Interaction of phosphorus and GA3 improved oilseed flax grain yield and phosphorus-utilization efficiency.

Introduction: Phosphorus nutrition and hormone concentration both affect crop yield formation. Ascertaining the interaction of phosphorus and GA3 has a synergistic effect on the grain yield and phosphorus utilization efficiency of oilseed flax in dryland. It is extremely important for improving grain yield and phosphorus utilization efficiency. Methods: A field experiment was conducted in 2019 and 2020 at the Dingxi Oil Crops Test Station to investigated the effects of phosphorus, gibberellin (GA3), and their interaction on the grain yield and phosphorus-utilization efficiency of oilseed flax plants. Phosphorus fertilizer was applied at three levels (0, 67.5, 135 kg P2O5·ha-1) and GA3 was also sprayed at three concentrations (0, 15, and 30 mg·L-1). Results: The results showed that application of 67.5 kg P2O5·ha-1 reduced leaves acid phosphatase (ACPase) activity, but increased phosphorus accumulation throughout the growth period, the 1000-kernel weight (TKW), and the number of grains per capsule. Spraying GA3 significantly increased the leaves ACPase activity, phosphorus accumulation after anthesis and its contribution to grain, phosphorus-utilization efficiency, the number of capsules per plant, and TKW. The phosphorus accumulation at the anthesis, kernel, and maturity stages under the treatment of fertilizing 67.5 kg P2O5·ha-1 and spraying 30 mg·L-1 GA3 were increased by 56.06%, 73.51%, and 62.17%, respectively, compared with the control (no phosphorus, no GA3). And the phosphorus accumulation after anthesis and its contribution to grain also increased. 67.5 kg P2O5·ha-1 combined with 30 mg·L-1 GA3 and 135 kg P2O5·ha-1 combined with 15 mg·L-1 GA3 both significantly increased grain yield of oilseed flax, reaching 1696 kg·ha-1 and 1716 kg·ha-1 across two years, respectively. And there was no significant difference between them. However, the former treatment significant increased the apparent utilization rate, agronomic utilization rate, and partial productivity of phosphorus. The interaction between phosphorus and GA3 was significant for grain yield. Conclusion: Therefore, the application of 67.5 kg P2O5·ha-1 in combination with 30 mg·L-1 GA3 is an effective fertilization approach for enhancing oilseed flax growth and grain yield in the experiment region and other similar areas.

Insights into starch synthesis and amino acid composition of common buckwheat in response to phosphate fertilizer management strategies.

To investigate the response and the regulatory mechanism of common buckwheat starch, amylose, and amylopectin biosynthesis to P management strategies, field experiments were conducted in 2021 and 2022 using three phosphorus (P) levels. Results revealed that the application of 75 kg hm-2 phosphate fertilizer significantly enhanced amylopectin and total starch content in common buckwheat, leading to improved grain weight and starch yield, and decreased starch granule size. The number of upregulated differentially expressed proteins induced by phosphate fertilizer increased with the application rate, with 56 proteins identified as shared differential proteins between different P levels, primarily associated with carbohydrate and amino acid metabolism. Phosphate fertilizer inhibited amylose synthesis by downregulating granule-bound starch synthase protein expression and promoted amylopectin accumulation by upregulating 1,4-alpha-glucan branching enzyme and starch synthase proteins expression. Additionally, Phosphate fertilizer primarily promoted the accumulation of hydrophobic and essential amino acids. These findings elucidate the mechanism of P-induced starch accumulation and offer insights into phosphate fertilizer management and high-quality cultivation of common buckwheat.

Sustainable regulation of calcium magnesium phosphate and rapeseed cake on soil-tea system in Mount Lushan, China.

