Search

This study investigated the effects of combining Phragmites australis-based biochar, prepared at 400 °C, with various types of phosphate fertilizers-soluble, insoluble, and organic-on the content and transformation of phosphorus fractions in saline-alkali soil. Additionally, we explored microbiological mechanisms driving these transformations. The results showed that this combination significantly increased the concentrations of dicalcium phosphate (Ca 2 P), octacalcium phosphate (Ca 8 P), aluminum phosphate (AlP), moderately labile organic phosphorus (MLOP), and resistant organic phosphorus (MROP) in soil. Conversely, the levels of hydroxyapatite (Ca 10 P) and highly resistant organic phosphorus (HROP) decreased. The increase in labile organic phosphorus (LOP) content or decrease in iron phosphate (FeP) was found to effectively enhance the availability of Olsen phosphorus (Olsen-P) in soil. Furthermore, the study revealed that biochar mixed with organic phosphate fertilizers increased the activity of soil acid phosphatase (ACP) and neutral phosphatase (NEP), while reducing alkaline phosphatase (ALP) activity. In contrast, biochar combined with soluble and insoluble phosphate fertilizers decreased the activity of ACP (22.59 % and 28.57 %, respectively) and NEP (62.50 % and 11.11 %, respectively), with the combination with insoluble fertilizers also reducing ALP activity by 55.84 %, whereas the soluble combination increased it by 190.34 %. Additionally, the co-application of biochar and phosphate fertilizers altered the composition and abundance of the gene phoD-harboring microbial community, enhancing the abundance of Proteobacteria and reducing that of Actinobacteria. Correlation analysis between phoD-functional microbial species and various phosphorus fractions showed that Rhodopseudomonas was significantly associated with several phosphorus components, exhibiting a positive correlation with Ca 2 P, Ca 8 P, AlP, LOP, MLOP, and MROP, but a negative relationship with Ca 10 P. These findings suggest that the combined application of biochar and phosphate fertilizers could change the abundance of Rhodopseudomonas, potentially influencing phosphorus cycling in the soil. This research provides a strong scientific foundation for the efficient combined use of biochar and phosphate fertilizers in managing saline-alkali soil., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bacterial inoculants have been used in agriculture to improve plant performance. However, laboratory and field requirements must be completed before a candidate can be employed as an inoculant. Therefore, this study aimed to evaluate the parameters for inoculant formulation and the potential of Bacillus subtilis (B70) and B. pumilus (B32) to improve phosphorus availability in maize (Zea mays L.) crops. In vitro experiments assessed the bacterial ability to solubilize and mineralize phosphate, their adherence to roots, and shelf life in cassava starch (CS), carboxymethyl cellulose (CMC), peat, and activated charcoal (AC) stored at 4 °C and room temperature for 6 months. A field experiment evaluated the effectiveness of strains to increase the P availability to plants growing with rock phosphate (RP) and a mixture of RP and triple superphosphate (TS) and their contribution to improving maize yield and P accumulation in grains. The B70 was outstanding in solubilizing RP and phytate mineralization and more stable in carriers and storage conditions than B32. However, root adherence was more noticeable in B32. Among carriers, AC was the most effective for preserving viable cell counts, closely similar to those of the initial inoculum of both strains. Maize productivity using the mixture RPTS was similar for B70 and B32. The best combination was B70 with RP, which improved the maize yield (6532 kg ha -1 ) and P accumulation in grains (15.95 kg ha -1 ). Our results indicated that the inoculant formulation with AC carrier and B70 is a feasible strategy for improving phosphorus mobilization in the soil and maize productivity., (© 2023. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Improving phosphorus (P) use efficiency is a challenge to promote a circular economy and greening the phosphorus cycle towards planetary sustainability. The disruptive innovation for phosphate fertilizers may help to reduce some unwelcome reactions that occur to P in soils. Monoammonium phosphate (MAP) coating with biodegradable organic polymers and the addition of magnesium (Mg) - a nutrient with a synergistic effect on the uptake of P, zinc (Zn), and boron (B) - emerge as a smart strategy to applying these micronutrients uniformly in soils. The objectives of this study were: to characterize the coated-MAP with biodegradable organic polymers, quantify the diffusion and availability of P in the soil, and evaluate the corn crop nutrition and yield during two crop seasons. The treatments were: MAP, MAP coated with biodegradable organic polymer (BOP), MAP + BOP + 1.3% of Zn + 0.33% of B, and MAP + BOP + 1.76% of Mg. The laboratory tests showed that the diffusion of MAP-based fertilizers was: MOMg (7.86 mm) = MO (8.82 mm) = MAP (8.84 mm) = MOM (8.51 mm) after 432 h. Coatings did not cause delays in the P-release in water at 25 °C since more than 95% of P was released within 24 h. In the field trials, the application of Mg, Zn, and B in the MAP coating did not increase nutrient leaf concentration. In the summer crop season, grain yield increased up to the P-rates of 85 kg of P 2 O 5 ha -1 , reaching the value of 6731 kg ha -1 . Physical and chemical characteristics of MAP-fertilizers tend to improve with the coatings. The addition of biodegradable organic polymers, Mg, B, and Zn, as MAP-coatings did not enhance P diffusion, release, and availability in the soil and the crop nutrition. Coated-MAP improved corn yield only in the 2 nd crop season., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Phosphate-solubilizing bacteria can release phosphorus (P) from insoluble minerals and benefit either soil fitness or plant growth. Bulk sized P compounds have been suggested but little is known about solubilization of nanosized materials such as hydroxyapatite nanoparticles (HANP). A screening of the initial 43 strains from vanilla rhizospheres for phosphate solubilization with bulk Ca 3 (PO 4 ) 2 was carried out. Subsequently, 6 strains were selected on bulk rock phosphate (RP) and HANP. Two kinetics experiments were run out regarding evaluation at 5, 10 and 20 days after inoculation (dai). Bacterial biomass production was similar in both experiments; the lowest biomass was found at 20 dai. In all cases, bacteria reduced the original culture medium pH; which was related with phosphate solubilization from the production of organic acids. Citric acid was produced by all strains. Enterobacter cloacae CP 31 was the most interesting bacterium: produced the lowest culture pH at 20 dai (4) with both Ca 3 (PO 4 ) 2 and RP, and 3.7 at 10 dai with HANP correlating with high soluble P concentration (536, 64 and 13 mg L -1 with these P sources, respectively). This bacterium should be tested as an inoculant in plants to reveal its potential as plant promoter growth and HANP to suggest its role in the potential use of nano-P fertilizers.

As a primary nutrient in agricultural soils, phosphorus plays a crucial but growth-limiting role for plants due to its complex interactions with various soil elements. This often results in excessive phosphorus fertilizer application, posing concerns for the environment. Agri-research has therefore shifted focus to increase fertilizer-use efficiency and minimize environmental impact by leveraging plant growth-promoting rhizobacteria. This study aimed to evaluate the in-field incremental effect of inorganic phosphate concentration (up to 50 kg/ha/P) on the ability of two rhizobacterial isolates, Lysinibacillus sphaericus (T19), Paenibacillus alvei (T29), from the previous Breedt et al. (Ann Appl Biol 171:229–236, 2017) study on maize in enhancing the yield of commercially grown Duzi® cultivar wheat. Results obtained from three seasons of field trials revealed a significant relationship between soil phosphate concentration and the isolates' effectiveness in improving wheat yield. Rhizospheric samples collected at flowering during the third season, specifically to assess phosphatase enzyme activity at the different soil phosphate levels, demonstrated a significant decrease in soil phosphatase activity when the phosphorus rate reached 75% for both isolates. Furthermore, in vitro assessments of inorganic phosphate solubilization by both isolates at five increments of tricalcium phosphate-amended Pikovskaya media found that only isolate T19 was capable of solubilizing tricalcium at concentrations exceeding 3 mg/ml. The current study demonstrates the substantial influence of inorganic phosphate on the performance of individual rhizobacterial isolates, highlighting that this is an essential consideration when optimizing these isolates to increase wheat yield in commercial cultivation. [ABSTRACT FROM AUTHOR]

