Polyphosphate coated fertilizers and a process for the production thereof

Abstract

According to some demonstrative embodiments, there is provided herein a fertilizer granule comprising: a core comprising at least one fertilizer; a coating covering said core, comprising polyphosphate; and wherein said polyphosphate comprises a cation based on sodium or ammonium having a chain length of 10 or more units.

Description

[0001] POLYPHOSPHATE COATED FERTILIZERS AND A PROCESS FOR THE PRODUCTION THEREOF

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to the field of agriculture, specifically to improving the sustainability and efficiency of fertilizers.

[0004] BACKGROUND OF THE INVENTION

[0005] The current state of agricultural practices, particularly in relation to phosphorus (P) fertilization, presents significant challenges and inefficiencies that necessitate innovation and improvement. Phosphorus, being an essential macronutrient, plays a pivotal role in various structural and biochemical processes in plants. However, the predominant issue with phosphorus utilization in agriculture stems from its limited availability due to strong fixation to soil constituents. This fixation is especially pronounced in acidic soils, where phosphate rapidly binds with metal oxides, reducing the efficiency of phosphorus fertilizers and increasing costs for farmers.

[0006] Despite the high total amount of phosphorus in soils, a major portion of it exists in forms that are not readily available to plants. This issue is compounded in acidic soils, where phosphorus predominantly reacts with elements like iron and aluminum, and in alkaline soils with calcium, forming poorly soluble complexes. As a result, a significant proportion of applied phosphorus fertilizers is not effectively utilized by crops, with estimates suggesting that about 80% of the applied phosphorus is adsorbed, precipitates, or is converted into organic form, thereby remaining inaccessible to plants.

[0007] Current phosphorus fertilizers, primarily derived from finite phosphate rock resources, include popular forms like single superphosphate (SSP) and triple superphosphate (TSP). These fertilizers, while beneficial, are limited in their efficiency due to soil dynamics and environmental conditions. Furthermore, the increasing cost of phosphate rock due to its depletion raises concerns about the sustainability of these fertilizers. One promising area of research involves the utilization of polyphosphates (poly- P), which consist of multiple orthophosphate units. These compounds, upon application to soil, undergo hydrolysis, releasing phosphorus in a more plant-accessible form. However, the exact mechanisms and efficiency of poly-P fertilizers in different soil types and conditions are not fully understood, and existing studies provide mixed results regarding their effectiveness.

[0008] The hydrolysis reaction of pyrophosphate is shown below:

[0009] P2O24+ H2O ~^ 2HP0 ~

[0010] In light of these challenges, there is a pressing need to develop novel strategies and materials that can enhance phosphorus availability and utilization in agricultural soils. Potential approaches include modifying soil pH, leveraging competition at adsorption sites, and utilizing phosphatase activity. Additionally, understanding the interaction between plant roots and phosphorus availability in the soil, including root exudation of carboxylates and phosphatases, could provide insights into more effective phosphorus utilization strategies. Given the complexity of soil dynamics and plant-soil interactions, comprehensive research and innovative solutions are essential to address the inefficiencies in current phosphorus fertilization practices and to ensure sustainable agricultural productivity.

[0011] SUMMARY OF THE INVENTION

[0012] According to some demonstrative embodiments, there is provided herein a fertilizer granule comprising: a core comprising at least one fertilizer; a coating covering said core, comprising polyphosphate; and wherein said polyphosphate comprises a cation based on sodium or ammonium having a chain length of 10 or more units (also referred to herein as “long-chain”).

[0013] According to some demonstrative embodiments the fertilizer may comprise a phosphorous-based fertilizer.

[0014] According to some demonstrative embodiments, said granule may increase phosphorous nutrient efficiency by 5-600% in both alkaline and acidic soils, compared to an uncoated fertilizer. According to some demonstrative embodiments, the application of said composition may result in an increase in crop biomass of 10-20% on a dry weight basis compared to crops treated with uncoated fertilizer.

[0015] According to some demonstrative embodiments, the polyphosphate coating may be applied at a level ranging from 1-5% by weight of the total fertilizer composition. According to some demonstrative embodiments, the granule may further comprise a second coating comprising a wax or gum.

[0016] According to some demonstrative embodiments the gum may preferably be Rosin gum. According to some demonstrative embodiments, the coated fertilizer may be compatible with urea, allowing for the creation of effective nitrogen and phosphorous (N+P) fertilizer blends.

[0017] According to some demonstrative embodiments, there is provided a process for coating a phosphorous-based fertilizer with polyphosphate, the process comprising: preparing a phosphorous-based fertilizer (core); preparing a polyphosphate coating solution with a chain length of 10 or more units; and applying said polyphosphate coating to the phosphorous-based fertilizer (core) in an amount of 1-5% by weight of the entire granule weight.

[0018] According to some demonstrative embodiments, there is provided herein a method for increasing crop yield and biomass, the method comprising applying the fertilizer composition discussed hereinabove to agricultural crops, wherein the application of the coated fertilizer enhances phosphorous uptake and biomass production in the crops.

[0019] DETAILED DESCRIPTION OF THE INVENTION

[0020] According to some demonstrative embodiments, there is provided herein a fertilizer granule comprising a core comprising at least one fertilizer and a coating covering the core, comprising polyphosphate.

[0021] According to some embodiments, the polyphosphate may comprise a cation based on sodium, potassium or ammonium having a chain length of 6 or more units.

[0022] According to some demonstrative embodiments, the fertilizer may be selected from the group including TSP Fertilizers, blends including mixes of phosphorus (P) and potassium (K), e.g., often enhanced with additional nutrients like magnesium (Mg) and sulfur (S). Polyhalite-based products, Monoammonium Phosphate (MAP), Mono Calcium Phosphates (MCP), Diammonium Phosphate (DAP), Potassium Phosphate, Compound Fertilizers with N-P-K Ratios and the like. In certain embodiments, the fertilizer may also include phosphorus recovered from secondary sources such as sewage sludge ash, including processed or refined phosphate products obtained via thermochemical or wet-chemical recovery methods.

[0023] According to some preferable embodiments, the polyphosphate may comprise a cation based on sodium, potassium or ammonium having a chain length of 10 or more units (also referred to herein as “long chain”)

[0024] According to some embodiments, the polyphosphate coating may be applied at a concentration ranging from 0.5%-10% w / w of the total fertilizer composition, preferably 1-5% w / w.

[0025] According to some embodiments, the polyphosphate coating may include Long chain Polyphosphates, like Sodium Hexametaphosphate (SHMP) and Long Chain N- Polyphosphates, like Ammonium Polyphosphate (APP).

[0026] According to some embodiments, the coated fertilizer may be compatible with urea, allowing for the creation of effective nitrogen and phosphorous (N+P) fertilizer blends. According to some embodiments, the compatibility of Mono Calcium Phosphates (MCP) based phosphorous fertilizers with urea, a commonly used nitrogen fertilizer, may be improved through appropriate coating strategies. This compatibility is particularly beneficial as it allows for the creation of effective N+P blends, which were technically challenging to achieve prior to this invention.

[0027] According to some embodiments, the polyphosphate coating may be defined as a first coating and may optionally be coated with a second coating which comprises at least one organic source based on combination of wax and gum.

