Granular fertilizer and its manufacturing method

Abstract

Coated granules and methods of making the coated granules that prevent the coated granules from floating and / or drifting away due to water currents and wind are disclosed. The coated granules may include a core having a water soluble compound such as a fertilizer, a controlled release layer, a surface treatment including a surfactant to reduce water tension, and an optional coating disposed between the controlled release layer and the surface treatment layer that includes a gelling agent such as a superabsorbent polymer that helps to anchor the coated granules to the soil surface and may reduce the likelihood of movement due to rolling.

Description

[Technical field]

[0001] The present disclosure relates generally to granular fertilizers and methods of making and using same. More specifically, the present disclosure relates to coated fertilizer granules having a core containing a water-soluble fertilizer material, a controlled release layer, an optional coating layer, and an outer surface treatment layer. [Background technology]

[0002] Although there have been significant improvements in the production of controlled release fertilizers, further advances are still needed as controlled release fertilizers relate to crops grown under irrigated conditions. For example, many of the coated fertilizers currently on the market share one common undesirable trait: they float. Once the coated granules begin to float, water currents and / or wind will carry the fertilizer to areas with low plant populations, and areas with increased plant populations will not be able to take advantage of the benefits provided by the controlled release fertilizer. The polymers and waxes that generally make up the outer barrier of the fertilizer are extremely hydrophobic, causing the granules to float. Much of the coated fertilizer once spread evenly on a farmer's field will be transferred to the lowest elevations in the area. This undesirable occurrence is very common when farmers attempt to use coated fertilizers on pre-irrigated or post-irrigated fields.

[0003] Therefore, there remains a need in the art to prevent coated fertilizers from floating and drifting with water currents and wind. Summary of the Invention

[0004] The problems discussed above and others are addressed by the following invention, although it should be understood that not all embodiments of the invention described herein address each of the above problems. The present disclosure provides coated granules and methods for making coated granules that facilitate settling and / or adhesion to an underlying surface (such as soil). The coated granules include a gelling agent that serves to anchor the coated granules to the soil surface and reduces the likelihood of movement due to rolling. Some embodiments of the granules include an external wetting agent, such as a surfactant, that promotes settling.

[0005] In a first aspect, there is provided a coated fertilizer granule having a core comprising a water soluble fertilizer material, a coating having a urethane layer impregnated with a superabsorbent polymer, the urethane layer being formed from the reaction product of one or both of (i) a polyol mixed with a superabsorbent polymer and reacted with an isocyanate and / or (ii) an isocyanate mixed with a superabsorbent polymer reacted with a polyol, a controlled release layer disposed between the core and the coating, and a surface treatment layer disposed around the coating comprising a surfactant and a solvent.

[0006] In a second aspect, there is provided a coated granule comprising a core comprising a water-soluble compound, a coating comprising a gelling agent, a controlled release layer between the core and the coating, and a surface treatment layer disposed around the coating comprising a surfactant and a solvent.

[0007] In a third embodiment, the absorbent polymer is impregnated Coated granules are provided that include a urethane coating and a core, the urethane coating being formed from the reaction product of one or both of (i) a polyol mixed with an absorbent polymer and reacted with an isocyanate and / or (ii) an isocyanate mixed with an absorbent polymer reacted with a polyol. In one embodiment, the granule includes a core that includes a water soluble fertilizer material. In another embodiment, the granule includes a surface treatment layer disposed about the coating, the surface treatment layer being formed from a surfactant and a solvent.

[0008] In a fourth aspect, there is provided a fertilizer granule comprising a core comprising a water soluble fertilizer material, a controlled release layer disposed about the core, and a surface treatment layer disposed about the controlled release layer comprising a surfactant and a solvent.

[0009] In any of the above aspects, the surfactant may be an alcohol ethoxylate, a silicone surfactant, or a combination thereof. In another embodiment, the surfactant may be an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof. In yet another embodiment, the surfactant is a mixture of an alkyl polyglycoside, an ethoxylated sorbitan ester, and a polyhydric alcohol. In any of the above aspects, the solvent may be tripropylene glycol.

[0010] In a fifth aspect, there is provided a method of making a coated fertilizer granule comprising the steps of providing a core comprising a water soluble fertilizer material; applying a controlled release layer disposed over the core; applying a coating over the controlled release layer, the coating comprising a urethane layer impregnated with a superabsorbent polymer, the urethane layer being formed from a reaction product of one or both of (i) a polyol mixed with a superabsorbent polymer and reacted with an isocyanate, and / or (ii) an isocyanate mixed with a superabsorbent polymer and reacted with a polyol; and applying an exterior treatment layer over the coating, the exterior treatment layer comprising a surfactant and a solvent.

[0011] In a sixth aspect, there is provided a method of producing a controlled release granule, comprising the steps of providing a core containing a water-soluble compound, applying a controlled release layer over the core, applying a coating of a gelling agent over the controlled release layer, and applying an outer surface treatment layer over the coating.

[0012] In a seventh aspect, there is provided a method of making coated granules comprising applying a urethane layer impregnated with a superabsorbent polymer over a core, the urethane layer being formed from a reaction product of one or both of: (i) a polyol mixed with a superabsorbent polymer and reacted with an isocyanate, and (ii) an isocyanate mixed with a superabsorbent polymer and reacted with a polyol.

[0013] In an eighth aspect, there is provided a method of producing a fertilizer granule, the method comprising the steps of applying a controlled release layer over a core, the core comprising a water soluble fertilizer material, and applying a surface treatment layer over the controlled release layer, the surface treatment layer comprising a surfactant and a solvent.

[0014] In any of the above methods of making coated granules or fertilizer granules, the surfactant may be an alcohol ethoxylate, a silicone-based surfactant, or a combination thereof. In another embodiment, the surfactant may be an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof. In yet another embodiment, the solvent may be tripropylene glycol.

[0015] In a ninth aspect, there is provided a coated granule or fertilizer granule made by any one of the above methods.

[0016] In a tenth aspect, there is provided a method of releasing fertilizer comprising the steps of applying coated granules or fertilizer granules to soil, the soil being pre-irrigated or post-irrigated during the period in which the coated granules are present, and the gelling agent becomes hydrated, thereby forming a gel that assists soil adhesion.

[0017] In an eleventh aspect, there is provided a method of cultivating a plant comprising the step of placing a coated granule or a fertilizer granule according to any one of the preceding claims in proximity to the plant to allow controlled release of the fertilizer.

