Restoring Soil Health Research Articles

Combining insitu rainwater harvesting and integrated nutrient management of organic manure improves soil moisture, fertility and crop yields in marginalized areas: A review

Soil moisture stress and infertility are major biophysical constraints which limit crop production and food security in marginalized areas. Marginal areas are mainly associated with low rainfall which is insufficient to support crops until maturity is reached. The use of insitu rainwater harvesting methods such as planting pits, tied ridges, mulching, Zai pits and half-moon can be a solution to reduce moisture stress. This alone cannot improve crop yields hence the need to use integrated nutrient management (INM) of animal manure, biofertilisers, mineral fertiliser and composts to improve soil fertility, structure and increase water retention ability. Combining rainwater harvesting with INM has the potential to mitigate effects of climate change, improve crop yields and meet food demand in marginal areas. Various nutrient sources used as INM can restore soil health, increase microbial population, nutrient mineralisation and improve soil quality. Use of biofertilisers in agriculture reduces soil toxicity, improve nutrient availability and create a conducive environment for crop growth and development. Integration of tied ridges with cattle manure and mineral fertiliser has the potential of increasing infiltration rates, reducing surface runoff and increase crop yields with 50-150% regardless of soil type. This chapter sought to come up review the effects of rainwater harvesting methods and INM on soil fertility, moisture stress and crop yields in marginalized areas.

Comprehensive Analysis of Agricultural Practices in Adapting Soil, Water and Pest Management to Climate Change in Sub-Saharan Africa

Agriculture constitutes the primary economic sector in Sub-Saharan African (SSA) countries, engaging over 70% of the population, predominantly vulnerable rural communities. For decades, agriculture in SSA has grappled with climatic constraints, intensifying the vulnerability of impoverished communities. In response, communities have developed indigenous practices to adapt to these climatic hazards, warranting greater recognition for potential optimization. This review identifies agricultural practices related to climate change adaptation, specifically focusing on soil management, water, and pests. The operational mechanisms of the most widely utilized practices were scrutinized through a thorough analysis. The study concludes by identifying nine practice categories. Results indicate that water collection practices and the use of organic fertilizers are the most prevalent in soil and water management. Additionally, agricultural and biological control practices dominate pest management. The comprehensive analysis underscores that the most frequently cited practices may not always be the easiest to implement. Nevertheless, these practices are agro-ecologically sustainable, contributing to soil health restoration, efficient water management, and pest control in Sub-Saharan African countries. The findings suggest a need for a research program that concentrates on the simultaneous application of these practices, enabling their optimization for more sustainable agriculture, particularly in the context of climate change adaptation and soil fertility restoration in Sub-Saharan Africa.

Soils and ecosystem services: policy narratives and instruments for soil health in the EU

European soils and their status is a matter of concern that has entered the policy arena and the objective to restore soil health is part of the Soil strategy to 2030. Aim of this study is to explore the integration of the concept of soil health and the provision of soil ecosystem service by conducting i) a content analysis of EU policies and ii) a scoping review of literature over policy instruments for soil governance. Results show a focus on soil fertility, mainly soil organic matter, while services such as conservation of biodiversity or cultural heritage still appear underrepresented. Findings are reinforced by the gap in literature, providing little evidence of policy instruments contributing to soil health. A more coordinated effort among policy sectors is required to prioritize soil health in the EU; invesitgating the role of market-based instruments could complement what public policies are lacking.

