Soil Physicochemical Parameters Research Articles

Evaluation of Physico-chemical Parameters of Soil in Different Cropping Systems and their Co-relation with Earthworm Diversity

Aim: The present study is an attempt to evaluate the impact of earthworm diversity on physico-chemical parameters of soil in different cropping systems (i.e. basmati-wheat, basmati-chickpea, soybean-wheat, moong-wheat) under organic and conventional farming systems.
 Place and Duration of Study: The study was conducted at the School of Organic Farming, Punjab Agricultural University, Ludhiana, Punjab, India from June, 2020 to March 2021.
 Methodology: The four earthworm species found during the study period are Metaphire posthuma, Lampito mauritti, Amynthas morissia and Travoscolides chengannure, which belong to two families i.e. Megascolicidae and Octochateidae. Out of these Travoscolides chengannure was reported for the first time in Punjab.
 Results: The results indicate that richer earthworm diversity was found in the organic farming systems as compared to the conventional farming systems. The correlation analysis of earthworm abundance with the physicochemical parameters of soil in different farming systems revealed that the abundance of earthworms in organic farming system shows positive but non-significant correlation with pH, nitrogen and potassium levels. In conventional farming system, significant positive correlation (p=0.01) was found for organic carbon, electric conductivity and nitrogen.
 Conclusion: The findings of this encourage switching from conventional to organic farming practices. These practices not only increase earthworm diversity, but enrich the soil with many major and micro-nutrients. The agriculture practices which are earthworm-friendly should be adopted for long-term soil productivity.

Pedogenesis at the coastal arid-hyperarid transition deduced from a Late Quaternary chronosequence at Paposo, Atacama Desert

Under hyperarid climate conditions, pedogenesis is driven by the atmospheric deposition and subsequent accumulation of easily to moderately soluble salts forming extreme types of Aridisols. In contrast, the processes and timescales of soil formation in coastal desert environments are as yet not well understood. Therefore, a soil chronosequence at the arid-hyperarid transition in the south-central coastal Atacama Desert is investigated. We measured physicochemical soil parameters of shallow soil profiles on four generations of a multi-stage alluvial fan system, assisted by micromorphological analysis, allowing to deduce the soil-forming processes. We further established a geochronological framework by applying 10Be cosmogenic nuclide exposure dating on the abandoned surface generations, which allowed to infer the timescales for soil formation. The results indicate initial yet clearly identifiable pedogenesis occurring since MIS 5e–c. Along the Late Quaternary chronosequence, physicochemical soil properties show decreasing trends with growing age for the median grain size, salinity, long-term pH development, and CaCO3 contents. Contrarily, organic carbon, the ratio of organic to total phosphorus, the redness, and the contents of total and poorly crystalline pedogenic iron oxides tend to increase with age. This provides evidence for soil formation under an arid to hyperarid coastal climate characterized by (i) redistribution of salts by leaching causing topsoil desalinization; (ii) decalcification coupled with (iii) dealkalinization in totally decalcified horizons; (iv) accumulation of soil organic matter; (v) initial rubification through formation of pedogenic iron oxides (i.e. hematite); and (vi) initial loamification that, in turn, might have impeding effects on the translocation of soil constituents on timescales larger than 105 a. Furthermore, in situ pedogenesis might be superimposed considerably by aeolian dust influx. At Atacama’s south-central coast, the state of pedogenic alteration scales with the cumulative precipitation received throughout the entire Late Quaternary, yet evolved strongest between MIS5 and the MIS4/3-transition.

