STABILIZED UREA CALCIUM SULPHATE ADDUCT COATED WITH A BASE AN UREASE INHIBITOR

Abstract

A fertilizer granule containing a core containing, phosphoric acid and an urea adduct containing urea and calcium sulfate, and a coat containing an urease inhibitor and a base, the coat forming a coating on an outer surface of the core. Methods of making and using the fertilizer granule are also disclosed.

Claims

1. A fertilizer granule comprising: a core comprising phosphoric acid and an urea adduct comprising urea and calcium sulfate; and a coat comprising an urease inhibitor and a base, the coat forming a coating on an outer surface of the core.

2. The fertilizer granule of claim 1, wherein the base is an oxide, carbonate, bicarbonate, acetate, and/or hydroxide of a group 1 metal, group 2 metal, group 13 metal, and/or ammonium.

3. The fertilizer granule of claim 1, wherein the base is CaO and/or MgO.

4. The fertilizer granule of claim 1, wherein the urease inhibitor is a thiophosphoric triamide derivative.

5. The fertilizer granule of claim 1, wherein the coat comprises an alkaline coating layer comprising the base and an inhibitor coating layer comprising the urease inhibitor, wherein the alkaline coating layer and the inhibitor coating layer form separate coating layers.

6. The fertilizer granule of claim 5, wherein at least a portion of the alkaline coating layer is arranged between the core and the inhibitor coating layer.

7. The fertilizer granule of claim 5, wherein at least a portion of the inhibitor coating layer is arranged between the core and the alkaline coating layer.

8. The fertilizer granule of claim 1, wherein the base is comprised in particulate solids.

9. The fertilizer granule of claim 8, wherein the particulate solids have an average diameter of 0.1 μm to 150 μm.

10. The fertilizer granule of claim 1, wherein the core comprises: 47 wt. % to 79.5 wt. % of urea; 20 wt. % to 45 wt. % of calcium sulfate; and 0.1 wt. % to 3 wt. % of phosphoric acid, based on the total weight of the core.

11. The fertilizer granule of claim 1, wherein 90 wt. % to 99 wt. % of the fertilizer granule is comprised of the core.

12. The fertilizer granule of claim 1, wherein the fertilizer granule comprises 0.2 wt. % to 7 wt. % of the base.

13. The fertilizer granule of claim 1, wherein the fertilizer granule comprises 0.01 wt. % to 0.2 wt. % of the urease inhibitor.

14. The fertilizer granule of claim 1, wherein at least a portion of the calcium sulfate in the core is obtained from phosphogypsum.

15. The fertilizer granule of claim 14, wherein the phosphogypsum is obtained from a phosphoric acid manufacturing process.

16. The fertilizer granule of claim 1, comprised in a fertilizer blend or a compounded fertilizer.

17. A method for making the fertilizer granule of claim 1, the method comprising: forming or providing a core comprising phosphoric acid and an urea adduct comprising urea and calcium sulfate; and coating an outer surface of the core with a urease inhibitor and a base to form a coat.

18. The method of claim 17, wherein the coat is formed by contacting the outer surface of the core with a solution comprising the urease inhibitor to form an inhibitor coated core, and contacting an outer surface of the inhibitor coated core with particulate solids comprising the base.

19. The method of claim 17, wherein the coat is formed by contacting the outer surface of the core with particulate solids comprising the base to form a base coated core, and contacting an outer surface of the base coated core with a solution comprising the urease inhibitor.

20. A method of fertilizing, the method comprising applying a fertilizer granule of claim 1 to at least a portion of a soil, a crop, or the soil and the crop.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

[0062] FIG. 1A) A fertilizer granule according to one example of the present invention. FIG. 1B) A fertilizer granule according to another example of the present invention.

[0063] FIG. 2A) a flowchart of a method for producing a fertilizer granule according to one example of the present invention. FIG. 2B) a flowchart of a method for producing a fertilizer granule according to another example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0064] The fertilizer granule of the present invention can contain a urease inhibitor and a base coating a core. The core can contain phosphoric acid and an urea adduct containing urea and calcium sulfate. As illustrated in a non-limiting manner in Example 1, it was found that adding a base to a fertilizer particle core containing UCS and phosphoric acid can reduce degradation of a urease inhibitor in a coating on the core.