[0018] The present disclosure also relates to a coated fertilizer granule comprising a core comprising a water-soluble fertilizer material, a coating having a urethane layer impregnated with a gelling agent, a controlled release layer disposed between the core and the coating, and a surface treatment layer disposed on the coating and comprising a surfactant and a solvent. In one embodiment, the urethane layer is formed from the reaction product of one or both of (i) a polyol mixed with a gelling agent and reacted with an isocyanate and / or (ii) an isocyanate mixed with a gelling agent reacted with a polyol. In another embodiment, the surfactant comprises an alcohol ethoxylate, a silicone-based surfactant, or a combination thereof. In yet another embodiment, the at least one surfactant comprises an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof. In yet another embodiment, the surfactant comprises a mixture of an alkyl polyglycoside, an ethoxylated sorbitan ester, and a polyhydric alcohol, and the solvent may be selected from dipropylene glycol, tripropylene glycol, glycerin, propylene carbonate, vegetable oil, and combinations thereof.

[0019] In some aspects, the gelling agent is a superabsorbent polymer. In yet another embodiment, the gelling agent comprises at least one of polyacrylamide, polyacrylate, vegetable starch, bentonite clay, or montmorillonite clay. The gelling agent may comprise a water-absorbing polymer having a water-holding capacity of at least about 20 g water / g absorbent polymer.

[0020] In another aspect, the water soluble fertilizer material comprises primary nutrients including urea, ammonium sulfate, calcium nitrate, diammonium phosphate, monoammonium phosphate, potassium nitrate, sodium nitrate, single superphosphate, triple superphosphate, calcium phosphate, monopotassium phosphate, dipotassium phosphate, tetrapotassium pyrophosphate, potassium metaphosphate, potassium chloride, potassium nitrate, potassium sulfate, or combinations thereof. In another aspect, the water soluble fertilizer material further comprises secondary nutrients including calcium sulfate, calcium chloride, calcium carbonate, calcium silicate, calcium phosphate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium carbonate, elemental sulfur, ammonium sulfate, or combinations thereof.

[0021] The present disclosure also relates to a fertilizer granule having a core comprising a water-soluble fertilizer material, a surface treatment layer comprising a surfactant and a solvent, and a controlled release layer disposed between the core and the surface treatment layer, the controlled release layer comprising at least one urethane layer and at least one wax layer. In one embodiment, the controlled release layer comprises a plurality of alternating urethane and wax layers. In another embodiment, the controlled release layer has a thickness of about 1 μm to about 150 μm. In yet another embodiment, the fertilizer granule further comprises a coating disposed between the controlled release layer and the surface treatment layer.

[0022] The present disclosure also relates to a method of making a coated fertilizer granule, comprising the steps of providing a core comprising a water soluble fertilizer material, applying a controlled release layer disposed over the core to form a controlled release core, applying a coating over the controlled release core to form a coated core, the coating having a urethane layer impregnated with a gelling agent, and applying a surface treatment layer over the coated core, the outer surface treatment layer comprising a surfactant and a solvent.

[0023] In one aspect, the urethane layer is formed from a reaction product of one or both of (i) a polyol mixed with a gelling agent and reacted with an isocyanate and / or (ii) an isocyanate mixed with a gelling agent and reacted with a polyol. In another aspect, the gelling agent comprises a superabsorbent polymer. In yet another aspect, the water soluble fertilizer material comprises a water soluble pest control agent. In yet another aspect, the solvent is selected from dipropylene glycol, tripropylene glycol, glycerin, propylene carbonate, vegetable oil, and combinations thereof.

[0024] Further features and advantages can be ascertained from the following detailed description, provided in conjunction with the drawings listed below. [Brief description of the drawings]

[0025] [Figure 1] FIG. 2 illustrates layers of coated granules according to an exemplary embodiment of the present disclosure. [Diagram 2] 1 shows the coated granules prior to the formation of the gelatinous encapsulating layer / coating. [Diagram 3] 1 shows a coated granule having a gelatinous encapsulating layer / coating according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art. Terms, such as those defined in commonly used dictionaries, should be interpreted to have a meaning consistent with their meaning in the context of this specification, and should not be interpreted in an idealized or overly formal sense unless expressly defined as such in this specification. Well-known functions or structures may not be described in detail for brevity or clarity.

[0027] The terms "about" and "approximately" are generally intended to mean a degree of error or variation that may be tolerated for a measured quantity given the nature or precision of the measurement. Typical exemplary degrees of error or variation are within 20 percent (%), preferably within 10%, more preferably within 5%, and even more preferably within 1% of a given value or range of values. Numerical quantities given herein are approximate unless otherwise indicated, meaning that the term "about" or "approximately" can be inferred when not expressly stated.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms (i.e., "at least one") unless the context clearly dictates otherwise.

[0029] Terms such as "first", "second", etc. are used herein to describe various features or elements, but these features or elements should not be limited by these terms. These terms are used only to distinguish one feature or element from another. Thus, a first feature or element discussed below can be referred to as a second feature or element, and similarly, a second feature or element discussed below can be referred to as a first feature or element without departing from the teachings of the present disclosure.

[0030] Terms such as "at least one of A and B" should be understood to mean "A only, B only, or both A and B." The same interpretation should apply to longer lists (e.g., "at least one of A, B, and C").

[0031] The term "consisting essentially of" means that in addition to the recited elements, the claimed thing may also contain other elements (steps, structures, ingredients, components, etc.) that do not adversely affect the operability of the claimed thing for its intended purposes as set forth in this disclosure. The term excludes other elements that adversely affect the operability of the claimed thing for its intended purposes as set forth in this disclosure, even if such other elements may increase the operability of the claimed thing for some other purpose.

[0032] The term "may" as used herein refers to an optional feature (i.e., "may or may not") and should not be construed as limiting what is being described.

[0033] The term "on" as used herein refers to any layer, coating, or component that is further from the center of the granule than another layer, coating, or component. For example, "X is on Y" should be interpreted to mean that X is further from the center of the granule than Y. X may be in direct contact with Y ("directly on"), or there may be an intervening distance and / or component. It is contemplated that any instance of the term "on" may be limited to "directly on".

[0034] It is understood that any given element of the disclosed embodiments of the present invention may be embodied in a single structure, a single step, a single material, etc. Likewise, a given element of the disclosed embodiments may be embodied in multiple structures, steps, materials, etc.

[0035] Coated Granules The present disclosure provides coated granules that can settle when dropped into stagnant water, can resist movement as water passes over the granules, or both. The coated granules described herein can also produce a gelatinous encapsulation layer to provide resistance to movement by soil adhesion. In some embodiments, the coated granules can have a particle size ranging from about 0.10 mm to about 20 mm. In another embodiment, the coated granules can have a particle size ranging from about 1.0 mm to about 5.0 mm. In yet another embodiment, the coated granules can have a particle size ranging from about 2.5 mm to about 4.0 mm.