Lushan Yunwu tea quality is limited by soil acidity and sterility. This article examined a 3-year localization experiment at 1100 m altitude to demonstrate the sustainable management of conditioners, calcium magnesium phosphate (P), rapeseed cake (C), and combination application (P + C) by one-time application on the soil-tea system in Mount Lushan. The study found that conditioners (P, C, P + C) reduced soil acidification and maintained a pH of 4.75-5.34, ideal for tea tree development for 3 years. Phosphorus activation coefficient (PAC), nitrogen activation coefficient (NAC), and organic matter (OM) content were significantly higher (P < 0.05) in the first year after conditioner treatment, with P + C being the best. After P + C, PAC, NAC, and OM rose by 31.25%, 47.70%, and 10.06 g kg-1 compared to CK. In comparison to the CK, tea's hundred-bud weight (BW), free amino acids (AA), tea polyphenols (TPC), and chlorophyll (Chl) content of P + C treatment got 29.98%, 14.41%, 22.49%, and 28.85% increase compared to that of the CK, respectively. In the second year, the three treatments of P, C and P + C still had significant moderating effects on the physicochemical properties of the soil and the quality indexes of the tea leaves. The PAC of the soil under the three treatments increased by 0.06%, 0.07% and 0.18%, respectively, as compared to the control.P + C increased BW, AA, TPC and Chl of tea for 2 years. Three conditioners had 2-year regulatory impacts on soil fertility indicators, tea output, and quality. C and P + C both increased soil OM by 18.59% and 21.78% compared to CK in the third year, outperforming P treatment. Redundancy analysis revealed that the primary physicochemical factors influencing tea output and quality were soil OM and pH, with available phosphorus, urease, acid phosphatase, and available nitrogen following closely afterwards.

[Effects of phosphorus application rate on distribution of 13C assimilates and spike formation in different til-lers of wheat with supplementary irrigation]. / 补灌条件下施磷量对小麦不同茎蘖13CåŒåŒ–ç‰©åˆ†é åŠå ¶æˆç©—çš„å½±å“.

To clarify the appropriate rate of phosphorus application and physiological mechanism for promoting wheat tillering and efficient utilization of phosphorus fertilizer with supplementary irrigation, we used 'Jimai 22' wheat variety as the test material, to set up three phosphorus application treatments, including low (90 kg P2O5·hm-2, P1), medium (135 kg P2O5·hm-2, P2), and high (180 kg P2O5·hm-2, P3) application rates, with no phosphorus application as the control (P0). We increased the relative soil water content of each treatment at join-ting stage and anthesis stage to 70%, and measured the area of tiller node, the content of endogenous hormones, the number of tillers in each tiller position, photosynthetic parameters, the distribution of 13C assimilates in each stem and tiller, as well as the grain yield and partial productivity of phosphate fertilizer. The results showed that compared with P0 and P1 treatments, P2 significantly increased the area of tiller node and the trans-zeatin (tZ), the photosynthetic parameters of the uppermost expanded leaves of the main stem, the total tillers per plant, and the distribution of 13C assimilates in each tiller. The number of ears per plant was increased by 0.51 and 0.36, and grain yield was increased by 40.3% and 13.2%, respectively. In P3 treatment, the number of tillers increased, but the panicles per plant, and the grain yield and phosphate fertilizer partial productivity decreased. Our results suggested that the moderate phosphorus treatment (135 kg·hm-2) under supplementary irrigation was suitable for high yield and high efficiency of wheat.

Impact of Modifications from Potassium Hydroxide on Porous Semi-IPN Hydrogel Properties and Its Application in Cultivation.

This study synthesized and modified a semi-interpenetrating polymer network hydrogel from polyacrylamide, N,N'-dimethylacrylamide, and maleic acid in a potassium hydroxide solution. The chemical composition, interior morphology, thermal properties, mechanical characteristics, and swelling behaviors of the initial hydrogel (SH) and modified hydrogel (SB) in water, salt solutions, and buffer solutions were investigated. Hydrogels were used as phosphate fertilizer (PF) carriers and applied in farming techniques by evaluating their impact on soil properties and the growth of mustard greens. Fourier-transform infrared spectra confirmed the chemical composition of SH, SB, and PF-adsorbed hydrogels. Scanning electron microscopy images revealed that modification increased the largest pore size from 817 to 1513 µm for SH and SB hydrogels, respectively. After modification, the hydrogels had positive changes in the swelling ratio, swelling kinetics, thermal properties, mechanical and rheological properties, PF absorption, and PF release. The modification also increased the maximum amount of PF loaded into the hydrogel from 710.8 mg/g to 770.9 mg/g, while the maximum % release of PF slightly increased from 84.42% to 85.80%. In addition, to evaluate the PF release mechanism and the factors that influence this process, four kinetic models were applied to confirm the best-fit model, which included zero-order, first-order, Higuchi, and Korsmeyer-Peppas. In addition, after six cycles of absorption and release in the soil, the hydrogels retained their original shapes, causing no alkalinization or acidification. At the same time, the moisture content was higher as SB was used. Finally, modifying the hydrogel increased the mustard greens' lifespan from 20 to 32 days. These results showed the potential applications of modified semi-IPN hydrogel materials in cultivation.