Some types of fertilizers may contain various amounts of natural radionuclides like 238U, 232Th, 226Ra, 40K (Kuzmanoviæ et al. in J Radioanal Nucl Chem 331(12):5825–5834, 2022. 10.1007/s10967-022-08646-x; H Hamamo et al. in J Radioanal Nucl Chem 194(2): 331–336, 1995. 10.1007/BF02038431; M García-León et al. in J Radioanal Nucl Chem 197(1): 173–184, 1995. 10.1007/BF02040229). In this study 16 samples of commercially available fertilizers produced in Poland were selected for preliminary radiological evaluation. The samples were measured by means of low background gamma spectrometry. The results showed high concentrations of 40K in potassium and multinutrient fertilizers (2.3–13.8 kBq kg−1), and relatively high concentrations of uranium and radium isotopes in phosphate fertilizers. The obtained results allowed to calculate radium equivalent activity, absorbed dose rate increase and increase in annual effective dose equivalent. [ABSTRACT FROM AUTHOR]

Pinus taeda plantations in subtropical regions of South America commonly occur on highly weathered soils of low natural fertility, especially phosphorus (P). Thus, phosphate fertilization is necessary in Pinus. The proposition of critical levels (CL) and sufficiency ranges (SR) of P in needles and soil can assist forest managers to decide the use of phosphate fertilizers, reducing the cost of production and the potential for contamination. The study aimed to propose critical levels and sufficiency ranges of phosphorus in young Pinus taeda submitted to phosphate fertilization in southern Brazil. The parameters height, stem diameter, P concentration in needles, soil available P, electron transport rate (ETRm), maximum potential quantum yield of PSII (Fv/Fm), initial (Fo) and maximum fluorescence (Fm), chlorophyll a (Chl a), b (Chl b) and total (Chl total) concentration, and acid phosphatase (APase) activity were evaluated. Productivity factor, CL and SR of P in needles and soil were calculated. The CL of P in needles in relation to relative productivity factor was 1.5 g P kg− 1. The CL of P for photosynthetic parameters were 1.5 and 1.7 g P kg− 1 for Chl b and ETRm, respectively. CL of P in soil was 2.3 mg P dm− 3. The results may contribute to appropriate recommendations for phosphate fertilizer, reducing production costs and possible P–fertilizer losses in Pinus taeda plantations. [ABSTRACT FROM AUTHOR]

The objective of this study is to seek correlations between phosphate fertilization rates in potato cultivation and the chemical composition and physicochemical properties of the potato starch. Potato starches are prepared from the potato tubers cultivated in two different districts in Hokkaido, Japan, with different soil characteristics using varied phosphate fertilization rates. The chemical composition of the potato starches such as the amylose, phosphorus, and potassium contents and their physicochemical properties such as the swelling power, solubility, and pasting and thermal properties are evaluated. The results show that the phosphate fertilization rate has a moderate and positive correlation with the amylose content, while no correlations are found with any other chemical composition and physicochemical properties, including the phosphorus content. One plausible explanation for the lack of the correlation between the phosphate fertilization rate and the phosphorus content in the starch is that a sufficient amount of phosphorus has already been accumulated in the soils to phosphorylate the starch to the highest possible degree without further application of phosphate fertilizers. The present results imply that reducing the phosphate fertilization rate in potato cultivation in the studied fields has no negative impact on the chemical composition and physicochemical properties of potato starch. [ABSTRACT FROM AUTHOR]

The object of this research is the phosphate serves, as a fundamental and crucial raw material with diverse applications, primarily utilized in producing phosphoric acid and fertilizers. However, dolomitic impurities within the ore can greatly impede its effectiveness. Therefore, it is essential to minimize these impurities to the lowest feasible levels to mitigate their adverse effects. This ensures optimal performance and quality in various industries reliant on phosphate, promoting efficiency and sustainability in the production process. Through a comprehensive assessment, it becomes feasible to gauge the enrichment potential and propose viable methods to realize it. Among these methods, flotation stands out as one of the most effective for enhancing phosphate ore, despite its inherent drawbacks of costliness and environmental impact stemming from chemical reagents. This study endeavors to investigate the feasibility of employing electrostatic separation as an alternative method for enriching phosphate ore sourced from the Tebessa region in Algeria. Such exploration aims to offer insights into potentially more sustainable and economically viable approaches to ore enrichment in the region of Bir Elater Wilaya of Tebessa. Tests were carried out using different types of electrostatic separators at the Angouleme site of the PPRIME Institute: a multifunctional metal-belt-type separator, a free-fall plate-electrodes-type separator and an electrostatic separator with coaxial wire–cylinder electrode system. The experimental findings demonstrate significant promise, indicating that electrostatic separation enhanced the P2O5 content from 25% to 29% in an untreated phosphate ore sample. Simultaneously, it efficiently eliminated 82.80% of MgO, achieving a P2O5 recovery rate more than 80% and a yield of 70%. Consequently, employing this method proves effective in reducing the MgO content of the ore to below than 1%, aligning with industrial standards for commercial phosphate products. This underscores the viability of electrostatic separation as a viable and efficient technique in phosphate ore processing, offering substantial improvements in both quality and yield. [ABSTRACT FROM AUTHOR]

In this study, the development of a nano-biocomposite adsorbent based on spent coffee grounds (SCG) and nano-Zirconia (n-ZrO2) was presented to meet the increasing demand for effective and low-cost phosphate adsorbents and contribute to sustainable development goals (SDGs). The adsorption performance of raw SCG and SCG modified with n-ZrO2 (n-ZrO2-mSCG) was tested. The characterization of materials was performed by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), BET surface area analysis, thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), Dispersive X-ray spectroscopy (EDS), and Transmission electron microscopy (TEM). The n-ZrO2-mSCG exhibited superior adsorption capacity compared to SCG. The influences on the adsorption of factors such as initial concentration, pH, stirring time, temperature, and coexisting ions were evaluated. The results showed the maximal adsorption capacity of modified SCG was 15.8 mg/g at pH 2, using a stirring time of 150 mins. Among investigated coexisting anions, sulfate (SO42-) and bicarbonate (HCO3−) affected the phosphate adsorption performance of n-ZrO2-mSCG, when they existed in aqueous solution at predominant levels. The n-ZrO2-mSCG displayed high selectivity toward phosphate and sustained efficacious phosphate adsorption after three successive cycles of adsorption/desorption, proposing a prospective low-cost and reusable adsorbent material for phosphate removal and a potential alternative to conventional fertilizers. [ABSTRACT FROM AUTHOR]

The article discusses the need to revise agricultural methods used during the Green Revolution, which led to a significant increase in cereal yields but also had negative side effects such as environmental pollution and rising fertilizer prices. The focus of the article is on the regulation of phosphate transport in plants, which is crucial for plant growth. The article presents reviews on various aspects of phosphate transport and response mechanisms in plants, including the chemical aspects of phosphate utility, phosphate uptake from the external environment, Pi starvation signaling, shoot-root Pi partitioning, and the balance between phosphate and nitrogen acquisition. The article also highlights the challenges and complexity of understanding these regulatory mechanisms and the potential for advancements in cell biology to provide insights. [Extracted from the article]

