Rock Phosphate Deposits Research Articles

Isolation of a potential rock phosphate solubilizing Aspergillus sp. towards development of biofertilizer

Phosphorus (P) is one of the key bio elements that limits agricultural production. Although Sri Lanka is endowed with rock phosphate deposits, practical means to utilize this resource are limited. Phosphate-solubilizing fungi (PSF) play an important role in enhancing the bioavailability of soil phosphorus to plants. In this study, fungi from eight soil samples in Kaikawala, Sri Lanka, were isolated using spread plate method and analyzed for its phosphate solubility capacity. One fungal isolate with significant halo zones on Pikovskaya’s agar (PVK) plates, containing 0.5% tricalcium phosphate, was identified. After purification, the isolate was transferred to three media setups: PVK with 0.5% apatite (ERP) as the phosphate source, PVK with 0.5% tricalcium phosphate as a positive control, and PVK without P source as a negative control and analyzed for the solubilization index (SI). DNA sequences of the internal transcribed spacers with 5.8S region of ribosomal DNA (ITS1-5.8S-ITS2) was analyzed with universal primer pair ITS4-F/ITS5-R to determine the identity of the species. Fungal isolate PSF01 showed a phosphate solubilizing activity on both PVK media, ERP (1.07 ± 0.03 cm SI) and tricalcium phosphate (1.07 ± 0.01 cm), with similar effects (p > 0.05). However, the SI in the negative control was 1.00 ± 0.00 cm without halo zone (p < 0.05). The fungal strain is fast growing with initially white but quickly changing to black colonies after producing conidial spores on potato dextrose agar with distinctive conidial heads and pale-yellow lower surface characterized as Aspergillus. Sanger DNA sequencing identified the fungus as Aspergillus niger (99%) and a phylogenetic tree was constructed using MEGA11 software using reference data obtained from NCBI GenBank data to identify the isolated PSF01. Consequently, our preliminary studies demonstrate the importance of examining more soil samples to identify PSF for sustainable agricultural applications in the future.

Advances for Improving Phosphorus Use Efficiency in Agriculture

An impending crisis is the continuous availability of phosphate fertilizers, which underlie global food production. The rock phosphate deposits on which the world depends are not only finite but many are polluted and many are located in geopolitically unstable locations, implying that significant changes will be required to maintain food supply for an increasing global population. There is no single solution, but a combination of phosphorus management measures is required not just to extend the life of the remaining non-renewable rock phosphate sources, but also to result in a more efficient, sustainable phosphorus cycle. Improving the effectiveness of fertilizer applications to agricultural land, as well as a better understanding of phosphorus cycling in soil-plant systems and the interplay between soil physics, chemistry and biology in conjunction with plant characteristics are among the solutions. The finite nature of rock phosphate supply and the development of other sources of phosphorus fertilizers is unavoidable. There are clear prospects and it is now critical to prioritize a concerted effort to increase phosphorus usage efficiency.

Phosphorus Availability from German Sewage Sludge Ashes to Plants Cultivated in Soilless Growing Media of Contrasting pH

Sewage sludge ash (SSA) as a secondary phosphorus (P) source may help to conserve global rock phosphate deposits if used in the base fertilization of soilless growing media. Plant availability of SSA-P was studied in a pot experiment with marigolds in a peat-based growing medium of contrasting pH (4.5, 6.0). Six SSAs were included in the study and compared to water-soluble monocalcium phosphate (MCP) and rock phosphate (RockP). In addition to the efficacy of SSA-P, calcium chloride + diethylenetriaminepentaacetate (CAT) and calcium-acetate-lactate (CAL), as commonly used extractants in Germany to analyze plant-available P in growing media, were tested in terms of their ability to predict plant P uptake. No SSA reached the relative P use efficiency (rPUE) observed for MCP. However, at a growing medium pH of 4.5, the average rPUE for SSA was 70% of the MCP rPUE. Compared to RockP, at a growing medium pH of 6.0, SSAs resulted in an rPUE of nearly the same low level. In contrast, at pH 4.5, the rPUE from SSAs was mostly lower than that from RockP, and there were differences in rPUE among SSA origins. Therefore, in addition to a variation in particle size distribution, there might be differences in the P-bearing phase. Sewage sludge ashes represent a promising substitute for primary P sources only in crops requiring a low pH in the growing medium. The extractants CAT and CAL, on their own or in combination, did not reflect plant P uptake from SSA. To improve the prediction of plant-available SSA-P, solvent modifications or additional extractants might be promising and should be subjected to further research.

