Phosphate Rock Research Articles

Impact of Organic and Natural Farming Practices on Growth, Yield Attributes and Yield of Joha Rice

Aims: The aim of the experiment was to study the impact of organic and natural farming practices on the growth, yield attributes and yield of Bokul Joha variety of rice Study Design:  The experiment was laid in a randomized block design with three replications. Place and Duration of Study: Assam Agricultural University-Assam Rice Research Institute, Titabar, Assam, India, during the kharif season of 2022-2023 Methodology: The number of treatments used were eight in total including control which were T1 [Absolute control], T2 [(Natural farming, Beejamrit as root dip treatment (3%) (100 L ha-1) + Jeevamrit as spray (3%) (100 L ha-1) + Ghanajeevamrit as soil treatment at 100 kg (Jeevamrit and Ghanajeevamrit at 30, 60 and 90 DAT)], T3 [(Enriched compost (5 tha-1) + Biofertilizer (Azospirillum, PSB as seedling root dip) (4 kg ha-1)], T4 [Enriched compost (5 t ha-1)], T5 [Vermicompost (5 t ha-1)], T6 [Enriched compost (2.5 t ha-1) + Vermicompost (2.5 t ha-1)], T7 [Fresh azolla as dual crop (400 kg ha-1) + Biofertilizers (Azospirillum, PSB and KSB mix as seedling root dip) (4 kgha-1)] and T8 [Vermicompost (1 tha-1), mixed inocula of Azospirillum amazonense A-10 and Bacillus megaterium P-5 (4 kg ha-1), rock phosphate (10 kg P2O5  ha-1)]. The experiment was laid in a randomized block design with three replications. Where T= Treatment, PSB = Phosphate Solubilizing Bacteria, KSB=Potassium Solubilizing Bacteria, DAT = Days After Transplanting and NF=Natural Farming.  Results: Plants that were noticeably taller were observed with treatment T8: application of vermicompost (1 tha-1), mixed inocula of Azospirillum amazonense A-10 and Bacillus megaterium P-5 (4 kg ha-1), rock phosphate (10 kg P2O5) i.e., at 45 DAT (81.78 cm),90 DAT (128.15 cm) and at harvest (145.71 cm). The same treatment recorded the highest no. of tillers 45 DAT (8.31m-2), at 90 DAT (13.79 m-2) and at harvest (10.40 m-2). Also, dry weight was noted to be highest for the same treatment, at 45 DAT (29.34 g plant-1), 90 DAT (79.11 g plant-1) and at harvest (92.29 g plant-1). Additionally, the same treatment resulted in highest grain (34.62 qha-1) and straw (70.30 q ha-1) yield. Conclusion: Combined application of vermicompost (1 t/ha) along with inocula of Azospirillum amazonense A-10 and Bacillus megaterium P-5 (4kg/ha) and rock phosphate (10 kg P2O5) can be used as a suitable treatment for attaining higher growth, yield attributes and yield in Bokul Joha variety of rice.

Phosphate solubilizing Pseudomonas and Bacillus combined with rock phosphates promoting tomato growth and reducing bacterial canker disease

Nowadays, sustainable agriculture approaches are based on the use of biofertilizers and biopesticides. Tomato (Solanum lycopersicum L.) rhizosphere could provide rhizobacteria with biofertilizing and biopesticide properties. In this study, bacteria from the rhizosphere of tomato were evaluated in vitro for plant growth promotion (PGP) properties. Five Pseudomonas isolates (PsT-04c, PsT-94s, PsT-116, PsT-124, and PsT-130) and one Bacillus isolate (BaT-68s), with the highest ability to solubilize tricalcium phosphate (TCP) were selected for further molecular identification and characterization. Isolates showed phosphate solubilization up to 195.42 μg mL−1. All isolates showed phosphate solubilization by organic acid production. The six isolates improved seed germination and showed effective root colonization when tomato seeds were coated with isolates at 106 cfu g−1 in axenic soil conditions. Furthermore, the selected isolates were tested for beneficial effects on tomato growth and nutrient status in greenhouse experiments with natural rock phosphate (RP). The results showed that inoculated tomato plants in the presence of RP have a higher shoot and root lengths and weights compared with the control. After 60 days, significant increases in plant Ca, Na, P, protein, and sugar contents were also observed in inoculated seedlings. In addition, inoculated tomato seedlings showed an increase in foliar chlorophyll a and b and total chlorophyll, while no significant changes were observed in chlorophyll fluorescence. In greenhouse, two Pseudomonas isolates, PsT-04c and PsT-130, showed ability to trigger induced systemic resistance in inoculated tomato seedlings when subsequently challenged by Clavibacter michiganensis subsp. michiganensis, the causal agent of tomato bacterial canker. High protection rate (75%) was concomitant to an increase in the resistance indicators: total soluble phenolic compounds, phenylalanine-ammonia lyase, and H2O2. The results strongly demonstrated the effectiveness of phosphate-solubilizing bacteria adapted to rhizosphere as biofertilizers for tomato crops and biopesticides by inducing systemic resistance to the causal agent of tomato bacterial canker disease.