Saline-alkali soil is a major threat to global food security. Phosphorus (P) fertilizer is essential for crop growth and yield production. Nevertheless, the optimal phosphate fertilizer application rates for summer maize under coastal saline–alkali soil are still unclear. A field experiment with five phosphate application rates (0, 45, 90, 135, and 180 kg ha−1, referred to as T1, T2, T3, T4, and T5, respectively) was conducted during the 2018–2020 summer maize seasons study the effects of phosphate rates on the grain yield, biomass, and nitrogen (N), P and potassium (K) accumulation, and N, P, and K physiological efficiency (denoted as NPE, PPE and KPE, respectively). Results showed that P application notably improved maize grain and biomass yield, the total uptake of N, P, K, and NPE and KPE across three seasons. As the P addition increased to 135 kg ha−1, the grain yield achieved a maximum of 7168.4 kg ha−1, with an average NPE of 2.15 kg kg−1, PPE of 0.19 kg kg−1, and KPE of 1.49 kg kg−1. However, PPE continuously decreased with the input of phosphate. P application rates exceeding 135 kg ha−1 were not considered effective due to a decline in grain yield, nutrient uptake, and NPE. Furthermore, the effect of the planting season was significant on the total uptake of N and K, and the use efficiency of N, P, and K. TOPSIS revealed that a phosphate application rate of 90–135 kg ka−1 was the optimal pattern for maize production. These results may give a theoretical basis for the phosphate management of maize production in saline–alkali soil. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Removal of phosphate from water is very crucial for protecting the ecological environment since massive phosphorus fertilizers have been widely used and caused serious water deterioration. Thus, we fabricated a series of calcium carbonate–loaded mesoporous SBA-15 nanocomposites with different Ca:Si molar ratio (CaAS-x) as phosphorus adsorbents via a simple wet-impregnation method. The multiply approaches including X-ray diffraction (XRD), N2 physisorption, thermogravimetric mass spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) were used to characterize the structure, morphology, and composition of mesoporous CaAS-x nanocomposites. The phosphate adsorption efficiency of the CaAS-x nanocomposites was studied through adsorption and desorption batch tests. Results showed that the increases of Ca:Si molar ratio (rCa:Si) improved the phosphate removal capacity of CaAS nanocomposites, especially CaAS with the optimum synthesis molar ratio of Ca:Si as 0.55 showed the high adsorption capacity of 92.0 mg·g−1 to high concentration of phosphate (> 200 mg·L-1). Note that the CaAS-0.55 had a fast exponentially increased adsorption capacity with increasing the phosphate concentration and correspondingly showed a much faster phosphate removal rate than pristine CaCO3. Apparently, mesoporous structure of SBA-15 contributed to high disperse of CaCO3 nanoparticles leading to the monolayer chemical adsorption complexation formation of phosphate calcium (i.e., =SPO4Ca, =CaHPO4–, and =CaPO4Ca0). Therefore, mesoporous CaAS-0.55 nanocomposite is an environmental-friendly adsorbent for effective removal of high concentration of phosphate in neutral contaminated wastewater. [ABSTRACT FROM AUTHOR]

The productive potential of soils in tropical regions is limited by the low availability of nutrients, especially phosphorus (P). Owing to soil physicochemical characteristics, a substantial part of the amount provided through fertilization is unavailable for plants. Despite numerous studies, disagreements remain regarding the best way to use the various phosphate sources available in Brazil. The objective of this study was to evaluate soybean yield, yield components, and P concentration under different phosphate fertilizer sources and rates in two soil types. Triple superphosphate (TSP) provided the highest grain yield and shoot dry weight, while Supraphos and Algerian natural phosphate (NPAr) showed intermediate values. Mehlich-1 and resin extractants were highly correlated with each other and were efficient in the evaluation of available P. The agronomic efficiency index (AEI) and triple superphosphate equivalent (EqTSP) were better in sandy soil. At the highest P rate (200 mg kg−1), the NPAr and Supraphos sources tended to match the activity of TSP. [ABSTRACT FROM AUTHOR]

Phosphate solubilizing microorganisms (PSMs) in soil have been shown to reduce mineral phosphate fertilizer supplementation and promote plant growth. Nevertheless, only several P-solubilizing microorganisms capable of solubilizing both organic and mineral sources of soil phosphorus have been identified up to now. The aim of this study was to evaluate the inorganic soil phosphate solubilizing activity of phytate-hydrolyzing Pantoea brenneri soil isolates. We showed that the strains efficiently solubilize a variety of inorganic phosphates. We optimized the media composition and culturing conditions to improve the solubilization efficiency of the strains and investigated the mechanisms of their phosphate solubilization. Through HPLC analysis, it was determined that P. brenneri produce oxalic, malic, formic, malonic, lactic, maleic, acetic, and citric acids as well as acid and alkaline phosphatases while growing on insoluble phosphate sources. Finally, we analyzed the influence of P. brenneri strains with multiple PGP-treats on plant growth in greenhouse experiments and showed their ability to promote growth of potato. [ABSTRACT FROM AUTHOR]

Phosphorus recovery is indispensable due to the rapid depletion of its natural reserves and excessive utility in agriculture. Though human urine has high nutrient content including phosphate, nitrogen and potassium; direct use as a fertilizer is restricted due to hygienic, environmental, social and ethical issues. To overcome these limitations, the nutrients are precipitated by the external addition of magnesium (Mg) to form a slow-releasing fertilizer called struvite. The present study aims to maximize phosphate recovery through optimizing struvite production by an emerging electrocoagulation technique. A maximum of 95% phosphate recovery was achieved using inter-electrode distance of 0.5 cm, 2 A current from undiluted urine using Mg–Mg electrodes in a reaction time of 30 min. Further, kinetic modeling of phosphate recovery through electrocoagulation was conducted to comprehend the intended mechanism through the order of kinetics. The results revealed that the data best correlated with first-order kinetics with a correlation coefficient of 0.95. Electrocoagulation improved the supernatant quality by reducing the ion concentrations other than phosphate (30–50%), salinity (40–45%), and microbial population (99%). Qualitative assessment of the precipitate through sophisticated analysis further confirmed the presence of struvite crystals. [ABSTRACT FROM AUTHOR]

Nitrates and phosphates, found in fertilizers, are the most common eutrophication-causing agents. Douglas fir biochar (BC), a syngas byproduct, was treated with different Al/Mg ratios of sulfate (5% w/w metal loading) followed by an NaOH treatment. The greatest phosphate uptake at 25 °C and pH 7 was attributed to the composite with a Mg/Al 2:1 ratio prepared at pH 13 (AMBC). Batch AMBC phosphate uptake was optimized for initial pH, equilibrium time, temperature, and initial phosphate concentration. Phosphate removal following pseudo-2nd-order kinetics and increases gradually before reaching a max at pH 11, with 95% phosphate uptake in 15 mins. The Sips isotherm model provided the best sorption data fit resulting in a 42.1 mg/g capacity at 25 °C and pH 11. Endothermic and spontaneous adsorption were determined using van 't Hoff's plots. BET, XRD, XPS, SEM, TEM, and EDS were used to characterize the biochar before and after phosphate sorption. Used AMBC has the potential to be exploited as a phosphate fertilizer as a key part of an environmentally friendly agricultural management plan. [ABSTRACT FROM AUTHOR]

A novel strategy for reclamation and reuse of phosphate from aqueous solution was developed using Mg-enriched biochar prepared from anaerobically digested sludge (ADBC). The ADBC pyrolyzed at 600°C (ADBC-600) exhibited the maximum phosphate removal capacity of 23.2 mg/g, which was much higher than that of raw sludge biocha (10.1 mg/g). Adsorption kinetic and isotherm experiments showed that the adsorption of phosphate on ADBC-600 could be well described by the pseudo-second-order model and Langmuir model, indicating that the adsorption was mainly dominated by chemisorption process. The postsorption characterization results suggested that Mg-induced precipitation was likely the main P adsorption mechanism by ADBC. Moreover, the spent biochar was re-utilized as an efficient phosphate fertilizer for improving wheat seed germination and growth. Provided a sustainable and eco-friendly strategy for sludge treatment and phosphate recovery in wastewater treatment plants (WWTPs) and potential agronomic application. [ABSTRACT FROM AUTHOR]