Indexation of Soil Physico-Chemical Parameters and Fertility Status of Soils of D.G. Khan, South Punjab (Pakistan) in the Light of Climate Change Scenario

Indexation of Soil Physico-Chemical Parameters and Fertility Status of Soils of D.G. Khan, South Punjab (Pakistan) in the Light of Climate Change Scenario

Seasonal variation of the rhizosphere soil aggregation in an Oxisol

Soil aggregation is a key process that results in soil structure formation and stabilization and controls several soil functions. The root system and its mycorrhiza symbiosis contribution to aggregate stabilization have been widely studied. However, only a few studies have considered a large variety of cropping systems under different seasons within tropical environments. Our goal was to better understand the response of aggregate stability in the rhizosphere (RS) and bulk soil (BS) to six cropping systems in an Oxisol, in the summer and winter seasons. Readily-dispersible clay and mechanically-dispersible clay were evaluated as aggregate stability indicators. RS and BS were also characterized for soil physical (i.e., water content), chemical (i.e., soil organic carbon, K, P, Ca, Mg, Al, potential acidity), and physicochemical (i.e., pH, ΔpH, and point of zero charge) properties. Dispersible clay was approximately 1.2 times lower (p < 0.05) within the RS than in the BS, which suggests that the crop root systems increased aggregate stability, but their influence on soil aggregation differed among cropping systems. Aggregate stability was approximately 3 times higher (p < 0.05) in the winter compared to the summer season. In general, RS had better chemical and physicochemical soil parameters than BS. Winter season also showed better chemical and physicochemical parameter values. Overall, these results reflect (i) the positive root system influence of the winter crops on soil structure stability, (ii) the negative response of soil structure stability to the addition of high doses of chemical fertilizers to soybean and maize (cash crops) in the summer season, (iii) the minimal influence of soybean and maize root system on formation and stabilization of the aggregates in the summer season, and (iv) the different weather condition in the summer and winter seasons. Thus, better erosion control practices and crops that promote soil aggregation should be adopted in the summer season. Finally, attention should also be given to the root exudates and their relationship with soil, as they can either increase or decrease soil aggregation.

Altitudinal gradient drives significant changes in soil physico-chemical and eco-physiological properties of Rhododendron anthopogon: a case study from Himalaya

The best natural laboratories for studying the ecological responses of plants are high-altitude areas like the Himalaya, where many gradients coexist on a relatively small spatial scale. Here, we investigate the effect of soil physico-chemical and eco-physiological properties on the broadleaf evergreen woody shrub Rhododendron anthopogon D.Don along an altitudinal gradient in the Kashmir Himalaya. We collected leaf and soil samples for eco-physiological and soil physico-chemical analysis, respectively, at five different sites along an altitudinal gradient (3,220–3,908 m). Our results demonstrate a significant difference between soil physico-chemical and eco-physiological parameters along the altitudinal gradient. A significant correlation was observed between different studied parameters and altitude. Principal component analysis of studied soil physico-chemical and eco-physiological parameters revealed that all the sites were grouped into four clusters according to altitude, suggesting a more pronounced effect of altitude. Our findings showed that soil infiltration capacity increased with altitude, which would be helpful for the growth and development of R. anthopogon. We also observed significant variations in eco-physiological parameters, demonstrating their critical involvement in adapting R. anthopogon to the harsh environment of the alpine regions of Kashmir Himalaya. Therefore, the present study adds to our understanding that R. anthopogon has sufficient soil physico-chemical and eco-physiological plasticity, which should be favorable for its survival in future climates, offering an adaptive advantage and expanding its range shortly.

Effect of elevation on composition and diversity of fungi in the rhizosphere of a population of Deyeuxia angustifolia on Changbai Mountain, northeastern China.