Analysis of cultivar variability in arbuscular mycorrhizal responsiveness in soybean varieties

ABSTRACT In modern agricultural systems, high crop yields depend on the high input of orthophosphate-based fertilizers. Owing to the looming scarcity of rock phosphate in the near future, utilization of arbuscular mycorrhizal (AM) symbiosis for the efficient uptake of phosphorus is a necessary approach to maintain crop yield. Plant responsiveness to AM fungi is assessed based on the difference in biomass between plants with and without AM fungal inoculation. Soybean is a plant which establishes both mycorrhizal and rhizobial symbiosis. Therefore, it is difficult to eliminate the symbiotic effects of rhizobial nitrogen fixation during long-term cultivation until soybean harvest. In this study, Bradyrhizobium diazoefficiens USDA110 was inoculated at the same time as soybean seeds were sown, and soybean was grown under Rhizophagus irregularis inoculated and non-inoculated conditions to verify whether the mycorrhizal inoculation effect was observed at the yield level. In 2013, two soybean cultivars Tachinagaha and Williams 82, were grown at five levels of phosphate availability (0, 5, 10, 20, and 40 kg P 10a−1) in an open greenhouse in Tsukuba, Japan. Among the several growth indices analyzed, seed weight per plant was selected as a reliable indicator of plant response. Mycorrhizal inoculation showed a positive effect on soybean under 20 kg P 10a−1 phosphorus fertilization for Williams 82, while Tachinagaha showed almost no effect. This trend was replicated in 2014 and 2016, indicating that Tachinagaha has a lower AM responsiveness than Williams 82.

Arsenic-Hyperaccumulator Pteris vittata Effectively Uses Sparingly-Soluble Phosphate Rock: Rhizosphere Solubilization, Nutrient Improvement, and Arsenic Accumulation.

Sparingly-soluble phosphate rock (PR), a raw material for P-fertilizer production, can be effectively utilized by the As-hyperaccumulator Pteris vittata but not most plants. In this study, we investigated the associated mechanisms by measuring dissolved organic carbon (DOC) and acid phosphatase in the rhizosphere, and nutrient uptake and gene expression related to the As metabolism in P. vittata. The plants were grown in a soil containing 200 mg kg-1 As and/or 1.5% PR for 30 days. Compared to the As treatment, the P. vittata biomass was increased by 33% to 4.6 g plant-1 in the As+PR treatment, corresponding to 27% decrease in its frond oxidative stress as measured by malondialdehyde. Due to PR-enhanced DOC production in the rhizosphere, the Ca, P, and As contents in P. vittata fronds were increased by 17% to 9.7 g kg-1, 29% to 5.0 g kg-1, and 57% to 1045 mg kg-1 in the As+PR treatment, thereby supporting its better growth. Besides, PR-induced rhizosphere pH increase from 5.0 to 6.9 promoted greater P uptake by P. vittata probably via upregulating low-affinity P transporters PvPTB1;1/1;2 by 3.7-4.1 folds. Consequently, 29% lower available-P induced the 3.3-fold upregulation of high-affinity P transporter PvPht1;3 in the As+PR treatment, which was probably responsible for the 58% decrease in available-As content in the rhizosphere. Consistent with the enhanced As translocation and sequestration, arsenite antiporters PvACR3/3;3 were upregulated by 1.8-4.4 folds in the As+PR than As treatment. In short, sparingly-soluble PR enhanced the Ca, P, and As availability in P. vittata rhizosphere and improved their uptake via upregulating genes related to As metabolism, suggesting its potential application for improving phytoremediation in As-contaminated soils.