Efficient Recovery of Phosphate from Water Media by Iron-Magnesium Functionalized Lignite: Adsorption Evaluation, Mechanism Revelation and Potential Application Exploration.

Selective phosphorus removal from aquatic media has become an ideal strategy to mitigate eutrophication and meet increasingly stringent discharge requirements. To achieve phosphorus control and resource utilization of low-calorific-value lignite, iron and magnesium salts were used to functionalize lignite, and iron-magnesium functionalized lignite (called IM@BC) was prepared for phosphate recovery from water media. The adsorption properties of IM@BC were systematically evaluated, especially the influence of ambient pH and co-existing ions. The kinetic, isothermal, and thermodynamic adsorption behaviors of IM@BC were analyzed. The adsorption mechanism was revealed by microscopic characterization. The potential application of phosphate-containing IM@BC (P-IM@BC) was explored. The results show that IM@BC has a strong phosphate adsorption capacity, and the maximum adsorption capacity is 226.22 mgP/g at pH = 3. Co-existing CO32- inhibits phosphate adsorption, while coexisting Ca2+ and Mg2+ enhance the effect. At the initial adsorption stage, the amount of phosphate adsorbed by IM@BC continues to increase, and the adsorption equilibrium state is gradually reached after 24 h. The adsorption process conforms to the pseudo-second-order kinetic model (PSO) and Langmuir isothermal adsorption model, and the adsorption process is mainly chemical adsorption. The phosphate absorption capacity is positively correlated with temperature (283.15 K~313.15 K), and the adsorption process is spontaneous, endothermic, and entropy-increasing. Its adsorption mechanism includes electrostatic attraction, ion exchange, surface precipitation, and coordination exchange. IM@BC can efficiently recover phosphate from actual phosphorus-containing wastewater with a recovery efficiency of up to 90%. P-IM@BC slowly releases phosphate from pH 3 to 11. Plant growth experiments showed that P-IM@BC could be used as a slow-release fertilizer to promote the root growth of cowpeas. The novelty of this work lies in the development of a highly efficient phosphate recovery adsorbent, which provides a feasible method of phosphorus control in water media and resource utilization of lignite.

Combined Remediation Effects of Sewage Sludge and Phosphate Fertilizer on Pb-Polluted Soil from a Pb-Acid Battery Plant.

Pb soil pollution poses a serious health risk to both the environment and humans. Immobilization is the most common strategy for remediation of heavy metal polluted soil. In this study, municipal sewage sludge was used as an amendment for rehabilitation of Pb-contaminated soils, for agricultural use, near a lead-acid battery factory. The passivation effect was further improved by the addition of phosphate fertilizer. It was found that the leachable Pb content in soils was decreased from 49.6 mg kg-1 to 16.1-36.6 mg kg-1 after remediation of sludge for 45 d at applied dosage of municipal sewage sludge of 4-16 wt%, and further decreased to 14.3-34.3 mg kg-1 upon extension of the remediation period to 180 d. The addition of phosphate fertilizer greatly enhanced the Pb immobilization, with leachable Pb content decreased to 2.0-23.6 mg kg-1 with increasing dosage of phosphate fertilizer in range of 0.8-16 wt% after 180 d remediation. Plant assays showed that the bioavailability of Pb was significantly reduced by the soil remediation, with the content of absorbed Pb in mung bean roots decreased by as much as 87.0%. The decrease in mobility and biotoxicity of the soil Pb is mainly attributed to the speciation transformation of carbonate, Fe-Mn oxides and organic matter bound Pb to residue Pb under the synergism of reduction effect of sludge and acid dissolution and precipitation effect of phosphate fertilizer. This study suggests a new method for remediation of Pb-contaminated soil and utilization of municipal sewage sludge resources.