[0036] In one embodiment, about 80% to about 100% by weight of the coated granules (based on the total weight of the coated granules) fall within the above particle size range. By way of example, in this aspect, about 80% to about 100% by weight of the coated granules have a particle size ranging from about 0.1 mm to about 20 mm, about 1.0 mm to about 5.0 mm, or 2.5 mm to about 4.0 mm, depending on the embodiment. In another embodiment, about 85% to about 95% by weight of the coated granules (based on the total weight of the coated granules) fall within the above particle size range. In this aspect, about 85% to about 95% by weight of the coated granules may have a particle size ranging from about 0.1 mm to about 20 mm, about 1.0 mm to about 5.0 mm, or 2.5 mm to about 4.0 mm, depending on the embodiment. In yet another embodiment, about 88% to about 92% by weight of the coated granules (based on the total weight of the coated granules) fall within the above particle size range. In yet another embodiment, about 90% to about 98% by weight of the coated granules (based on the total weight of the coated granules) fall within the above particle size ranges. In yet another embodiment, about 92% to about 100% by weight of the coated granules (based on the total weight of the coated granules) fall within the above particle size ranges. In yet another embodiment, the particle size distribution requires that at least about 90% by weight of the coated granules fall within these size ranges.

[0037] FIG. 1 shows various layers of a coated granule 100 according to an exemplary embodiment of the present disclosure. As shown in FIG. 1, the coated granule 100 includes a core 1. The core 1 may include a water-soluble compound, such as a water-soluble fertilizer or pesticide. In one embodiment, the core 1 includes a water-soluble fertilizer. In this embodiment, the fertilizer may include a soluble, bioavailable form of a primary nutrient. As used herein, a "soluble, bioavailable form" refers to an element or compound that is available to a living organism for uptake or adsorption and can be dissolved. The primary nutrient may be at least one of nitrogen, phosphorus, and potassium. For example, the primary nutrient may be in the form of at least one of urea, ammonium sulfate, calcium nitrate, diammonium phosphate, monoammonium phosphate, potassium nitrate, sodium nitrate, superphosphate, triple superphosphate, calcium phosphate, monopotassium phosphate, dipotassium phosphate, tetrapotassium pyrophosphate, potassium metaphosphate, potassium chloride, and potassium sulfate. In one embodiment, the primary nutrient may be in the form of a urea fertilizer having at least 40% molecular weight nitrogen, more preferably 46% molecular weight nitrogen. The core 1 may be at least about 5% by weight of primary nutrients. Further embodiments of the core may have a minimum primary nutrient concentration of 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 96, 97, 98, and 99% by weight. Particular embodiments of the core are 100% by weight of primary nutrients. In another embodiment, the core comprises about 85% or more by weight of primary nutrients (based on the total weight of the core). In yet another embodiment, the primary nutrients make up about 60% to about 100% by weight of the core (based on the total weight of the core). In yet another embodiment, about 70% to about 99% by weight of the core (based on the total weight of the core) are primary nutrients. In yet another embodiment, about 75% to about 95% by weight of the core (based on the total weight of the core) are primary nutrients.

[0038] In some embodiments, Core 1 can be a homogenous melt of nitrogen and one or both of potassium and phosphorus. In this embodiment, the ratio of nitrogen to phosphorus to potassium (N:P:K) can be, for example, 29-3-4, 22-3-14, 22-7-10, 21-7-14, 21-5-10, 20-28-5, 20-11-18, 20-5-10, 18-6-18, 16-4-8, 15-15-15, 15-5-10, 13-13-13, 12-11-18, 12-6-24, 10-10-10, 21-0-21, and 15-0-15.

[0039] In some embodiments, the fertilizer may include secondary nutrients in a soluble, bioavailable form. The secondary nutrients may be at least one of calcium, magnesium, and sulfur. For example, the secondary nutrients may be in the form of one or more of calcium sulfate, calcium chloride, calcium carbonate, calcium silicate, calcium phosphate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium carbonate, elemental sulfur, and ammonium sulfate. Some embodiments of the core 1 may have about 0.5% to about 15% by weight (based on the total weight of the core) of secondary nutrients. In further embodiments, the core 1 may have about 5% to about 10% by weight (based on the total weight of the core) of secondary nutrients. Further embodiments of the core 1 may have a secondary nutrient content of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15% by weight (based on the total weight of the core). In another embodiment, the core includes about 85% or more by weight of secondary nutrients (based on the total weight of the core). In yet another embodiment, the primary nutrients comprise from about 1% to about 8% by weight of the core (based on the total weight of the core). In yet another embodiment, from about 1% to about 6% by weight of the core (based on the total weight of the core) are primary nutrients. In yet another embodiment, from about 1% to about 5% by weight of the core (based on the total weight of the core) are primary nutrients.

[0040] In other embodiments, the fertilizer may include micronutrients. The micronutrients may include one or more of boron, chlorine, copper, iron, manganese, molybdenum, nickel, and zinc. For example, the micronutrients may be in the form of one or more of boric acid, sodium borate, sodium tetraborate, sodium octaborate, sodium metaborate, potassium borate, potassium tetraborate, potassium octaborate, potassium metaborate, metal chlorides, copper chelates, copper chloride, copper oxide, copper sulfate, ferrous chloride, ferrous oxide, ferrous sulfate, ferric chloride, ferric oxide, ferric sulfate, manganese chelates, manganese chloride, manganese oxide, manganese sulfate, ammonium molybdate, sodium molybdate, nickel chelates, nickel nitrate, nickel sulfate, zinc chelates, zinc chloride, zinc oxide, zinc sulfate, and zinc oxysulfate. Core 1 may include about 0.01% to about 5.0% by weight of the micronutrients. In another embodiment, the core 1 may include about 0.1% to about 2.0% by weight of micronutrients.

[0041] Optionally, a precoat layer 2 may be placed on the core 1 as shown in FIG. 1. The precoat layer 2 may be used to fill and smooth any surface irregularities of the fertilizer. The precoat layer 2 improves the coating efficiency and the overall coating functionality. In one embodiment, the precoat layer 2 includes a layer of non-reactive minerals and reactive oils. For example, the precoat layer 2 may include calcium carbonate mineral powder carried by epoxidized vegetable oil. In another embodiment, the precoat layer 2 may include a wax layer to retard the diffusion mechanism and control the release of the fertilizer. The wax may be paraffin, petrolatum, polyamide, microcrystalline wax or a mixture thereof. In another embodiment, the wax is a mixture of at least two of the following waxes: olefin wax, paraffin wax, petrolatum wax, polyamide wax and microcrystalline wax. In one embodiment, the precoat layer 2 is applied to the fertilizer in an amount of about 0.01% to about 5% by weight (based on the total weight of the coated granule). In another embodiment, the precoat layer 2 is applied to the fertilizer in an amount of about 0.25% to about 2% by weight (based on the total weight of the coated granules). In yet another embodiment, the precoat layer 2 is applied to the fertilizer in an amount of about 0.5% to about 1% by weight (based on the total weight of the coated granules).