Recycling of silicon-rich agro-wastes by their combined application with phosphate solubilizing microbe to solubilize the native soil phosphorus in a sub-tropical Alfisol

It is imperative to find suitable strategies to utilize the native soil phosphorus (P), as natural rock phosphate deposits are at a verge of depletion. We explored two such cost-effective and eco-friendly strategies for native soil P solubilization: silicon (Si)-rich agro-wastes (as Si source) and phosphate solubilizing microorganism (PSM). An incubation study was conducted in a sub-tropical Alfisol for 90 days at 25°C under field capacity moisture. A factorial completely randomized design with 3 factors, namely: Si sources (three levels: sugarcane bagasse ash, rice husk ash, and corn cob ash), PSM (two levels: without PSM, and with PSM); and Si doses [three levels: no Si (Si0), 125 (Si125) and 250 (Si250) mg Si kg-1 soil] was followed. The PSM increased solution P and soluble Si level by ∼22.2 and 1.88%, respectively, over no PSM; whereas, Si125 and Si250 increased solution P by ∼60.4 and 77.1%, as well as soluble Si by ∼41.5 and 55.5%, respectively, over Si0. Also, interaction of PSM×Si doses was found significant (P<0.05). Activities of soil enzymes (dehydrogenase, acid phosphatase) and microbial biomass P also increased significantly both with PSM and Si application. Overall, PSM solubilized ∼4.18mgkg-1 of inorganic P and mineralized ∼5.92mgkg-1 of organic P; whereas, Si125 and Si250 solubilized ∼3.85 and 5.72mgkg-1 of inorganic P, and mineralized ∼4.15 and 5.37mgkg-1 of organic P, respectively. Path analysis revealed that inorganic P majorly contributed to total P solubilization; whereas, soluble and loosely bound, iron bound and aluminium bound P significantly influenced the inorganic P solubilization. Thus, utilization of such wastes as Si sources will not only complement the costly P fertilizers, but also address the waste disposal issue in a sustainable manner.

Economic Impact of Developing Value-Added Products from Sri Lankan Eppawala Rock Phosphate Deposit

Many countries rich in natural resources lack sustainable resource management under economic utilization has become a common global issue. However, obtaining the right compensation for natural resources and long-term benefits from resource-related wealth has become a timely requirement. Therefore, the current paper aims to discuss both the economic importance and impact of value addition to Sri Lankan Eppawala rock phosphate (non-renewable resource) via innovative commercial products with a variety of economic benefits to Sri Lanka.&#x0D; For that, Eppawala High Grade Rock Phosphate was successfully converted into Eppawala Hydroxyapatite ceramic types with several properties and applications using chemical processes including; solid - state sintering, sol-gel acidified and alcoholic routes, products were analyzed using several characterization techniques to obtain their chemical and physical properties. Next, it was incorporated with Methyl Methacrylate (MMA) and 2- hydroxyethyl methacrylate (HEMA) liquid monomers to obtain their composites. Processed composites were analyzed to find out their applicability on biomedical applications, compared and contrasted their properties with currently using commercial bone cement and dental filling material in clinicals. Furthermore, novel product manufacturing costs were compared and contrasted with the raw material costs and commercial product costs to find out Economic impact.&#x0D; Results show that Synthesized Eppawala Hydroxyapatite product types can be applied directly as bioceramic material due to its similar characteristics to human hard tissues and its manufacturing cost is lower compared to synthetic Hydroxyapatite commercial product in the market. Processed Eppawala Hydroxyapatite composites are also low cost, can be applied to biomedical applications in the fields of orthopedics, dentistry, profitable than manufacturing fertilizers, and can be exported into the global market and local high-cost imports can be reduced. Considering better performance, low cost and eco-friendliness, novel composites can be applied clinically, export to global market and get much better foreign income into the country and by doing, improve living standards in Sri Lankan citizens.&#x0D; Keywords: Sri Lankan Economy, Rock phosphate, Orthopedics, Dentistry, Biomedical applications