Increased Growth of RED Jabon (Anthocephalus macrophyllus) Seedlings using Various Doses of Compost Fertiliser on Used Gold Mine Planting Media

Mining operations disrupt the equilibrium of terrestrial ecosystems, leading to a decline in soil fertility and overall environmental quality. The adverse effects of such activities can severely impact forest ecosystems, resulting in disturbances to physical, chemical, and biological conditions. Consequently, initiatives aimed at restoring soil health to its pre-mining state are essential, often involving revegetation efforts. The cultivation of red jabon trees in nutrient-deficient and less fertile soils necessitates the incorporation of organic matter to enhance soil quality, typically achieved through the application of compost. This study aimed to evaluate the effects and optimal ratios of compost mixed with ex-gold mining soil on the growth of red jabon seedlings. The experimental design included four treatment groups and five replications, yielding a total of 20 experimental units. The treatments for compost application were as follows: D1 = control (no compost), D2 = 10% compost + 90% ex-gold mining soil, D3 = 30% compost + 70% ex-gold mining soil, and D4 = 50% compost + 50% ex-gold mining soil. The parameters observed included survival rate, height growth, diameter growth, dry weight of the plants, and root-to-crown ratio. The findings indicated that the application of compost significantly influenced the growth of red jabon seedlings. Notably, treatment D4 (50% compost + 50% ex-gold mining soil) yielded the most favorable results, achieving a survival rate of 100%, a height increase of 16.56 cm, a diameter increase of 2.21 mm, a dry weight of 40.73 g, and a root-to-crown ratio of 4.84.

Effect of long-term tillage practices on soil nitrogen, phosphorus and sulfur release under different nitrogen management options

The conservation agriculture (CA), presents a promising alternative for restoring soil health and achieving sustainable crop production. In addition, one cannot follow the same nitrogen management of conventional framing in the CA as the crop residue retained leads to N mineralization/immobilization. Hence, the present research was aimed to determine the effect of CA and nitrogen managements on soil nitrogen, phosphorus and sulfur release and the enzymes involved in their mineralization. The results revealed that the CA practice significantly enhanced the mineral N, Olsen P and CaCl2–S release and the soil enzymes involved in this mineralization cycles compared to CT + R plots. Similarly, all the nitrogen fertilizer receiving subplots also recorded significantly higher mineral N, Olsen P and CaCl2–S release and the enzymes involved compared to the control. Furthermore, throughout the incubation period the Urea super granule + Greenseeker treatment significantly outperformed the RDN plot with respect to NO3–N and CaCl2–S release. Whereas, the Urea + Greenseeker treatment registered significantly higher NO3–N and CaCl2–S over RDN plot from 30 and 45 days after incubation, respectively. The NH4–N and Olsen P release had increasing trend up to 45 days after incubation and thereafter it decreased. In nutshell, the research emphasizes the significance of CA alongside optimum nitrogen management approaches in enhancing the soil enzymatic activities and nutrient mineralization. These outcomes hold significance for both farmers and researchers seeking ecologically sound and productive agricultural methods to enhance crop output and maintain soil quality.

Endophytic bacterium Sphingomonas panaciterrae NB5 influences soil properties and improves growth, nutrient contents, and yield of red amaranth (Amaranthus tricolor L.)

Plant growth promoting rhizobacteria (PGPR) are crucial for enhancing plant growth and restoring soil health. Despite the excellent plant growth promoting traits, information is limited on the efficacy of Sphingomonas as a PGPR, especially in vegetable crops. In this study, we used Sphingomonas panaciterrae NB5 as a biofertilizer in leafy vegetable red amaranth in three methods: seed priming (SP), root drenching + foliar (RD + FA), and bacterial culture filtrate (BCF) foliar application. Bio-inoculation of NB5 significantly increased the plant height, number of leaves, leaf area, stem girth, total chlorophyll, vitamin C, and antioxidant contents of red amaranth in all methods of application. Bacterial treatment resulted in notable alterations to the root structure, consisting of the formation of secondary, tertiary, and fibrous roots, particularly in the BCF foliar application and RD + FA treatment.The fresh and dry biomass significantly increased both in root and shoot, resulting in improved yield. The nutritional profile revealed that bacterial application significantly increased the nitrogen, potassium, magnesium, iron, and zinc content, with a slight increase in phosphorus content, in shoots and roots in all the methods of bacterial application compared to control. In post-harvest soil, NB5 boosted total nitrogen, available phosphorus, calcium, and sulfur, as well as soil organic carbon (SOC) and total bacterial populations, regardless of the application methods. The RD+FA treatment outperformed the other methods of application in most of the plant and soil parameters, and the next was the BCF foliar application. Multivariate analysis also confirmed the better performance of RD+ FA and BCF foliar applications. Therefore, simultaneous application of NB5 through root drenching and foliar application could be recommended to the farmers for increasing the yield of red amaranth with improved nutrients and restoring soil health and productivity.