Use of wastewater alum-coagulation sludge as a phosphorus fertiliser - a mini review.

The use of aluminium (Al) salts, particularly alum, in coagulation is a widespread and conventional treatment method for eliminating pollutants, including phosphorus (P) which can cause eutrophication, from wastewater. However, a significant challenge of this process is the substantial amount of sludge generated, necessitating proper disposal. Historically, land disposal has been a common practice, but it poses potential issues for plant life on these lands. Despite the associated drawbacks, sludge contains elevated concentrations of vital plant nutrients like P and nitrogen, presenting an opportunity for beneficial use in agriculture. Given the imminent scarcity of P fertilizers due to the eventual depletion of high-grade P ores, this review explores the potential advantages and challenges of utilizing Al sludge as a P source for plants and proposes measures for its beneficial application. One primary concern with land application of Al sludge is its high levels of soluble Al, known to be toxic to plants, particularly in acidic soils. Another issue arises from the elevated Al concentration is P fixation and subsequently reducing P uptake by plants. To address these issues, soil treatment options such as lime, gypsum, and organic matter can be employed. Additionally, modifying the coagulation process by substituting part of the Al salts with cationic organic polymers proves effective in reducing the Al content of the sludge. The gradual release of P from sludge into the soil over time proves beneficial for plants with extended growth periods.

Iron-coated nutshell waste bioadsorbents: Synthesis, phosphate remediation, and subsequent fertilizer application.

The increasing incidence of freshwater nutrient pollution worldwide has highlighted the need for improved phosphate capture technologies. Successful phosphate recovery from agricultural sources and commercial wastewater can help prevent freshwater algal bloom contamination, while also reducing the dependency on finite phosphate reserves. Biodegradable biosorbents have the potential to remove phosphate from water; however, their potential as slow-release fertilizers has not been tested. Novel biosorbents were developed by coating pistachio and walnut shells with iron oxides; batch and column experiments were conducted to investigate their adsorption capacities and performances. Surface characterization studies were also conducted to investigate changes in the surface area and morphology. The potential of using iron-coated shells loaded with phosphorus as slow-release fertilizers was also evaluated. Advanced characterization techniques (scanning electron microscopy, Brunauer-Emmett-Teller (BET) physisorption analysis, and x-ray diffraction) showed that hematite was successfully coated onto the surface, resulting in increased surface area and roughness. The iron-coated pistachio and walnut shell phosphate removal capacity was 12.63 mg g-1 and 9.25 mg g-1, respectively. The phosphate sorption data fitted well with the Freundlich isotherm model and pseudo-second-order kinetics. Inner sphere complex formation, coprecipitation, diffusion, and electrostatic attraction were the main uptake mechanisms. Results from sequential release experiments with simulated pore water suggested both fast and slow desorption components. The Mehlich-3 extraction revealed that more than 90% of the released phosphate was available for plant uptake. In addition, nutrient priming showed that corn seed shoot growth increased by more than 43% when pretreated with phosphate-loaded biosorbents, demonstrating that the released phosphate could be used for plant growth. This research provides a pathway for two important zero-waste, cyclical economic goals: (1) the beneficial use of agricultural waste, and (2) a low-cost technology that can recover phosphorus from waste streams while potentially adding an additional unconventional phosphate source to apatite mineral ores.

Fluoride contents in commonly used commercial phosphate fertilizers and their potential risks in China.