Soil fungi are a key component of terrestrial ecosystems and play a major role in soil biogeochemical cycling. Although the diversity and composition of fungal communities are regulated by many abiotic and biotic factors, the effect of elevation on soil fungal community diversity and composition remains largely unknown. In this study, the soil fungal composition and diversity in Deyeuxia angustifolia populations along an elevational gradient (1,690 m to 2020 m a.s.l.) were assessed, using Illumina MiSeq sequencing, on the north-facing slope of the Changbai Mountain, northeastern China. Our results showed that soil physicochemical parameters changed significantly along with the elevational gradients. The Ascomycota and Basidiomycota were the most dominant phyla along with the gradient. Alpha diversity of soil fungi decreased significantly with elevation. Soil nitrate nitrogen (NO3--N) was positively correlated with fungal richness and phylogenetic diversity (PD), indicating that soil nitrate nitrogen (NO3--N) is a key soil property determining fungal community diversity. In addition to soil nitrate content, soil pH and soil moisture were the most important environmental properties determining the soil fungal diversity. Our results suggest that the elevational changes in soil physicochemical properties play a key role in shaping the community composition and diversity of soil fungi. This study will allow us to better understand the biodiversity distribution patterns of soil microorganisms in mountain ecosystems.

A Review of the Current State of Microplastic Pollution in South Asian Countries

Microplastic contamination has become a concerning topic of study in recent decades. This review discusses the development of microplastic pollution based on a selection of South Asian countries consisting of Bangladesh, Iran, Philippines, Thailand, India, Indonesia, and Vietnam. The condition of microplastic pollution related to the abundance of microplastic found in various environments as well as the presence of microplastics in food and the air, is covered in this review. Several reports found that drinking water sourced from taps was found to have about 83% of microplastic particles in the year 2017 based on results from 14 nations, and in the year 2018, 260 bodies of water for human consumption in 11 countries were found to have about 93% of microplastic particles. Micro debris pollution in seas and oceans worldwide is predicted to be at an amount of 236,000 metric tons based on a statistical report. A mean value of 30 micro debris per liter of glacier water was recovered from the top of Mount Everest, whereas about 2200 small particles per liter were discovered in the deep waters of the Mariana Trench. The main environments that are severely microplastic-contaminated are water-based places such as rivers, estuaries, and beaches. The presence of microplastics in food items, such as tea bags, sugar, shrimp paste, and salt packets, has been reported. In terms of impacts on the environment, microplastic contamination includes the ingestion of microplastics by aquatic creatures in water environments. The impacts on terrestrial environments relate to microplastics sinking into the soil, leading to the alteration of the physicochemical parameters of soil. Meanwhile, the impacts on the atmospheric environment include the settling of microplastics on the external bodies of animals and humans.

A global meta-analysis of the correlation between soil physicochemical properties and lead bioaccessibility

Soil physiochemical properties play a vital role in bioaccessibility-based health risk assessment as it can determine the bioaccessibility and the true risk of potentially toxic elements in soil. However, the effects of soil properties on bioaccessibility still remains unclear. In this paper, 17 of the 1454 literatures with 474 samples were identified, screened and reviewed for exploring the correlation between soil physicochemical properties and lead bioaccessibility (BAcPb) through a meta-analysis approach. Five soil physicochemical parameters including pH, SOM, Clay, CEC and T-Pb were systematically analyzed using Principal component analysis, Pearson correlation analysis and survival analysis. The results showed that pH of simulated gastric juice is a major source of heterogeneity of the correlation between soil pH and BAcPb. In the gastric phase, the effect of alkaline soil on high BAcPb (BAc >50%) is more sensitive, and the effect of acidic soil on low BAcPb (BAc <50%) is more sensitive. However, in the small intestinal phase, soil pH displays little impacts on BAcPb in acidic, alkaline and neutral soils. Although three principal components explained 66.2% and 64.9% of the total variance of the urban, agricultural, and mining soils in gastric and small intestinal phases, respectively, there was no strong evidence that soil type can influence the BAcPb. The results of present study provide insights into the correlation between soil properties and BAcPb, and prediction of the bioaccessibility and bioavailability of Pb in different types of soil.