Field study on the integration of a hydrogen-producing microbiome in restoring Phellinus noxius-affected rhizosphere

At National Kaohsiung University of Science and Technology (NKUST), a mesophilic anaerobic bioreactor system produces a hydrogen-producing microbiome (HMb) containing beneficial bacteria such as Bacillus sp. This HMb, known for degrading cellulose and remediating soil, is being tested in Kaohsiung City, Taiwan, to treat tree root rot caused by Phellinus noxius (P. noxius). The study aims to evaluate HMb's effectiveness in restoring the rhizosphere, enhancing soil health, and increasing tree resistance by assessing soil bioactivity and microbial diversity.Field experiments showed that HMb treatment improved tree health by 24 % at the highest health level but reduced it by 20 % at the next level. Post-treatment soil organic matter (SOM) and total Kjeldahl nitrogen (TKN) levels remained stable, indicating minimal impact on soil fertility. HMb also lowered soil pH in some plots, potentially suppressing pathogens and enhancing nutrient absorption. The study found that HMb increased microbial diversity in the rhizosphere, particularly Acidobacteria and Proteobacteria, which inhibited fungal growth. However, HMb had no significant impact on P. noxius populations. Overall, HMb treatment shows promise in enhancing plant health by improving microbial diversity and soil conditions, but further research is needed to understand its full impact on pathogen suppression and soil health restoration.

Enhanced Phytoremediation of Heavy Metals By Soil-applied Organic And Inorganic Amendments: Heavy Metal Phytoavailability, Accumulation, And Metal Recovery

ABSTRACT Phytoremediation, an eco-friendly and cost-effective technique for remediating heavy metal-contaminated soils, can be significantly enhanced through the application of soil amendments. This study investigates the impact of Foliar spraying of both organic (fulvic acid, auxin, Compost, and coconut coir) and inorganic (sulfur) amendments on the phytoavailability, accumulation, and recovery of heavy metals: Arsenic-As, Mercury-Hg, Cadmium-Cd and Lead-Pb in contaminated soils. Field experiment was conducted using hyperaccumulator plant species; T. capensis and H. psittacorum with varying amendment treatments to assess their effectiveness in improving phytoremediation outcomes. The results demonstrate that specific amendments significantly increase heavy metal uptake and translocation within plants by altering soil pH, cation exchange capacity, and microbial activity, thus enhancing metal solubility and bioavailability. Furthermore, the study evaluates the potential of these amendments to not only facilitate metal recovery but also to restore soil health and fertility. The findings underscore the potential of tailored amendment strategies in optimizing phytoremediation processes, offering a sustainable solution for heavy metal remediation in polluted environments.

There is a need to better take into account forest soils in the planned soil monitoring law of the European Union

Key messageA Soil Monitoring Law to improve soil health across all land uses has been proposed by the European Commission. As forests soils have different chemical and physical properties as well as biogeochemical dynamics compared to agricultural land, they also face different challenges in maintaining and restoring soil health. Examples are soil acidification, eutrophication by atmospheric deposition, responses to climate change, and loss of biodiversity. Therefore, we propose forest soil specific health descriptors and thresholds based on experience and knowledge from existing long-term monitoring programs.

A practical guide to the discovery of biomolecules with biostimulant activity.