The application of phosphate fertilizer is an important source of anthropogenic fluoride in agricultural soil. However, relatively few studies have examined the fluoride content of phosphate fertilizers, and that has limited our understanding of the phosphate fertilizer contribution to soil fluoride accumulation and distribution. To examine this problem, we first quantified the total fluoride (TF) and water-soluble fluoride (WF) contents of six of the most commonly used commercial phosphate fertilizers in China (potassium dihydrogen phosphate (MKP), calcium superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), ternary compound fertilizer (NPK), and water-soluble macroelement fertilizer (WSF)). After calculating the [P2O5]/TF ratio for each of those fertilizers, we used those ratios and the average P2O5 application per crop of five typical crops grown in China (apples, greenhouse vegetables, wheat, corn, and rice) to estimate the annual fluoride accumulations in their soils after application of each type of phosphate fertilizer. Among the six fertilizer types, SSP, DAP, and NPK had much higher total fluoride and water-soluble fluoride contents than MKP, MAP, and WSF had. During crop production, the risk of fluoride accumulation was lower with MKP, MAP, and WSF (high [P2O5]/TF ratios) and higher with SSP, DAP, and NPK (low [P2O5]/TF ratios), especially in cash crops (fruit and greenhouse vegetables), which traditionally have unreasonably high P2O5 applications. Based on our findings, we proposed steps that should be taken to help effectively mitigate fluoride accumulation in China's agricultural soils.

Review of the State of Impurity Occurrences and Impurity Removal Technology in Phosphogypsum.

A variety of co-existing impurities in phosphogypsum limit its large-scale and high-value utilization. This paper summarizes the common contents of major impurity components (silicon and phosphorus) and trace impurity components (fluorine, iron, aluminum, and carbon) in phosphogypsum and discusses the harm of impurity components to the comprehensive utilization of harmless phosphogypsum chemical resources. The occurrence status of impurity components in phosphogypsum and the research progress of various impurity removal technologies are summarized, and the effects of these impurity removal technologies on different contents of impurity components are evaluated. On this basis, the goal of improving the whiteness of phosphogypsum samples and the development of technology for further removal of impurities in phosphogypsum to improve the purity of the main content of calcium sulfate are speculated.

[Effect of Biochar with Phosphorus Fertilizer on Soil Nutrients, Enzyme Activity, and Nutrient Uptake of Alfalfa].

Biochar is widely used in agricultural production practices as a soil conditioner that can be used both alone and jointly with chemical fertilizer. However, there are few studies on the effects of the combined application of biochar and phosphate fertilizer with different particle sizes on soil and plants. In this experiment, pot experiments were used to study the effects of biochar with different particle sizes on soil nutrients, enzyme activity, and Alfalfa nutrient absorption under two phosphorus levels (according to diameter, the biochar was divided into C1:>1 mm and C2:<0.01 mm). This study showed that the combined application of biochar and phosphorus significantly improved soil nutrients, enzyme activity, and Alfalfa nutrient absorption. Among them, the C2 treatment significantly increased the soil available phosphorus content and phosphatase activity (P<0.05), whereas the C1 treatment had a significant effect on ammonium nitrogen, nitrate nitrogen, urease, and catalase activities (P<0.05). Moreover, the differences in nutrients and enzymes among biochar treatments with different particle sizes were affected by soil phosphorus levels. At the P0 level, there was no significant difference in ammonium nitrogen and nitrate nitrogen contents between the C1 and C2 treatments. At the P1 level, the contents of NH4+-N and NO3--N in the C1 treatment were 24.19% and 18.68% higher than those in the C2 treatment (P<0.05), but there was no significant difference between the C1 and C2 treatments. Phosphorus addition significantly increased the N and P contents of Alfalfa above ground and in the ground (P<0.05), but there was no significant effect on the nutrient content of Alfalfa between different particle sizes of biochar. In conclusion, biochar and phosphate fertilizer can be used as an effective means of soil improvement. In addition, when using biochar for soil improvement, the impact of particle size on soil nutrients and soil enzymes should be considered.

Effects of different fertilization methods on Lolium multiflorum Lam. growth and bacterial community in waste slag.