[0028] According to some embodiments, increasing nutrient use efficiency (NUE) is considered critical for sustainable agriculture, as it directly impacts crop productivity, environmental health, and economic viability. NUE refers to the efficiency with which plants utilize available nutrients, particularly nitrogen (N) and phosphorus (P), to produce biomass and yield. Enhanced NUE reduces the need for excessive fertilizer applications, minimizes nutrient losses to the environment, and lowers the ecological footprint of agricultural activities. This is increasingly important as global food demand rises, putting pressure on agricultural systems to produce more while minimizing environmental harm.

[0029] According to some demonstrative embodiments of the present invention, a fertilizer composition is provided comprising a phosphorus-based core granule and one or more functional coating layers, formulated to improve phosphorus uptake efficiency in both acidic and alkaline soils. These embodiments leverage a surface modification strategy to overcome known limitations associated with conventional phosphorus fertilizers such as Triple Superphosphate (TSP) and Single Superphosphate (SSP), which are often characterized by low agronomic efficiency and incompatibility with nitrogen-based fertilizers, particularly urea.

[0030] In certain demonstrative embodiments, a single coating layer may be applied to the phosphorus fertilizer granule. The coating may comprise a polyphosphate or other phosphate-soluble polymer material designed to enhance the nutrient use efficiency (NUE) of the applied product. This single-coating configuration may be sufficient to delay fixation reactions in soil, improve nutrient mobility, and support sustained nutrient release.

[0031] In other demonstrative embodiments, a dual -coating system is employed. The first (inner) coating layer may comprise a polyphosphate or related material that promotes improved phosphorus availability and mobility in the rhizosphere. The second (outer) coating layer may comprise a material selected from waxes, gum resins (such as rosin), or other hydrophobic binders. This outer layer may be configured to improve physical handling properties, reduce premature dissolution, and, importantly, enhance compatibility with urea-containing fertilizers.

[0032] Fertilizer compatibility, as referred to herein, describes the ability of different fertilizer components to remain physically and chemically stable when blended or stored together. According to some demonstrative embodiments, the coated phosphorus granules exhibit enhanced compatibility with urea, remaining free-flowing, non-agglomerated, and resistant to caking or liquefaction under standard storage and field blending conditions. In contrast, uncoated phosphorus fertilizers may exhibit significant incompatibility when combined with urea, including undesirable moisture uptake, particle adhesion, and the formation of large agglomerates that hinder uniform field application. According to additional demonstrative embodiments, the core granule may further include one or more micronutrients, either incorporated within the core matrix or within the coating layers. For example, boron (e.g., in the form of borax) or zinc (e.g., in the form of zinc sulfate or zinc oxide) may be incorporated. These micronutrients may be pre-dispersed in a coating slurry (e.g., a SHMP -based solution), enabling uniform micronutrient delivery without compromising granule integrity or flowability. Furthermore, according to some demonstrative embodiments, the combination of polyphosphate-based coatings with hydrophobic second layers provides a synergistic effect, i.e., simultaneously improving nutrient efficiency, enhancing physical stability, and ensuring compatibility with co-applied nitrogen fertilizers. This enables the delivery of multi -nutrient solutions tailored to specific crop and soil requirements while maintaining ease of handling and application.

[0033] Several challenges make increasing NUE complex. One primary issue is nutrient loss, which occurs through leaching, volatilization, and run-off, particularly in poorly managed or extreme soil conditions. This not only wastes fertilizer resources but also contributes to pollution, such as nitrogen leaching into groundwater or phosphorus runoff causing algal blooms in waterways.

[0034] Moreover, achieving high NUE across diverse soil types and varying climate conditions requires tailored approaches, as nutrient availability and uptake mechanisms vary significantly with environmental factors. Soil acidity, for example, can reduce phosphorus availability, whereas basic (alkaline) soils may restrict certain forms of nitrogen.

[0035] Another challenge lies in synchronizing nutrient release with plant uptake. Traditional fertilizers often release nutrients faster than plants can absorb them, resulting in inefficiencies.

[0036] In certain exemplary embodiments, the first coating, which is a polyphosphate coating, enhances the nutrient use efficiency (NUE) of the fertilizer described in this invention. Specifically, the first coating demonstrates effectiveness across both acidic and alkaline soil conditions. This effectiveness is measured by the increased biomass production or elevated phosphorus uptake by plants when the same quantity of fertilizer is applied. In other words, by applying the first coating of the present invention to the fertilizer this may lead to greater biomass yield or improved phosphorus absorption by plants, as compared to using an uncoated fertilizer.

[0037] According to some embodiments, compatibility between different fertilizers is essential to ensure they can be mixed, applied together, or used sequentially without causing adverse reactions, nutrient loss, or crop damage. Here are some of the key challenges in achieving compatibility between two fertilizers:

[0038] Chemical Reactions Leading to Precipitation: Some fertilizers contain compounds that can react when mixed, leading to precipitation or crystallization. For instance, mixing calcium-containing fertilizers with phosphates can form insoluble calcium phosphate, reducing nutrient availability. Such reactions can clog application equipment and make nutrients unavailable to plants. pH Incompatibility: Different fertilizers can alter the pH of the solution when mixed. For example, Ammonium-based fertilizers may temporarily lower pH due to nitrification, while elemental sulfur or sulfur-oxidizing compounds may also acidify the soil over time. In contrast, sulfate-based fertilizers generally have minimal effect on soil pH.. A significant shift in pH can cause nutrient imbalances or precipitate essential elements, making them unavailable to plants and leading to uneven nutrient application.

[0039] Salt Index and Plant Toxicity: Combining fertilizers with high salt indices can lead to increased salinity in the soil or application solution, risking plant root toxicity. Overloading salts around the root zone can damage plant tissues and reduce nutrient uptake, which is particularly harmful to sensitive crops.

[0040] Inconsistent Nutrient Release Rates: Some fertilizers are designed for slow release, while others provide immediate nutrient availability. Combining these may lead to inconsistent nutrient delivery to plants, as one fertilizer may release nutrients faster than the other. This mismatch can result in periods of nutrient deficiency or excess, affecting plant growth and health.

[0041] Compatibility with Application Methods: Fertilizers applied through foliar sprays, fertigation, or soil application each have specific formulation requirements. Mixing incompatible fertilizers can cause clogging in fertigation systems or uneven foliar coverage. Liquid fertilizers, for example, may need special compatibility checks to avoid blockages or reactions in drip irrigation systems. Increased Risk of Leaching and Runoff: When highly soluble fertilizers are used, the granules may dissolve rapidly upon contact with moisture, increasing the exposure of nutrients — particularly nitrogen — to potential leaching or runoff. This not only reduces the efficiency of nutrient uptake but also poses environmental risks from nutrient runoff into water sources.

[0042] Temperature Sensitivity and Stability: Some fertilizers are temperature-sensitive, and when combined, they may destabilize each other. For instance, urea can react with other fertilizers at high temperatures, leading to ammonia volatilization. Temperature sensitivity must be carefully considered to maintain nutrient stability.

[0043] Physical Incompatibility: Granular fertilizers mixed together may differ in particle size and density, causing segregation during transport or application. This uneven distribution can result in inconsistent nutrient delivery in the field, affecting crop growth and yield.

[0044] Combining phosphorus fertilizers with urea poses challenges due to chemical reactions that reduce nutrient availability. Urea’s rapid hydrolysis increases soil pH locally, leading to phosphorus precipitation and ammonia volatilization, both of which diminish nutrient efficiency.. The combined application also risks salt accumulation near roots, which can lead to osmotic stress and reduced nutrient uptake.