[0042] A controlled release layer for fertilizer nutrient release may be disposed on the core 1 (or the precoat layer 2, if used). As used herein, "controlled release layer" refers to a layer designed to slowly release any of the above fertilizer nutrients in a long-term controlled manner. The controlled release layer may be composed of a urethane layer and a wax layer. As shown in FIG. 1, the controlled release layer may include multiple alternating urethane layers 3, 5, 7, 9, 11 and wax layers 4, 6, 8, 10. Although FIG. 1 illustrates the use of five urethane layers and four wax layers, any number of alternating urethane and wax layers may be used depending on the desired total weight of the coating. In this regard, when a controlled release layer (regardless of the number or type of layers used therein) is disposed around the core 1 (or the core 1 with the optional precoat layer 2 thereon), the controlled release core is conveniently referred to or designated as 11a.

[0043] In one embodiment, the controlled release layer comprises a urethane having a solubility of less than 0.10 g / L in deionized water at 100 kPa and 20° C. The urethane layer can be water impermeable or semi-permeable. In a preferred embodiment, the urethane layer is semi-permeable to allow diffusion of water and fertilizer through the controlled release layer. The urethane layer can be formed by reacting a polymer such as a polyol with an isocyanate and curing the layer to form a durable layer.

[0044] A wax layer may be applied between the urethane layers. The wax layer acts as a sealant that aids in the controlled release of fertilizer nutrients. In one embodiment, the wax layer comprises an olefin wax. For example, the olefin wax may be an alpha-olefin wax having at least 20 carbon atoms, more preferably at least 30 carbon atoms. In another embodiment, the wax may be paraffin, petrolatum, polyamide, microcrystalline wax or a mixture thereof. In another embodiment, the wax is a mixture of at least two of the following waxes: olefin wax, paraffin wax, petrolatum wax, polyamide wax and microcrystalline wax.

[0045] In one embodiment, the controlled release layer is about 0.01% to about 20% by weight of the total weight of the coated granule. For example, the controlled release layer is about 5% to about 15% by weight of the total weight of the coated granule. Each layer of the controlled release layer can be about 0.2% to about 5% by weight of the total weight of the coated granule. In another embodiment, each layer of the controlled release layer can be about 0.3% to about 3% by weight of the total weight of the coated granule. In yet another embodiment, each layer of the controlled release layer can be about 0.5% to about 1.5% by weight of the total weight of the coated granule.

[0046] In one embodiment, the thickness of the controlled release layer can range from about 1 μm to about 150 μm. In another embodiment, the thickness of the controlled release layer can range from about 2 μm to about 130 μm. In yet another embodiment, the controlled release layer has a thickness of about 5 μm to about 100 μm. In yet another embodiment, the controlled release layer has a thickness of about 10 μm to about 75 μm. In yet another embodiment, the controlled release layer has a thickness of about 30 μm to about 100 μm. In yet another embodiment, the controlled release layer has a thickness of about 1 μm to about 50 μm, about 2 μm to about 20 μm, or about 3 μm to about 10 μm.

[0047] In some embodiments, the controlled release layer allows the nutrients to be released from the core at a rate of at least about 4% of the total amount of nutrients in the core per 7 days. In another embodiment, the controlled release layer allows the nutrients to be released from the core at a rate of at least about 7% of the total amount of nutrients in the core per 7 days. In yet another embodiment, the controlled release layer allows the nutrients to be released from the core at a rate of at least about 10% of the total amount of nutrients in the core per 7 days.

[0048] In other embodiments, the controlled release layer allows nutrients to be released from the core over a period of at least 7 days. In another embodiment, the controlled release layer allows nutrients to be released from the core over a period of at least 21 days. In yet another embodiment, the controlled release layer allows nutrients to be released from the core over a period of at least 35 days. In yet another embodiment, the controlled release layer allows nutrients to be released from the core over a period of at least 56 days. For example, the controlled release layer allows nutrients to be released from the core over a period of 70 days. In one aspect, the controlled release layer allows nutrients to be released from the core for at least 90 days. In another aspect, the controlled release layer allows nutrients to be released from the core for as long as 120 days.

[0049] In another aspect, after about 7 days, about 2% to about 25% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. For example, in one embodiment, after about 7 days, about 4% to about 20% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. In yet another aspect, after about 14 days, about 5% to about 55% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. For example, in one embodiment, after about 14 days, about 15% to about 55% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. In yet another aspect, after about 21 days, about 10% to about 70% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. For example, in one embodiment, after about 21 days, about 35% to about 65% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. In yet another embodiment, after about 70 days, about 65% to about 100% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. For example, in one embodiment, after about 70 days, about 75% to about 100% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. In yet another embodiment, after about 90 days, about 25% to about 1% of the nutrients (based on the total amount of nutrients in the coated granules) remain in the core. For example, in one embodiment, after about 90 days, about 15% to about 1% of the nutrients (based on the total amount of nutrients in the coated granules) remain in the core. In yet another embodiment, after about 120 days, about 90% to 100% of the nutrients (based on the total amount of nutrients in the coated granules) are released from the core. In this embodiment, 100% of the nutrients may be released from the core after about 120 days.

[0050] As shown in Figure 1, a coating 12 may be applied over a controlled release layer comprised of alternating urethane layers 3, 5, 7, 9, 11 and wax layers 4, 6, 8, 10. The wax used in any of the wax layers of the coating may be an olefin wax. In one embodiment, the wax may be paraffin, petrolatum, polyamide, microcrystalline wax or a mixture thereof. In another embodiment, the wax is a mixture of at least two of the following waxes: olefin wax, paraffin wax, petrolatum wax, polyamide wax and microcrystalline wax.

[0051] In some embodiments (and with certain surfactants used in the surface treatment layer), the coating 12 provides the advantage of soil adhesion and settling capabilities. In one embodiment, the coating 12 includes a gelling agent. The gelling agent advantageously prevents accelerated release of fertilizer that may otherwise occur when certain surfactants are present in the granule. The coating 12 is also positioned to allow hydration of the gelling agent when the coated granule comes into contact with water. Figures 2 and 3 show a coated granule 100 before and after hydration of the gelling agent, respectively. As shown in Figure 3, the gelling agent in the coating 12 creates a gelatinous mass 110 around the coated fertilizer when exposed to liquid water. In the illustrated embodiment of the granule, the encapsulating gel utilizes its adhesive capabilities to prevent fertilizer migration while also changing the particle shape to avoid rolling. Without wishing to be bound by any hypothetical model, it is envisioned that coating 12 may further promote the formation of a nutrient-rich gel matrix that provides a pathway for nutrient entrapment and increased resistance to volatilization and leaching, and that the gel matrix serves as a growth medium for nutrient-solubilizing microorganisms that improve the overall health of the soil and plants.