Unravelling diversity, drivers, and indicators of soil microbiome of Trillium govanianum, an endangered plant species of the Himalaya

In an era of global environmental change, conservation of threatened biodiversity and ecosystem restoration are formidable ecological challenges. The forest understory strata and the belowground soil environment including rhizospheric microbial communities, which are crucial for ecosystem functioning and overall forest biodiversity maintenance, have remained understudied. Here, we investigate the soil microbiome of Trillium govanianum – an endangered Himalayan Forest herb, to unravel the underground diversity, drivers, and potential indicators of the microbial community. We collected rhizospheric and bulk soil samples for microbiome and physicochemical analysis at three sites along an elevation gradient (2500–3300 m) in Kashmir Himalaya. Amplicon sequencing of 16 S rRNA and ITS was used to identify the bacterial and fungal soil microorganisms. We found significant differences in the structure and diversity of microbial community (bacterial and fungal) between the rhizosphere and bulk soil along the altitudinal gradient, and noticeable shifts in the nutrient level in dominant microbial phyla associated with T. govanianum. A significant difference between soil physicochemical parameters and increasing altitude suggests that microbial community structure is determined by altitude and soil type. Similarly, the microbial communities showed a significant (P < 0.05) correlation with soil physicochemical variables along the altitudinal gradient. The moisture content in bacterial and total organic carbon in fungal communities showed the most substantial impact on the physiochemical drivers. We also identify potential bacterial and fungal plant growth promoter indicator species in the soil microbiome of T. govanianum. Overall, our findings provide novel research insights that can be pivotal in designing integrated species recovery programs and long-term restoration plans for T. govanianum, with learnings for biodiversity conservation elsewhere.

Effects of rumen microorganisms on the decomposition of recycled straw residue.

Recently, returning straw to the fields has been proved as a direct and effective method to tackle soil nutrient loss and agricultural pollution. Meanwhile, the slow decomposition of straw may harm the growth of the next crop. This study aimed to determine the effects of rumen microorganisms (RMs) on straw decomposition, bacterial microbial community structure, soil properties, and soil enzyme activity. The results showed that RMs significantly enhanced the degradation rate of straw in the soil, reaching 39.52%, which was 41.37% higher than that of the control on the 30th day after straw return. After 30 d, straw degradation showed a significant slower trend in both the control and the experimental groups. According to the soil physicochemical parameters, the application of rumen fluid expedited soil matter transformation and nutrient buildup, and increased the urease, sucrase, and cellulase activity by 10%‒20%. The qualitative analysis of straw showed that the hydroxyl functional group structure of cellulose in straw was greatly damaged after the application of rumen fluid. The analysis of soil microbial community structure revealed that the addition of rumen fluid led to the proliferation of Actinobacteria with strong cellulose degradation ability, which was the main reason for the accelerated straw decomposition. Our study highlights that returning rice straw to the fields with rumen fluid inoculation can be used as an effective measure to enhance the biological value of recycled rice straw, proposing a viable solution to the problem of sluggish straw decomposition.

Soil organic carbon distribution and factors affecting carbon accumulation in natural and plantation forests in tropical China

Tropical rainforests are the most complex forest ecosystem in the world, and play an important role in the global carbon cycle. To investigate the accumulation characteristics of soil organic carbon (SOC) in tropical rainforests of different origins, soil samples from plantation and natural forests of tropical mountain rainforests in Wuzhi Mountain (WM), Qixian Mountain (QM) and Diaoluo Mountain (DM) in eastern Hainan Island, China, were collected at various depths (0–10, 10–30 and 30–50 cm). SOC concentrations of different-forest-origin soils were analysed and compared, and the effects of soil physicochemical parameters on SOC concentration in natural and plantation forests were investigated. SOC concentrations in plantation forests in WM, QM and DM were higher than those in natural forests, although the difference was not statistically significant. In the 0–50 cm soil depth, the SOC concentrations of different-forest-origin soils decreased with increasing soil depth, with SOC concentrations in the surface layer (0–10 cm) of natural forests being significantly higher than those in the middle layer (10–30 cm) and bottom layer (30–50 cm) (P < 0.05). Natural forests have lower pH than plantation forests. Correlation analysis revealed significant negative correlation (P < 0.05) between SOC concentration in both forest origins and soil pH. The proportion of clay and silt is greater in natural forests than in plantation forests, but the proportion of sand is greater in plantation forests.

