Soil Microbial Populations Research Articles

Lower soil nitrous oxide emissions by a high lipid genetically modified perennial ryegrass line compared to its wild type

AbstractWe describe an experiment where cattle urine was applied at a rate of 420 kg N ha−1, equivalent to 10 L m−2, to mesocosm swards of a high lipid genetically modified perennial ryegrass line (HME) and its wild type (WT). We measured N pools and fluxes in the plant and soil, soil microbial populations and N2O production. HME plants produced 21% greater biomass than WT (p = .02), resulting in greater N uptake (27% higher in HME, p = .05). Urine N recovery in total plant biomass during the experiment in HME and WT swards were 54.7% and 33.9% respectively. The nitrification potential of soil was significantly lower (p = .01) in HME than WT. Partial least square‐discriminant analysis using microbial gene abundance data indicated that HME and WT plant growth induced distinct microbial populations in the soil. These differences in plant soil microbial interactions between HME and WT swards resulted in significantly lower N2O emissions from the HME sward. Total N2O emissions over the 4 weeks after urine application was 38% lower (p < .03) in HME swards than in WT swards. The next step in this work is to identify the specific changes in HME traits that drive the reduction in N2O.

Valorisation of hydrothermal liquefaction wastewater in agriculture: effects on tobacco plants and rhizosphere microbiota.

Industrial wastewater obtained from hydrothermal liquefaction (HTL-WW) of food wastes for biofuels production could represent a source of crop nutrients since it is characterized by a high amount of organic and inorganic compounds. In the present work, the potential use of HTL-WW as irrigation water for industrial crops was investigated. The composition of the HTL-WW was rich in nitrogen, phosphorus, and potassium with high level of organic carbon. A pot experiment with Nicotiana tabacum L. plants was conducted using diluted wastewater to reduce the concentration of some chemical elements below the official accepted threshold values. Plants were grown in the greenhouse under controlled conditions for 21 days and irrigated with diluted HTL-WW every 24 hours. Soils and plants were sampled every seven days to evaluate, over time, the effect of wastewater irrigation both on soil microbial populations, through high-throughput sequencing, and plant growth parameters, through the measurement of different biometric indices. Metagenomic results highlighted that, in the HTL-WW treated rhizosphere, the microbial populations shifted via their mechanisms of adaptation to the new environmental conditions, establishing a new balance among bacterial and fungal communities. Identification of microbial taxa occurring in the rhizosphere of tobacco plants during the experiment highlighted that the HTL-WW application improved the growth of Micrococcaceae, Nocardiaceae and Nectriaceae, which included key species for denitrification, organic compounds degradation and plant growth promotion. As a result, irrigation with HTL-WW improved the overall performance of tobacco plants which showed higher leaf greenness and increased number of flowers compared to irrigated control plants. Overall, these results demonstrate the potential feasibility of using of HTL-WW in irrigated agriculture.

Total Mikroba pada Tanah yang Dicemari Sludge Limbah Pabrik Kertas dengan Perlakuan Pupuk Guano