[0045] In certain embodiments, the second coating may improve the compatibility of phosphorus fertilizers with urea. Compatibility between such fertilizers presents a significant challenge, as mixing incompatible fertilizers can lead to issues such as uneven distribution, poor adherence, clumping, and aggregation. Fertilizers that lack compatibility often bind together, form lumps, and aggregate, which can hinder effective application and nutrient availability. According to some embodiments, the ratio between the wax and gum may be between 1 :3-l :5.

[0046] According to some embodiments, the compatibility of MCP -based phosphorus fertilizers with urea, a commonly used nitrogen fertilizer, may be enhanced through specific coating strategies. This improved compatibility is particularly beneficial, as it enables the formulation of stable and effective N+P fertilizer blends — an outcome that was previously difficult to achieve due to physicochemical incompatibilities between the components. In some embodiments, the dual-layer coating may be applied to the fertilizer, enhancing nutrient use efficiency (NUE) through a synergistic effect. The second layer, containing wax or gum, preferably gum rosin, plays a crucial role by delaying phosphorus availability. The wax or gum may effectively block water penetration, reducing the immediate solubility of phosphorus and preventing reactions between water and phosphorus. This controlled release effect lowers phosphorus fixation in the soil, allowing a gradual release at low concentrations, thereby increasing phosphorus availability for plant uptake. Additionally, gum rosin promotes microbiome activity in the soil, enhancing phosphorus mineralization and further improving nutrient accessibility for plants.

[0047] According to some embodiments, application of the granule of the present invention onto soil may result in an increase in crop biomass of about 10-20% on a dry weight basis compared to crops treated with uncoated fertilizer.

[0048] According to some embodiments, application of the granule of the present invention onto soil may allow for increasing of phosphorous nutrient efficiency by 5-600%, preferably 9-500% in both alkaline and / or acidic soils, compared to an uncoated fertilizer.

[0049] According to some demonstrative embodiments, there is provided herein a fertilizer coated with a coating which includes one or more polyphosphate ingredients.

[0050] According to some embodiments, there is provided a coating process using polyphosphate ingredients. This coating may be applied to commodity phosphorus fertilizers, such as Triple Superphosphate (TSP) and Single Superphosphate (SSP), as well as their derivatives, e.g., PK, NP, and NPK fertilizers. In some embodiments, the coating process may also be applied to phosphate fertilizers recovered from secondary sources, including those produced from sewage sludge ash, thereby extending the utility of the invention to recycled or circular-economy phosphorus products. According to some embodiments, the polyphosphate coating may significantly reduce the fixation of phosphorous to soil constituents, a common issue that limits the effectiveness of traditional fertilizers.

[0051] According to some embodiments, this reduction in fixation enhances the availability of phosphorous to plants, thereby increasing the nutrient efficiency of the fertilizers.

[0052] According to some embodiments, when comparing against conventional granular Triple Super Phosphate (TSP), the phosphate use efficiency (PUE) can be increased in the range of 9-500% depending on type of soil, type of crop and fertilization procedure Broadcasting or Top Dressing vs soil applications ( incorporation ).

[0053] On alkaline soils, the PUE defined as Phosphorus absorption efficiency ([Dry Matter (g) x P (%)] / P given as base fertilizer (P g)) increased up to 24% when the fertilizer was incorporated in the soil and up to 130% when the fertilizer was not incorporated in the soil.

[0054] On acid soils, the PUE defined as Agronomic efficiency ([Yield-Yield of negative control] / P given as base fertilizer (P g)) increased up to 90% on a Soybean crop and up to 500% on a Maize crop.

[0055] Improved Phosphorous Uptake and Crop Yield:

[0056] According to some embodiments, use of the phosphate coating may enhance the uptake of phosphorous by targeted crops. According to some embodiments, the granule of the present invention may be beneficial for various crops, including for example, Com and Grains, Cotton and Wool, Fruit and Tree Nuts, Rice, Soybeans and Oil Crops, Sugar and Sweeteners, Vegetables and Pulses, Wheat and the like.

[0057] However, according to some preferable embodiments, the granule of the present invention may be especially suitable for the following crops: Solanaceous crops, e.g., Tomato, peppers, potatoes; Leguminous crops such as soybean, beans, alfalfa; Graminaceous crops such as maize, wheat, rice, sugarcane and barley; and Brassica crops such as rapeseed, cabbage, cauliflower and broccoli.

[0058] This is achieved by coating current phosphorous fertilizers with polyphosphate. The result is an increase in crop yield and a reduction in phosphorous loss to the environment.

[0059] According to some embodiments, there is provided herein a process for coating a phosphorous-based fertilizer with polyphosphate, the process comprising: preparing a core of a granule comprising a phosphorous-based fertilizer, preparing a polyphosphate coating solution with a chain length of 6 or more units; and applying said polyphosphate coating to the core in an amount of 0.5-10% w / w of the entire granule weight.

[0060] According to some embodiments, the coating process may include spray coating (in a soluble form or slurry form), e.g., in a coating drum at a temperature of 65-90°C. According to some embodiments, the polyphosphate coating solution may include a concentration of 40-70% w / v of polyphosphate in water.

[0061] According to some embodiments, the polyphosphate coating is applied to the core in an amount of 1-5% w / w of the entire granule weight.

[0062] According to further embodiments, there is provided herein a fertilizer granule comprising a polyphosphate-based outer coating further comprising one or more micronutrient elements and / or biostimulants, wherein said micronutrients are selected from the group consisting of iron (Fe), manganese (Mn), Zinc (Zn), copper (Cu), Boron (B), magnesium (Mg), Molybdenum (Mo), Chlorine (Cl), silicon (Si), and combinations thereof, and are present in said coating in a concentration of less than 0.5% w / w of the total granule composition.

[0063] In some embodiments, said micronutrients and / or biostimulants are incorporated into the polyphosphate or polyphosphate / gum rosin mixture in liquid form prior to application to the granule, thereby forming a surface-deposited coating. This configuration enables enhanced dispersion of the micronutrient and / or biostimulant ingredients across the granule surface, improving their bioavailability and reducing the total active ingredient required to achieve a desired agronomic effect.

[0064] In certain embodiments, the polyphosphate acts as a chelating and stabilizing carrier for said micronutrients, while the gum rosin component provides a hydrophobic barrier that regulates release and mitigates interaction with incompatible fertilizer components (e.g., urea or calcium salts).

[0065] According to some embodiments, the advantages of this configuration include: improved uniformity and consistency of micronutrient delivery; reduction in the required active load to achieve physiological responses; simplified integration into mass-scale fertilizer coating operations, overcoming operational challenges associated with high- solid or microdosed additives; and avoidance of agglomeration or uneven embedding typically observed in granules with internally embedded micronutrients.