Response mechanisms of bacterial communities and nitrogen cycle functional genes in millet rhizosphere soil to chromium stress.

A growing amount of heavy metal contamination in soil disturbs the ecosystem's equilibrium, in which microbial populations play a key role in the nutrient cycle of soils. However, given the different sensitivity of microbial communities to different spatial and temporal scales, microbial community structure and function also have varied response mechanisms to different heavy metal contaminated habitats. In this study, samples were taken prior to Cr stress (CK) and 6 h and 6 days after Cr stress (Cr_6h, Cr_6d) in laboratory experiments. High-throughput sequencing revealed trends in the structure and diversity of the bacterial communities, and real-time fluorescence quantitative polymerase chain reaction (qPCR) was used to analyze trends in nitrogen cycle functional genes (AOA-amoA, AOB-amoA, narG, nirK, and nifH). The findings showed that (1) the composition structure of the soil bacterial community changed considerably in Cr-stressed soils; α-diversity showed significant phase transition characteristic from stress to stability (p < 0.05). (2) With an overall rising tendency, the abundance of the nitrogen cycle functional genes (AOA-amoA and AOB-amoA) decreased considerably before increasing, and α-diversity dramatically declined (p < 0.05). (3) The redundancy analysis (RDA) and permutational multivariate analysis of variance (PERMANOVA) tests results showed that the soil physicochemical parameters were significantly correlated with the nitrogen cycle functional genes (r: 0.4195, p < 0.01). Mantel analysis showed that available nitrogen (N), available potassium (K), and available phosphorus (P) were significantly correlated with nifH (p = 0.006, 0.008, 0.004), and pH was highly significantly correlated with nifH (p = 0.026). The PLS-ME (partial least squares path model) model further demonstrated a significant direct effect of the soil physicochemical parameters on the nitrogen cycling functional genes. As a result, the composition and diversity of the bacterial community and the nitrogen cycle functional genes in Cr-stressed agricultural soils changed considerably. However, the influence of the soil physicochemical parameters on the functional genes involved in the nitrogen cycle was greater than that of the bacterial community. and Cr stress affects the N cycling process in soil mainly by affecting nitrification. This research has significant practical ramifications for understanding the mechanisms of microbial community homeostasis maintenance, nitrogen cycle response mechanisms, and soil remediation in heavy metal-contaminated agricultural soils.

Integrated effects of vermicompost, climatic factors and soil mixing on selected soil fertility indicators

A field experiment was carried out to investigate the effects of vermicompost (0, 10, and 15 tha-1), climatic elements i.e. soil moisture (50%, 70%, and 100%) and elevation of soil temperature (1 to 20C) on the physico-chemical properties and nutrient availability of post-harvest calcareous-acid mixed soils after rice production. A total of 18 treatments assembling the afore-mentioned doses was applied. The analyses of the soils demonstrated significant variation in effects (p ≤0.05) of the treatments on both the available nutrient status and the physicochemical properties of soils. Except for available sulfur; soil pH, EC, organic carbon (OC), available nitrogen, phosphorous, potassium, calcium, and sodium were detected in the higher amounts in 1:1 (calcareous : acid-soils) mixed soils than those of 1:3 mixed counterpart both in initial and post-harvest soil conditions. The highest levels of soil pH, OC, available P and Zn were determined in the treatment T13. Whereas, treatment T6 proved to be the best dose for the highest availability of Ca and Mg. The treatments T1, T2, T11, and T16 were recorded to have the lower OC, available N, P, Ca, Mg, Zn and S contents in soils. In particular, the availability of Na was found to be in lesser amounts in all the subplots. In a nutshell, most of the treatments exerted favourable influence in maintaining a healthy level of soil physico-chemical parameters owing to their inherent characteristics. Dhaka Univ. J. Biol. Sci. 32(1): 119-134, 2023 (January)