The growing demand for sustainable solutions in agriculture, which are critical for crop productivity and food quality in the face of climate change and the need to reduce agrochemical usage, has brought biostimulants into the spotlight as valuable tools for regenerative agriculture. With their diverse biological activities, biostimulants can contribute to crop growth, nutrient use efficiency, and abiotic stress resilience, as well as to the restoration of soil health. Biomolecules include humic substances, protein lysates, phenolics, and carbohydrates have undergone thorough investigation because of their demonstrated biostimulant activities. Here, we review the process of the discovery and development of extract-based biostimulants, and propose a practical step-by-step pipeline that starts with initial identification of biomolecules, followed by extraction and isolation, determination of bioactivity, identification of active compound(s), elucidation of mechanisms, formulation, and assessment of effectiveness. The different steps generate a roadmap that aims to expedite the transfer of interdisciplinary knowledge from laboratory-scale studies to pilot-scale production in practical scenarios that are aligned with the prevailing regulatory frameworks.

Biomass Source of Biochar and Genetic Background of Tomato Influence Plant Growth and Development and Fruit Quality

Maintaining healthy soils and restoring marginal lands are necessary to ensure efficient food production and food security. Biochar, a porous carbon-rich material generated from the pyrolysis of organic feedstock, is receiving attention as a soil amendment that can potentially restore soil health and enhance crop yields. However, the physical and chemical properties of biochar are influenced by pyrolysis parameters and organic feedstock sources. These determine its interaction with the soil, influencing its impact on soil health and plant productivity. While most studies report the evaluation of one biochar and a single plant cultivar, the role of genetic background in responding to biochar as a soil amendment remains unexplored. The impact of six biochars on agronomic performance and fruit quality of three tomato (Solanum lycopersicum) cultivars was evaluated to test the hypotheses that (1) biochars derived from different feedstock sources would produce unique phenotypes in a single cultivar of tomato, and (2) single feedstock-derived biochar would produce different phenotypes in each of the three tomato cultivars. The data supported both hypotheses. This study demonstrated that plant genetic background and biomass source are important variables that must be considered for using biochar as a soil amendment.

Phytomicrobiomes: A Potential Approach for Sustainable Pesticide Biodegradation

Globally, pest-induced crop losses ranging from 20% to 40% have spurred the extensive use of pesticides, presenting a double-edged sword that threatens not only human health but also our environment. Amidst various remediation techniques, bioremediation stands out as a compelling and eco-friendly solution. Recently, the phytomicrobiome has garnered increasing attention as endophytic microbes, colonizing plants from their roots, not only foster plant growth but also enhance the host plant’s resilience to adverse conditions. Given the persistent demand for high crop yields, agricultural soils often bear the burden of pesticide applications. Biodegradation, the transformation of complex pesticide compounds into simpler forms through the activation of microbial processes and plant-based enzymatic systems, emerges as a pivotal strategy for restoring soil health. Manipulating the phytomicrobiome may emerge as a viable solution for this purpose, offering a native metabolic pathway that catalyzes pollutant degradation through enzymatic reactions. This review delves into the pivotal role of phytomicrobiomes in the degradation of diverse pesticides in soil. It explores contemporary innovations and paves the way for discussions on future research directions in this promising field.

Three-dimensional space and time mapping reveals soil organic matter decreases across anthropogenic landscapes in the Netherlands

For restoring soil health and mitigating climate change, information of soil organic matter is needed across space, depth and time. Here we developed a statistical modelling platform in three-dimensional space and time as a new paradigm for soil organic matter monitoring. Based on 869 094 soil organic matter observations from 339,231 point locations and the novel use of environmental covariates variable in three-dimensional space and time, we predicted soil organic matter and its uncertainty annually at 25 m resolution between 0–2 m depth from 1953–2022 in the Netherlands. We predicted soil organic matter decreases of more than 25% in peatlands and 0.1–0.3% in cropland mineral soils, but increases between 10–25% on reclaimed land due to land subsidence. Our analysis quantifies the substantial variations of soil organic matter in space, depth, and time, highlighting the inadequacy of evaluating soil organic matter dynamics at point scale or static mapping at a single depth for policymaking.