[0052] In some embodiments, the gelling agent in the coating 12, if included, may include a water-absorbent polymer. The absorbent polymer has a high water-holding capacity, for example at least about 20 g water / g absorbent polymer. The absorbent polymer advantageously allows the coated granule to adhere to the soil when the absorbent polymer is hydrated. For example, the gelling agent may contain a superabsorbent polymer. As used herein, "superabsorbent polymer" refers to a polymer having a water-holding capacity of at least about 50 g water / g absorbent polymer. Some embodiments of the superabsorbent polymer have a water-holding capacity of at least 100 g water / g absorbent polymer. Further embodiments of the superabsorbent polymer may have a water-holding capacity of at least 200 g water / g absorbent polymer. Further embodiments may have a water-holding capacity of at least about 280 g water / g absorbent polymer. In further embodiments, the superabsorbent polymer may have a water-holding capacity of at least about 350 g water / g absorbent polymer. In yet another embodiment, the superabsorbent polymer may have a water retention capacity of up to about 500 g water / g absorbent polymer. In yet another embodiment, the superabsorbent polymer may have a water retention capacity of up to about 1000 g water / g absorbent polymer. In this aspect, the superabsorbent polymer may have a water retention capacity of about 50 g to about 1000 g water / g absorbent polymer. For example, the superabsorbent polymer may have a water retention capacity of about 200 g to about 1000 g water / g absorbent polymer.

[0053] The absorbent polymer may be an acrylate polymer, such as a sodium-based or potassium-based polyacrylate polymer, a vegetable starch, or a silicate. In one embodiment, the superabsorbent polymer is a sodium-based or potassium-based polyacrylate polymer. In some embodiments, the superabsorbent polymer may include particles having a particle size of up to about 300 μm. For example, the superabsorbent polymer may include particles having a particle size of up to about 200 μm. In yet other embodiments, the superabsorbent polymer may include particles having a particle size of up to about 100 μm. In this aspect, the superabsorbent polymer may include particles having a particle size of about 1 μm to about 300 μm, about 1 μm to about 200 μm, about 1 μm to about 100 μm, or about 1 μm to about 50 μm.

[0054] In other embodiments, the gelling agent in coating 12 may comprise at least one of polyacrylamide, polyacrylate, vegetable starch, bentonite clay, or montmorillonite clay. The gelling agent may comprise up to about 5% by weight of the total weight of the coated granule. In another embodiment, the gelling agent may comprise about 0.1% to about 1.0% by weight of the total weight of the coated granule. In yet another embodiment, the gelling agent may comprise about 0.2% to about 0.5% by weight of the total weight of the coated granule. Specific embodiments of the granules include 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0% by weight of the gelling agent.

[0055] Coating 12 may be formed from a urethane layer impregnated with a gelling agent. For example, coating 12 may be formed from a urethane layer impregnated with a superabsorbent polymer. In this embodiment, the urethane layer may be formed from the reaction product of one or both of: (i) a polyol mixed with a gelling agent, such as a superabsorbent polymer, and reacted with an isocyanate, and / or (ii) an isocyanate mixed with a gelling agent, such as a superabsorbent polymer, and reacted with a polyol.

[0056] In one embodiment, the coating thickness can range from about 1 μm to about 100 μm. In another embodiment, the coating thickness can range from about 1 μm to about 75 μm. In yet another embodiment, the coating has a thickness of about 1 μm to about 50 μm. In yet another embodiment, the coating has a thickness of about 1 μm to about 40 μm. In yet another embodiment, the coating has a thickness of about 75 μm or less. In yet another embodiment, the coating has a thickness of about 70 μm or less, about 60 μm or less, or about 50 μm or less.

[0057] The coated granule 100 may include a surface treatment layer 13 applied over the coating 12 (or directly over the controlled release layer in other embodiments) as shown in FIG. 1. The surface treatment layer 13 reduces the surface tension of the water, causing the coated granule to settle. In one embodiment, the surface treatment layer 13 includes a mixture of a surfactant and a solvent. In one aspect, the surfactant may include at least one of an alcohol ethoxylate, a silicone-based surfactant, or a combination thereof. For example, the surfactant may be Niax™ silicone L-5420 surfactant or a TDA-6 ethoxylate surfactant. In another aspect, the surfactant may include an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof. In one embodiment, the surfactant is a mixture of an alkyl polyglycoside, an ethoxylated sorbitan ester, and a polyhydric alcohol. The solvent may be dipropylene glycol, tripropylene glycol, glycerin, propylene carbonate, vegetable oil, or a combination thereof. In one embodiment, the solvent is dipropylene glycol. In another embodiment, the solvent is tripropylene glycol.

[0058] The mixture may comprise about 25% to about 100% by weight of surfactant and up to about 75% by weight of solvent. In one embodiment, the mixture is comprised of 100% by weight of surfactant. In another embodiment, the mixture may comprise about 25% to about 50% by weight of surfactant and about 50% to about 75% by weight of solvent. In yet another embodiment, the mixture may comprise about 35% to about 50% by weight of surfactant and about 50% to about 65% by weight of solvent. In yet another embodiment, the mixture may comprise about 50% to about 65% by weight of surfactant and about 35% to about 50% by weight of solvent. In yet another embodiment, the mixture may comprise about 50% to about 75% by weight of surfactant and about 25% to about 50% by weight of solvent.

[0059] In some embodiments, the surface treatment layer 13 may account for about 0.01% by weight to about 5% by weight of the total weight of the coated granule. In other embodiments, the surface treatment layer 13 may account for about 0.1% by weight to about 1% by weight of the total weight of the coated granule. In yet other embodiments, the surface treatment layer 13 may account for about 0.15% by weight to about 0.5% by weight of the total weight of the coated granule.

[0060] In one embodiment, the thickness of the surface treatment layer may be in the range of about 0.5 μm to about 30 μm. In another embodiment, the thickness of the surface treatment layer may be in the range of about 0.5 μm to about 10 μm. In yet another embodiment, the surface treatment layer has a thickness of about 1 μm to about 5 μm.

[0061] The final coated granule 100 utilizes alternating controlled release layers of urethane layers 3, 5, 7, 9, 11 and wax layers 4, 6, 8, 10 to provide a controlled release of fertilizer nutrients. In some embodiments, the gelling agent impregnated coating 12 attaches the coated fertilizer to the soil by creating an encapsulating gelatinous layer around each individual particle. In this aspect, the surface treatment layer 13 reduces the surface tension of the water, causing the coated fertilizer to settle to the surface of the soil. In one embodiment, the combined functionality of the final coated granule 100 has the properties of controlled release of fertilizer nutrients, resistance to floating, and soil adhesion that ensures that the coated granule remains in close proximity to the plant being fertilized. In some embodiments using certain surfactants in the surface treatment layer, the gelling agent may serve to slow the release of soluble compounds that may otherwise be released too quickly in the presence of these certain surfactants alone.