The Effects of Rhizobium Phaseoli and Phosphate-Solubilizing Microorganisms on Phaseolus Vulgaris Amended with Rock Phosphate and Biogas Spent Slurry

Phaseolusvulgaries seeds were inoculated with Rhizobium phaseoli, Phosphate solubilizing Microorganisms (PSM) with rock phosphate in plots containing poultry droppings slurry of biogas plant. This experiment was carried out in 4 treatments with control (T1, T2, T3, T4 and T0).The samples were collected at seedling, preflowering, blooming and end stages to learn the phenotypical nature, NPK and chlorophyll contents. Studies on microbes have also been conducted on plants at every stage of development. Comparing the plant supplied by R.phaseous PSM with rock phosphate to control and other application combinations, the results showed that the plant recorded the highest values in the morphological, biochemical, and microbiological features.From the seedling stage on, the plants' NPK content also rose. (1.262%, 0.28% & 0.26%) to the flowering stage. In the T4 treatment, there are likewise 36 nodules, and each nodule weighs 0.268 g. The weight is roughly 0.039g, and the lowest nodule number (07nos) was discovered in the control. The enriched manure that produced the best results was the combination of SPDS+PSM+RP+R.phaseoli (T4). The yield was 2.435tons/hectare and PSM+RP (T2), which produced 1.890 tons/hectare; PSM+RP (T3), 1.101 tons/hectare in inorganic manure (T1), and control (0.821 tons/hectare) (T0). The study report highlighted the critical roles that PSO, R. phaseoli, and rock phosphate played in P. vulgaries nodulation, nitrogen fixation, and good yield.

A new methodology for efficiency calibration of uncharacterized Ge detectors by using characterized Ge detectors

The measurement of gamma emitters natural radionuclides is a very relevant subject in environmental radioactivity in many fields. For this, a valid calibration based on the full-energy peak efficiency (FEPE) is essential, which can be carried out for gamma-ray spectrometry using Monte Carlo codes (Geant4, LabSOCS, MNCP, etc.) without needing a source preparation and with much less time consuming compared to experimental methodologies. Therefore, this work aims to develop a methodology for the FEPE determination of uncharacterized Ge detectors by using characterized Ge detectors with known FEPE. For this, a general relationship was found between the simulated FEPE (εsim) for characterized Ge detectors by LabSOCS and the experimental one (εexp) for uncharacterized Ge detectors obtained for a problem sample (phosphate rock (PR) in our case), where εsim and εexp were factorized using three correction factors: geometrical, photon self-absorption and true coincidence summing (TCS) effects. Thus, the εsim/εexp ratio (FEPER) was obtained for two couples of Ge detectors (2 characterized and 1 uncharacterized detectors), using 4 different cylindrical geometries (C) and 2 Marinelli (M) ones, and varying the sample thickness (h), and gamma energy (Eγ) (from 46 keV (210Pb) to 1765 keV (214Bi)). The consistency obtained for the FEPERs for C geometries suggested a constant geometric factor, finding some deviations for M geometries only at Eγ < 150 keV. Given a pair of detectors, the behavior of the FEPERs was found to be very similar for all geometries, and h at each specific Eγ. Moreover, a constat relationship between the FEPERs of both detector couples versus Eγ was found. Then, the influence of the TCS effects was also studied varying the distance between the geometry bottom and detector window. The developed methodology was also validated confirming the consistency of the FEPERs, which were found to be independent on the chemical composition and apparent density of the sample, supporting our theoretical hypothesis. Consequently, given that the FEPER was found to be independent on the sample type and h, using our developed methodology it is possible to obtain εexp for any sample, geometry and h using the FEPER, previously obtained at each Eγ for the sample selected for methodology development (PR in our case), and the εsim that is obtained for the desired case.

Influence of the use of remediated soil and agricultural drainage water on the safety of tomato fruits.