There are 83 paper mills in Indonesia recorded by the Indonesian Pulp and Paper Association (APKI) spread throughout the archipelago. These paper companies produce products in the form of tissues, various types of paper, and other fiber-based products. Efforts to meet the needs of this raw material produce innovations in the form of using waste paper by separating the ink from the fibers contained in the paper, this separation process is known as the deinking process. Paper mill solid waste can be in the form of sludge, pith, and biosludge. Sludge is a factory solid waste originating from the settling of WWTP which consists of 90% solid and 10% liquid. Paper mill waste in the form of solid waste from sludge contains heavy metals such as Cd, Cr, Pb, Ni, Cu, and Zn. These metals can be overcome by bioremediation using guano fertilizer which is an organic material derived from bat droppings which is rich in phosphate. The purpose of this study was to determine the microbial population in soil contaminated with paper mill sludge waste treated with guano fertilizer. The parameters observed in this study were the total number of bacteria and fungi that survive in soil contaminated with paper mill waste as an indication that the land can still be planted with certain plants. This research was conducted at the Laboratory of Soil Biology, Laboratory of Soil and Land Fertility Agrotechnopark – Faculty of Agriculture – University of Jember. This study used a 3x3 two factorial experimental design with the basic pattern of Randomized Block Design (RAK), namely between the concentration of paper mill effluent and the dose of guano fertilizer, each treatment was repeated three times. The microbial population can be determined by analyzing total bacteria, total fungi. Soil that had been contaminated with paper mill waste was incubated with guano fertilizer, each combination was analyzed at 15 hst and 30 hst for total bacterial and total fungal populations. During the incubation period, irrigation was carried out using a sprayer to maintain moisture in the incubation media. The results showed that the total population of bacteria and fungi in the growing media contaminated with paper mill sludge waste by administering different doses of guano showed results that were not significantly different, but the total population tended to increase. with increasing incubation period. Pollution of sludge waste in the planting medium has a significant effect on increasing the total Fungi Population when compared to the control. The relationship between paper mill effluent pollution and guano fertilization is very low with a coefficient of determination of less than 0.5.

Enhanced pearl millet yield stability, water use efficiency and soil microbial activity using superabsorbent polymers and crop residue recycling across diverse ecologies

Under changing climate scenarios, developing sustainable adaptation strategies in agriculture will be obligatory. To understand the effect of carbohydrate-based superabsorbent polymer (SAP) and crop-residue mulch (CRM) on pearl millet productivity and water-use efficiency (WUE), field experiments were undertaken for three consecutive years at 11 different locations (representing ⁓30 % of the global pearl millet growing area). Eight treatments, namely, Control; CRM 5.0 t/ha; SAP 2.5 kg/ha; SAP 5.0 kg/ha; SAP 7.5 kg/ha; SAP 2.5 kg/ha + CRM 5.0 t/ha; SAP 5.0 kg/ha + CRM 5.0 t/ha and SAP 7.5 kg/ha + CRM 5.0 t/ha were evaluated. Co-application of CRM and SAP increased pearl millet grain and stover yield by up to ⁓45 % and ⁓36 %, respectively. Pearl millet responded significantly up to 2.5 kg/ha SAP application (with or without CRM) only. Further, soil microbial biomass carbon improved significantly with CRM (20 %) and SAP (10.9–12.1 %) individually and with simultaneous application of CRM and SAP (⁓30 %). Likewise, dehydrogenase, alkaline phosphatase, acid phosphatase, and urease activities also improved significantly due to the co-use of CRM and SAP. Positive effects of CRM, SAP, and their co-application were also witnessed on soil microbial (bacterial, fungal, actinobacteria) populations and water-use efficiency (WUE) across environments. Among the locations, New Delhi and Aurangabad were the most desirable and stable ecologies, whereas Bikaner and Vijayapur remained the least consistent. Hence, to tackle the moisture-stress problem under pearl millet production systems and to achieve stable productivity, greater WUE and better soil microbial activity, CRM 5 t/ha in conjunction with SAP 2.5 kg/ha may be recommended across diverse ecologies.

Role of potash fertilization through organic and inorganic sources on growth and yield of turmeric

Aim: To investigate the possibility of substitution of inorganic inputs through organics and to evaluate the effects of bioorganic inputs on microbial population of soil. Methodology: A field experiment of RBD with 13 treatments and 3 replication using combination of organic manures viz., compost/vermicompost, potassic mobilising inoculants along with graded (100, 75 and 50%) levels of inorganic potassium were tried for partial substitution of inorganic potassium with organic source in turmeric cv. Suguna. Results: Considering the yield, the vermicompost + inorganic K (100%) + K mobiliser (32.35 t ha-1) was the best treatment, followed by Compost + K 100% + KM (31.13 t ha-1). Interpretation: These results indicate that soils were less fertile due to deficit in soil nutrients. Recommended doses of organic bio-fertilizer and inorganic fertilizer should be practiced for reclamation of soil status. Application of potassic mobilizer as biofertilizer in turmeric can reduce the application of inorganic potassium and support eco-friendly crop production. Key words: Compost, Curcuma longa, Organic manures, Potassic mobilizer, Turmeric, Vermicompost

Response of Weed Management Practices on Yield Loss, Soil Enzyme Activity and Microbial Populations in Maize (Zea mays L.)