Waste slag has low nutrient content, so it has insufficient nutrient cycling and transformation in the soil ecosystem. There are few studies on the application of oligotrophic phosphate-solubilizing bacteria and phosphate (P) fertilizer to improve the properties of waste slags. In this study, three oligotrophic bacterial strains with P solubilizing activity, namely, Bacillus subtilis 2C (7.23 µg/mL), Bacillus subtilis 6C (4.07 µg/mL), and Bacillus safensis 2N (5.05 µg/mL), were isolated from waste slags. In the pot experiment, compared with no application of P fertilizer, inoculation of Bacillus subtilis 2C with a 50% recommended dose of P fertilizer significantly increased the available phosphorus (AP), total phosphorus (TP), and total nitrogen (TN) in slag by 33.16%, 76.70%, and 233.33%, respectively. The N, P uptake and fresh weight of Lolium multiflorum Lam. were significantly improved by 114.15%, 139.02%, and 100%, respectively. The analysis of the bacterial community showed that the application of P fertilizer decreased the diversity and richness of the bacterial community, and with the addition of phosphorus fertilizer and Bacillus subtilis 2C, the bacterial community in the slag developed towards eutrophication. Redundancy analysis (RDA) showed that the TP content in the slag was significantly correlated with the bacterial community (P = 0.001, < 0.01), followed by the TN content. This study on different P fertilizer application methods can provide some basic ideas for improving the performance of waste slag.

Glyphosate-based herbicide use affects individual microbial taxa in strawberry endosphere but not the microbial community composition.

AIMS: In a field study, the effects of treatments of glyphosate-based herbicides (GBHs) in soil, alone and in combination with phosphate fertilizer, were examined on the performance and endophytic microbiota of garden strawberry. METHODS AND RESULTS: The root and leaf endophytic microbiota of garden strawberries grown in GBH-treated and untreated soil, with and without phosphate fertilizer, were analyzed. Next, bioinformatics analysis on the type of 5-enolpyruvylshikimate-3-phosphate synthase enzyme was conducted to assess the potential sensitivity of strawberry-associated bacteria and fungi to glyphosate, and to compare the results with field observations. GBH treatments altered the abundance and/or frequency of several operational taxonomic units (OTUs), especially those of root-associated fungi and bacteria. These changes were partly related to their sensitivity to glyphosate. Still, GBH treatments did not shape the overall community structure of strawberry microbiota or affect plant performance. Phosphate fertilizer increased the abundance of both glyphosate-resistant and glyphosate-sensitive bacterial OTUs, regardless of the GBH treatments. CONCLUSIONS: These findings demonstrate that although the overall community structure of strawberry endophytic microbes is not affected by GBH use, some individual taxa are.

The effects of phosphate fertilizer on the growth and reproduction of Pardosa pseudoannulata and its potential mechanisms.

In fields, the natural enemy spider, Pardosa pseudoannulata, plays important roles in insect pest control. Agrochemicals, such as phosphate fertilizer, disturb the ecosystem and weaken the pest control efficiency of the spider. According to the usual habitat of the spider in soil cracks, the soil-application of phosphate fertilizer was carried out to determine its effects on the growth and reproduction of P. pseudoannulata. Phosphate fertilizer treatment prolonged longevity and increased mortality in subadults. The treatment also negatively affected reproduction of P. pseudoannulata adults even with removing phosphate fertilizer stress before adult emergence, leading to a lower mating rate, fewer eggsacs and eggs per female, and fewer offsprings in the first eggsac. The transcriptomic sequencing analysis revealed the up-regulation of unigenes related to stress resistance and down-regulation of unigenes associated with protein processing and proteasomal degradation in phosphate fertilizer-treated P. pseudoannulata. Decline in proper protein processing by E3 ubiquitin-protein ligase complex and endopeptidase activity might provide a partial explanation for negative effects of phosphate fertilizer on the spider reproduction. The study put a notice on negative effects of phosphate fertilizer on beneficial arthropods, which provide a great potential in the protection of P. pseudoannulata and other predator spider species.

Carbonate weathering, phosphate fertilizer, and hydrologic controls on dissolved uranium in rivers in the US Corn Belt: Disentangling seasonal geogenic- and fertilizer-derived sources.