[0066] According to some preferred embodiments, the polyphosphate-micronutrient- gum matrix may be applied in a soluble form or slurry form, via drum spraying at elevated temperatures (e.g., 65-90°C) and in liquid concentrations of 40-70% w / v, as described for other coatings in this invention. The method may include applying the mixture as a single or multilayer coating depending on compatibility requirements. According to some demonstrative embodiments, the invention provides a fertilizer composition comprising a phosphorus-based fertilizer core and one or more coating layers applied to enhance nutrient use efficiency, compatibility with nitrogen fertilizers, and environmental stability. In some embodiments, the composition comprises:

[0067] 90-98% by weight of a phosphorus-based fertilizer core, such as TSP, SSP, or recycled phosphate sources (e.g., sewage sludge ash-derived phosphates);

[0068] 1-5%, preferably 1-3%, by weight of a polyphosphate coating, preferably comprising long-chain sodium or ammonium polyphosphates (e.g., chain lengths >10 units);

[0069] 0.1-0.5% by weight of one or more micronutrients selected from boron, zinc, iron, manganese, or their combinations, optionally co-dissolved or co-dispersed in the polyphosphate matrix.

[0070] According to some embodiments, the coated fertilizer granules are configured to reduce phosphorus fixation in acidic or alkaline soils. When applied in field or pot conditions, the coated granules may result in at least 50% higher phosphorus availability or uptake relative to an uncoated phosphorus fertilizer under similar conditions, as demonstrated by phosphorus use efficiency (PUE) metrics and crop biomass measurements.

[0071] In yet another embodiment, the invention provides a kit comprising:

[0072] (i) a polyphosphate coating formulation suitable for spray application;

[0073] (ii) a phosphorus-based fertilizer core, optionally granulated; and

[0074] (iii) instructions for applying said coating using conventional coating devices, such as rotary drum coaters or fluidized bed units, under controlled temperature and humidity conditions.

[0075] Examples

[0076] Example 1 - Rehagro Maize Acid Soils

[0077] Objective

[0078] To evaluate the agronomic performance and phosphorus use efficiency (PUE) of polyphosphate-coated triple superphosphate (TSP-PP) in comparison with conventional TSP under acidic soil conditions in tropical maize cultivation. The experiment was carried out at Rehagro Research Experimental Station, located on the BR 265 highway, Km 292, in the city of Nazareno, Minas Gerais state, at 1016 meters of altitude, during the period from November 30, 2021 to May 11, 2022.

[0079] The sowing of the NS80 hybrid was carried out on 11 / 30 / 2021, at a density of 72,000 Plants / Ha.

[0080] Seedling emergence occurred 7 days after planting, on 12 / 07 / 2021. Sowing fertilization was performed according to the treatments. All plots were fertilized in furrow with 25 kg / ha of N (urea). In V2 stage all plots were fertilized with 80 kg / ha of K2O (KC1) in broadcast application. In V4 stage all plots were fertilized with 150 kg / ha of N (urea) in broadcast application. The crop management were carried out in accordance with the Rehagro Research Management Procedure.

[0081] Grain yield data was obtained by weighing the grains harvested in the useful area of the plot experimental, with humidity corrected to 13.0%.

[0082] The trial was carried out in a randomized block design (CBD), with four replications. The experimental plot consisted of 5 lines of 5 m, with a spacing of 0.50 m.

[0083] The goal of this experiment was to evaluate the effect Polyphosphate coated TSP (TSP- PP) would have on yield parameters as compared to the conventional practice. For this purpose, 2 different fertilization levels were evaluated.

[0084] Treatments:

[0085] - Negative control: no P

[0086] - Positive control: TSP (Triple super phosphate)

[0087] Coating Treatment: TSP-PP (Triple super phosphate coated with Polyphosphate)

[0088] Results

[0089] For this trial, Phosphorus Use Efficiency (PUE) was evaluated as Agronomic efficiency ([Yield-Yield of negative control] / P given as base fertilizer (P g))

[0090] Table 1. Yield and Phosphorus Use Efficiency

[0091] This trial showed that compared to regular TSP, using TSP-PP increased maize yield by up to 19% and PUE by over 600%.

[0092] Conclusions

[0093] Yield Response: The highest yield (13,160.66 kg / ha) was observed in the TSP-PP 90 kg / ha treatment, marking a 19% increase over the best-performing conventional TSP treatment.

[0094] Phosphorus Efficiency:

[0095] TSP-PP at 90 kg / ha achieved a PUE of 29.09, compared to 6.16 with conventional TSP, which is a 372% improvement.

[0096] At the lower dose (67.5 kg / ha), TSP-PP still yielded a PUE of 27.55, >500% higher than standard TSP at the same dose.

[0097] Key Insight: The polyphosphate coating significantly enhanced phosphorus uptake and utilization efficiency, particularly in acidic soils where traditional phosphate fertilizers often underperform due to fixation.

[0098] Conclusion: TSP-PP consistently outperforms conventional TSP across both dosage levels in terms of yield and phosphorus efficiency, making it a superior agronomic choice for tropical acidic soils.

[0099] Conclusions

[0100] Yield Response: The highest yield (13,160.66 kg / ha) was observed in the TSP-PP 90 kg / ha treatment, marking a 19% increase over the best-performing conventional TSP treatment.

[0101] Phosphorus Efficiency:

[0102] TSP-PP at 90 kg / ha achieved a PUE of 29.09, compared to 6.16 with conventional TSP, which is a 372% improvement.

[0103] At the lower dose (67.5 kg / ha), TSP-PP still yielded a PUE of 27.55, >500% higher than standard TSP at the same dose. The polyphosphate coating significantly enhanced phosphorus uptake and utilization efficiency, particularly in acidic soils where traditional phosphate fertilizers often underperform due to fixation.

[0104] TSP-PP consistently outperforms conventional TSP across both dosage levels in terms of yield and phosphorus efficiency, making it a superior agronomic choice for tropical acidic soils.

[0105] Example 2 - Rehagro Soybean Acid Soils

[0106] Objective

[0107] To assess the impact of polyphosphate-coated triple superphosphate (TSP-PP) versus conventional TSP on soybean yield and phosphorus use efficiency (PUE) under acidic soil conditions typical of southeastern Brazil.

[0108] The trial was conducted at the Rehagro Research Experimental Station, located on the BR 265 highway, Km292, in the municipality of Nazareno - MG, at 1016 meters of altitude, during the period from November 30, 2021 to April 4, 2022. Climatic conditions prevailing during the conduction of the experiment were obtained from the automatic meteorological station of Rehagro Pesquisa.

[0109] Installation and conduct of the trial:

[0110] The sowing of the NS6010 IPRO cultivar was carried out on 30 / 11 / 2021, at a density of 280,000 plants. ha-1. Seedling emergence occurred 10 days after planting, on 10 / 12 / 2022. Sowing fertilization was carried out according to the protocol stipulated. All plots were fertilized one day after planting with 80 kg ha-1 of K2O (133 kg ha-1 of KC1) in broadcast application. Crop treatments were carried out in accordance with the Management Procedure - Rehagro Research Station Management.

[0111] Grain yield data was obtained by weighing the grains harvested in the useful area of the plot experimental, with humidity corrected to 13.0%.

[0112] The trial was carried out in a randomized block design (CBD), with four replications. The experimental plot consisted of 5 rows of 10 m, with a spacing of 0.50 m.

[0113] The goal of this experiment was to evaluate the effect Polyphosphate coated TSP (TSP- PP) would have on yield parameters as compared to the conventional practice. Treatments:

[0114] - Negative control: no P

[0115] - Positive control: TSP (Triple super phosphate)

[0116] Coating Treatment: TSP-PP (Triple super phosphate coated with Polyphosphate)

[0117] Results

[0118] For this trial, Phosphorus Use Efficiency (PUE) was evaluated as Agronomic efficiency ([Yield-Yield of negative control] / P given as base fertilizer (P g))

[0119] Table 2. Yield and Phosphorus Use Efficiency

[0120] This trial showed that compared to regular TSP, using TSP-PP increased Soybean PUE by 20%.