Background: Maize popularly known as “Queen of cereals”. Weeds resulted in the highest crop loss (33%), followed by pathogens (26%), insects (20%), storage pests (7%), rodents (6%) and others (8%) in India. Application of herbicides will affect various soil microbial processes and enzymatic activities in the soil, whose activity is very important for maintaining the soil fertility. Methods: The present field experiment was conducted during Rabi, 2017-18 and 2018-19 under irrigated conditions at wetland farm of S.V. Agricultural College, Tirupati Andhra Pradesh, with ten treatments and three replications in a randomized block design. Result: Higher kernel and stover yield of maize was recorded with hand weeding twice at 15 and 30 DAS and the yield loss was comparatively lower with atrazine 1.0 kg ha-1as PE fb topramezone 30 g ha-1or tembotrione 120 g ha-1 as PoE or atrazine 1.0 kg ha-1as PE fb HW at 30 DAS, while these were lowest with weedy check. Soil microbial count and enzyme activity was statistically comparable in all the pre followed by post emergence herbicide treatments.

Evaluation of integrated crop management, organic management and natural farming in basmati rice-wheat system under Upper Indo-Gangetic Plains

Field experimentation was conducted to evaluate the comparative performance of integrated crop management, organic management and natural farming on crop growth, productivity, profitability and soil health under basmati rice-wheat system in Upper Indo-Gangetic Plains. Treatments comprised of different management practices viz. integrated crop management (ICM), organic management, natural farming (NF) and control (no nutrient) were used in experimentation. Plant height, number of effective tillers, SPAD meter reading, panicle weight, filled grains/panicle, fertility percentage and 1000-grains weight of basmati rice and wheat were observed highest under ICM followed by organic management. A significant reduction in growth and yield attributes was recorded under NF as compared to ICM and organic management. Grain yield of basmati rice was reduced by 15.2%, 51.2% and 53.9% under organic management, NF and control as compared to ICM, respectively. Similarly, 49.5%, 58.6%, and 63.8% reduction in grain yield of wheat was recorded under organic management, NF and control as compared to ICM, respectively. In comparison to ICM, system rice equivalent yield (REY) was reduced by 32.6%, 55.0%, and 59.0% under organic management, NF and control, respectively. Further, net return was 44.1% and 67.2% lower under organic management and NF as compared to ICM, respectively. Highest soil organic carbon (0.60%), available N, P, and K were found in organic management. Significantly highest soil microbial population, glomalin content and different soil enzyme activities were recorded under organic management. Overall, the integrated crop management provided balanced and continuous supply of the nutrient that resulted in higher productivity and profitability of basmati rice-wheat system.

Nonlinear Effects Induced by Interactions among Functional Groups of Bacteria and Fungi Regulate the Priming Effect in Malagasy Soils.