[0062] In alternative embodiments, the fertilizer granule may be formed without the coating 12. For example, in one embodiment, the fertilizer granule may include a core, a controlled release layer disposed about the core, and a surface treatment layer 13 disposed on the controlled release layer. In this aspect, the surface treatment layer 13 may be formed from a surfactant and a solvent, where the surfactant is a mixture of an alkyl polyglycoside, an ethoxylated sorbitan ester, and a polyhydric alcohol. The solvent may be any of the solvents previously described. For example, the solvent may be tripropylene glycol.

[0063] Method for producing coated granules The present disclosure also provides a method for producing the coated granules described above. In one embodiment, the method includes providing a core 1 comprised of a fertilizer. The core 1 may be fed into a coater for preheating. In one embodiment, the core 1 is heated to a temperature of about 140°F to about 165°F. In another embodiment, the core 1 is heated to about 145°F to about 163°F. In yet another embodiment, the core 1 is heated to about 150°F to about 162°F. In yet another embodiment, the core 1 is heated to about 150°F to about 160°F. After the core 1 is heated, an optional precoat layer 2 may be applied to the core 1. As described above, the precoat layer 2 may be applied to a core having an uneven surface to smooth the surface and increase the coating efficiency. The precoat layer 2 may be applied by spraying or pouring onto the core 1. In some embodiments, sufficient time may be allowed for the precoat layer 2 to harden to ensure uniform distribution of the coating. For example, to ensure uniform distribution of the coating, the precoat layer 2 may take from about 45 seconds to about 2 minutes to cure. In another embodiment, the precoat layer 2 may take from about 50 seconds to about 75 seconds to cure. In yet another embodiment, the precoat layer 2 may take from about 55 seconds to about 65 seconds to cure.

[0064] The method may further include applying a controlled release layer formed of one or more urethane layers 3, 5, 7, 9, 11 and wax layers 4, 6, 8, 10 onto the core 1 or onto the precoat layer 2, if used. In one embodiment, the method may include forming a urethane layer by applying a polyol and an isocyanate onto the core 1 (or onto the precoat layer 2, if present) and curing the layer for a period of about 45 seconds to about 2 minutes, about 45 seconds to about 90 seconds, or about 45 seconds to about 60 seconds. After the urethane layer is formed, a wax layer may be applied onto the urethane layer. In some embodiments, the wax layer may be spread evenly onto the urethane layer for at least about 30 seconds. In one embodiment, the wax layer may be cured for about 30 seconds to about 90 seconds. In this aspect, the wax layer may be cured for about 30 seconds to about 60 seconds. The procedure for forming the urethane layer and the wax layer may be continuously repeated to reach a desired coating weight and thickness.

[0065] After application of the controlled release layer, in some embodiments, the method includes applying a coating 12 containing a gelling agent over the controlled release layer to ensure that the coated granules have soil adhesion capabilities. In other embodiments, the method includes forming the coated granules without the coating 12, i.e., by placing a surface treatment layer around the controlled release layer. If a coating is included, the step for applying the coating 12 may include mixing a gelling agent, such as a superabsorbent polymer, with a polyol and reacting the mixture of the gelling agent and the polyol with an isocyanate to form a urethane layer impregnated with a gelling agent, such as a superabsorbent polymer. In another embodiment, the step for applying the coating 12 may include mixing a gelling agent, such as a superabsorbent polymer, with an isocyanate and reacting the mixture of the gelling agent and the isocyanate with a polyol to form a urethane layer impregnated with a gelling agent, such as a superabsorbent polymer. In one embodiment, after application of coating 12, the method may include cooling the coated granules to a temperature of about 80°F to about 120°F, about 90°F to about 110°F, or about 95°F to about 105°F before applying surface treatment layer 13.

[0066] In some embodiments, the method includes applying an outer surface treatment layer 13 over the coating 12 (or, in some embodiments, immediately over the controlled release layer) to promote settling when dropped into liquid water and resistance to migration as liquid water passes over the coated granules. Application of the surface treatment layer 13 may be performed in a rotating drum, blender, or suitable equipment that promotes rolling and rotation of particles. Application of the surface treatment layer 13 may be performed by spraying, dripping, and / or pouring the contents of the surface treatment layer 13 onto the moving granules, so long as a uniform coating is achieved. After a period of about 30 seconds to about 180 seconds, for example about 45 seconds to about 60 seconds, the completed coated granules may be ready for storage or bagging.

[0067] How to use The coated granules described herein can be used to release fertilizer in a controlled manner. The present disclosure provides a method of releasing fertilizer. The method includes applying the coated granules described herein to soil, pre-irrigation or post-irrigation, for the period during which the coated granules are present. The gelling of the coated granules hydrates, thereby forming a gel that aids in soil adhesion. In this embodiment, the controlled release layer maintains its integrity upon hydration of the gelling agent and surfactant / solvent surface treatment. Examples of suitable irrigated soils include rice (Oryza sp.) paddy fields, cranberry bogs, water chestnut fields, spinach fields, watercress fields, wild rice (Zinzania sp.) fields, sugarcane fields, and taro fields.

[0068] In another embodiment, the present disclosure provides a method of cultivating a plant. The method includes placing a coated granule as described herein in proximity to the plant to allow for controlled release of fertilizer. The plant can be any cultivated plant. In some preferred embodiments, the plant is rice (Oryza sp.), cranberry, water chestnut, spinach, watercress, wild rice (Zinzania sp.), or taro. EXAMPLES

[0069] The mixer for producing the coated granules described in the examples below includes an independent variable speed rotating vessel and an independent variable speed mixing rotor to ensure uniform coating distribution on the coated granules. The rotor is composed of a shaft with angled blades that promote vigorous particle mixing. The vessel and rotor are controlled by a variable frequency drive and motor. A stationary scraper is attached inside the vessel to minimize coating build-up and aid in agitation of the granules. Core fertilizer ingredients can be added through the inlet opening. The coating ingredients are precisely measured and independently dosed into the coater using a series of open pipes. The coated granules exit by an open / close door hopper located below the coater.