[0121] Conclusions

[0122] Yield Improvement: TSP-PP resulted in the highest yield (3,256.34 kg / ha), improving production by 9.4% over the no-P control and by 1.5% over conventional TSP.

[0123] Phosphorus Use Efficiency: The PUE of TSP-PP (3.11 kg grain / kg P2O5) was 20% higher than that of conventional TSP (2.59 kg / kg).

[0124] Agronomic Implication: The polyphosphate coating appears to enhance phosphorus availability under acidic soil conditions by mitigating fixation and possibly improving early root uptake.

[0125] Conclusion: TSP-PP offers a measurable agronomic advantage over conventional TSP, particularly in acid soil environments where phosphorus efficiency is often constrained.

[0126] Example 3 - Rio Verde Maize Acid Soils

[0127] Objective To evaluate the agronomic performance and phosphorus use efficiency (PUE) of polyphosphate-coated triple superphosphate (TSP-PP) compared to conventional TSP in maize (Zea mays) cultivated on acidic tropical soils of the Brazilian Cerrado.

[0128] The trial was installed on the research station of the Rio Verde Research and Technological Development Foundation, located between the geographic coordinates 13°00'27” S - 55°58’07” W and 12°59'34” S - 55°57'50” W, with an average altitude of 387 meters, in the municipality of Lucas do Rio Verde - MT. The region is included in the Cerrado biome and its predominant climate is Aw (Tropical of Savana) according to the Kbppen-Geiger classification (Peel et al., 2007), with two well-defined seasons (rainy, from October to April and dry season from May to September), the soil is classified as a dystrophic yellow LATOSOL with a clayey texture (Embrapa, 2013).

[0129] The test was carried out during the 2021 / 22 season, using the corn hybrid MG 580 PWU sowed on December 15, 2021, with seed treatment using Poncho at a dose of 70.0 ml for 60,000 seeds.

[0130] All treatments were fertilized with 120.0 kg / Ha of ammonium sulfate and 133.3 kg / Ha of KCL in top dress at stage V2, and in stage V4 the application of 333.3 kg / Ha of Urea, totaling 175.2 kg / Ha of N, 80.0 kg / Ha of K2O, and 26.4 kg / Ha of S.

[0131] To determine the yield, the ears of two lines of four linear meters were manually collected at two points in the useful area of each plot on the date of 13 / 04 / 2021 when the crop was in the R6 stage (119 days after sowing), later the spikes were trodden on a stationary track and after cleaning the grains, these were weighed and determined their moisture content, so the yield was calculated in an area unit with correction of the moisture content for the commercial standard of 13%.

[0132] The design used was randomized blocks with FOUR replications, each plot consisted of fifteen sowing lines spaced 0.45 meters by 5.5 meters in length, totaling an area of 24.8 m2 per plot and 99.0 m2per treatment.

[0133] The goal of this experiment was to evaluate the effect Polyphosphate coated TSP (TSP- PP) would have on yield parameters as compared to the conventional practice.

[0134] Treatments:

[0135] - Negative control: no P - Positive control: TSP (Triple super phosphate)

[0136] Coating Treatment: TSP-PP (Triple super phosphate coated with Polyphosphate)

[0137] Results

[0138] For this trial, Phosphorus Use Efficiency (PUE) was evaluated as Agronomic efficiency ([Yield-Yield of negative control] / P given as base fertilizer (P g))

[0139] Table 3. Yield and Phosphorus Use Efficiency

[0140] This trial showed that compared to regular TSP, using TSP-PP increased maize yield by 3.5% and PUE by 47%.

[0141] Conclusions

[0142] Yield Advantage: TSP-PP increased maize yield by 3.5% compared to conventional TSP, and by 11.7% over the no-P control.

[0143] Phosphorus Efficiency: TSP-PP achieved a PUE of 10.98 kg grain / kg P2O5, which is 47% higher than the PUE of conventional TSP (7.44).

[0144] Soil-Responsive Technology: In acidic, clayey Latosols prone to phosphorus fixation, the polyphosphate coating likely improved P availability and sustained uptake during critical growth stages.

[0145] Conclusion: Polyphosphate coating enhances the agronomic efficiency of phosphorus fertilizers under acidic soil conditions, offering measurable yield gains and improved nutrient use efficiency.

[0146] Example 4 - Rio Verde Soybean Acid Soils

[0147] Objective To evaluate the agronomic performance and phosphorus use efficiency (PUE) of polyphosphate-coated triple superphosphate (TSP-PP) versus conventional TSP on soybean (Glycine max) grown under acidic tropical soil conditions representative of the Brazilian Cerrado.

[0148] The trial was installed on the research station of the Rio Verde Research and Technological Development Foundation, located between the geographic coordinates 13°00'27” S - 55°58’07” W and 12°59'34” S - 55°57'50” W, with an average altitude of 387 meters, in the municipality of Lucas do Rio Verde - MT. The region is included in the Cerrado biome and its predominant climate is Aw (Tropical of Savana) according to the Kbppen-Geiger classification (Peel et al., 2007), with two well-defined seasons (rainy, from October to April and dry season from May to September), the soil is classified as a dystrophic yellow LATOSOL with a clayey texture (Embrapa, 2013). The test was carried out during the 2021 / 22 season, using the soybean cultivar CZ 37B51 IPRO sown on November 26, 2021, with seed treatment using Standak Top at a dose of 2.0 ml per kg of seeds.

[0149] After sowing, application was carried out in coverage of 133,3 kg ha1of KCL in all treatments, to supply 80,0 kg ha1of K2O.

[0150] To determine the yield, plants from two lines of four linear meters were manually collected at two points in each plot on 01 / 03 / 2022 when the crop was at the R9 stage (99 days after sowing), then the mass of the plants were threshed on a stationary thresher and after cleaning the grains in specific equipment, they were weighed and their moisture content determined, then the yield was calculated in unit area with correction of the moisture content to the commercial standard of 13%.

[0151] The design used was randomized blocks with FOUR replications, each plot consisted of fifteen sowing lines spaced 0.45 meters by 5.5 meters in length, totaling an area of 37.1 m2 per plot and 148.5 m2per treatment.

[0152] The goal of this experiment was to evaluate the effect Polyphosphate coated TSP (TSP- PP) would have on yield parameters as compared to the conventional practice.

[0153] Treatments:

[0154] Negative control: no P - Positive control: TSP (Triple super phosphate)

[0155] Coating Treatment: TSP-PP (Triple super phosphate coated with Polyphosphate)

[0156] Results

[0157] For this trial, Phosphorus Use Efficiency (PUE) was evaluated as Agronomic efficiency ([Yield-Yield of negative control] / P given as base fertilizer (P g))

[0158] Table 4. Yield and Phosphorus Use Efficiency

[0159] This trial showed that compared to regular TSP, using TSP-PP increased soybean yield by 4% and PUE by 91%.

[0160] Conclusions

[0161] Yield Performance: TSP-PP increased soybean yield by 4% compared to conventional TSP, and by ~9% over the no-P control.

