy loam, sandy soils, and peat soils. The soil properties and farming practices were more important for 137Cs uptake than the initial deposition density. The transfer factor had a negative correlation with soil pH, clay, and fine silt content. No significant relationships were found with other soil variables, such as soil organic matter content and plant available potassium concentration. The median effective half-life of 137Cs in the grass was 4.5 years, with a range of 2-18 years. The uptake of 137Cs by plants did not correlate with the potassium concentration in grass tissues; however, the activity concentration of 137Cs in grass correlated negatively with the potassium content in the plants grown on fields with high deposition levels.

Potential of perennial forages on soil carbon sequestration across agroecological zones with varying management practices in Meru County, Kenya

The decline in soil organic carbon (SOC) due to continuous cultivation practices threatens soil productivity and compromises climate change mitigation efforts. This study investigates the effect of agro-ecological zones (AZ), management practices (MP), and specific forages on SOC and its related fractions: particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), in Meru County, Eastern Kenya. Thirty-five predetermined perennial forage fields with Brachiaria (B), Panicum (Panicum maximum) (P), Napier grass (P.P. Schumach) (N), paired with maize (Zea mays) (M) growers, and with two MP [farmyard manure (FYM) and inorganic fertilizer application] were selected per agro-ecological zone. A factorial plot design was employed, with zones as the main plots, the MP as split plots, and the forages as split-split plots. Soil samples were collected from 1 m-by-1 m plots across 35 farms at depths of 0–50 cm, and analyzed for pH, bulk density, SOC content, POC, MAOC, and other micronutrients. Soil samples were statistically analyzed using two-way ANOVA. From the survey, 70% of the respondents had perennial forages of more than 3 years except for panicum which majority had planted for <3 years. Most of the farmers interviewed applies organic manure. Bulk density ranged from 1.07 to 1.19 g cm−3, with the highest values under inorganic fertilizers and the lowest under FYM, showing significant differences between paired plots (p = 0.0011). Soil pH ranged from 5.13 to 5.36, and MP significantly affected all micronutrients, with FYM combined with Panicum having the highest cation exchange capacity (19.45 cmol/kg) and manganese (96.30 ppm), and FYM combined with maize showing the highest available phosphorus (54.08 cmol/kg). Results showed no significant differences in mean values of POC and MAOC across zones, though the Lower Zone (LZ) had higher POC (6.63 g C kg−1) and MAOC (7.24 g C kg−1) compared to the Mid Zone (MZ) and Upper Zone (UZ). Different forages exhibited varying levels of MAOC, POC, and SOCs, with Brachiaria showing the highest SOC (15.69 g C kg−1) and Panicum the lowest (14.84 g C kg−1). Particulate organic carbon and MAOC content were significantly different across forages and maize (p < 0.05), with Brachiaria having higher MAOC (5.37 g C kg−1) and POC (5.97 g C kg−1). FYM combined with Brachiaria resulted in the highest POC (6.09 g C kg−1) and MAOC (5.44 g C kg−1). POC and MAOC concentrations varied significantly with soil depth, showing higher values in the top 10 cm. The Mid Zone recorded significantly higher SOC, POC, and MAOC than the UZ and LZ. This study concludes that AZ and MP substantially influence SOC sequestration, with FYM and Brachiaria being most effective in LZ.

Eco-friendly utilization of rice husk ash for amending acid soils

Rice husk ash (RHA) contains appreciable amounts of exchangeable cations and plant nutrients which can be used as liming material for acid soil reclamation. Hence, the present study was carried out to assess the potential of rice husk ash for soil acidity reclamation and its effect on related soil properties. RHA was collected from a modern rice mill and its physical and chemical properties were assessed. The results confirmed the alkaline nature of RHA with a pH of 8.30 at 1:10 RHA-to-water suspension. An incubation experiment was conducted with five levels of RHA viz., 10, 20, 30, 40 and 50 t ha-1; compared with the treatments without liming material and the lime application as per lime requirement. Soil sampling was performed at 15, 30, 45 and 60 days after incubation (DAI) and analysed. The results indicated that the application of RHA 50 t ha-1, 40 t ha-1,30 t ha-1 and lime (100% lime) were comparable in enhancing the soil pH, effective cation exchange capacity and percent base saturation and reduced the total acidity and exchangeable Al. With all levels of RHA and lime application, favourable effects on soil properties related to acidic soil reclamation were observed over time. Exchangeable Ca and Mg were the highest in the 100% lime requirement, followed by RHA at 50 t ha-1. Exchangeable K and Na were the highest in rice husk ash at 50 t ha-1. The results emanated from this study ensured the potential of rice husk ash as a source of lime for acidic soils reclamation.