Recovery of struvite from wastewaters as an eco-friendly fertilizer: Review of the art and perspective for a sustainable agriculture practice in India

The limited rock phosphate deposits present in the earth’s crust are being used at a fast rate and therefore phosphate fertilizers use will be restricted in the future. Hence, there is an urgent need of conserving the use of phosphorous (P) and recover/reuse of P from wastewaters to the maximum extent. Struvite (MgNH4PO4) is a crystalline mineral composed of magnesium, ammonium, and phosphate, and is considered as an adequate source of nutrients especially P. Struvite can be used as raw material for fertilizer production or as slow-release fertilizer. Recently, there were a lot of researches carried out to explore the possibility of recovering the struvite from wastewater streams. This paper reviews the potential sources of P in wastewater streams and the techniques of struvite recovery available in the literature for practical applications. Anaerobic digester supernatant, urine from livestock and humans are identified as potential wastewater sources of P in India. Continuous stirred tank reactor technique can be easily adopted to recover P, which is known to recover 80–90% P in wastewater. Currently, India is the second largest consumer of P due to the low P in soil and depends on imported sources for meeting her demand on fertilizers. Therefore, the work presented in this review would help India to formulate suitable policy guidelines to meet a part of the P demand by recovering struvite from wastewater streams and apply in agricultural field as an eco-friendly fertilizer. Such an effort significantly contributes to promote circular economy and sustainable agriculture.

Economic Impact of Value addition to Sri Lankan Rock Phosphate Deposit: A Non-renewable Phosphate Source

Economic Impact of Value addition to Sri Lankan Rock Phosphate Deposit: A Non-renewable Phosphate Source

Low-cost chitosan-calcite adsorbent development for potential phosphate removal and recovery from wastewater effluent

Phosphorous (P) recovery from wastewater will become increasingly vital in the future as terrestrial rock phosphate deposits are expended. Effective management of P as a critical resource will require new techniques to recover P from wastewater, ideally in a form that can be used in agriculture as fertiliser. In this study, batch and fixed-bed column conditions were tested using a novel KOH deacetylated calcite-chitosan based adsorbent (CCM) for P removal from aqueous solutions and wastewater effluents. The unique characteristics of this adsorbent as a phosphate adsorbent were the result of rich surface functionality (amine and sulphur functional groups of the chitosan and proteins) and the CaCO3 content (providing donor ligands; and additionally beneficial if the material were used as fertiliser, buffering soil acidification caused by nitrogen application). The maximum P adsorption capacity was determined to be 21.36 mgP/g (at 22 °C) and the endodermic process reached equilibrium after 120 min. The experimental data was best described using a Langmuir isotherm and a pseudo-second order kinetic model. The diffusion kinetic analysis highlighted the importance of both film and intraparticle mass-transport. Material characterisation suggested that the adsorption process involved interactions between P and functional groups (mostly –NH3+) due to electrostatic interaction on the chitosan chain or involved ligand exchange with CO32−. Analysis of materials using X-Ray Powder Diffraction (XRPD) and Thermogravimetric Analysis (TGA) indicated a microprecipitation-type mechanism may occur through the formation of hydroxylapatite (Ca5(PO4)3(OH)). Desorption studies demonstrated that the P-laden CCM (derived from crab carapace) had the potential to be reused in soil amendment as a slow-release P fertiliser. The effects of different operating parameters were explored in a fixed-bed column, and the experimental data fitted well to the Clark model (R2 = 0.99). The CCM also showed excellent P adsorption potential from secondary and final wastewater effluent in dynamic conditions, even at low P concentrations. Finally, a scale-up approach with cost analysis was used to evaluate the price and parameters needed for a potential large-scale P recovery system using this adsorbent.