[0162] Phosphorus Use Efficiency: The agronomic efficiency of TSP-PP (2.54 kg grain / kg P2O5) was 91% higher than that of conventional TSP (1.33 kg / kg).

[0163] Mechanism of Benefit: The polyphosphate coating may have contributed to reduced phosphorus fixation in the acidic Latosol, improved P solubility, and sustained availability during critical growth stages.

[0164] Field Relevance: These findings demonstrate that TSP-PP offers a substantial advantage in acidic tropical soils where P availability is typically constrained by high fixation and low mobility.

[0165] Polyphosphate-coated TSP (TSP-PP) significantly improves phosphorus use efficiency and enhances soybean yield under acidic soil conditions of the Brazilian Cerrado, presenting a valuable advancement for sustainable and efficient fertilization strategies in tropical agriculture. Example 5 - R&D North Israel, Tomato and Maize, Alkaline Soils

[0166] Objective

[0167] To assess the agronomic performance and phosphorus use efficiency (PUE) of polyphosphate-coated triple superphosphate (TSP-PP) compared to uncoated TSP under alkaline soil conditions, using two application methods: broadcast (non -incorporated) and incorporated.

[0168] A pot trial was done in the MIGAL, Galilee Research Institute, R&D North facilities at HaHula Valley, Israel. The pots were filled with an alkaline clay loam soil.

[0169] The design used was randomized blocks with SIX replications, and each replication consisted of 5 pots.

[0170] For this trial, two crops were considered: maize and processing tomato. Additionally, 2 types of P fertilizer application were also considered: broadcasted (non-incorporated in the soil) and incorporated. The pots that had broadcasted P were irrigated with sprinklers, while the pots with incorporated P were irrigated with drippers.

[0171] All other nutrients besides Phosphorus were applied in sufficient amounts and equally for all treatments.

[0172] The goal of this experiment was to evaluate the effect Polyphosphate coated TSP (TSP- PP) would have on Phosphorus use as compared to the conventional practice.

[0173] Treatments:

[0174] - Negative control: no P

[0175] - Positive control: TSP (Triple super phosphate)

[0176] Coating Treatment: TSP-PP (Triple super phosphate coated with Polyphosphate)

[0177] Results

[0178] For this trial, Phosphorus Use Efficiency (PUE) was evaluated as Phosphorus absorption efficiency ([Dry Matter (g) x P (%)] / P given as base fertilizer (P g))

[0179] This trial showed that when the P fertilizers were not incorporated in the soil (broadcasted), the P fertilizations was less efficient than when they were incorporated in the soil. When focusing on the broadcasted method, the TSP-PP resulted in increased plant weight 11-22% and PUE 9-130% for Tomato and Maize respectively, as compared to regular TSP. In contrast, when the P fertilizers were incorporated, the TSP-PP treatment performed better only for tomatoes, increasing plant weight and PUE by 17 and 24% respectively.

[0180] Interpretation and Conclusions

[0181] Broadcasted Application:

[0182] TSP-PP outperformed conventional TSP in both crops under broadcast conditions, where phosphorus availability is typically reduced due to surface fixation in alkaline soils.

[0183] Maize: TSP-PP increased plant weight by 22% and PUE by -130% compared to TSP. Tomato: TSP-PP improved plant weight by 11% and PUE by -9%.

[0184] These findings highlight the potential of polyphosphate coatings to mitigate surface fixation and enhance phosphorus bioavailability when incorporation is not feasible.

[0185] Incorporated Application:

[0186] Overall, incorporated phosphorus was significantly more efficient than broadcasted phosphorus for both crops.

[0187] Tomato responded positively to TSP-PP under incorporated conditions, showing a 17% increase in biomass and 24% higher PUE compared to uncoated TSP.

[0188] Maize, however, showed a slightly lower performance with TSP-PP, suggesting that under incorporated conditions, conventional TSP may already deliver sufficient phosphorus to meet early maize growth demands, or that the coating may delay release below optimal timing. Key Conclusions

[0189] Polyphosphate coatings on TSP (TSP-PP) significantly enhance phosphorus efficiency in alkaline soils, especially when surface application is used.

[0190] TSP-PP is particularly beneficial in systems where incorporation is not practiced or is impractical (e.g., no-till, broadcasted base dressing).

[0191] The performance advantage of TSP-PP is crop- and context-dependent, with notable gains in tomato yield and phosphorus uptake under both incorporation and surface application.

[0192] Example 6 - Compatibility procedure

[0193] Objective

[0194] To evaluate the physical compatibility of coated and uncoated TSP and TSP-based formulations with both prilled and granulated urea under controlled humidity and temperature conditions. Compatibility was assessed using both short-term (3-hour humidity exposure) and long-term (30-day closed bottle) test protocols.

[0195] The test includes holding the dry fertilizer blends in a humidity chamber at the desired humidity for 3 hours at 30°C. After 3 hours the samples were placed to dry in the oven at 50°C for 24 hours. The degree of compatibility is determined according to the following definitions:

[0196] 0 - No reaction, no apparent changes.

[0197] 1 - Slight change in color.

[0198] 2 - Partial agglomeration. Agglomerates contain both products.

[0199] 3 - Caking, mixture is not free flowing.

[0200] 4 - Mixture is sticky, liquid phase is visible.

[0201] Products passed the test if they were given 0 or 1.

[0202] Test

[0203] Chemical compatibility in blend is the ability of two or more materials to remain dry and free flowing when blended together. The blend of materials can be as a single product or a physical blend (as in the case of a bulk blend). Incompatibility is evidenced by wetting, caking, gas evolution, and / or particle disintegration.

[0204] Procedure:

[0205] Material or a blend of material is placed into a glass bottle and tightly capped. The container is then placed in an over at 30°C for 30 days. The blend is inspected daily, and any wetting, caking, disintegration, or gas evolution is noted. At the end of the 30 days each blend is rated as: compatible, predominantly compatible, predominantly incompatible, and incompatible. The comparison and results are indicated in tables 10 and 11, as follows: Table 10 - Compatibility of a TSP and Polyhalite formulation with urea

[0206] Table 11 - Compatibility of TSP with urea 1. IMI Coater: In some embodiments, a lab-scale coating drum, referred to as the

[0207] "IMI Coater," developed by the Israel Mining Institute (IMI), may be utilized. The coating drum is a rotating unit designed to coat granules by spraying coating materials in various forms, including liquids, slurries, or powder solids. The coating process may be conducted at temperatures above or below 70°C. 2. Compatibility Testing Results: Based on compatibility tests following the

[0208] International Fertilizer Development Center (IFDC) standards, it was concluded that only materials with a 0.5% gum rosin coating achieved full compatibility on both prilled and granular urea.

[0209] 3. TSP and Polyhalite formulation (Also referred to as "PK+"): In some embodiments, the TSP and Polyhalite formulation may refer to granulated fertilizers formulated from combinations of Triple Super phosphate (TSP) and Polyhalite. Polyhalite is a mined product containing 13% potassium (K), 6% magnesium (Mg), and 19% sulfur (S). A typical TSP and Polyhalite formulation may follow an N-P-K ratio of 0-29-5.

[0210] 4. Additional Compounds: Some embodiments may include Long chain Polyphosphates, like Sodium Hexametaphosphate (SHMP) and Long Chain N- Polyphosphates, like Ammonium Polyphosphate (APP) as part of the fertilizer composition.