The objective of this study is to assess the effectiveness of different techniques employed in remediating contaminated soil and wastewater ecosystems to ensure the safety of tomato fruits (Solanum lycopersicum L. var. cerasiforme) cultivated in these environments. Three biochemical techniques T1-T3, besides two controls CCU and CCT, were used to remediate contaminated soil ecosystems using rock phosphate, elemental sulfur, bentonite, phosphate-dissolving bacteria, and Thiobacillus sp. The contaminated agricultural drainage water was remediated by a down-flow hanging sponge (DHS) system. Two experiments were conducted: a pot experiment took place in the greenhouse at the National Research Center of Cairo (Egypt) and a field experiment was carried out at the basin site in the village of El-Rahawy, applying the optimal treatment(s) identified from the greenhouse experiment. The health risk assessment for potentially toxic elements (PTEs) in the harvested tomato fruits was conducted by calculating estimated daily intake (EDI) and target risk quotient (THQ) values. Results from the greenhouse experiment indicated the high effectiveness of the DHS technique in remediating El-Rahawy agricultural drainage water. The content of PTEs after remediation was significantly reduced by 100%, 93.3%, 97.8, and 77.8% for cadmium, copper, manganese, and zinc, respectively. The application of treated drainage water in employed reclaimed soil ecosystems led to a remarkable decrease in PTE levels, especially under T3 treatment; the reduction reached 89.4%, 89.5%, and 78.4% for nickel, copper, and zinc, respectively. The bioremediation technique also reduced the content of PTEs in tomato fruits harvested from both greenhouse and field experiments; the cadmium content, for example, was below detection limits in all treatments. The T3 treatment applied in the greenhouse experiment caused the highest percentage decrease among the employed PTEs in tomato fruits grown in the greenhouse. The same trend was also reached in the field experiment. Microbiological analyses of tomato fruits revealed that E. coli, Salmonella, or S. aureus bacteria were identified on tomato fruits harvested from either greenhouses or field experiments, showing that the counted total bacteria were higher under the field experiment compared to the greenhouse experiment. The health risk assessment parameter THQ was below 1.0 for all tested metals under all treatments. This means that no potential health risk is expected from consuming tomato products produced under the different employed remediation treatments. In conclusion, the employed bioremediation techniques successfully reduced the PTE content and microbial load in both soil and drainage water ecosystems and in harvested tomato fruits. Henceforth, no health risks are expected from the consumption of this product.

Smoothing the Phosphorus Resource Stress under the Socioeconomic Development in China.

Phosphorus (P) is the key in maintaining food security and ecosystem functions. Population growth and economic development have increased the demand for phosphate rocks. China has gradually developed from zero phosphate mining to the world's leading P miner, fertilizer, and agricultural producer since 1949. China released policies, such as designating phosphate rock as a strategic resource, promoting eco-agricultural policies, and encouraging the use of solid wastes produced in mining and the phosphorus chemical industry as construction materials. However, methodological and data gaps remain in the mapping of the long-term effects of policies on P resource efficiency. Here, P resource efficiency can be represented by the potential of the P cycle to concentrate or dilute P as assessed by substance flow analysis (SFA) complemented by statistical entropy analysis (SEA). P-flow quantification over the past 70 years in China revealed that both resource utilization and waste generation peaked around 2015, with 20 and 11 Mt of mined and wasted P, respectively. Additionally, rapidly increasing aquaculture wastewater has exacerbated pollution. The resource efficiency of the Chinese P cycle showed a U-shaped change with an overall improvement of 22.7%, except for a temporary trough in 1975. The driving force behind the efficiency decline was the roaring phosphate fertilizer industry, as confirmed by the sharp increase in P flows for both resource utilization and waste generation from the mid-1960s to 1975. The positive driving forces behind the 30.7% efficiency increase from 1975 to 2018 were the implementation of the resource conservation policy, downstream pollution control, and, especially, the circular agro-food system strategy. However, not all current management practices improve the P resource efficiency. Mixing P industry waste with construction materials and the development of aquaculture to complement offshore fisheries erode P resource efficiency by 2.12% and 9.19%, respectively. With the promotion of a zero-waste society in China, effective P-cycle management is expected.