The priming effect (PE) occurs when fresh organic matter (FOM) supplied to soil alters the rate of decomposition of older soil organic matter (SOM). The PE can be generated by different mechanisms driven by interactions between microorganisms with different live strategies and decomposition abilities. Among those, stoichiometric decomposition results from FOM decomposition, which induces the decomposition of SOM by the release of exoenzymes by FOM-decomposers. Nutrient mining results from the co-metabolism of energy-rich FOM with nutrient-rich SOM by SOM-decomposers. While existing statistical approaches enable measurement of the effect of community composition (linear effect) on the PE, the effect of interactions among co-occurring populations (non-linear effect) is more difficult to grasp. We compare a non-linear, clustering approach with a strictly linear approach to separately and comprehensively capture all linear and non-linear effects induced by soil microbial populations on the PE and to identify the species involved. We used an already published data set, acquired from two climatic transects of Madagascar Highlands, in which the high-throughput sequencing of soil samples was applied parallel to the analysis of the potential capacity of microbial communities to generate PE following a 13C-labeled wheat straw input. The linear and clustering approaches highlight two different aspects of the effects of microbial biodiversity on SOM decomposition. The comparison of the results enabled identification of bacterial and fungal families, and combinations of families, inducing either a linear, a non-linear, or no effect on PE after incubation. Bacterial families mainly favoured a PE proportional to their relative abundances in soil (linear effect). Inversely, fungal families induced strong non-linear effects resulting from interactions among them and with bacteria. Our findings suggest that bacteria support stoichiometric decomposition in the first days of incubation, while fungi support mainly the nutrient mining of soil's organic matter several weeks after the beginning of incubation. Used together, the clustering and linear approaches therefore enable the estimation of the relative importance of linear effects related to microbial relative abundances, and non-linear effects related to interactions among microbial populations on soil properties. Both approaches also enable the identification of key microbial families that mainly regulate soil properties.

Autotoxins in continuous tobacco cropping soils and their management.

Tobacco belongs to the family Solanaceae, which easily forms continuous cropping obstacles. Continuous cropping exacerbates the accumulation of autotoxins in tobacco rhizospheric soil, affects the normal metabolism and growth of plants, changes soil microecology, and severely reduces the yield and quality of tobacco. In this study, the types and composition of tobacco autotoxins under continuous cropping systems are summarized, and a model is proposed, suggesting that autotoxins can cause toxicity to tobacco plants at the cell level, plant-growth level, and physiological process level, negatively affecting soil microbial life activities, population number, and community structure and disrupting soil microecology. A combined strategy for managing tobacco autotoxicity is proposed based on the breeding of superior varieties, and this approach can be combined with adjustments to cropping systems, the induction of plant immunity, and the optimization of cultivation and biological control measures. Additionally, future research directions are suggested and challenges associated with autotoxicity are provided. This study aims to serve as a reference and provide inspirations needed to develop green and sustainable strategies and alleviate the continuous cropping obstacles of tobacco. It also acts as a reference for resolving continuous cropping challenges in other crops.

Resistance and resilience of soil biological indicators: A case study with multi-walled carbon nanotube

Soil ecosystem is experiencing stresses due to climate change, and soil inhabitants try to demonstrate their inherent resistance and resilience against those stresses. Application of nanomaterials as agricultural inputs could bring shifts in resistance and resilience patterns of soil microbes and associated enzymes, especially under short-term heat stress. With this background, the impacts of multi-walled carbon nanotube (MWCNT) on the resistance and resilience of soil biological indicators were evaluated. An incubation experiment was conducted with varied MWCNT concentrations (0, 50, 100, 250, and 500 mg kg-1 soil) for 90 d after 24-h heat stress at 48 ± 2 °C to assess the impacts of MWCNT on soil enzyme activities and microbial populations vis-à-vis their resistance and resilience indices under short-term exposure to heat stress. Enzyme activities were reduced after exposure to heat stress. Resistance indices of enzyme activities were enhanced by MWCNT application on day 1 after heat stress, whereas there was no recovery of enzyme activities after 90-d incubation. Like soil enzyme activities, resistance index values of soil microbial populations followed the similar trend and were improved by MWCNT application. Multi-walled carbon nanotube has the potential to improve resistance indices of soil enzyme activities and microbial populations under heat stress, although they could not recover to their original state during periodical incubation after heat stress. This study helps to understand the relative changes of biological indicators under MWCNT and their ability to withstand heat stress.