[0211] Conclusions

[0212] Base Formulation Limitation:

[0213] Uncoated TSP and TSP + Polyhalite formulations are chemically incompatible with both prilled and granular urea, as evidenced by severe caking and water formation.

[0214] SHMP Alone Is Not Sufficient:

[0215] SHMP coatings at 1-3% reduced, but did not eliminate, agglomeration. Compatibility improved with SHMP applied at elevated granule temperatures (>70°C). Below this threshold, SHMP-coated samples also showed caking and / or moisture generation.

[0216] APP Shows Limited Improvement:

[0217] APP at 1% improved compatibility marginally — especially with granular urea — but 3% loadings led to caking, particularly in prilled blends.

[0218] Gum Rosin + SHMP Coating Is Most Effective:

[0219] Only the combination of gum rosin (0.5%) and SHMP (1-2%) achieved full compatibility with both forms of urea. This coating acts as a hydrophobic barrier and moisture regulator, preventing both caking and moisture-induced reactions.

[0220] Process Temperature Matters:

[0221] Coating application temperature significantly affects final compatibility. Processing below 70°C led to poor outcomes, even with SHMP present. Overall, the addition of gum rosin to the SHMP coating system was critical in achieving durable, urea-compatible TSP granules. These findings support further development and scaling of dual-layer coatings in enhanced efficiency fertilizer formulations.

[0222] Example 7

[0223] 1. Background.

[0224] As a part of EEF (Enhanced Efficiency Fertilizer) project, an outer layer of coating with Rosin Gum was additionally developed, proving to be effective for Urea compatibility. In this test, it was decided to extend the coating with SHMP in cooling drum stage to double-coating of SHMP + micronutrients.

[0225] The micronutrients selected for this experiment included: B (Boron) or Zn (ZnSO4 / ZnO) and these should be pre-mixed with SHMP solution before the spraying on TSP granules in cooling drum. Preliminary tests conducted showed that for the smooth mixing and spraying application, targeting coating of SHMP 1-2% of TSP, the ratio of micronutrients should preferably be limited to 0.2%.

[0226] In certain demonstrative embodiments, the preparation of micronutrient-enhanced coatings involves combining a polyphosphate component with one or more micronutrient sources under heated mixing conditions. The order of addition and mixing parameters may be adjusted to ensure a stable, sprayable composition. In some cases, specific mixing techniques may be employed to maintain homogeneity at elevated concentrations.

[0227] Objectives:

[0228] • To apply a micronutrient-containing polyphosphate coating to phosphorus-based fertilizer granules.

[0229] • To evaluate the physical and chemical performance of such coatings under laboratory-scale processing.

[0230] Coating Procedure:

[0231] Fertilizer granules are coated using a heated rotating drum and sprayed with aqueous compositions containing polyphosphates and optional micronutrients such as boron or zinc. The coating process may involve temperature control, gradual mixing, and post- application cooling to produce granules with desired handling and compatibility characteristics.

[0232] 4. Results

[0233] 4.1. Coating with Borax / SHMP

[0234] Coating with Borax / SHMP solution results are summarized on Table 12 below. As mentioned above, 50% SHMP solution was used for further dissolution of Borax, so the final composition appears in "coating solution" columns. The water ratio completes "coating solution" to 100% and is equal to the ratio of SHMP (starting solution is 50% SHMP). It should be also noted that resulted coating solutions were heated to 50-60°C, and besides being slightly viscous, they were stable during storage overnight and sprayed easily. The coating process went smoothly at the temperature above 75°C. After cooling granules are dry and free flowing. Concentration of B close to targeted, was confirmed in most tests, except in 0.1%B / l% SHMP.

[0235] Table 12: SHMP coating trials summary

[0236] Conclusions

[0237] Feasibility of double coating TSP granules with boron and SHMP was confirmed at lab scale, with stable and repeatable results. Borax readily dissolves in SHMP solution, forming a homogenous, sprayable mixture that maintains stability during storage. Optimal coating performance was observed when the granule bed temperature was maintained above approximately 75°C; lower temperatures led to minor sticking, likely due to condensation or incomplete drying. Boron content in coated granules closely matched target levels at higher concentrations (e.g., 0.25%), while slight deviation at lower loadings (e.g., 0.1%) may be attributed to process losses. Finished granules remained dry, free-flowing, and structurally intact, indicating suitability for downstream handling. Overall, this dual -coating system offers a practical and scalable method for micronutrient enrichment of phosphorus fertilizers while maintaining favorable physical and compatibility characteristics. Overall, the double coating with Borax / SHMP provides a practical and scalable route for micronutrient enrichment of phosphorus fertilizers, maintaining excellent handling characteristics and offering precise control over nutrient dosing.

[0238] 4.2. Coating with ZnSO4 / ZnO / SHMP solution

[0239] Double coating Zn / SHMP using both soluble and insoluble sources of Zn, or their mixes, was successfully implemented on the lab scale. In certain demonstrative embodiments, stable and sprayable mixtures containing zinc sources and polyphosphate were obtained by initially preparing a zinc-containing solution or suspension, followed by the gradual incorporation of polyphosphate under heated conditions. This approach facilitated uniform blending and coating performance.. The sticking appears when spray is applied at temperatures below 70°, similar to spraying only SHMP at the ratio of 1-2% to TSP, without incorporation of Zn. The results, including reference tests with SHMP only are summarized on Table 13 below.

[0240] Table 13: TSP granules coated with ZnSC / ZnO / SHMP 5. Conclusions

[0241] B (Borax):

[0242] Confirmed feasibility of double coating TSP granules with 0.1 -0.2% B and 1-2% of SHMP using Borax / SHMP solution.

[0243] Borax powder at required ratios is freely dissolved in 50% SHMP solution.

[0244] Resulted Borax / SHMP solution is stable and is regularly sprayed on heated TSP granules.

[0245] Light sticking was observed following spraying at < 70°C.

[0246] After cooling granules are dry and free flowing

[0247] Zn (ZnO / ZnSO4):

[0248] Confirmed feasibility of double coating TSP granules with 0.2% Zn and 1-2% of SHMP using ZnO, ZnSO4 or a mixture of thereof / SHMP solution.

[0249] Smooth air-nozzle application achieved after pre-mixing ZnO, ZnSO4 or a mixture of thereof with water and consequent dissolution of SHMP in regular mixer with heating to 60°C.

[0250] Spraying ZnO, ZnSO4 / SHMP solution is similar to spraying SHMP solution only.

[0251] Higher loads of Zn, or using prepared SHMP solution for mixing of ZnO, ZnSO4 confirmed in preliminary tests, would require high shear homogenizer.

[0252] Light sticking was observed following application at < 70°C.

[0253] Concentration of Zn close to targeted 0.2%, was confirmed.

[0254] The temperature of granules bed should preferably be kept above 70°C, similar to spraying with SHMP solution only.

[0255] Table 14. Preliminary tests with ZnO, using 50% SHMP solution for dispersion

[0256] Observations:

[0257] • ZnO can’t be dispersed in SHMP solution using conventional lab mixers.

[0258] • Better dispersion achieved with manual grinding and mixing in mortar (27-1) - spraying succeeded using very coarse nozzle (13G), but coating is not homogeneous

[0259] • Air nozzle-dispersible texture achieved immediately after Ultra-turrax homogenization (28-1).