Enhanced-Efficiency Urea Coated with Ground Phosphate Rock Powder, Inhibitor and Epoxy Resin: Preparation and Effects on Soil Nitrogen Supply Capacity, Wheat Yield and Nitrogen Use Efficiency

Enhanced-Efficiency Urea Coated with Ground Phosphate Rock Powder, Inhibitor and Epoxy Resin: Preparation and Effects on Soil Nitrogen Supply Capacity, Wheat Yield and Nitrogen Use Efficiency

An Integrated and Multi-Stakeholder Approach for Sustainable Phosphorus Management in Agriculture

Conventional agriculture relies on non-renewable rock phosphate as a source of phosphorus. The demand for food has led to increased phosphorus inputs, with a negative impact on freshwater biodiversity and food security. The importation of phosphorus fertilizers makes most food systems vulnerable to phosphorus supply risks. The geopolitical instability generated by the pandemic and the current Russia–Ukraine conflict, which has led to a 400% increase in phosphorus commodity prices, offers the international community and institutions an opportunity to embrace the global phosphorus challenge and move towards a more circular system. Here, we discuss an integrated and multi-stakeholder approach to improve phosphorus management in agriculture and increase the efficiency of the whole chain, highlighting the contribution of conventional breeding and genetic engineering, with a particular focus on low-phytic-acid (lpa) crops, whose grains may help in reducing phosphorus-management-related problems. In recent decades, the choice of short-term strategies—such as the use of phytase as a feed additive—rather than lpa mutants, has been carried out without considering the long-term money saving to be derived from lpa crops. Overall, lpa crops have the potential to increase the nutritional quality of foods and feeds, but more research is needed to optimize their performance.

Effectiveness of Phosphorus Solubilizing Bacteria on Enhancing Phosphorus Availability from Minjingu Phosphate Rock to Maize in Slightly Acid to Neutral Soils

The aim of this one-year field study was to evaluate the impact of phosphorus solubilizing bacteria (PSB) on increasing the availability of phosphorus locked up in insoluble Minjingu phosphate rock for the maize crop (Zea mays L.) in high soil pH. The study was carried out during one wet season in Nghumbi and Mlali villages in Kongwa District in the Dodoma Region, Tanzania. Based on the pH of their soil and the limiting nutrients, two farms from Mlali village and five from Nghumbi village were chosen at random for field trials. To determine the fertility status, composite soil samples were collected from the chosen farms and examined in a lab. Target treatments included the application of PSB inoculum in combination with various rates of Minjingu phosphate rock (MPR) (0, 20, 30, 40, and 60 KgP ha-1) as a basal fertilizer, placed beneath maize seed and covered with a thin layer of soil. Using a fully randomised block design, the treatments were set up three times. Inadequate levels of N, P, K, and Zn were found in the research area's soil samples. Results indicated the main effect of fields’ characteristics from field No.2 had the highest yield to other fields with significantly (P&lt; 0.001) highest grain yield being 4.4 t ha-1, biological yield of 5.6 t ha-1, and Straw P uptake of 19.63 kg ha-1. Using P or an inoculant (Mx) produced a negligible yield of grain and straw, according to the major effect of treatments. For the studied variables, none of the treatments showed any significant (P =0.427) interaction effects. An intriguing revelation that the study's maize response to native P is provided by interaction effects area is a factor of soil and amount of P released to the soil. We recommend more research on PSB for more than one season in high soil pH before ascertaining the technology to farmers.

Wastewater-Derived Struvite has the Potential to Substitute for Soluble Phosphorus Fertiliser for Growth of Chickpea and Wheat

AbstractPhosphorus (P) recycling from wastewater can reduce the reliance on the primary source for P fertilisers―rock phosphate reserves. In light of this, we compared the effects of struvite (ST), a sparingly soluble P product derived from wastewater, and readily soluble KH2PO4 (KP) on chickpea (Cicer arietinum L.) and wheat (Triticum aestivum L.) growth and P acquisition. Plants were grown in a temperature-controlled glasshouse in plastic pots containing a soil mixture with low P availability, with ST or KP applied at five P rates (7, 14, 28, 56 and 112 µg P g− 1 dry soil). Plants were harvested 56 days after sowing when there were visible differences in above-ground growth. Chickpea and wheat growth positively responded to increasing P rates of KP and ST. At low and medium P rates (7, 14, 28 and 56 µg P g− 1 dry soil) of KP and ST, the plants acquired similar amounts of P, while at a higher P rate (112 µg P g− 1 dry soil), plants supplied with ST, accumulated 1.2- to ~ 2.0- fold higher P than KP. Rhizosheath soil pH increased by ~ 0.1–0.7 units under ST than KP for both species. Wheat produced greater total root length but lower amount of rhizosheath carboxylates than chickpea under KP and ST, and wheat accumulated more P than chickpea under KP and ST. Chickpea and wheat can well access P from ST, indicating the great potential of ST as an alternative P fertiliser.