Soil and bedrock weathering and phosphate (P) fertilizers may both contribute to the uranium (U) load of rivers in agricultural regions, but controls over their relative influence are not well known. This study investigates the U sources to rivers in Ohio, United States, part of the Eastern Corn Belt in the Mississippi River watershed. We present a regional picture of seasonal U sources to rivers based on four analyses: 1) a spatial analysis of legacy soil and water data, 2) new measurements of U and carbonate weathering products from rivers at 50 locations across the state collected seasonally over two years, 3) a weekly time series with additional 234U/238U (n = 5) and 87Sr/86Sr (n = 5) measurements from an agricultural river, and 4) a mass-balance approach to U addition to the landscape based on reported P fertilizer use. Uranium concentrations in surface waters collected statewide ranged 0.1-21 nM (n = 132), with significantly higher concentrations in the glaciated agricultural portion of the state (mean = 7.3 nM; n = 105) than the non-glaciated portion (mean = 2.0 nM; n = 24). Concentrations in the glaciated region were highest during the spring and summer and decreased during baseflow. In the time-series, concentrations were ~7 nM during baseflow and ~14 nM during intermediate seasonal discharge conditions, indicating a second more surficial endmember source of U in addition to bedrock weathering that is well correlated with other carbonate weathering products. Systematic increases in 87Sr/86Sr and decreases in 234U/238U with increasing discharge confirm a changing source of carbonate and U weathering and a third surficial endmember during high discharge events. Our mass balance approach and geochemical analysis suggest that elevated U concentrations are the result of carbonate weathering deep in the soil column during elevated seasonal flow. Further work on U dynamics in agricultural rivers is required to understand mechanism controlling seasonal changes in U concentrations and 234U/238U in downstream rivers and U flux.

Fluoride accumulation characteristics in a northern China apple orchard that has had long-term phosphate fertilization.

Phosphate fertilizer can cause fluoride accumulation in the soil and excessive fluoride poses potential risks to soil and food crop safety. However, the effects of fertilization on soil and fruit fluoride accumulations through long-term positioning trials, especially in high-fertilizer application situations such as apple orchards, have received little attention. To close this knowledge gap, we conducted a field experiment to demonstrate the effects among five long-term (13-year) fertilizer treatments on fluoride accumulations at different soil depths and in the fruits of an apple orchard in Baishui, Shaanxi, China. The five treatments included no fertilization (CK); manure application (M); nitrogen and phosphate fertilization (NP); nitrogen, phosphorus, and potassium fertilization (NPK); and groundcover with nitrogen and phosphate fertilization (GNP). The results confirmed that all phosphate fertilizer treatments (NP, NPK, and GNP) had significant increases in total fluoride (TF) and water-soluble fluoride (WF) accumulations in the topsoil (0-20 cm). Among the phosphate fertilizer treatments, NP topsoil accumulated the most TF and WF, 79.4 and 7.7 mg kg-1 more than CK, respectively, and an average annual TF increase of 6 mg kg-1. However, the M treatment both experienced reduced fluoride content in the topsoil and had TF and WF contents 8.1 and 0.67 mg kg-1 lower than CK, respectively. There was no significant difference between all fertilizer treatments and CK in apple fluoride content. Furthermore, TF and WF accumulated mainly in the topsoil and the differences in soil fluoride content among the treatments decreased with soil depth. These findings showed that long-term phosphate fertilization increases the risk of fluoride accumulation in orchard topsoil. Altogether, these results improve the understanding of the characterization of soil and fruit fluoride accumulations in apple orchards under long-term fertilizer conditions and provide new insights into the use of manure as a possible alternative fertilization strategy that reduces fluoride accumulation.

Development of WEF-P Nexus based on product-supply chain: A case study of phosphorous fertilizer industry in Morocco.

The aim of this study was to analyze various sustainability strategies for phosphate and phosphorous fertilizer production systems from the perspective of their holistic impacts on water, energy, and CO2 emissions. The study was conducted using the Water-Energy-Food (WEF) Nexus Tool 2.0, adapted to include the phosphate industry (WEF-P tool). It assesses the scenarios based on priorities identified by the Moroccan phosphate industry, such as the environmental impact of transporting phosphate rock by train and phosphate slurry by pipeline and increased desalinated water use. Results show that each scenario's sustainability can be assessed in terms of phosphate production, processes, resource (water and energy) availability, and CO2 emissions in mining and manufacturing areas. The analytical methodology of the tool is based on an integrated supply chain and life cycle assessment, which includes the production flows linking mining phosphate and manufacturing phosphorous fertilizers and their water and energy supply systems. Field surveys were used to identify the supply chain and estimate the relationships between production and resource consumption in each process. The tool is a decision-support platform that produces sustainability indices for multiple scenarios of resource allocation (water and energy) and CO2 emissions, allowing stakeholders to compare potential outcomes and formulate decisions based on their understanding of the actual trade-offs involved.