Phosphorous (P) is a nonrenewable and one of the most important macronutrients for all living organisms. The formation of complexes with cations such as Al, Fe, and Ca reduces the solubility of P leading to limiting the absorption of P by plants. Therefore, we need to apply excessive amounts of P through conventional fertilizers. However, plants can use only a small portion of P of these added fertilizers whenever those become unavailable. Therefore, utilizing excess amounts of phosphate as fertilizers can lead to various environmental issues like eutrophication. Phosphate-solubilizing microorganisms (PSM) have the ability to solubilize soil phosphate through the production of organic acids, inorganic acids, enzymes, protons, siderophores, and exopolysaccharides resulting in the absorption of P by plants. The application of PSM has the potential to be used as an efficient, eco-friendly, and sustainable approach that can replace traditional fertilizers. This review aimed to give an overview of the diversity of PSM, methods of P solubilization, current trends, and technological advances that can assist in using PSM to achieve Sustainable Development Goals (SDGs). [ABSTRACT FROM AUTHOR]

Phosphorus raw materials are non-renewable, and their resources are shrinking faster and faster as a result of increased fertilizer production. This is due to the increasing population and the need to produce more food. Phosphorus, on the other hand, is one of the main nutrients of plants, without which it is impossible to conduct intensive agricultural production. There are no economically significant phosphate resources in Europe, so they must be imported. That is why it is so important to reduce losses and recover this element from waste streams, which was reflected in the new EU Regulation 2019/1009. A prospective option is to use waste phosphates from the production of polyether polyols. Previous studies show that they contain about 20% phosphorus. Due to their high water content, the most advantageous form of their application is the production of fertilizers in the form of a suspension. The aim of the study is to assess the possibility of using waste phosphates from the production of polyols as raw materials for the production of suspension fertilizers. [ABSTRACT FROM AUTHOR]

This study explored the potential application of silica nanoparticles (SiNPs) prepared from rice husk ash (RHA) to reuse phosphate from aqueous solution. The physicochemical analysis illustrated that the SiNPs, which were extracted from waste biomass, have a nonuniform shape with a size range of a few nanometer to hundreds of nanometers, a surface area of 15.56 m2·g−1, and an adsorption pore width of 4.06 nm. Those results carried out the possibility to utilize the SiNPs for removal of phosphate. Findings from the batch sorption experiments showed that the phosphate adsorption was controlled by experimental parameters, i.e., pH, adsorbent dosage, concentration of adsorbate, and adsorption time. The experimental results showed that the maximum phosphate adsorption capacity of SiNPs was achieved at around 9.08 mg·g−1 at adsorption conditions, i.e., pH 7, SiNPs dosage of 0.3 g, and adsorption time of 90 min. The phosphate removal based on SiNPs will offer several benefit such as an effective and low cost method, reliable to reuse as an effective slow release phosphate fertilizer. [ABSTRACT FROM AUTHOR]

Aims: Many soils in the developed world have been fertilized with phosphate for several decades. Appreciable phosphate has accumulated in such soils. This is referred to as "legacy P". The benefits of legacy P are not widely appreciated. Here, we report the effects of legacy P on buffering capacity and the consequent effects on the effectiveness of plant growth, and its effects on the continuing reaction between soil and P and the consequent effects in decreasing the decline of P effectiveness with time. Methods: We produced five levels of legacy P by incubating the soil with added phosphate at high temperatures for 30 days. We then measured the effect on sorption/desorption and on plant growth in response to further additions of phosphate. Results: Legacy P decreased soil buffering capacity, decreased hysteresis of desorption, and increased the amount of P in a similar state to that of the recently sorbed P. There were analogous effects of plant growth; effectiveness of P fertiliser increased; the decline in effectiveness with time decreased; and the amount of soil P accessible to plants increased. We think that soil tests reflect only the amount of soil P accessible to plants. Soil testing services which include estimates of phosphate buffering reflect its decrease and the consequent increase in fertilizer effectiveness. We propose a simple test to reflect the rate of decline in effectiveness with time. Conclusions: Managing phosphate applications using soil tests alone underestimates phosphate status and leads to over application of phosphate. It is necessary to also include estimates of the change in phosphate buffering and the change in the rate of decline in effectiveness with time. A simple way to estimate the rate of decline is suggested. [ABSTRACT FROM AUTHOR]

Copyright of Rudarsko-Geolosko-Naftni Zbornik is the property of Faculty of Mining, Geology & Petroleum Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective was to evaluate the morphological, productive and chemical characteristics of Crotalarias juncea, spectabilis and ochroleuca, and pigeon pea (Cajanus cajan) submitted to phosphate fertilization levels. The experimental design used was completely randomized in a 4 × 4 factorial scheme, with four doses of phosphorus (0, 100, 200, 300 kg ha−1 of P2O5) and four legume cultivars (Crotalaria juncea, Crotalaria spectabilis, Crotalaria ochroleucaanda and Cajanus cajan), with four repetitions. There was no interaction between the levels of phosphate fertilizer and the legume species for the productive characteristics studied. There was a positive linear effect for leaf dry matter production, stem dry matter production and total dry matter production as a function of phosphate fertilization. There was a positive linear effect for the levels of leaf crude protein, with enhanced levels of phosphorus. There was greater fertilizer efficiency in legumes, at a dose of 100 kg ha−1, with a response of 11.46 kg ha−1 for leaf dry matter production and 33.40 kg ha−1 for total dry matter production. Among legumes, Crotalaria spectabilis is recommended due to the higher total dry matter and leaf productivity, greater number of nodules, and better chemical composition and digestibility. [ABSTRACT FROM AUTHOR]

Phosphate-solubilizing bacteria (PSB) can alleviate available phosphorus deficiency without causing environmental pollution, unlike chemical phosphate fertilizers. However, the phosphate solubilization mechanisms of PSB are still unclear. Transcriptome sequencing was used to analyze the expression patterns of differential expressed genes (DEGs) of the phosphate-solubilizing bacterium W134 under the conditions of soluble phosphorus (group A), insoluble phosphorus (group B), and lacking phosphorus (group C). Nine DEGs in three different groups were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Then, high performance liquid chromatography (HPLC) was applied to detect the concentrations and composition of organic acids. Compared with group A, Gene Ontology (GO) annotation showed that the cluster of W134 DEGs in groups B and C were basically the same. Besides, the results of enrichment Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway indicated that genes in the Citrate cycle (TCA cycle) pathway closely related to organic acid production were significantly upregulated. The qRT-PCR results were almost consistent with the expression trends of the transcriptome data. The HPLC results showed that the formic acid, ascorbic acid, acetic acid, citric acid, and succinic acid concentrations were significantly increased in group B and C (p < 0.05), while the contents of lactic acid and malic acid were significantly increased in group B (p < 0.05). The above results provided further validation that the upregulated genes should be related to W134 secretion of organic acids. Our study revealed several potential candidate genes and tried to explain phosphate solubilization mechanisms. This provides a new insight for calcareous reclaimed soil, and it will reduce the need of chemical phosphate fertilizers to promote environmentally friendly agriculture. [ABSTRACT FROM AUTHOR]