[0260] • After cooling and dwelling viscosity of ZnO / SHMP solution rises drastically

[0261] • Homogenized slurry applied smoothly, at wide range of temperatures (65- 75°C )

[0262] After cooling granules are dry and free flowing

[0263] Conclusions:

[0264] Boron (Borax / SHMP) Coating:

[0265] Double coating with 0.1-0.2% B and 1-2% SHMP using Borax-SHMP solutions was successfully achieved.

[0266] Borax dissolves readily in SHMP at target ratios, forming a stable sprayable solution.

[0267] Light sticking occurs below 70°C, but granules remain dry and free-flowing after cooling.

[0268] Zinc (ZnO / ZnSO SHMP) Coating:

[0269] Feasibility of double coating TSP granules with 0.2% Zn and 1-2% SHMP using ZnO, ZnSO4, or their mixtures was confirmed.

[0270] Best coating uniformity was achieved using high-shear homogenization (Ultra- Turrax) followed by air-nozzle spraying.

[0271] The Zn-SHMP mixture behaves similarly to SHMP-only solutions in terms of application, but mixing order and temperature are critical. High Zn concentrations or use of pre-prepared SHMP solutions with Zn require advanced homogenization.

[0272] Light sticking was observed at temperatures below 70°C, reinforcing the need for spraying at elevated temperatures.

[0273] Overall, the coating process yields stable, free-flowing granules and offers a promising method for effective micronutrient delivery via surface application.

[0274] Example 8

[0275] Chemical compatibility in a blend refers to the ability of two or more fertilizer materials to remain dry, free-flowing, and physically stable when mixed. The blended materials may form a singular composite product or remain a physical mixture (e.g., a bulk blend). Chemical incompatibility is typically manifested through visual or physical degradation, such as moisture uptake (wetting), agglomeration (caking), evolution of gas, or disintegration of the granules.

[0276] Procedure:

[0277] The material or blend is placed in a sealed glass container and stored in a controlled environment at 30°C for a period of 30 days. The samples are visually inspected daily for signs of physical or chemical instability including wetting, caking, particle breakdown, or gas release. At the conclusion of the test period, each blend is rated on a four-tier scale: Compatible, Predominantly Compatible, Predominantly Incompatible, or Incompatible.

[0278] Results:

[0279] Table 15: Compatibility test

[0280] According to some demonstrative embodiments, compatibility between fertilizer components — such as phosphate-based granules and nitrogen-based fertilizers like urea — is assessed using visual, qualitative methods. This approach follows established industry protocols, including those adapted from the International Fertilizer Development Center (IFDC). The procedure involves storing physical blends of materials in controlled environmental conditions (e.g., 30°C for 30 days) and monitoring for physical changes such as caking, wetting, particle disintegration, or gas evolution. These changes indicate the level of incompatibility. Based on visual inspection, blends are classified into categories such as "compatible," "limited compatibility," or "incompatible." Due to the inherently qualitative and observational nature of this assessment, compatibility is not assigned a numerical value but instead relies on standardized descriptors to ensure consistency and reproducibility across tests.

[0281] Example 9

[0282] According to some demonstrative embodiments, the compatibility of various phosphorus-based fertilizers with urea was evaluated according to the International Fertilizer Development Center (IFDC) chemical compatibility protocol for bulk-blend fertilizers. This test measures the ability of two or more fertilizer materials to remain dry and free-flowing when mixed and stored under controlled conditions.

[0283] Test Procedure:

[0284] Each fertilizer blend was placed in a sealed glass container and maintained at 30°C for 30 days. The blends were inspected daily for evidence of incompatibility such as wetting, caking, gas evolution, or particle disintegration. At the end of the test period, the samples were visually assessed and classified as compatible, limited compatibility, or incompatible. Products Tested:

[0285] Five phosphorus-based fertilizers were tested with urea, using either an oil-based coating or a rosin-based coating.

[0286] Table 16 - Compatability test

[0287] Conclusions:

[0288] As is evident, application of a rosin-based coating to phosphorus fertilizers significantly improved their chemical compatibility with urea compared to oil-based coatings. While oil-coated fertilizers showed caking and loss of flowability, the rosin-coated products maintained structural integrity and remained free-flowing throughout the 30-day test. These results confirm that the rosin-based coating provides a practical solution for formulating stable N+P fertilizer blends, overcoming long-standing compatibility challenges in mixed fertilizer systems.

[0289] While this invention has been described in terms of some specific examples, many modifications and variations are possible. It is therefore understood that within the scope of the appended claims, the invention may be realized otherwise than as specifically described.

Claims

What is claimed is:

1. A coated fertilizer granule, comprising: a core comprising at least one fertilizer; and a first coating layer covering said core, said first coating layer comprising a polyphosphate; wherein said polyphosphate comprises a sodium- or ammonium-based cation and has an average chain length of ten (10) or more phosphate units.

2. The coated fertilizer granule of claim 1, wherein the fertilizer in said core comprises a phosphorus-based fertilizer.

3. The coated fertilizer granule of claim 2, wherein the phosphorus-based fertilizer is selected from the group consisting of triple superphosphate (TSP), single superphosphate (SSP), monoammonium phosphate (MAP), monocalcium phosphate (MCP), diammonium phosphate (DAP), and potassium phosphate.

4. The coated fertilizer granule of claim 2, wherein application of the coated granule to acidic or alkaline soils increases phosphorus use efficiency (PUE) by between 5% and 600% compared to an uncoated phosphorus fertilizer.

5. The coated fertilizer granule of claim 2, wherein application of the coated granule results in an increase in crop biomass of between 10% and 20% on a dry weight basis compared to crops treated with an uncoated fertilizer.

6. The coated fertilizer granule of claim 1, wherein the polyphosphate coating is applied at a concentration ranging from 1% to 5% by weight relative to the total weight of the fertilizer granule.

7. The coated fertilizer granule of claim 1, further comprising a second coating layer disposed over the first coating layer, wherein said second coating comprises a hydrophobic material selected from the group consisting of waxes, gums, or natural resins.

8. The coated fertilizer granule of claim 7, wherein said second coating comprises rosin gum.

9. The coated fertilizer granule of claim 8, wherein the coated granule exhibits compatibility with urea, remaining free-flowing and nonagglomerated when blended with urea-based fertilizers.

10. The coated fertilizer granule of claim 1, wherein said coating further comprises one or more micronutrients selected from the group consisting of iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), boron (B), magnesium (Mg), molybdenum (Mo), chlorine (Cl), silicon (Si), and combinations thereof, wherein the total micronutrient content is less than 0.5% by weight of the total granule.

11. A process for preparing a coated phosphorus-based fertilizer granule, comprising: providing a phosphorus-based fertilizer granule as a core; preparing a polyphosphate coating solution comprising polyphosphates having a chain length of ten (10) or more phosphate units and cations selected from sodium or ammonium; and applying said polyphosphate coating solution to the core in an amount of 1% to 5% by weight of the total granule.

12. The process of claim 11, further comprising applying a second coating layer over the polyphosphate coating, wherein said second coating comprises a wax or gum to enhance storage stability and compatibility with urea-based fertilizers.

13. A method for enhancing crop yield and phosphorus uptake, comprising applying the coated fertilizer granule of claim 1 to a crop or soil, wherein the application enhances phosphorus availability and increases biomass or yield relative to an equivalent uncoated fertilizer.

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