Phosphorus use efficiency and fertilizers: future opportunities for improvements

The continued supply of phosphate fertilizers that underpin global food production is an imminent crisis. The rock phosphate deposits on which the world depends are not only finite, but some are contaminated, and many are located in geopolitically unstable areas, meaning that fundamental changes will have to take place in order to maintain food production for a growing global population. No single solution exists, but a combination of approaches to phosphorus management is required not only to extend the lifespan of the remaining non-renewable rock phosphate reserves, but to result in a more efficient, sustainable phosphorus cycle. Solutions include improving the efficiency of fertilizer applications to agricultural land, alongside a better understanding of phosphorus cycling in soil-plant systems, and the interactions between soil physics, chemistry and biology, coupled with plant traits. Opportunities exist for the development of plants that can access different forms of soil phosphorus (e.g., organic phosphorus) and that use internal phosphorus more efficiently. The development of different sources of phosphorus fertilizers are inevitably required given the finite nature of the rock phosphate supplies. Clear opportunities exist, and it is now important that a concerted effort to make advances in phosphorus use efficiency is prioritized.

ENVIRONMENTAL IONIZING RADIATION DOSE OUTDOOR IN AN INHABITED AREA WITH A HIGH CONCENTRATION OF URANO-PHOSPHATE IN NORTHEAST OF BRAZIL.

A marine phosphorus region with high concentrations of phosphate, coastwise of Pernambuco, Northeast of Brazil, is densely inhabited. Rock phosphate deposits naturally contain uranium ore that produces ionizing radiation from it and its natural descendants, furthermore, its thorium and potassium concentrations are comparable to those usually found in soils. Radiological monitoring of this environment is important to verify the occurrence of harmful effective doses for the adjacent population. This study aimed at the in situ radiometric monitoring in four cities of the north of the Metropolitan Region of Recife-Pernambuco, estimating the effective environmental dose to which the local population is subject. In total, 91 points were monitored with a discriminator-type detector. The outdoor environmental effective dose rates ranged from 1.99 ± 0.09 to 7.59 ± 0.36 mSv y-1, with an average of 2.60 ± 0.69 mSv y-1.

Effect of Eppawela High Graded Rock Phosphate (HERP) Applied with Vinasse on Yield and Quality of Sugarcane (Variety CO775)

The disposal of Vinasse, effluent from the ethanol industry is a main pollutant to the environment. HERP is a locally available cheap source of Phosphorous fertilizer, manufactured from Eppawela Rock Phosphate deposit in Sri Lanka, which is less soluble and has limited use in sugarcane cultivation. Therefore, an experiment was conducted to investigate the effect of different rates of HERP as the P source, and Vinasse on Sugarcane yield and quality. This was conducted at the fields of Sugarcane Research Institute (SRI), UdaWalawe, using variety CO775. Five levels of HERP (50, 75, 100, 125, 175 P2O5 kg/ha) with and without Vinasse were tested on the yield, juice quality, leaf P and available soil P of Plant crop and first Ratoon. Vinasse was applied at the rate recommended by SRI to furrows of both Plant and Ratoon crop. The study revealed that the cane yield and millable cane count in ratoon crop has significantly increased by applying Vinasse. Leaf P content of Plant and Ratoon crop has improved by the application of vinasse. Moreover, Vinasse has improved available soil P tested after plant crop harvest. In addition, cane juice quality parameters in both plant and ratoon crop were not affected by applying HERP as P source with or without Vinasse. Thus, there is a potential to use HERP with Vinasse as a cheap source of Phosphorous for sugarcane in Sri Lanka.