[Display omitted] • A closed-loop anion recovery process from phosphogypsum leachate was proposed. • 98.80 % of fluoride, 99.91 % of phosphate and 99.89 % of sulfate were recovered. • The effluent met the discharge standards in phosphate fertilizer industry. • Detailed insights during the recovery process have been discussed. Phosphogypsum (PG) is a large-scale industrial by-product generated during the production of phosphoric acid, typically being deposited in landfills worldwide. The leaching of fluoride (F−), phosphate (PO 4 3−), and sulfate (SO 4 2−) anions from PG into water bodies through rainfall results in significant environmental pollution. Herein, we propose a stepwise precipitation combined with electrodialysis and crystallization strategy for efficient recovery and valorization of multiple anions from PG leachate. Our method demonstrates effectiveness both theoretically and practically. Consequently, fluoride anions were precipitated as CaF 2 and Ca 5 (PO 4) 3 F at pH 4.7, with a recovery rate of 98.80 %; phosphate anions as MgNH 4 PO 4 ·H 2 O at pH 8.5, with a recovery rate of 99.91 %; and sulfate anions through electrodialysis and crystallization with a recovery efficiency of 99.89 %, ensuring effluent met discharge standards. In addition, the concentrated sulfate-rich solution was employed for electrochemical production of persulfate, yielding ammonium persulfate salts after cooling crystallization. Our integrated approach for multiple anion recovery from PG leachate offers significant environmental and economic benefits, providing valuable insights and references for future research and practical production. [ABSTRACT FROM AUTHOR]

The limited resources of phosphorus raw materials, which are located outside of Europe, make it necessary to obtain phosphorus from the waste stream. This is reflected in the new EU Regulation 2019/1009, which concerns making fertilizing products available on the market. Its main goal is to harmonize the standards for fertilizers obtained from organic or secondary raw materials in the EU and to create new opportunities for their production and sale. The fertilizer sector uses almost 90% of the phosphorus raw material, for which there is no substitute, and the demand for fertilizers is constantly growing, stimulated by the growing number of people. A substitute for expensive imported raw materials can be waste sodium–potassium phosphate from the production of polyols. This study analyzes the composition and form of waste from PCC Rokita S. A. from Brzeg Dolny in Poland, in terms of the possibility of using it in the production of fertilizers according to the new EU regulations. Research shows that it contains nearly 19% phosphorus, as well as potassium and sodium. Low-level impurities and low organic matter content classify it as a raw material for the production of inorganic fertilizers. Due to the high water content, the most advantageous form of its use is the production of fertilizers in the form of a suspension. A certain difficulty in the production of this type of fertilizer may be the layers of crystals of different sizes precipitating in the waste. [ABSTRACT FROM AUTHOR]

Background. The enterprises "Maxam-Chirchiq", "Navoiyazot", "Farg`onaazot", "Ammofos-Maxam", "Qo`qon superfosfat zavodi", "Dehqonobod kaliyli o`g`itlar zavodi", "Elektrokimyozavod" produce mineral fertilizers, for which the actual problem is the development of technologies for mono- and dicalcium phosphate fertilizers. Purpose. Obtaining NPCa-fertilizer based on the decomposition of the Kyzylkum phosphorus concentrate (MOFC) with nitric acid. Methodology. The filtration of the nitrate-calcium-phosphate pulp formed from MOPA with nitric acid was used; monocalcium phosphate was obtained by neutralizing the liquid phases with ammonia. Originality. It has been shown that to improve filtration, the nitro-calcium-phosphate pulp was settled, the main fraction settled by 80%, forming 4-7% of the thickened part of the total mass of the pulp; the rest is filtered and separated into solid and liquid phases. Findings. The decomposition processes were carried out on the basis of adding 55% nitric acid to MOPA at a rate of 80-120%, the ratio T : L = 1 : (2.5-3.3), a temperature of 40°C and a process duration of 40 minutes. Mono- and dicalcium phosphate fertilizers have been obtained. [ABSTRACT FROM AUTHOR]

Ammonium in landfill leachates is a major contributor to environmental degradation if not effectively treated. However, it could be converted to a valuable fertilizer when it is co-precipitated with phosphate and magnesium as struvite. Low-cost magnesium and phosphate sources are sought to offset the co-precipitation treatment costs, but most of the identified alternative magnesium sources have significant amounts of calcium, which may negatively impact the ammonium removal rates. In this study, the effects of calcium on ammonium removal from high-strength aged field landfill leachate as struvite were investigated. Laboratory-scale batch tests were conducted to assess the effects of the pH, Mg2+:NH4+:PO43−, and Ca2+:Mg2+ molar ratios on ammonium removal. Magnesium chloride salt was used as a model dissolved magnesium source, whereas different compounds derived from dolomite (CaMg(CO3)2) were used as model solid-phase magnesium sources. X-ray powder diffraction and activity ratio diagrams were used to delineate the ammonium removal mechanisms and struvite stability. The ammonium removal rate of the magnesium salt decreased from approximately 97% to 70%, upon increasing the Ca2+:Mg2+ molar ratio from 0 to 1.0, for the Mg2+:NH4+:PO43− molar ratio of 1.25:1:1.25 and pH = 9.5. For similar pH values, as well as the Mg2+:NH4+:PO43− and Ca2+:Mg2+ molar ratios, the ammonium removal rates by the dolomite-derived compounds reached up to 55%, which highlighted the limited availability of magnesium in solid phases, in addition to the negative impacts of calcium. The diffractometric analysis and thermodynamic calculations revealed the stable regions of struvite in the presence of competing solid phases. The new findings in this study could aid in the design of ammonium and phosphate removal and recovery systems by struvite precipitation. [ABSTRACT FROM AUTHOR]

Precipitation of mineral phosphates from wastewater treatment processes is an excellent method for phosphorus recovery, leading to the formation of compounds with high fertilizing value. Conventionally, P-precipitation processes are mostly applied to supernatant of anaerobic sludge digestates, due to their high P and N residual contents. This study concerns P-recovery in a pilot-scale side-stream reactor from aerobic (activated sludge) wastewater liquor. The effect of process retention time and pH was determined using sodium hydroxide and calcium hydroxide as alternative pH buffer reagents, in both synthetic and real wastewater. Equilibrium mass balance calculations were first applied to estimate the theoretical final composition of P-precipitates under different process conditions; then, actual precipitation experiments were carried out with synthetic wastewater to define optimal process operating parameters in controlled conditions. Results showed that phosphorus precipitation was affected mainly by solution pH and did not significantly depend on the reactor's retention time. These findings were validated by operating the process with real wastewater: on average, 61.2% and 90.4% phosphorus precipitation (recovery) were achieved at pH = 8.5 and 9.0 under a controlled Mg:NH4:P molar ratio of 5:5:1, using sodium hydroxide as acidity buffer. The main fraction of final precipitates consisted of calcium phosphate compounds, while struvite, bobierrite and calcite showed up in smaller proportions. It was also shown that dosage of calcium hydroxide for pH adjustment, without any other chemicals for molar ratios adjustment of the solution, has great potential for P recovery in the form of a calcium phosphate-rich precipitate, usable for fertilizer, with 75.6% phosphorus removal in mineral form at pH = 8.5. The process is much less costly to operate than struvite precipitation, and more energetically sustainable. This scheme could be ideally suited for application in facilities operating under an enhanced phosphorus removal process scheme. [ABSTRACT FROM AUTHOR]

• A novel adsorbent was prepared from eggshell and fly ash for p adsorption. • The proportion of eggshells affects the final product of the adsorption process. • EFG has an excellent phosphorus adsorption capacity of up to 49.92 mg P/g. • The EFG remains intact morphological structure after the adsorption process. Fly ash (FA) and eggshells (ES) are common solid wastes with significant potential for the recovery of phosphorus from water. This study focuses on synthesizing a low-cost and environmental-friendly phosphate adsorbent called eggshell-fly ash geopolymer composite (EFG) using eggshells instead of chemicals. The CaO obtained from the high-temperature pyrolysis of eggshells provides active sites for phosphate adsorption, and CO 2 serves as a pore-forming agent. The phosphate adsorption performance of EFG varied with the eggshell-fly ash ratios and achieved a maximum of 49.92 mg P/g at an eggshell-fly ash ratio of 40 %. The adsorption process was well described by the pseudo-second-order model and the Langmuir model. EFG also exhibited a good regeneration performance through six-cycle experiments and achieved the highest phosphate desorption at pH 4.0. The results of the column experiment showed that EFG can be used as a filter media for phosphorus removal in a real-scale application with low cost. Soil burial test indicated saturated EFG has a good phosphate slow-release performance (maintained for up to 60 days). Overall, EFG has demonstrated to be a promising adsorbent for phosphorus recovery. [Display omitted] [ABSTRACT FROM AUTHOR]