Vineyard Management and Physicochemical Parameters of Soil Affect Native Trichoderma Populations, Sources of Biocontrol Agents against Phaeoacremonium minimum

Native strains of Trichoderma in vineyard soil represent an opportunity for reducing the incidence of grapevine trunk diseases (GTDs) in vineyards. Moreover, its relationship with the environment (physicochemical soil characteristics and farming management practices) remains unclear. In the current study, a survey was carried out on farming management used by viticulturists, and soil samples were studied to analyze their physicochemical properties and to isolate Trichoderma strains. Later, statistical analyses were performed to identify possible correlations between Trichoderma populations, soil management and soil characteristics. In addition, in vitro tests, including antibiosis and mycoparasitism, were performed to select those Trichoderma strains able to antagonize Phaeoacremonium minimum. In this study a positive correlation was found between the iron content and pH in the soil, and a lower pH increases Trichoderma populations in soils. Vineyard management also affects Trichoderma populations in the soil, negatively in the case of fertilization and tillage and positively in the case of herbicide spraying. Two Trichoderma native strains were selected as potential biocontrol agents (Trichoderma gamsii T065 and Trichoderma harzianum T087) using antibiosis and mycoparasitism as mechanisms of action. These results led to the conclusion that native Trichoderma strains hold great potential as biological control agents and as producers of secondary metabolites.

Rational Assessment of Physico-Chemical Parameters of Agricultural Soil from Selected Places of Banepa, Nepal

Physico-chemical parameters are among the basic attributes for the study of soil as they play a critical role in the assessment of soil health. In the present study, an attempt was made to study the physicochemical parameters in soil samples collected from six places of Banepa (Sinagal, Budole, Janagal, Chandeswori, Nayabasti, and Dhaneswor). The soil characterization was carried out for parameters like moisture content (%), pH, electrical conductivity (EC), chloride (Cl-), sulphate (SO42-), and phosphate (PO43-) ions. Chloride and sulphate were analyzed by argentometric titration and gravimetric method. The molybdenum blue method was employed for analysis of phosphate. In the present study, the pH of different soil samples ranged from 4.02-6.46 indicating a strongly to slightly acidic nature. EC values ranged from 0.05-0.45 mS/cm which showed that all soil samples were non-saline. The concentration of Cl-, SO42- and PO43- were in the range of 10142-16904 ppm, 1440-3907 ppm, and 1.8-3.8 ppm, respectively. Analysis of these parameters helps to determine the nature, fertility status of soil which is important for agricultural chemists for plant growth and soil management. Such studies provide the necessary information required to maintain optimum fertility year after year.

Effects of concentration-dependent graphene on maize seedling development and soil nutrients

The long-term use of chemical fertilizers to maintain agricultural production has had various harmful effects on farmland and has greatly impacted agriculture's sustainable expansion. Graphene, a unique and effective nanomaterial, is used in plant-soil applications to improve plant nutrient uptake, reduce chemical fertilizer pollution by relieving inadequate soil nutrient conditions and enhance soil absorption of nutrient components. We investigated the effects of graphene amendment on nutrient content, maize growth, and soil physicochemical parameters. In each treatment, 5 graphene concentration gradients (0, 25, 50, 100, and 150 g kg−1) were applied in 2 different types (single-layer and few-layers, SL and FL). Soil aggregates, soil accessible nutrients, soil enzyme activity, plant nutrients, plant height, stem diameter, dry weight, and fresh weight were all measured throughout the maize growth to the V3 stage. Compared to the control (0 g kg−1), we found that graphene increased the percentage of large agglomerates (0.25–10 mm) in the soil and significantly increased the geometric mean diameter (GMD) and mean weight diameter (MWD) values of > 0.25 mm water-stable agglomerates as the increase of concentration. Soil available nutrient content (AN, AP, and AK) increased, peaking at 150 g kg−1. Graphene boosted nutrient absorption by maize plants, and aboveground total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents rose with the increasing application, which raised aboveground fresh weight, dry weight, plant height, and stalk thickness. The findings above confirmed our prediction that adding graphene to the soil may improve maize plant biomass by enhancing soil fertility and improving the soil environment. Given the higher manufacturing cost of single-layer graphene and the greater effect of few-layer graphene on soil and maize plants at the same concentration, single-layer graphene and few-layer graphene at a concentration of 50 g kg−1 were the optimal application rates.