Effect of Arbuscular Mycorrhizal Fungi and Rock Phosphate on Growth, Physiology, and Biochemistry of Carob under Water Stress and after Rehydration in Vermicompost-Amended Soil.

In the Mediterranean region, reforestation programs record failures following successive drought periods. The use of different plant-growth-promoting amendments and the understanding of drought-induced physiological and biochemical responses of carob will contribute to the reforestation program's success. In this study, the effects of arbuscular-mycorrhizal-fungi (AMF), vermicompost (VC), and rock phosphate (RP) on carob seedlings under drought stress (DS) and recovery (REC) conditions were evaluated. A greenhouse experiment was conducted with carob seedlings grown in the presence of AMF, VC, and RP, applied alone or in combination under well-watered (WW), DS (by stopping irrigation for 12 days), and recovery (REC) conditions. The obtained results indicated that the triple combination (AMF + VC + RP) presented the highest improvement in water potential, photosynthetic pigment content, stomatal conductance, and chlorophyll fluorescence compared to the controls under DS and after REC. In addition, this combination resulted in improved tolerance of carob seedlings to DS and a high potential for rapid recovery after rehydration due to a high accumulation of sugars, proteins, and antioxidant enzymes. In summary, the results underline the importance of inoculating carob with AMF in combination with (in)-organic amendments in improving its tolerance to DS and its recovery performances.

Effect of Organic Nutrient Management Practices on Growth, Yield and Pests Incidence of Scented Rice (Oryza sativa L.) in Rainfed Situation of Assam

The field experiment was conducted in organic block on experimental farm of AAU-Assam Rice Research Institute, Assam Agricultural University, Titabar, Assam during kharif season of 2019 and 2020 to study the effect of organic nutrient management practices on growth, yield and pests incidence of scented rice (Oryza sativa L.) in rainfed situation of Assam. Eight treatment combinations of organic inputs were laid out in Randomized Block Design with three replications including one control where no organic nutrients were added. The study revealed that combined application of different proportion of green manure, enriched compost, azolla, vermicompost, neem cake with bio fertilizer consortium and rock phosphate as different treatment significantly improved the growth behavior, yield and also reduced pests incidence of scented rice. Among the organic nutrient management treatments, combination of Green manure (2.5 t/ha)+ Vermicompost (2.5 t/ha)+ Biofertilizer consortium (4 kg/ha seedling) as root dip +Rock phosphate (17 kg/ha)+Azolla (20 kg/ha) recorded the highest yield (3.80 t/ha) by improving yield attributing parameters, viz., Panicles (276.3 /m2), Spikelet /panicle (25.50 number) and Panicle weight (3.37g). The organic treatments also significantly enhanced the growth physiology viz., leaf area index (4.32), and specific leaf weight (8.56 mg/cm2) at panicle initiation stage (90 DAT). In organic management treatments, pests and disease incidence significantly reduced compared to control plot. Highest reduction of dead heart (DH%) and white ear head (WEH%) infestation due to stem borer, gall midge (silver shoot) and leaf folder damage was noticed in the treatment combination of Green manure (2.5 t/ha) + Vermicompost ( 2.5 t/ha)+ Biofertilizer consortium (4 kg/ha seedling) as root dip+Rock phosphate (17 kg/ha)+Azolla (20 kg/ha).

Ball-milled sepiolite/phosphate rock for simultaneous remediation of cadmium-contaminated farmland and alleviation of phosphorus deficiency symptoms in pepper

Herein, ball-milled combination of sepiolite and phosphate rock was carried out for synergistic passivation of Cd in soil and alleviation of phosphorus deficiency in pepper. The as-prepared BM-Sep2PR1 exhibited extensive pH adaptability and fast uptake for Cd(II) with maximal uptake capacity of 78.67 mg/g. After application of 0.5 % BM-Sep2PR1, the bioavailability of Cd in soil decreased by 58.2 %, and its unstable forms declined by 57.0 % with transformation into residual speciation such as Cd3(PO4)2 and CdnCa5-n(PO4)3OH. Moreover, BM-Sep2PR1 significantly decreased the amount of Cd in pepper shoot (77.8 %) and root (54.8 %), and the bioconcentration factors (soil-root) and translocation factors (root-shoot) were significantly reduced by 54.8 % and 50.8 %, respectively. Notably, the soil available phosphorus, pepper root vitality, and photosynthetic pigment content increased by 202.8 %, 136.4 %, and 58.4 %, respectively, thus significantly alleviating the phosphorus deficiency symptoms of pepper. Additionally, BM-Sep2PR1 improved soil microbial community structure, especially enhanced the abundance of microorganism involved in nutrient cycling and heavy metal resistance. The Cd passivation mechanisms of BM-Sep2PR1 were identified as pore filling, electrostatic attraction, ion exchange, surface complexation, and chemical precipitation. Overall, this study provided a potential strategy for synergetic soil remediation and plant nutrient supplement by using ball-milled functional materials.