Community structure and diversity of myxobacteria in soils from Inner Mongolia, China

Myxobacteria are a special kind of Gram-negative bacteria that can slide and produce a variety of bioactive substances against bacteria, fungi, and viruses. It has great development and research value in medicine and agriculture. Although myxobacteria have become a research hotspot at home and abroad, there are few systematic studies on the relationship between its diversity, geographical location, and environment factors. In order to solve these problems, 133 soil samples were collected from the east to the west of Inner Mongolia Autonomous Region and divided into five groups. The water content, pH, organic matter, available phosphorus, hydrolytic nitrogen, and available potassium content of soil samples were determined by national standards and other methods. The quantitative assessment of the abundance of myxobacteria in the soil sample was performed by quantitative real-time PCR. The composition of myxobacteria in the soil was determined by 16S rRNA high-throughput sequencing technology to analyze the differences in the community structure of myxobacteria among different groups, explore the relationship between the diversity of myxobacteria resources and the distribution and physical and chemical properties of the soil, and predict and analyze its community function. The results showed that there were abundant myxobacteria resources in the soils of Inner Mongolia, and the average relative abundance of myxobacteria in the soil samples from the central part of Inner Mongolia was higher than that in the eastern and western parts, but the richness and diversity of samples from the central to eastern regions were significantly higher than those from the western regions. The myxobacteria resources in the whole region included 10 families and 22 genera, among which the dominant genera were Labilitrix, Sandaracinus, Archangium, and Haliangium. The analysis of the species composition of myxobacteria among different groups found that the distribution of soil and soil type had an impact on the species composition of the samples. The species with significant differences in relative abundance among the five groups of samples were Labilitrix, Archangium, Sandaracinus, Minicystis, Polyangium, and Myxococcus. In addition, the latitude and longitude of the sampling point and the soil pH, water content, available phosphorus content and organic matter content had a greater impact on the myxobacteria community structure of samples, while the altitude of the soil sample and the contents of available potassium and alkaline nitrogen had a relatively small impact. Our data suggest that the distribution, type and nutrient composition of soil samples have an impact on the relative abundance and species composition of myxobacteria community. The completion of this work can provide basic data for the in-depth study of myxobacteria in the soil.

The Impact of Abiotic Environmental Stressors on Fluorescence and Chlorophyll Content in Glycine max (L.) Merrill

In this study, we present the results of the impact of abiotic environmental (chemical) stressors in the soil environment (salinity, acidification, inorganic elements from industry—red mud waste containing Al) on the content and fluorescence of chlorophyll in the assimilating tissues of Glycine max (L.) Merrill, cv. ES Mentor. Under controlled conditions of a pot experiment during the 2023 growing season, we applied graded doses of these stressors (salinity—doses of 20, 30, and 60 g NaCl per 2 dm3 of water used for plant irrigation; acidity—pH 6, pH 5, and pH 4; red mud—200 g, 400 g, and 600 g per pot) and assessed their impact on the effective and maximum quantum yield of photosystem II (PSII), yield Y(II), or the ratio of variable to maximum fluorescence—the Fv/Fm test. These tests are used to detect plant stress. The Y(II) test yielded values in the range of 0.627–0.800. Significant differences (variance analysis, 95% Least Significant Difference—LSD, post hoc test of analysis of variance—ANOVA) in reducing PSII chlorophyll fluorescence (Y(II)) were found between the medium and high doses of all three stressors compared to the control, indicating plant stress response. The Fv/Fm test yielded values between 0.668 and 0.805 and similarly detected stress responses in plants to all medium and high doses of stressors. The evaluated cultivar showed tolerance to moderately increased salt (NaCl) content and red mud levels. This was also confirmed by the chlorophyll content expressed as the Chlorophyll Content Index (CCI). The highest (significantly confirmed) chlorophyll content was found in the control variant and the variants with lower salt content and a soil pH of 6, with values of 35.633–37.467 CCI, compared to variants with higher red mud content (15.533–18.133 CCI) and higher soil acidity with pH 4 (22.833 CCI). Based on the results obtained, we conclude that the ES Mentor cultivar is tolerant to lower doses of the assessed stressors and can be cultivated in agricultural practice. However, medium to high doses of stressors trigger a strong stress response in plants and, therefore, we do not recommend cultivating this variety in contaminated environments.