Diversity and abundance of bacterial and fungal communities in rhizospheric soil from smallholder banana producing agroecosystems in Kenya

In agroecosystems, microbial communities play a crucial role in delivery of various ecosystem services. These microbial communities are affected by several factors such as soil physicochemical properties which contribute to the diversity of bacterial and fungal communities. In this study, we investigated the soil physicochemical parameters and the diversity and abundance of bacterial and fungal communities in rhizospheric soil collected from banana growing regions in Kisii, Nyamira and Embu Counties of Kenya. Rhizospheric soil samples from the three regions showed significant differences at (P= 0.01) with the lowest recorded pH being 4.43 in Embu County. Based on Next-generation sequencing results, there was a significant diversity and abundance of bacterial division Proteobacteria while the predominant fungal division was basidiomycota, Several genera in the fungal division such as Penicillium and Cladosporium as well as bacterial genera such as Acidobacterium and Pseudomonas sp. were those associated with soil. There were several plant pathogenic and beneficial bacteria and fungi. Based on redundancy analysis (RDA) the distribution of these microbes was affected negatively by soil parameters such as total organic carbon (TOC) and pH. In conclusion, Soil health and continuous mono-cropping systems play a significant role in the diversity and abundance of both beneficial and harmful soil microbes. Metagenomics approaches in studying microbial communities in agroecosystems is a revolutionary approach which will aid in the development of sustainable tools in agriculture that improve microbiome structures as well as overall productivity.

Implication of land use shifting on land degradation and restoration potential of conservation agriculture in India's North-West Himalayan region

The soil organic matter is a crucial factor in determining soil characteristics and productivity; however various land management practices degrade or aggrade the soil health. The objective of this study was to look at the influence of land-use conversion on soil health by using the concept of stratification ratio (SR) of soil organic carbon (SOC) and total nitrogen (TN) and appraise SR as a predictor of SOC and TN stock and soil health for India's North-West Himalayan region. The research is oriented toward assessing the consequences of various land use regimes' impacts on SOC and TN depth distribution, storage, and stratification and, hence, identifying appropriate sustainable tillage techniques for the region. The research was accomplished in 2020–21 in the long-term experimental plot with four land uses, namely control [natural sal forest (Shorea robusta L.), conventional tillage (CT), reduced tillage (RT), and zero tillage (ZT)] in a rainfed system of north-western Indian Himalayas. A decrease of 79% in the mean weighted diameter of CT was observed after conversion from forest land to CT; however, the decrease was only 50% in the case of the adoption of ZT. Further, the surface soil (0–5 cm) SOC was significantly different from each other, with forest soil having the highest SOC (27.5 ± 0.21 g kg−1) and CT having the lowest SOC (11.0 ± 0.09 g kg−1). The stock of SOC and TN increased significantly with increment in soil depth, and among landuses, the highest SOM was observed with forest and the lowest with CT. Among the treatments, forest (56.56 ± 1.90 Mg ha−1) had significantly higher SOC storage than conservation agriculture (CA) (42.84 ± 0.27 Mg ha−1, ZT, and 41.41 ± 1.84 Mg ha−1, RT) and CT (41.33 ± 1.19 Mg ha−1) based on equivalent soil mass approach. For forest land use, except the surface layer (0–5:5–10), all the soil layers had SR >2, whereas, for ZT, the bottom two layers (0–5:20–25 and 0–5:25–30) had SR >2 and for RT, only the bottom layer (0–5:25–30) was having SR > 2. It was observed that the conversion of land use to CT reduced the SR of SOM drastically; however, by adopting CA, the SR had been restored to near normal in forest land use. The carbon pool index (CPI) was used to determine the effects of soil tillage and residue incorporation on soil quality improvement with respect to a sal forest. The CPI value increased significantly with an increase in soil depth for three land uses, and also, at each soil depth, the CPI followed the ZT > RT > CT trend. Thus, CA may be considered a viable alternative to CT for improving soil physicochemical parameters.