Microdialysis probes and digital twins reveal the rapid removal of fertiliser phosphate from the soil solution with an impact on crop nutrition in the short-term

Global food production depends on the application of phosphorus (P) fertilisers, usually sourced from rock phosphate, a non-renewable resource. Optimising P use to ensure sustainable P application is necessary to supply food worldwide and to protect the environment from P runoff. However, standard models used to guide P application on fields are limited due to assumptions that fail to consider the short-term dynamics of P in the soil solution. This study combined time-resolved microdialysis sampling with 4D spatial information from X-ray computed tomography to inform an image-based model for assessing P-soil-plant interactions over the start of a growing season. The time-resolved microdialysis measurements revealed that P released from the granules is rapidly removed from the soil solution in the short-term. We demonstrate that the standard equilibrium models typically used to characterise P transport in soil are not representative of the experimental system on the time scales considered. Instead, an Absorption-Diffusion model, where a single sink term accounts for all the processes removing P from the soil solution was required to correctly characterise experimental observations. Our study provides the basis for a model which could be adapted to predict within-season fertilisation scenarios in different soil conditions, and provides a conceptual description of plant/crop yield response to P fertilisation.

Effect of Bone Char Application on Soil Quality, Soil Enzyme and in Enhancing Crop Yield in Agriculture: A Review

Soil quality, in contrast to air or water, exhibits a heightened level of heterogeneity and necessitates closer examination due to its impact on the well-being of flora, fauna, and human beings. Organic carbon is considered a fundamental indicator of soil quality, as it plays a significant role in strategies aimed at mitigating climate change. The generation of bone char arises from a thermochemical conversion process involving defatted bones. Specific attention is focused on the solubility of P compounds, which serves to classify bone chars as potential slow-release P fertilizers. The introduction of P into the soil can be enhanced through an &amp;quot;internal activation&amp;quot; process facilitated by the adsorption of reduced S compounds. Additional properties of agronomic significance originate from the porosity of bone char, which promotes water retention and provides a habitat function for soil microorganisms. The evaluation of soil quality has been a longstanding practice, involving an examination of physical and chemical characteristics such as pH, nitrogen levels, soil organic carbon, bulk density, accessible water, aggregate stability, particle size distribution, and soil structure. Recently, the concept of soil quality has been expanded to encompass the notion of soil health, which is perceived as a finite, non-renewable resource that undergoes constant change. Research also demonstrates the crucial role of soil biota in the assessment of soil quality, as they exhibit rapid responsiveness to disturbances. Animal bones undergo a process of defatting, degelatinization, and subsequent incineration at temperatures ranging from 600-800°C to produce bone char (BC). Reports indicate that typical BC contains 152 g P kg&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;, 280 g Ca kg&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;, and 6.5 g Mg kg&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;, with carbon content typically falling below 100 g kg&amp;lt;sup&amp;gt;-1&amp;lt;/sup&amp;gt;. The solubility of bone char in the soil depends on factors such as pH and the soil&amp;apos;s capacity to absorb P, situating it within the range between rock phosphate and triple super phosphate (TSP). The application of bone char to the soil can enhance soil health, resulting in increased crop yield and improved quality.