[0070] [Example 1] Coated granules containing urea The mixer was preheated to a temperature of about 100°F to about 120°F. During preheating, the rotating pan and rotor were operated in a clockwise direction at 6.00 m / s and 1.95 m / s, respectively. 4536 g of uncoated urea having an average particle size of 3.0-3.5 mm was charged to the mixer. The uncoated urea was preheated to a temperature of about 150°F to 160°F. Once the uncoated urea was preheated, the mixer parameters were adjusted for the coating process. The rotating pan was operated in a clockwise direction at a speed of 12.00 m / s and the rotor was operated in a counterclockwise direction at a speed of 6.00 m / s. 14.6 g of polyol was then charged to the mixer and mixed for 30 seconds, followed by 23.4 g of isocyanate. These ingredients were rotated and allowed to react for 60 seconds, after which a 5.9 g charge of wax was added and rotated for an additional 30 seconds. The polyol, isocyanate and wax addition steps and mixing times were repeated. Charges of polyol and isocyanate were then added to achieve the desired coating thickness for the controlled release layer. The controlled release coated core was spun and cured for 60 seconds.

[0071] The coating layer required to achieve soil adhesion capability was created by first charging 29.6 g of isocyanate to the mixer containing the controlled release coated cores and mixing for 30 seconds to ensure uniform coating of all coated cores. A second charge of 33.5 g of polyol / polymer mixture containing 55 wt. % polyol and 45 wt. % superabsorbent polymer was added. After mixing the coated granules for an additional 60 seconds, the rotation of the mixer was slowed to 6.00 m / s and the rotor speed reduced to 1.95 m / s. The coated granules were cooled to approximately 100°F-110°F with ambient temperature air provided by a blower. The coated granules were then discharged from the mixer and allowed to cool to ambient temperature.

[0072] Surface treatment to promote particle settling was performed by placing a quantity of coated granules into a rotating drum that gently tumbled the granules at a rotation speed of 28 RPM. The coated granules were then treated with a surfactant / solvent mixture consisting of 25% by weight Niax L-5420 silicone surfactant and 75% by weight dipropylene glycol (DPG). The treated granules were allowed to tumble for approximately 60 seconds to ensure uniform coating before being discharged from the drum, packaged, and labeled.

[0073] [Example 2] Coated granules containing AMIDAS® A mixer similar to that utilized in Example 1 was operated at the same temperature and rotation speed. 4536 g of AMIDAS®, a substrate having an uneven, rough surface, was added to the mixer. This substrate required a precoat layer. 23.9 g of a precoat mixture containing 50 wt. % epoxidized soybean oil (ESO) and 50 wt. % calcium carbonate was added to the mixer. After allowing 60 seconds of rotation time, the same coating process and treatment applied in Example 1 was applied. The total coating was 6.5 wt. % of the final product weight.

[0074] Example 3: Coated granules containing a urea core with a precoat A mixer similar to that utilized in Examples 1 and 2, operated under the same parameters, was charged with 4536 g of uncoated urea. A precoat layer was applied to improve coating longevity. 48.0 g of molten wax was charged to the mixer. The mixer was allowed to rotate for 60 seconds, after which the same coating process and treatment applied in Examples 1-2 was applied. The total coating was 7.0 wt% of the final product weight.

[0075] [Example 4] Coated granules with urea core Into a mixer similar to that described in the previous example, operated under the same parameters, 4536 g of uncoated urea was charged. The uncoated urea was preheated to a temperature of about 150°F to 160°F. The rotating pan was operated in a clockwise direction and the rotor rotated in a counterclockwise direction. 13.6 g of polyol was charged into the mixer and mixed for about 30 seconds to distribute evenly on the granule surface, then 21.8 g of isocyanate was charged. These ingredients were rotated and allowed to react for an additional 60 seconds, after which a 7.9 g charge of wax was added and rotated and allowed to react for an additional 30 seconds. The polyol, isocyanate and wax addition steps and mixing times were repeated. The polyol and isocyanate charges were then added to achieve the desired coating thickness for the controlled release coating to form the controlled release coated cores. The controlled release coated cores were cooled to about 100°F to 110°F by ambient temperature air provided by a blower.

[0076] Once the controlled release coated cores had cooled to room temperature and the controlled release coating was fully reacted, 1000 grams of the controlled release cores were loaded into a rotating coating drum. The rotating drum was equipped with 1 / 4 inch diameter anti-skid rod internals evenly spaced around the inner circumference of the drum shell. The anti-skid rod drum internals were provided to facilitate the rolling action of the controlled release coated cores and promote particle to particle surface contact. The controlled release coated cores were preheated to a temperature of about 120°F to 130°F. A coating layer was then applied by first loading 1.6g of isocyanate, waiting 60 seconds to ensure uniform coating of all the controlled release coated cores, followed by a second load of 3.4g of a polyol / polymer mixture containing 55% by weight polyol and 45% by weight superabsorbent polymer. The coated granules were mixed for an additional 180 seconds to ensure the polymers were fully reacted and the granules were free flowing. Ambient temperature air supplied by a blower cooled the coated granules to approximately 100° F. to 110° F. The drum rotation speed was 32 RPM.

[0077] Surface treatment was then carried out by loading 800 g of the preformed coated granules into a rotating drum that gently tumbled the granules at a rotation speed of 28 RPM. The coated granules were then treated with 2 g of a surfactant / solvent mixture containing 40% by weight of Surfactant Mixture 1A and 60% by weight of dipropylene glycol (DPG). The treated particles were allowed to tumble for approximately 90-120 seconds to ensure uniform coating, after which they were discharged from the drum, packaged, and labeled.

[0078] Example 5: Surface-treated non-floating granules with a urea core Into a mixer similar to that described in the previous example, operated under the same parameters, 4536 g of uncoated urea was charged. The uncoated urea was preheated to a temperature of about 150°F to 160°F. The rotating pan was operated in a clockwise direction and the rotor rotated in a counterclockwise direction. 13.6 g of polyol was charged into the mixer and mixed for about 30 seconds to distribute evenly on the granule surface, then 21.8 g of isocyanate was charged. These ingredients were rotated and allowed to react for an additional 60 seconds, after which a 7.9 g charge of wax was added and allowed to rotate and react for an additional 30 seconds. The polyol, isocyanate and wax addition steps and mixing times were repeated. The polyol and isocyanate charges were then added to achieve the desired coating thickness for the controlled release coating. The controlled release coated cores were cooled to about 100°F to 110°F with ambient temperature air provided by a blower.

[0079] Surface treatment to promote particle settling was performed by placing 800 g of the controlled release coated cores in a rotating drum that gently tumbled the cores at a rotation speed of 28 RPM. The controlled release coated cores were then treated with 2 g of a surfactant / solvent mixture consisting of 40 wt. % Surfactant Mixture 1A and 60 wt. % Dipropylene Glycol (DPG). To ensure uniform coating, the treated granules were tumbled for approximately 90-120 seconds before being discharged from the drum, packaged, and labeled.

[0080] [Example 6] Coated urea Coated granules were formed according to Example 1, except that the coated granules were treated with Surfactant Mixture 11A and 75% by weight tripropylene glycol (TPG). The treated granules were tumbled for about 60 seconds to ensure uniform coating before being discharged from the drum, packaged, and labeled.