Efficient phosphate and ammonium removal is crucial to control eutrophication. With the gradual development of green chemical engineering, the reutilization of by-products following nutrient removal is becoming a new hotspot. Magnesium-based biochar composites are envisaged to play a significant role as media in green chemical engineering. In this study, ultrasonic cavitation was used to enhance the adsorption sites of magnesium-based biochar composites, improving their adsorption capacity for ammonium and phosphate, and their ability for green recycling. The resulting ultrasonic magnesium-based biochar composite (UMBC) was characterized for its ability to adsorb ammonium and phosphate and reusability through batch experiments. 1200 W and 60 min (UMBC-5) was demonstrated as the optimized ultrasonic power and time, respectively, for the modification of magnesium-based biochar (MBC) through carbon bond breakage. With increasing ultrasonic power and time (from UMBC-1 to UMBC-5), the removal rate (RR) of phosphate saw an improvement from 93.0% to 96.6%, while the RR of ammonium substantially increased from 23.9% to 50.6%. Both pseudo-first-order and pseudo-second-order kinetic models fitted the ammonium and phosphate adsorption process on UMBC-5 well. Ultrasound greatly affected electrostatic attraction between ammonium and UMBC-5 via improving the surface hydrophilic functional groups. The main forms of NP-loaded UMBC-5 are phosphate (58.4%) and struvite (15.51%, high-quality slow-release fertilizer). It not only efficiently recovered nutrients but also significantly increased plant fresh biomass and soil moisture through the combination of abundant hydrophilic functional groups, achieving the green recycling of adsorbate by-products. [Display omitted] • The optimal condition to get the highest removal rate of biochar was 1200 W for 60 min. • The removal rate of phosphate was 96.6%, and that of ammonium was 50.6%, on UMBC-5. • Protonation, ligand exchange, electrostatic interaction, were enhanced by ultrasound. • The N-P @ UMBC-5 can serve as a nutrient carrier, enabling eco-friendly reuse. [ABSTRACT FROM AUTHOR]

The residual responses of crops to phosphate fertilizers in weathered soils depend on the mineralogy and the nature of the phosphate reaction residue formed by soil–phosphate interactions. The study examined the metastable phosphate residues formed from soil-phosphate interactions along a tropical semi-arid toposequence by solubility criteria principles after soil-phosphate incubation for 28 weeks. The powder X-ray diffraction of the sand and silt-sized particles showed the dominance of K-feldspars in association with quartz and muscovite, while the oriented clay fractions indicated a preponderance of kaolinite and illite derived from the weathering of K-feldspars that were the surviving primary silicates in the soils. Soil-phosphate incubation with 12.5 mmol P kg−1 for 28 weeks showed, by the 7th week, phosphate, H P O 4 2 − , activities in apparent equilibrium with montgomeryite, Ca2Al2(PO4)3(OH).7(H2O), solubility at pH ≥ 6.0. After 28 weeks, the HPO42- activities were in apparent equilibrium with hydroxyapatite, Ca5(PO4)3OH at the pH range of 6.5 to 7.2. The study provides an indirect evidence of the existence of montgomeryite as the potential metastable phosphate residue of soil-phosphate reactions in these slightly acid tropical semi-arid soils, before reverting to the more stable hydroxyapatite with time. [ABSTRACT FROM AUTHOR]

As the awareness on the ecological impact of chemical phosphate fertilizers grows, research turns to sustainable alternatives such as the implementation of phosphate solubilizing bacteria (PSB), which make largely immobile phosphorous reserves in soils available for uptake by plants. In this review, we introduce the mechanisms by which plants facilitate P-uptake and illustrate how PSB improve the bioavailability of this nutrient. Next, the effectiveness of PSB on increasing plant biomass and P-uptake is assessed using a meta-analysis approach. Our review demonstrates that improved P-uptake does not always translate in improved plant height and biomass. We show that the effect of PSB on plants does not provide an added benefit when using bacterial consortia compared to single strains. Moreover, the commonly reported species for P-solubilization, Bacillus spp. and Pseudomonas spp., are outperformed by the scarcely implemented Burkholderia spp. Despite the similar responses to PSB in monocots and eudicots, species responsiveness to PSB varies within both clades. Remarkably, the meta-analysis challenges the common belief that PSB are less effective under field conditions compared to greenhouse conditions. This review provides innovative insights and identifies key questions for future research on PSB to promote their implementation in agriculture. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is one of the most important elements used in fertilizing soils in tropical regions due to the low efficiency of phosphate fertilization. This work aimed to fractionate inorganic P (Pi) in tropical soils of different mineralogical compositions and to relate these fractions with their respective phosphate buffer capacity (PBC) indicators. The soils were characterized physically, chemically and mineralogically. Additionally, we evaluated the P concentration that remained in solution of soil after equilibrium was met; this was termed P remaining (P-rem). In general, the Pi fractions of soils did not correlate with the PBC indicators. The P-H2O fraction showed a negative correlation with the P-Al fraction. Ferric minerals did not influence P fixation. P-rem showed a strong correlation with the maximum P adsorption capacity, adsorption energy, and the amorphous and crystalline forms of Fe. The minerals of aluminum contributed the most to P fixation. P-rem was the best estimator of PBC. The soils with high, moderate and low rates of P fixation showed high amounts of the fractions P-Al, P-Ca, and P-Fe, respectively. The results showed that P fixation was influenced by the fractions of P in the soil, suggesting that the efficiency of phosphate fertilizers in tropical soils depends on the mineralogy of the clay fraction within those soils. [ABSTRACT FROM AUTHOR]

Copyright of Egyptian Journal of Experimental Biology (Botany) is the property of Egyptian Society of Experimental Biology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The object of research in this work is model aqueous solutions containing phosphate ions. Phosphorus is an essential nutrient for all life forms and determines the trophic state of freshwater ecosystems. The existing problem is that when excessive phosphorus enters water bodies, it causes their eutrophication, and, as a result, the accumulation of biotoxins, deterioration of water quality, death of aquatic organisms, etc. Phosphorus comes to surface water from domestic wastewater containing phosphates as components of synthetic detergents, photoreagents and water softeners. A significant contribution is made by the washout of phosphate fertilizers and pesticides from agricultural land, and runoff from livestock farms and industrial enterprises. Among the methods of wastewater treatment from phosphates, a special place is occupied by sorption. An analysis of modern scientific publications on this topic shows that the search for new effective sorbents obtained using resource-saving technologies is an important scientific and practical problem. The work was aimed precisely at the search for such sorbents. Iron is known to have a high affinity for phosphate. Therefore, the paper proposes to use the sediments of groundwater iron removal stations as a sorbent. These sludges are produced in significant quantities and create significant environmental problems. The sorption of iron-containing sorbent, which is a waste of iron removal stations with respect to phosphate ions, has been studied. It has been established that this sorbent is effective for extracting phosphate ions from water with an adsorption capacity of 72.67 mg/g. The sorption process is quite accurately described by the pseudosecond order sorption kinetic equation (determination coefficient R² = 0.9737). The rate constant of the sorption process was calculated to be 3.8·10–4 g/mg PO43–·min1/2. The use of the proposed sorbent will allow solving two environmental issues: replenishment of the list of cheap effective sorbents for removing phosphates and utilization of sludge from iron removal stations. [ABSTRACT FROM AUTHOR]