Effect of Integrated Weed Management Practices on Microbial Population in Soil, Yield and Economics in Wet Direct Seeded Rice

An experiment had been conducted at the Agronomy Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, (C.G.) in the kharif season of 2019, to determine the effects of integrated weed management practices on microbial population in soil, yield and economics in wet direct seeded rice. Pre-emergence herbicides (Oxadiargyl and Pretilachlor) were followed by post-emergence herbicide (Bispyribac-Na), mechanical and manual weeding. Plots treated with oxadiargyl performed better than pretilachlor. When Oxadiargyl was integrated with Hand Weeding (HW) at 35 days after sowing (DAS) gave results which were better than twice HW plot (T10). Oxadiargyl @ 70g/ha at 7-11 DAS fb HW at 30-35 DAS (T4) proved to be superior over all the treatments when yield and economics of wet direct seeded rice was concerned and was statistically at par with twice HW plot (T10) and oxadiargyl @ 70 g/ha at 7-11 DAS fb bispyribac-Na @ 25 g/ha at 30-35 DAS (T2). The unsprayed and two-hand weeding treatments had much lower levels of fungi, actinobacteria, and bacteria than the other weed control methods. The herbicidal treatments had much higher microbial populations at all stages of observation.

Shifting the paradigm for phosphorus fertilization in the advent of the fertilizer crisis

AbstractCrop production and food security will be challenged by the availability of phosphate rock and its derived phosphorus (P) fertilizers in the coming decades. Croplands around the world have traditionally received huge amounts of P fertilizers. However, P can quickly become unavailable in soil due to its fast adsorption or fixation on the surface of soil particles. Here, we propose the use of microbially mediated mechanisms of soil‐borne populations to solubilize historically accumulated P over years. We argue that microbially mediated solubilization of P can be enhanced through elemental imbalances that intentionally alter the soil carbon:nitrogen:P ratio, enabling a greater P demand by some soil microbial populations. This strategy may potentially reduce our dependence on conventional and exhausting P fertilizers, but the main caveats are also discussed.

Effect of Corm and Soil Treatments with Organic Liquid Formulations on Performance of Elephant Foot Yam in Jharkhand, India

A field experiment was carried out at the farm of Divyayan Krishi Vigyan Kendra, Ramakrishna Mission Ashrama, Morabadi, Ranchi during kharif season of 2022 with 10 treatments (T1: control or no treatment, T2: Corm treatment with Beej Sanjeevani, T3: Corm treatment with Beejamrit, T4: Soil application of Jiwamrit, T5: Soil application of Panchagavya, T6: Soil application of Jiwamrit + Panchagavya, T7: Corm treatment with Beej Sanjeevani + soil application of Jiwamrit, T8: Corm treatment with Beej Sanjeevani + soil application of Panchagavya, T9: Corm treatment with Beejamrit + soil application of Jiwamrit, T10: Corm treatment with Beejamrit + soil application of Panchagavya) placed in three times replicated randomized block design to study the growth, yield and production economics of elephant foot yam under uses of organic corm and soil treatments. Results revealed that corm treatment with Beejamrit + soil application of Jiwamrit resulted in higher growth attributes, corm length (23.3 cm), dimeter (26.9 cm) and yield (32.8 t/ha). This corm + soil treatment also recorded the highest gross return (INR.2,62,400/ha), net return (INR.1,69,189/ha) and B:C (2.82). It also increased soil microbial population dynamics especially total bacteria (69.7 CFU × 106/g of soil).