[0081] The specifications for Examples 1-6, including the types and amounts of different additives, were tracked and recorded in Table 1 below. Coating weights and additive amounts are percentages of the total weight of the final coated granules.

[0082] [Table 1]

[0083] Example 7: Determine the rate of nutrient release from coated granules Nutrient solutions were prepared by dissolving various known concentrations of nutrients in distilled water. The refractive index of the known concentrations was measured with a refractometer so that a calibration curve of refractive index versus concentration could be constructed. Then, 10 g of coated granules for each of the different types of granules in Table 1 (test items 1-17) were accurately weighed into a small jar and 100 g of water was added. The samples were gently rotated and allowed to stand until the required measurement time. Before each new measurement, the samples were gently rotated to ensure homogeneity. A small sample of the solution was placed in the refractometer and the measurements were recorded. Comparison with the calibration curve gives the nutrient concentration in the solution. The percentage of nutrients released from the coated granules was calculated. The experiments were performed at ambient temperature, e.g., 22°C. The measured nutrient release percentages are shown in Table 2 below.

[0084] [Table 2]

[0085] As shown in Table 2, the coated granules provide a controlled release of nutrients for a period of at least 49 days. In some examples, the coated granules provide a controlled release of nutrients for a period of up to 70 days.

[0086] The above description illustrates and describes the method, product, composition, and other teachings of the present disclosure. Moreover, the present disclosure illustrates and describes only certain embodiments of the disclosed method, product, composition, and other teachings, but as stated above, it is to be understood that the teachings of the present disclosure can be used in various other combinations, modifications, and environments, and changes or modifications within the scope of the teachings set forth herein are possible, commensurate with the skill and / or knowledge of those skilled in the art. The above embodiments are further intended to illustrate certain best modes known for carrying out the method, product, composition, and other teachings of the present disclosure, and to enable those skilled in the art to utilize the teachings of the present disclosure in such or other embodiments, with various modifications required by a particular application or use. Thus, the method, product, composition, and other teachings of the present disclosure are not intended to be limited to the precise embodiments and examples disclosed herein. All section headings herein are provided solely for the purpose of conformity with the proposed 37 CFR §1.77 or to provide other organizational queues. These headings are not intended to limit or characterize the invention described herein.

Claims

1. A coated fertilizer granule comprising: a core containing a water soluble fertilizer material; a coating having a urethane layer impregnated with a gelling agent; a controlled release layer disposed between the core and the coating; a surface treatment layer disposed on the coating and containing a surfactant and a solvent as essential components; A coated fertilizer granule comprising:

2. 2. The coated fertilizer granule of claim 1, wherein the urethane layer is formed from a reaction product of one or both of: (i) a polyol mixed with the gelling agent and reacted with an isocyanate, and / or (ii) an isocyanate mixed with the gelling agent reacted with a polyol.

3. 2. The coated fertilizer granule of claim 1, wherein the surfactant comprises an alcohol ethoxylate, a silicone-based surfactant, or a combination thereof.

4. 2. The coated fertilizer granule of claim 1, wherein the surfactant comprises an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof.

5. 2. The coated fertilizer granule of claim 1, wherein the surfactant comprises a mixture of an alkyl polyglycoside, an ethoxylated sorbitan ester, and a polyhydric alcohol.

6. 2. The coated fertilizer granule of claim 1, wherein the solvent is selected from dipropylene glycol, tripropylene glycol, glycerin, propylene carbonate, vegetable oil, and combinations thereof.

7. 2. The coated fertilizer granule of claim 1, wherein the gelling agent is a superabsorbent polymer.

8. 2. The coated fertilizer granule of claim 1, wherein the gelling agent comprises polyacrylamide, polyacrylate, vegetable starch, bentonite clay, or montmorillonite clay.

9. 2. The coated fertilizer granule of claim 1, wherein the gelling agent comprises a water-absorbing polymer having a water retention capacity of at least about 20 g water / g absorbent polymer.

10. 2. The coated fertilizer granule of claim 1, wherein the water soluble fertilizer material comprises primary nutrients including urea, ammonium sulfate, calcium nitrate, diammonium phosphate, monoammonium phosphate, potassium nitrate, sodium nitrate, superphosphate, triple superphosphate, calcium phosphate, monopotassium phosphate, dipotassium phosphate, tetrapotassium pyrophosphate, potassium metaphosphate, potassium chloride, potassium nitrate, potassium sulfate, or combinations thereof.

11. 11. The coated fertilizer granule of claim 10, wherein the water soluble fertilizer material further comprises a secondary nutrient comprising calcium sulfate, calcium chloride, calcium carbonate, calcium silicate, calcium phosphate, magnesium sulfate, magnesium chloride, magnesium oxide, magnesium carbonate, elemental sulfur, ammonium sulfate, or a combination thereof.

12. A fertilizer granule comprising: a core containing a water soluble fertilizer material; A coating layer; a controlled release layer disposed between the core and the coating layer, the controlled release layer comprising at least one urethane layer and at least one wax layer; a surface treatment layer disposed on the coating layer and containing a surfactant and a solvent as essential components; A fertilizer granule having

13. 13. The fertilizer granule of claim 12, wherein the controlled release layer comprises a plurality of alternating layers of urethane and wax.

14. 14. The fertilizer granule according to claim 13, wherein the controlled release layer has a thickness of from about 1 μm to about 150 μm.

15. The fertilizer granule of claim 12, wherein the surfactant comprises an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof.

16. 1. A method for producing coated fertilizer granules, comprising: Providing a core comprising a water soluble fertilizer material; providing a controlled release layer disposed over the core to form a controlled release core; applying a coating over the controlled release core to form a coated core, the coating having a urethane layer impregnated with a gelling agent; a step of applying a surface treatment layer onto the coated core, the surface treatment layer being essentially composed of a surfactant and a solvent; A method comprising:

17. 17. The method of claim 16, wherein the urethane layer is formed from a reaction product of one or both of: (i) a polyol mixed with the gellant and reacted with an isocyanate, and / or (ii) an isocyanate mixed with the gellant and reacted with a polyol.

18. The method of claim 16 , wherein the gelling agent comprises a superabsorbent polymer.

19. 17. The method of claim 16, wherein the water soluble fertilizer material comprises a water soluble pest control agent.

20. 17. The method of claim 16, wherein the solvent is selected from dipropylene glycol, tripropylene glycol, glycerin, propylene carbonate, vegetable oils, and combinations thereof.

21. The method of claim 16, wherein the surfactant comprises an alkyl polyglycoside, an ethoxylated sorbitan ester, a polyhydric alcohol, or a combination thereof.

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