Rock phosphate is the fundamental component for the manufacture of phosphoric acid and phosphate fertilizers. The aim of this study is to predict how sample preparation of Kef Essennoun phosphate responds to heat treatment and to estimate the purity of the raw and calcined phosphates. The influence of temperature (600–900 °C) was evaluated. The evolution of thermal treatment and the characterization of the Kef Essennoun ore (Djebel Onk mine, Algeria) were carried out by various analytical techniques including X-ray diffraction (XRD), wavelength-dispersive X-ray fluorescence, Fourier-transform infrared spectroscopy, thermogravimetric analysis/differential thermal analysis, and scanning electron microscopy (SEM). The results showed that the raw phosphate is a mixture of six phases, of which carbonate hydroxyapatite [Ca10(PO4)3(CO3)3(OH)2] is the dominant phase. With heat treatment, at 700 °C, a fluorapatite [Ca5(PO4)3F] phase appeared, as confirmed by XRD analysis, with good crystallization indicated by SEM. The P2O5 content was increased from 28.389% in raw phosphate to 31.085% in the calcined product. The dissolution of the calcined phosphate at 900 °C was completed by HNO3 acid attack, and occurred rapidly at ambient temperature. The results show that the production of phosphoric acid by Ca5(PO4)3F was more easily achieved with optimized consumption of the acid attack. [ABSTRACT FROM AUTHOR]

The evaluation of phosphorus (P) transformations in soil after application of manure or mineral P can improve soil management and optimise P use by plants. The objectives of the present study were to assess organic and inorganic P forms in two soils treated with dairy manure and triple superphosphate and to establish relationships between soil P fraction levels and P availability. Soil organic and inorganic P fractions were quantified using a pot experiment with two soils, a typical Hapludox and an arenic Ffapludult, with three types of fertiliser treatments applied (no fertiliser application, application of dairy manure, and application of triple superphosphate, by adding 100 mg P d[m.sup.-3] in the form of fertiliser in the two latter treatments) and four incubation times (15, 45, 90, and 180 days). Inorganic P was fractionated into aluminium-bound, iron-bound, occluded, and calcium-bound P. Organic P was extracted sequentially using sodium bicarbonate, hydrochloric acid, microbial biomass, sodium hydroxide, and residual organic P. After incubation, maize plants were cropped to quantify dry matter yield and absorbed P. Application of dairy manure resulted in a significant increase in most of the organic P fractions, and application of triple superphosphate led to a significant increase in inorganic P fractions. Both fertilisers raised labile organic P fractions in the two soils. The major sinks of P in Hapludox were occluded and fulvic acid-associated P. In contrast, the major sink of P in Hapludult was iron-bound P. The available P levels were stable after application of dairy manure, and decreased with time when fertilised with triple superphosphate. In the Hapludox, the organic P fractions had a significant positive correlation with P uptake by plants. The results suggest that organic P mineralisation plays a more significant role in plant P uptake in the Hapludox soil and inorganic P forms are the main contributors to plant P uptake in the Hapludult soil. Additional keywords: nuclear magnetic resonance, organic fertiliser, phosphorus availability, phosphorus pools. Received 1 November 2018, accepted 12 December 2019, published online 20 January 2020, Introduction Manures can be an important source of plant nutrients and are frequently used as fertilisers in agriculture. Cattle manure is commonly applied to soil as a source of nitrogen [...]

Novel adsorbents that remove P from contaminated waters can be potentially used as slow release P-fertilizers. In this study, Mg-Al layered double hydroxide (Mg-Al-LDH) and Mg-Al-LDH functionalized apple wood biochar and hydrochar were prepared to remove phosphate from aqueous solutions and then P-loaded LDH-biochar/hydrochar composites used as fertilizers for maize production in calcareous soils under controlled conditions. After five successive desorption cycles, the LDH, LDH-biochar, and LDH-hydrochar desorbed 18, 22, and 27% of adsorbed-P into a 0.03 M KCl solution, respectively, while, these adsorbents desorbed 52, 63, and 66% of adsorbed-P into a 0.1 M Na2CO3 solution, respectively. Additionally, increasing solution pH from 3.0 to 10 increased P desorption. The results revealed that the P-loaded LDH-biochar and LDH-hydrochar significantly increased available-P, maize shoot and root dry matters, and P uptake as compared with control. The integration of monocalcium phosphate fertilizer with ‎biochar, hydrochar, LDH-biochar, and LDH-hydrochar increased available-P, ‎maize shoot and root dry matters, and P uptake; while P integration with P-loaded LDH-biochar/hydrochar decreased shoot dry matter. Therefore, the P-loaded LDH-biochar/hydrochar can be added to soil as P-fertilizers without any chemical P-fertilizer. Application of biochar, hydrochar, and LDH-biochar/hydrochar accompany with chemical P-fertilizers is recommended to increase available-P and maize growth. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/Mg-LDH was dispersed on commercial high surface area Douglas fir biochar (LDHBC). • LDHBC phosphate capacity (1279 mg/g) was six-fold greater than LDH (234 mg/g). • 1 M NaOH stripped phosphate but reduced following P uptake. • Ion-exchange, chemisorption and precipitation mechanisms were considered. Phosphate is a primary plant nutrient, serving integral role in environmental stability. Excessive phosphate in water causes eutrophication; hence, phosphate ions need to be harvested from soil nutrient levels and water and used efficiently. Fe-Mg (1:2) layered double hydroxides (LDH) were chemically co-precipitated and widely dispersed on a cheap, commercial Douglas fir biochar (695 m2/g surface area and 0.26 cm3/g pore volume) byproduct from syn gas production. This hybrid multiphase LDH dispersed on biochar (LDHBC) robustly adsorbed (~5h equilibrium) phosphate from aqueous solutions in exceptional sorption capacities and no pH dependence between pH 1–11. High phosphate Langmuir sorption capacities were found for both LDH (154 to 241 mg/g) and LDH-modified biochar (117 to 1589 mg/g). LDHBC was able to provide excellent sorption performance in the presence of nine competitive anion contaminants (CO 3 2–, AsO 4 3−, SeO 4 2−, NO 3 –, Cr 2 O 7 2−, Cl−, F−, SO 4 2−, and MoO 4 2−) and also upon remediating natural eutrophic water samples. Regeneration was demonstrated by stripping with aqueous 1 M NaOH. No dramatic performance drop was observed over 3 sorption-stripping cycles for low concentrations (5 ppm). The adsorbents and phosphate-laden adsorbents were characterized using Elemental analysis, BET, PZC, TGA, DSC, XRD, SEM, TEM, and XPS. The primary sorption mechanism is ion-exchange from low to moderate concentrations (10–500 ppm). Chemisorption and stoichiometric phosphate compound formation were also considered at higher phosphate concentrations (>500 ppm) and at 40 °C. This work advances the state of the art for environmentally friendly phosphate reclamation. These phosphate-laden adsorbents also have potential to be used as a slow-release phosphate fertilizer. [ABSTRACT FROM AUTHOR]

There is a strong impetus to establish a circular phosphorus economy by securing internally renewable phosphate (Pi) resources for use as agricultural fertilizers. Reversible Pi adsorption technologies such as ion exchange can remove and recover Pi from water/wastewater for reuse. However, existing reversible adsorbents cannot effectively discriminate against arsenate (As(V)) due to the similarity between As(V) and Pi chemical structure. If As(V) is co‐recovered with Pi, the value of the recovered products for agricultural reuse is low. The objective of this study was to construct an immobilized phosphate‐binding protein (PBP)‐based Pi removal and recovery system and analyze its selectivity for Pi adsorption in the presence of As(V). A range of conditions was tested, including independent, sequential, and simultaneous exposure of the two oxyanions to immobilized PBP (PBP resin). The purity of the recovered Pi product was assessed after inducing controlled desorption of the adsorbed oxyanions at high pH (pH 12.5). Pi constituted more than 97% of the adsorbed oxyanions in the recovered product, even when As(V) was initially present at twofold higher concentrations than Pi. Therefore, PBP resin has potential to selectively remove Pi, as well as release high‐purity Pi free of As(V) contamination suitable for subsequent agricultural reuse. Practitioner points: Existing reversible phosphate (Pi) adsorbents cannot effectively discriminate against arsenate (As(V)) due to the similarity in their chemical structure.Co‐recovery of As(V) with Pi can reduce the recovered product's reuse as a fertilizer.An immobilized phosphate‐binding protein (PBP)‐based system can be highly selective for Pi even in the presence of As(V).Pi constituted more than 97% of the recovered product, even when As(V) was present at 2‐fold higher concentrations than Pi.Immobilized PBP offers advantages over existing Pi adsorbents by providing high‐purity Pi products free of As(V) contamination for reuse. [ABSTRACT FROM AUTHOR]