Screening of phosphate-solubilizing bacteria and their abilities of phosphorus solubilization and wheat growth promotion.

BACKGROUND: Phosphate-solubilizing bacteria (PSB) can enhance plant growth and phosphorus (P) solubilization, it also has been reported to reduce the negative effects of overused agricultural fertilizer in farmland and protect the soil environment. However, the mechanism behind this interaction has not been fully elucidated. RESULTS: In this study, we screened out Pseudomonas moraviensis, Bacillus safensis, and Falsibacillus pallidus which can both solubilize P efficiently and produce indole-3-acetic acid (IAA) from sandy fluvo-aquic soils. The yield of wheat (Triticum aestivum) under PSB inoculation significantly increased up to 14.42% (P < 0.05) compared with the control treatment in phosphate fertilizer-used farmland. Besides promoting wheat growth, we found the labile P fraction in soil was significantly increased by over 122.04% (P < 0.05) under PSB inoculation compared with it in soils without, in parallel, the stable P fraction was significantly reduced by over 46.89% (P < 0.05). Furthermore, PSB inoculation increased the soil microbial biomass and activity, indicating that PSB screened out in this work performed a remarkable ability to colonize the soils in the wheat field. CONCLUSION: PSB from sandy fluvo-aquic soil improve wheat growth and crop productivity by increasing the labile P fraction and IAA content in the greenhouse and wheat field. Our work provides an environment and economy-friendly bacterial resource that potentially promotes sustainable agricultural development in the long term.

Cadmium exposure in adults across Europe: Results from the HBM4EU Aligned Studies survey 2014-2020.

The objectives of the study were to estimate the current exposure to cadmium (Cd) in Europe, potential differences between the countries and geographic regions, determinants of exposure and to derive European exposure levels. The basis for this work was provided by the European Human Biomonitoring Initiative (HBM4EU) which established a framework for alignment of national or regional HBM studies. For the purpose of Cd exposure assessment, studies from 9 European countries (Iceland, Denmark, Poland, Czech Republic, Croatia, Portugal, Germany, France, Luxembourg) were included and urine of 20-39 years old adults sampled in the years 2014-2021 (n = 2510). The measurements in urine were quality assured by the HBM4EU quality assurance/quality control scheme, study participants' questionnaire data were post-harmonized. Spatially resolved external data, namely Cd concentrations in soil, agricultural areas, phosphate fertilizer application, traffic density and point source Cd release were collected for the respective statistical territorial unit (NUTS). There were no distinct geographic patterns observed in Cd levels in urine, although the data revealed some differences between the specific study sites. The levels of exposure were otherwise similar between two time periods within the last decade (DEMOCOPHES - 2011-2012 vs. HBM4EU Aligned Studies, 2014-2020). The age-dependent alert values for Cd in urine were exceeded by 16% of the study participants. Exceedances in the different studies and locations ranged from 1.4% up to 42%. The studies with largest extent of exceedance were from France and Poland. Association analysis with individual food consumption data available from participants' questionnaires showed an important contribution of vegetarian diet to the overall exposure, with 35% higher levels in vegetarians as opposed to non-vegetarians. For comparison, increase in Cd levels due to smoking was 25%. Using NUTS2-level external data, positive associations between HBM data and percentage of cropland and consumption of Cd-containing mineral phosphate fertilizer were revealed, which indicates a significant contribution of mineral phosphate fertilizers to human Cd exposure through diet. In addition to diet, traffic and point source release were identified as significant sources of exposure in the study population. The findings of the study support the recommendation by EFSA to reduce Cd exposure as also the estimated mean dietary exposure of adults in the EU is close or slightly exceeding the tolerable weekly intake. It also indicates that regulations are not protecting the population sufficiently.