Changes in Soil Enzyme Activity and Microbial Population with Incorporation of Crop Residue along with Microbial Consortium in Black Cotton Soils

Changes in Soil Enzyme Activity and Microbial Population with Incorporation of Crop Residue along with Microbial Consortium in Black Cotton Soils

An Investigation of the Impact of Compost Tea Applications on Turf Quality and Soil Microbial Activity

AbstractThis study investigated the effect of compost tea applications on turf quality and soil microbial activity. Evaluations of turfgrass quality were based on The National Turfgrass Evaluation Program's guidelines while soil samples were analyzed for chemical attributes and microbial activity. Four sites and treatments for the study included: 1) a soil drench compost tea application with irrigation, 2) a soil drench compost tea application with no irrigation, 3) no compost tea application with irrigation, and 4) no compost tea application nor irrigation. Fifteen soil samples and turf quality observations from each treatment were collected for pretest data. Then, post-test data were collected after each additional seasonal test period over the course of one year for each of the four plots. For the four plots, the site which received compost tea applications and regular irrigation received significantly higher turf quality ratings, and compost tea improved turf quality ratings beyond that of regular irrigation. No differences were found in microbial populations given the compost tea application. While the study results provided evidence of the value of compost tea to overall turf quality aesthetics, more research is recommended regarding compost tea applications and beneficial soil microbial populations in turf.Species used in this study: Bermudagrass (Cynodon dactylon) L. Pers.

Effect of Water-Soluble Fertilizers and PGPR on Soil Microbial Population, Nodule Count and Economics of Black Gram

Effect of Water-Soluble Fertilizers and PGPR on Soil Microbial Population, Nodule Count and Economics of Black Gram

Comparing the Effect of Organic and Inorganic Amendments on Soil Health

Background: Fertilizers are important source of nutrients required by plants at different growth stages. These fertilizers can be organic and inorganic. Organic and inorganic fertilizers are different from each other in their action and contain different types of nutrients. Each fertilizer has its own effect on soil and plants. Excessive use of chemical fertilizers reducees the soil fertility by affecting the soil physical, chemical and biological properties, so it is essential to balance the negative effect of inorganic fertilizers with the use of organic fertilizers. Organic fertilizers contain nutrients required for optimum plant growth. With the increase in soil organic matter, the percentage of nitrogen and phosphorus in soil also increases. Methods: A pot culture experiment was conducted to study the effect of organic and inorganic fertilizers on soil properties. Experiment consisted of six treatments, comprising of organic and inorganic treatments and absolute control. Inorganic treatment received recommended dose of fertilizer (RDF). Organic treatments received different dose of organic manures like vermicompost and farm yard manure. Result: Application of organic manure viz vermicompost remarkably improved in soil fertility. Soil pH was not significantly influenced by organic and inorganic treatments. However, relatively higher EC was recorded with the application of 100 per cent RDF. Application of organic manure viz vermicompost resulted in the buildup of soil organic carbon and markedly enhanced the nutrient availability of nitrogen, phosphrous and potassium in soil. Soil microbial population viz., bacteria, fungi and actinomycetes were increased due to the application of organic manure through vermicompost.

Efficacy of Herbicides on Nutrient Uptake of Crop, Weed and Its Impact on Soil Microflora of Irrigated Maize (Zea mays L.)

Aim: Field experiment was conducted to study the suitable weed management methods to check the nutrient depletion by weeds, check the dynamics of microbial population and in relation to improve the biomass stover yield of maize (Zea mays L.).
 Study Design: This experiment laid out in a randomized block design and 8 different weed management treatments with three replications.
 Place and Duration of Study: Field experiment was conducted at Agricultural College and Research Institute, Madurai, Tamil Nadu Agricultural University, Tamil Nadu in kharif 2019.
 Methodology: TNAU maize hybrid CO-6 was used for this experiment. Treatments were application of pre-emergence herbicide atrazine at 0.25 kg/ha or pendimethalin 1 kg/ha applied singly on 3 days after sowing and in combination with post-emergence herbicide tembotrione 120 g/ha or halosulfuron methyl 90 g/ha on 25 DAS, weed free check, unweeded check in maize crop. Weed nutrient depletion and microbial population was analysed in laboratory.
 Results: The application of pre-emergence atrazine 0.25 kg/ha followed by post-emergence tembotrione 120 g/ha effective in controlling of grasses and BLW and enhance the nutrient uptake of maize. The stover maize yield increased with application of herbicides and sequential application of herbicides achieved 88% improved stover yield over unweeded check. Sequential application of herbicides initially reduce the population of soil microflora but the population gradually build up in all the herbicide applied plots at 60 days after application.
 Conclusion: Based on the results of the experiment, it was concluded that pre-emergence atrazine 0.25 kg/ha followed by post emergence tembotrione 120 g/ha effective in controlling of weeds and enhance the nutrient uptake and stover yield of maize without much adverse impact on soil microbial population.