Phosphate-solubilizing (PS) microbes are important to improve phosphorus availability and transformation of insoluble phosphate, e.g., rock phosphate (RP). The use of phosphate solubilizing bacteria (PSB) as inoculants have been proposed as an alternative to increase phosphate availability in RP and composting fertilizers. In this study, the effect of compound PSB coinoculation and single-strain inoculation on the transformation of insoluble phosphate were compared in a liquid medium incubation and RP-enriched composting. The goal of this study was to understand the possible mechanisms of insoluble phosphate transformation driven by the interactions of compound PS microbes during composting. The correlations between organic acids production, P-solubilization capacity and bacterial community with PSB inoculation were investigated in the RP-enriched composting by redundancy analysis (RDA) and structural equation models (SEM). Results showed that both single-strain and compound PSB inoculants had a high P-solubilization capacity in medium, but the proportion of Olsen P to total P in composts with inoculating compound PS microbes was 7% higher than that with single strain. PS inoculants could secrete different organic acids and lactic was the most abundant. However, RDA and SEM suggested that oxalic might play an important role on PS activity, inducing RP solubilization by changing pH during composting. Interaction between compound microbes could intensify the acidolysis process for insoluble P transformation compared to the single strain. Our findings help to understand the roles of complex microbial inoculants and regulate P availability of insoluble phosphate for the agricultural purposes. [ABSTRACT FROM AUTHOR]

Nutrient distribution and phosphate fertilizers can impact maize growth, but how to match the type of phosphate fertilizer and the application method to enhance root-foraging capacity for phosphorus (P) is unclear. This study was aimed at characterizing the effects of different phosphate fertilizers and placements on maize growth, grain yield, root properties and rhizosphere processes on calcareous soil. A soil column experiment with five different phosphate fertilizers [single superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), urea phosphate (UP) and ammonium polyphosphate (APP)] applied either uniformly or locally 10–20 cm deep in a greenhouse. In addition, a 2-year field experiment with five P fertilizer treatments (non-fertilization and broadcast MAP, DAP, UP or APP) was conducted. In the soil column experiment, localized application of SSP, MAP, UP and APP significantly promoted the growth and P uptake of maize by modifying the root morphology. Localized application of each P fertilizer increased (by up to 74 %) the first-order lateral root density and first-order lateral root length of maize in the fertilizer-enriched layer, resulting in a significant increase in the efficiency of root P acquisition by maize. In the field experiment, the rhizosphere pH of maize supplied with MAP, UP or APP was reduced by 0.5–0.7 units in comparison to DAP in 2018. Compared with MAP and DAP, application of UP or APP in the field did not show significantly improve maize growth and P uptake. These results show that optimizing P fertilizer types and placement modified root morphology and physiology, and consequently promoted maize growth and P accumulation, but further characterization of the localized application of different P fertilizers in the field is needed. Engineering root properties and rhizosphere processes by manipulating fertilizer types and placement improves fertilizer-use efficiency and reduces environmental footprint of food production. • Localized application of SSP, MAP, UP or APP (but no DAP) promoted maize growth. • In P fertilizer patches, the maize 1st lateral root length and density increased. • Localized application of SSP, MAP, UP or APP improved root efficiency for P uptake. • MAP, UP and APP have the potential of decreasing pH in the maize rhizosphere soil. • Root and rhizosphere management improves fertilizer-use efficiency for maize. [ABSTRACT FROM AUTHOR]

In this study, we developed a composite slurry using industrial hazardous solid waste phosphate tailings and yellow phosphorus for the simultaneous removal of SO 2 and NO. Additionally, the migration and transformation of the P element within the slurry were thoroughly investigated. The experimental results revealed that this composite slurry exhibited efficient removal of both SO 2 and NO. Further investigations indicated that Ca 5 (PO 4) 3 F and CaMg(CO 3) 2 within the composite slurry acted as the primary active phases during the SO 2 removal process. On the other hand, the yellow phosphorus (P 4) components facilitated the conversion of O 2 to O 3 , which subsequently oxidized NO to nitrate. Throughout the course of the reactions, significant amounts of the P element in the solid phase (Ca 5 (PO 4) 3 F and yellow phosphorus (P 4) were leached out as PO 4 3−, accumulating in the liquid phase. The resulting solution containing NO 3 − and PO 4 3− could potentially serve as a valuable raw material for the production of nitrogen-phosphorus composite fertilizers. Additionally, a small portion of the P element within the composite slurry was oxidized to P 2 O 5 and released into the gas phase, resulting in a partial loss of the P element. [Display omitted] • Resource of industrial solid waste phosphorus tailings and mud phosphorus. • Mechanism of simultaneous removal of SO 2 and NO by composite slurry. • Enrichment and loss modes in phosphorus transport transformation pathways. [ABSTRACT FROM AUTHOR]

Municipal biosolids contain organic and inorganic phosphorus (P) that could be recovered for reuse as P fertilizer. Inorganic P compounds include iron phosphates that precipitate and/or adsorbed phosphate ions as a consequence of soluble iron addition in order not to exceed total phosphorus (TP) emission limits. The inorganic orthophosphate (o-Pi) minerals within biosolids can have low solubilities. One P recovery strategy is to maximize the dissolution of o-Pi from biosolids for reuse. Dissolving iron phosphates in biosolids by adding sodium sulfide was assessed as an o-Pi dissolution strategy. 10 % w/w biosolids slurries with a total phosphorus (TP) of 0.97 ± 0.03 mmol P/dry g were mixed with sulfide/TP (S2−/TP) molar ratios from 0 to 4 for up to 96 h. The maximum o-Pi concentration (48 ± 7 mM, or 42 ± 6 % of TP) was obtained for 4 S2−/TP after 24 h at room temperature (RT). Iron concentrations measured by colorimetry (ferrozine) reduced from 0.6 ± 0.1 mM to less than 0.01 mM (S2−/TP > 1). X-ray diffraction and FTIR suggest that sulfide treatment preferentially dissolved amorphous o-Pi-containing solids, vivianite, and minerals with iron, aluminum, phosphate, sulfate, and other subsitutions. Poorly crystalline erdite (NaFeS 2 ·2H 2 O) was detected in products after S2−/TP treatment ratios ≥ 2. Incubation at RT or 37 °C did not affect the o-Pi concentrations for 0 or 4 S2−/TP over 47 h. Sulfide addition could also increase the risk of construction material corrosion, and reduce the efficiency of P recovery by precipitation. There are disadvantages to using sulfide to dissolve o-Pi from biosolids as a potential P recovery process. [Display omitted] • Sulfide dissolved vivianite, amorphous, and substituted iron phosphates in biosolids. • Increasing sulfide concentration increased orthophosphate dissolution from biosolids. • Erdite (NaFeS 2.2H 2 O) was identified if the sulphide to total P molar ratios were >1. • The maximum phosphate concentration was 48 ± 7 mM for 10% biosolids, 4 S2−/TP, 24 h. • Sodium sulfide addition may not be an effective P-recovery strategy for biosolids. [ABSTRACT FROM AUTHOR]