Farm‐level variability in soil biological health indicators in Michigan is dependent on management and soil properties

AbstractSoil biology is vital for maintaining productivity, enhancing soil health, and creating resilient agroecosystems. However, many questions remain on how microbial communities are impacted by different soil properties and management practices, especially on grower‐managed fields. This study examined soil biological health properties (0–15 cm) and field history data from 310 grower‐managed fields within Michigan between Fall 2019 and Spring 2021. The objectives were to evaluate the impact of soil texture, tillage, and crop diversity on microbial populations and examine the relationship between soil health indicators and microbial community. Phospholipid fatty acid analysis was used to estimate total microbial abundance and composition of broad taxonomic groups like bacteria, fungi, arbuscular mycorrhizal fungi, actinomycetes, and eukaryotes. Other soil health indicators measured were organic carbon, permanganate oxidizable carbon, potentially mineralizable nitrogen, phosphorus, calcium, potassium, magnesium, and water‐stable aggregation. Soil texture did not significantly influence microbial community except for actinomycetes, which were significantly higher in fine‐textured soils. Tillage had the largest influence on microbial communities, with significantly lower values for all microbes in tilled compared to no‐till fields. Crop diversity had a minimal impact, affecting only arbuscular mycorrhizal fungi and eukaryote populations. All measured soil health indicators were positively associated with microbial populations except for phosphorous, which had a negative correlation (r = −0.56 to −0.66). Overall, we conclude that tillage is the dominant driver of soil biological health on grower‐managed fields across Michigan. Consequently, adoption of no‐till management practices where possible can help restore soil health and long‐term sustainability in agroecosystems.

Enhanced phytoremediation of metal contaminated soils aimed at decreasing the risk of antibiotic resistance dissemination

The enhanced phytoremediation of metal contaminated soils holds great promise for the recovery of soil health and functionality, while providing a range of co-benefits, from an environmental and human health perspective, derived from the revegetation of the degraded sites and the concomitant delivery of ecosystem services. Due to diverse evolutionary co-selection mechanisms between metal resistance and antibiotic resistance in bacteria, metal contaminated soils are considered potential reservoirs of antibiotic resistant bacteria (ARB) which can contribute to the existing antibiotic resistance crisis. During the enhanced phytoremediation of metal contaminated soils, the application of organic wastes (e.g., manure, slurry, sewage sludge) as soil amendments can aggravate the risk of antibiotic resistance spread, because they often contain ARB which harbor antibiotic resistance genes (ARGs) that can then be propagated among soil bacterial populations through horizontal gene transfer (HGT). Due to the magnitude and criticality of the antibiotic resistance crisis, as well as the higher risk of spread and dispersal of ARB and ARGs (they make copies of themselves) compared to metals, it is proposed here to aim enhanced phytoremediation strategies towards decreasing the soil resistome (and, hence, the risk of its potential link with the human resistome), while reducing total and/or bioavailable metal concentrations and restoring soil health and the delivery of ecosystem services. To this purpose, a decalogue of practices is tentatively suggested. Finally, a proper management of plant and soil microbial compositions is a most crucial aspect, together with the selection of the right organic wastes and phytoremediation practices.