Cow urine as a potential source for struvite production

Rock phosphate deposits are non-renewable and are facing a decline. Due to this, phosphate fertilizers are going to be limited in future. Struvite is a crystalline mineral substance containing equimolar amount (1:1:1) of magnesium ammonium and phosphate ions (MgNH4PO4·6H2O), a good source of phosphorus and a slow release fertilizer. In the present study it was crystallized from cow urine using brine as cheap source of magnesium. Cow urine and brine was mixed at different proportion to find out the optimum concentration for struvite crystallization. Crystallized struvite was characterized by X-ray diffraction, thermogravimetric and differential thermal analysis, Fourier transform infrared spectroscopy and scanning electron microscopy and energy dispersive spectroscopy. The ratio of 1:0.5 cow urine and brine mixing gave the best quality struvite at pH 9. The analysis of struvite for phosphate, magnesium and ammonium ions showed 5.85, 3.16, and 0.56 % respectively. The fertilizer potential of struvite was evaluated on the growth of Vigna radiata. The best growth was observed in the pots where struvite was added at a concentration of 2 g/kg of soil. Struvite is a good source of phosphate and it can be recovered from livestock waste such as cow urine. Struvite can be made from a renewable source for a sustainable agricultural development. Theoretically at the yield of 40 g/L a total of 12,176 tons struvite could be made per day all over India for fertilizer use.

Effect of Carbon, Nitrogen Sources and Abiotic Stress on Phosphate Solubilization by Bacterial Strains Isolated from a Moroccan Rock Phosphate Deposit

Experiments were conducted to evaluate the solubilization of tri-calcium phosphate (TCP) by phosphatesolubilizing bacterial isolates PSB 4, 5 and 6 identified as Enterobacter sp., Bacterium DR172, and Enterobacter hormaechei, respectively, in addition to Acinetobacter sp. used as a positive control strain. The study was carried out in culture media using different carbon and nitrogen sources, and under different abiotic stress conditions such as high salt, pH, and temperature. The effect of EDTA on growth was also tested. Organic acids produced by the PSB isolates were also determined by reverse phase HPLC. The isolates behave differently with different types of N- and C-sources and seem to adapt to different conditions, with glucose significantly promoting TCP solubilization in all cases. The highest production of orthophosphate (866 mg.L-1, pH 3.2) was showed by Enterobacter hormaechei using glucose as C-source, (NH 4 ) 2 SO 4 as N-source, at 37°C and pH 7, and without any addition of EDTA. The solubilized phosphate also did attaint 110.71% in comparison with control when sorbitol was used as a C-source by Bacterium DR172. We also noticed a decrease in pH due to the organic acids secreted to the medium. Newly carboxylic acids were identified to be produced by these strains in addition to others previously identified, 2 ketogluconic acid was found when galactose was used as a C-source for all isolates except for Acinetobacter sp. which secreted lactic, glutaric and glucuronic acids. Analysis of the Solubilization Index (SI) of the bacterial strains at different temperatures revealed different effectiveness to degrade and assimilate TCP, the SI being maximal at 25°C for the three isolates (4.17, 3.83 and 4.44, for PSB4, 5 and 6), whereas for Acinetobacter sp. the highest SI (3.83) was achieved at 30°C.

Significance of carbonaceous shales and vanadium geochemical haloes in the exploration for rock phosphate deposits in the southern Georgina Basin, central Australia

Significance of carbonaceous shales and vanadium geochemical haloes in the exploration for rock phosphate deposits in the southern Georgina Basin, central Australia

Effect of organic and inorganic P fertilizers on sustainability of soil fertility and grain yield in a rice-pulse system

The use of indigenous rock phosphate (RP) as fertilizer is becoming increasingly important in India. The RP deposit in India was estimated to be about 260 t (Narayanasamy and Biswas 1998). Khasawnch and Doll (1986) reported that RP is as effective as water-soluble P fertilizer under suitable environments. As the availability of RP increases slowly and continuously when in contact with the soil, its effectiveness was two to three times more than that of triple superphosphate (Chien and Hammond 1988).