Bacterial Community Structure, Diversity, and Fertility of Soil with and without Press Mud in Two Sites in Panay, Philippines

Sugarcane farmers commonly use press mud as organic fertilizer to improve the properties of soil and increase crop production. This study compared the effects of press mud on bacterial community structure, bacterial diversity, and physicochemical parameters of sugar mill soil in two sites, the URC Passi Sugar Central and Passi Sugar Central, Inc. both in Panay, Philippines. DNA and soil analyses were conducted to characterize the soil samples with and without press mud from both sites. The results showed that all nutrient contents increased in both areas after press mud application, except in URC Passi Sugar Central, where no increase in phosphorus and sulfur was observed. Bacterial diversity did not significantly increase six months after press mud application. Community pattern results showed that if soil samples within sites were compared, soil with press mud was significantly higher compared to the soil without press mud in terms of OTU richness (Capiz sugar central: 46.00±1.00, 40.00±1.50, respectively; URC Passi Sugar Central: 48.00±0.50, 45.00±0.00, respectively) and carrying capacity (Capiz sugar central: 169±7.36, 125±9.48, respectively; URC Passi Sugar Central: 181±3.80, 162±0.00, respectively) (p&lt;0.05). The same trend was observed in soil samples between sites that were compared. Soil without press mud from URC Passi Sugar Central had a significantly higher compared with soil without press mud of Capiz Sugar Central in terms of OTU richness (45.00±0.00, 40.00±1.50, respectively) and carrying capacity (162±0.00, 125±9.48, respectively) (p&lt;0.05). However, no significant difference was observed in soil with press mud between the two sites in OTU richness, carrying capacity, Shannon, and Evenness analyses (p&gt;0.05). The phylogenetic tree analysis showed that Massilia sp. is closely related to Burkholderia arboris, and Lysobacter sp. is closely related to both Massilia sp.and B. arboris. Generally, press mud application helps increase the available nutrients, diversity, and community patterns in soil, making it good organic fertilizer.

Variations in bacterial spectrum and physicochemistry of top soils exposed to gas flaring in Ologbo community, Edo state

Nigeria is a major exporter of petroleum and natural gas and a majority of the petroleum exploratory activities takes place in the Niger Delta area, where high rates of gas flaring associated with exploration and production of these products occur. The study investigated changes in bacterial flora and physicochemistry of soils within the Oredo flow station facility. Seven soil samples were collected in triplicates at radial distances of 40m, 80m, 120m, 160m, 200m, 1km from the flare stack and the control sample was collected from a farmland far from the flow-station but within the community. Standard methods were employed in evaluating the physicochemical parameters and bacteriological analysis was conducted using serial dilution and pour plate methods. The results revealed that gas flaring had significant effects on some soil physicochemical parameters. The impact of gas flare was found to lower the moisture content at 4.44 % for soils collected at 40m whilst for the control soil, it was 12.83%. The nitrate and total nitrogen content of the soil varied from 9.96±1.44 to 12.21±0.13mg/kg and 0.01±0.00 to 0.2±0.01%. The total heterotrophic bacteria count varied from 0.4 ± 0.33 to 14.67±3.77 ×106 cfu/g. Identified bacterial species were; Streptococci sp., Corynebacterium sp., Stenotrophomonas sp., Staphylococcus sp., Micrococcus sp., Bacillus sp., Acinetobacter sp., Burkholderia sp. and Bacillus sp. The results revealed that gas flaring had a negative effect on soil bacteria population and physicochemical properties.