Integrated application of metal tolerant P. fluorescens and press mud for conferring heavy metal tolerance to aloe vera (Aloe barbadensis)

Soil pollution due to heavy metal (HM) contamination has emerged as a global issue worldwide owing to their adverse impacts on plant growth. Bioremediation approaches employing living organisms for HM alleviation have gained considerable attention among scientific community. Biological agents such as plant growth-promoting rhizobacteria (PGPR) offer a sustainable way to restore soil health, and their combination with different organic amendments such as press mud (PM) can serve as potential approach for immobilizing HMs in soil. We performed a pot experiment to evaluate the role of individual and combined application of press mud and PGPR strain ‘FQ6’ (identified as Pseudomonas fluorescens) in the phytoremediation of different HMs (Pb, Ni and Cd) and growth promotion of aloe vera. Combined application of FQ6 strain and PM yielded more significant outcomes in terms of all the growth and yield attributes such as leaf length (123 %), plant height (57 %), number of leaves (115 %), fresh and dry weights of gel (246 and 280 %), gel contents (96 %), root length (164 %), root diameter (220 %), no. of root tips (138 %) and root area (315 %), as compared to control. Combined application of FQ6 and PM also led to a significant improvement in different antioxidant activities i.e., CAT (129 %), SOD (48 %), APX (17 %) and POD (83 %) as compared to control. Contrastingly, mobility of these HMs was reduced under combined application of Pseudomonas strain ‘FQ6’ and PM, as there existed a considerable difference between HMs concentrations in soil and plant body. We concluded that joint application of HM-tolerant Pseudomonas FQ6 strain and PM could be an ideal option to alleviate the HM induced adverse impacts on aloe vera by immobilizing them in soil, and subsequently, improving plant growth.

Amendment-driven soil health restoration through soil pH and microbial robustness in a Cd/Cu-combined acidic soil: A ten-year in-situ field experiment

Soil health arguably depends on biodiversity and has received wide attention in heavy-metal (HM) contaminated farmland remediation in recent years. However, long-term effects and mechanisms of soil amendment remain poorly understood with respect to soil microbal community. In this in-situ field study, four soil amendments (attapulgite-At, apatite-Ap, montmorillonite-M, lime-L) at three rates were applied once only for ten years in a cadmium (Cd)–copper (Cu) contaminated paddy soil deprecated for over five years. Results showed that after ten years and in compared with CK (no amendment), total Cd concentration and its risk in plot soils were not altered by amendments (p > 0.05), but total Cu concentration and its risk were significantly increased by both Ap and L, especially the former, rather than At and M (p < 0.05), through increased soil pH and enhanced bacterial alpha diversity as well as plant community. Soil microbial communities were more affected by amendment type (30%) than dosage (11%), microbial network characteristics were dominated by rare taxa, and soil multifunctionality was improved in Ap- and L-amended soils. A structural equation model (SEM) indicated that 57.3% of soil multifunctionality variances were accounted for by soil pH (+0.696) and microbial network robustness (−0.301). Moreover, microbial robustness could be potentially used as an indicator of soil multifunctionality, and Ap could be optimized to improve soil health in combined with biomass removal. These findings would advance the understanding of soil microbial roles, especially its network robustness, on soil multifunctionality for the remediation of metal contaminated soils and metal control management strategies in acidic soils. Environmental ImplicationFarmland soil contamination by heavy metals (HMs) has been becoming a serious global environmental challenge. However, most studies have been conducted over the short term, leading to a gap in the long-term remediation efficiency and ecological benefits of soil amendments. For the successful deployment of immobilization technologies, it is critical to understand the long-term stability of the immobilized HMs and soil health. Our study, to the best of our knowlege, is the first to state the long-term effects and mechanisms of soil amendments on soil health and optimize an effective and eco-friendly amendment for long-term Cd/Cu immobilization.

Impact of the sustainable agricultural practices for governing soil health from the perspective of a rising agri-based circular bioeconomy