Local rock phosphate deposits are a good source of phosphorus fertilizer for rice production in Cambodia

Phosphate is needed to increase yields over most of Cambodia's rice area. Imported P fertilizers are expensive and difficult to obtain for many Cambodian farmers. Local rock phosphate (PR) is potentially a viable alternative to the imported P fertilizers. Field and greenhouse experiments were conducted to compare the use of triple superphosphate (TSP) and several products developed from the local phosphate as fertilizers for rice production. The experiments were conducted over several seasons and soil types. In the field experiment, P application increased grain yields from 0 to 2.5 t ha-1 in the first season, 1.0 to 2.5 t ha-1 in the second season and 0.5 to 1.0 t ha-1 in the third season. In all the seasons the effect of P on grain yield was the same regardless of the type of P fertilizer applied. In the first season, however, plants receiving TSP had more than 10% higher P concentrations in their shoots than plants receiving PRo Conversely, in the final season, plants receiving TSP tended to have a lower P concentration in the straw than plants receiving PRo In the greenhouse, P fertilizer increased shoot growth from 5 to 15 g pot-Ion a sandy soil and from 2 to 30 g pot-Ion a clayey soil. Growth of plants receiving PR on all the soils, however, was as good as or better than that of the plants receiving TSP. The relationship between shoot growth and shoot P concentration was the same across all soil types when TSP and PR were applied but varied with the soil type when the PR product was applied. New fertilizer products developed from local rock phosphate deposits appear to be effective for rice production in Cambodia. With this technology, given the widespread P deficiency in most of the soils and the low cost of the PR product there is a potential to dramatically improve the efficiency of rice farming in Cambodia. New relationships between P applied as PR and grain yield, however, will need to be studied in order to formulate accurate fertilizer recommendations for the new product.

Use of solubility curves as a method to characterize phosphogypsum and its constituents

Abstract Phosphogypsum (PG), the by‐product of wet acid production of phosphoric acid from rock phosphate, is much more widely distributed than natural rock phosphate deposits. It is a major source of S and Ca for crops. It was found to be effective as a soil conditioner for sodic, solonets, and solonetzic soils and as an ameliorant for Al toxicity and subsoil acidity. In addition, it was found to be effective in promoting aggregation in hard‐setting clays and in subsoil hardpans. Unlike mine gypsum, PG contains impurities whose release into the soil and ground water need to be monitored. The results of this study show that use of solubility curves can be an effective method to characterize the solubility rates and solubility characteristics of PG and its constituents. Percentages of the total content of each element studied, namely: Ca, P, Al, Fe, Zn, Cu, and Mn, dissolved in Mehlich I solution were significantly correlated with the percent of PG dissolved. The solubility curves of Ca, P, and F in water followed closely that of PG, but the correlations coefficients (r) were not significant due to lack of spread of the individual values.

Isolation and screening of microorganisms dissolving low-grade rock phosphate.

Several yeasts, fungi and bacteria isolated from the rhizosphere of leguminous crops and soils of rock phosphate deposit area were found to solubilize low-grade Mussorie rock phosphate. Of the several yeasts and fungi,Schawanniomyces occidentalis, Aspergillus awamori andPenicillium digitatum were better than others in rock phosphate solubilization. Among bacterial isolates from soils of rock phosphate deposits, Gram-negative motile rods were more effective than Gram-negative non-motile rods in dissolving rock phoshates. The most efficient bacteria were identified as strains ofPseudomonas striata. All the microorganisms acidified the liquid medium but there was no relationship between the rock phosphate dissolved and the decrease in pH of the culture broth.