Preliminary assessment of arbuscular mycorhizal inoculation in teak and napier grass agroforestry practice treated with soil amendments

Soil amendments are known to improve soil structure, increase moisture content, improve fertility and facilitate soil microbial functions. The objective of this study was to determine the effects of gypsum on colonization of arbuscular mycorrhizas in teak plantations planted as fences for napier grass. Teak seedlings were planted in October 2019 and divided into 4 blocks, A, B, C and D comprising 32 seedlings. Plots of A and C were treated with treatments of 3 kg of gypsum and 3 kg of compost (1:1), whereas B and D were control plots. NPK fertilizer was applied at every seedling at the rate of 0.05 kg for all blocks. Seedling heights and mean basal diameter (mm) were assessed at 9 months after planting. Soil samples for microbial study were taken before and after planting at 30 cm depth and screened for mycorrhizal spores and roots at the end of the experiment. Increased values for seedling heights and mean basal diameter (20-35%) were recorded for treatments B and C. Results pointed out that the amount of spore percentages were somewhat reduced in C and D and a slight increase was seen in treatments A and B. Root inoculation percentages in A and C were somewhat higher (1- 6%) as compared to B and D (0.5%). Early findings point out that application of gypsum and composts were not detrimental to the microbial population of arbuscular mycorrhiza as these treatments showed higher presence of hyphae and vesicles in fine roots and did not hamper physical growth. The role of soil amendments needs to be further investigated in terms of enhancing soil microbial population.

Effects of spent hydrocarbon on bacteria population

This study aimed at the effect of spent hydrocarbon contamination on microbial population in soil. Standard microbiological methods were used to determine the total heterotrophic count hydrocarbon utilization, isolation and identification of bacterial and effect of pH and spent hydrocarbon concentration on bacterial. The total heterotrophic bacterial count (THB) ranges from 6.2 ± 0.13 x106 to 3.2± 0.10 x106 cfu/g. The total hydrocarbon utilizing bacterial count ranges from 3.2 ± 0.13 x106 to 1.2± 0.10 x106 cfu/g. The bacterial isolated were Bacillus subtilis, Pseudomonas flourescens, Klebsiella aerogenes and Proteus hauseri. It was observed that Bacillus subtiliis had the highest occurrence from location E (50.0%). Pseudomonas flourescens from location A and B (33.3%) and Proteus hauseri had the highest occurrence from location C (66.6%). The effect of pH on bacterial growth rate analyzed showed that Bacillus subtilis had the highest turbidity at pH 6.5 (0.511 ± 0.15 nmm), Klebsiella aerogenes had the highest turbidity at pH 7.5 (0.233 ± 0.33nm), Pseudomonas flourescens was at pH 6.5 (0.723 ± 0.61 nm) and Proteus sp recorded highest turbidity at pH 6.5 (0.373 ± 0.22nm) followed by pH 5.5 (0.237 ± 0.19 nm). The effect of spent hydrocarbon concentration showed that Bacillus subtilis recorded highest turbidity at 10% concentration (0.744 ± 0.03 nm), Klebsiella aerogenes recorded highest at 10% concentration (0.321 ± 0.21 nm), Pseudomonas flourescens was at 10% concentration (0.887 ± 0.23 nm) and Proteus sp recorded highest turbidity at 10% concentration (0.378 ± 0.13 nm). From this study it was observed that indigenous bacterial had the ability to utilized the spent hydrocarbon if the pH of the soil is regulated.