Soil is a precious and nonrenewable source for agroecosystems of which own health state over time is becoming a focus of global concern. A healthy soil is a harmonious and very complex social system with a good structure, an optimal functional state, and an efficient buffering capacity to maintain a dynamic balance among all productivity factors. There is an urgent need to develop new approaches for the sustainable management of soil quality in depleted soils from a long-term perspective for increasing agricultural productivity and maintaining food security due to global population expansion. Since high crop yield mainly depends on the improvement of soil quality, further efforts must be addressed to develop advanced technologies/processes in reusing waste biomass accordingly with the circular bioeconomy principles. Although the knowledge of relationships between intrinsic factors of soil fertility and crop productivity is the baseline for the optimal soil management, this issue is nevertheless overlooked by stakeholders. Soil organic matter (SOM) associates carbon availability with the plant nutrients (mainly nitrogen, phosphorus, and potassium) leading to the strongest positive impacts of the environmental functions and food production. Unfortunately, there is a progressive trend to lose the SOM stock, so altering the biological functions of the soils. Despite, farmer overlooks the mechanisms for preserving SOM accumulation by adopting inappropriate practices to counteract soil decline consequently to climate change and deterioration of agroecosystems. A wide spread of microplastic and nanoplastic pollutants (MNPs) in the environment have added further concerns due to their potentially hazardous risks for soil health thanks to their ubiquitousness and persistence. Nonetheless, the interactions of MNPs with the soil components, microbial communities, plants, and fauna that could determine the strongest impacts on the nutrient availability and food security are still poorly explored. This review work launches some challenges to reader by providing practical solutions, viewpoints, future challenges, and new perspective for restoring soil health by contrasting soil decline from a long-term perspective in organic farming systems in a sustainable agri-based circular bioeconomy system.

Surge of native rare taxa in tailings soil induced by peat bacterial invasion

The pivotal role of the native bacterial community in maintaining soil health, particularly in degraded tailings environments, is often overlooked. This study utilized peat, rich in microorganisms, to investigate its impact on soil function and native bacteria response in copper tailings-soil. Through 16S rRNA gene sequencing, changes in nutrient cycling, organic matter decomposition, and microbial activity were assessed post one-year peat remediation. Results from FEAST and cluster analysis revealed that peat-derived species disproportionately influenced tailings microbial community remediation, supported by the microbial invasion theory. Tailings responded positively to these species, with optimal function achieved at 5 % peat dosage. Peat biomarkers (Actinobacteriota, Bacteroida, Chloroflexi, and Firmicutes) played key roles in heavy metal removal and nutrition fixation. The Random Forest model and co-occurrence network highlighted contributions from native rare species (Dependentiae and Latescibacterota) activated by peat addition. These insights underscore the resilience of rare taxa and provide a foundation for soil health restoration in tailings areas. By emphasizing the importance of peat as a potential exogenous solution for activating indigenous microbial functions, these findings offer valuable insights for developing effective and sustainable remediation strategies in mining-affected regions.

Isolation and Optimization of Phosphorus Solubilizing Bacteria from Maize Rhizosphere in Nasarawa State, Nigeria

Phosphorus solubilizing bacteria (PSB) are a type of plant growth-promoting rhizobacteria which has the ability to convert insoluble phosphate into plant available forms. They are used as biofertilizers to restore soil health and fertility. In the present investigation, isolation, characterization and optimization of phosphate solubilizing activity of these microbes at different pH, temperature and carbon source was carried out. Eight phosphorus solubilizing rhizospheric bacteria (PSRB) isolates isolates were recovered from different farms in six local government from maize rhizosphere using the spread plate method on Pikovskaya agar. Amongst these eight isolates, five were recovered from Lafia local government while three were recovered from Kokona local government with the development of a prominent halozone. All isolates were morphologically characterised, amplified, and sequenced for taxonomic identification using 16S primers. The results indicated they belong to member of the genus Acinetobacter, Ochrobactrum, Brucella, Curtobacterium, Leifsonia and Microbacterium respectively. These strains when grown at different conditions of external carbon sources, temperature and pH showed highest phosphorus solubilizations of 326.23 µg/ml ± 0.21 at 30 °C, 325.50µg/ml ± 1.13 at a pH of 7 and 320.30µg/ml ± 0.36 with glucose as carbon source. The results from these findings could indicate the use of these isolate as trial biofertilizers on the field which will help improve crop yield and enhance plant growth promotion