Kinetics of Estonian Phosphate Rock Dissolution in Hydrochloric Acid

The kinetics of the dissolution of Estonian phosphate rock and the governing reaction mechanisms in hydrochloric acid in technological processes were investigated. The influences of particle size and acid concentrations of 0.5–1.5 M on the reaction rate and the pH variation during the process were studied at a dosage of 2.1 moles of HCl per mole of calcium for 60 min. The results indicated that the solubility of phosphorus reached 94%–100% for the fine samples and 82%–99% for the coarse samples. The time required to achieve an apparent steady-state pH reduced with the increasing acid concentrations and decreasing particle sizes. It was determined that the CaF2 precipitation in solutions starting at 1 M was faster at higher concentrations. The SEM surface analysis of the insoluble particles proved the existence of etch pit formation. The XPS and EDX analyses affirmed that the dissolution was incongruent. The surface composition of the unreacted particles gave a stoichiometry of CaF1.8, showing the formation of CaF2 on the surface. The dissolution kinetics were analyzed using the shrinking core model and showed a combination of chemical reaction, diffusion or interfacial transfer, and diffusion, sequentially for coarse particles or simultaneously for fine fractions.

Geochemical Characteristics of Trace Elements and Mineralization Model of the Ediacaran-Early Cambrian Phosphorites, South China.

As a nonrenewable resource, phosphate rock is an important support for the development and survival of the national economy. The regional distribution and output of phosphate rock in China are extremely uneven, and the amount of high-quality ore resources is relatively poor, which seriously restricts the development and utilization of phosphate rock resources in China. This paper briefly summarizes the distribution characteristics of phosphate rock resources and summarizes the characteristics and research progress of Ediacaran-early Cambrian phosphorus mineralization types, geological characteristics, and deposit genesis of the Yangtze platform in South China. The Ediacaran-early Cambrian sedimentary phosphorite deposits in China are mainly distributed in Yunnan, Guizhou, Hubei, Sichuan and Hunan provinces of the Yangtze platform, in which the early Cambrian phosphate deposits are also rich in rare earth elements, associated with uranium, nickel, molybdenum, vanadium, and other beneficial metal elements. The increase of atmospheric oxygen content at the Ediacaran-Cambrian boundary may have promoted the extensive oxygenation of the late Neoproterozoic oceans, so the Ediacaran-early Cambrian oceans generally showed a reductive environment, and there may be dynamic chemical stratification of the oxidation zone-sulfide zone-iron zone. Up to the early Cambrian, the redox stratified structure of Precambrian seawater may still be inherited, showing that the surface water is an oxidizing environment, changing to a reduction environment, and even wedge-shaped sulfide water is developed at the bottom of the deep basin. The main phosphorus sources are deep phosphorus-rich seawater, continental weathering, and deep hydrothermal activity of Ediacaran-early Cambrian marine sedimentary phosphorite deposits in South China. The genetic mechanisms of phosphorite deposits in the Yangtze platform in South China are mainly biogenic, upwelling phosphorus-forming theory, mechanical mineralization, and syn-sedimentary hot water mixed genesis. In the future, it is still necessary to further explore the internal relationship between phosphorus deposits and major geological events, the in situ analysis of microstructure of phosphate rock ores, and the genetic mechanism of phosphate deposits and the reconstruction of paleo-marine environment.

Treatment of Cadmium-Contaminated Water Systems Using Modified Phosphate Rock Powder: Contaminant Uptake, Adsorption Ability, and Mechanisms

Cadmium (Cd) water pollution threatens environmental systems and human health. Adsorption is the preferred method for purifying water bodies polluted by Cd, and the development of effective adsorption materials is critical. The performance of original phosphate rock powder (PRP) as an adsorption medium for purifying water bodies polluted by Cd was compared with that of phosphate rock powder modified with fulvic acid, chitosan, MnO2, and sulfhydryl, respectively, and their appearance and adsorption properties were investigated. The surface structures of all modified powders were rougher than the original, and their functional groups were richer. The greatest Cd2+ adsorption capacity, 1.88 mg g−1, was achieved with chitosan-modified PRP (CMPRP). This was 106.59% greater than that of PRP. The capacities of fulvic acid and MnO2 were 15.38% and 4.40% greater than that of the original, respectively. When the fulvic acid-modified PRP, CMPRP, and manganese dioxide PRP reached adsorption equilibrium, the removal rates of Cd2+ were 51.86%, 93.26%, and 46.70%, respectively. Moreover, the removal rate of Cd2+ by CMPRP was 104.43% higher than that of PRP. The main Cd2+ adsorption mechanisms for the MPRPs were electrostatic interactions, ion exchange, co-precipitation, and complexation. Moreover, the processing of the phosphate rock powder was straightforward, harmless to the environment, and could be effectively used for the removal of Cd. These results show that CMPRP is promising as a new adsorption material to treat Cd-contaminated water.