[0065] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Fertilizer Granules

[0066] The fertilizer granule can contain a core and a coat forming a coating on the core. The fertilizer granule can contain 90 wt. % to 99 wt. % of the core, e.g., the fertilizer granule is comprised of 90 wt. % to 99 wt. % or at least any one of, equal to any one of, or between any two of 90 wt. %, 91 wt. %, 92 wt. %, 93 wt. %, 94 wt. %, 95 wt. %, 96 wt. %, 97 wt. %, 98 wt. % and 99 wt. % of the core. The core can contain an urea adduct and phosphoric acid. The urea adduct can be a urea-calcium sulfate (UCS) adduct and can contain urea and calcium sulfate. The UCS adduct can be CaSO.sub.4.4CO(NH.sub.2).sub.2. In some aspects, the core can contain 40 wt. to 85 wt. % or at least any one of, equal to any one of, or between any two of 40 wt. %, 45 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, 80 wt. %, and 85 wt. % of the UCS adduct. In certain aspects, the core can further contain free urea that is not contained in the UCS adduct and/or free calcium sulfate that is not contained in the UCS adduct. In some aspects, the core can contain i) 47 wt. % to 79.5 wt. %, or at least any one of, equal to any one of, or between any two of 47 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, and 79.5 wt. %, of urea in total, present freely and/or within the UCS adduct, ii) 20 wt. % to 45 wt. %, or at least any one of, equal to any one of, or between any two of 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, and 45 wt. % of CaSO.sub.4 in total, present freely and/or within the UCS adduct and iii) 0.1 wt. % to 3 wt. %, or at least any one of, equal to any one of, or between any two of 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.7 wt. % 0.8 wt. %, 0.9 wt. %, 1 wt. %, 1.2 wt. %, 1.4 wt. %, 1.6 wt. %, 1.8 wt. %, 2 wt. %, 2.2 wt. %, 2.4 wt. %, 2.6 wt. %, 2.8 wt. %, 3 wt. % of phosphoric acid. based on the total weight of the core.

[0067] The UCS adduct in the core can be formed by an adduct forming reaction between calcium sulfate from phosphogypsum and urea. The calcium sulfate present freely and contained within the UCS adduct in the core can be obtained from phosphogypsum. The phosphoric acid in the core can be obtained from phosphogypsum. In some aspects, the phosphogypsum can be obtained from a phosphoric acid manufacturing process. In some aspects, the core does not contain or is substantially free of a binder, filler, pH buffer, urease inhibitor, and/or nitrification inhibitor.

[0068] The core can be of any suitable shape. Non-limiting shapes include spherical, cuboidal, cylindrical, puck shape, oval, and oblong shapes. In some aspects, the core can be of cylindrical shape with a circular, elliptical, ovular, triangular, square, rectangular, pentagonal, or hexagonal cross section, although cylindrical shaped core having a cross-section of other shapes can also be made. In some aspects, the core can have a dimension such as length, width, height and/or cross-sectional diameter between 0.5 mm to 5 mm or at least any one of, equal to any one of, or between any two of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm. In some particular aspects, the core can have a substantially spherical shape with an average diameter 1 mm to 5 mm or at least any one of, equal to any one of, or between any two of 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, and 5 mm.

[0069] The fertilizer granule can contain 0.2 wt. % to 8 wt. % of the coat, e.g., 1 wt. % to 6 wt. % or at least any one of, equal to any one of, or between any two of 0.2 wt. %, 1 wt. %, 2 wt. %, 3 wt. %, 4 wt. %, 5 wt. %, 6 wt. %, 7 wt. % and 8 wt. % of the fertilizer granule can be comprised of the coat. The coat can contain an urease inhibitor and a base. The base can contain an oxide, carbonate, acetate and/or hydroxide of a group 1 metal, group 2 metal, group 13 metal, and/or ammonium. In certain aspects, the group 1 metal can be lithium (Li), sodium (Na), and/or potassium (K). In certain aspects, the group 2 metal can be beryllium (Be), magnesium (Mg), calcium (Ca), barium (Ba), and/or strontium (Sr). In certain aspects, the group 13 metal can be aluminum (Al), gallium (Ga), indium (In), or thallium (Tl). In certain aspects, the base can contain CaO and/or MgO. In some particular aspects, the base can be MgO. In certain aspects, the base such as MgO can be comprised in particulate solids. In some aspects, the micronized particles can have an average size, e.g., an average diameter, of 0.1 μm to 150 μm, or 1 μm to 50 μm, or at least any one of, equal to any one of, or between any two of 0.1 μm, 0.3 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, and 150 μm. In some aspects, the fertilizer granule can contain 0.2 wt. % to 7 wt. % or at least any one of, equal to any one of, or between any two of 0.2 wt. %, 0.5 wt. %, 1 wt. %, 2 wt. %, 3 wt. %, 4 wt. %, 5 wt. %, 6 wt. %, 7 wt. % of the base, such as MgO. In certain aspects, the urease inhibitor can contain a thiophosphoric triamide derivative or phenyl phosphorodiamidate (PPDA). In certain aspects, the thiophosphoric triamide derivative can be N-(n-butyl) thiophosphoric triamide (NBPT). In some aspects, the fertilizer granule can comprise 0.01 wt. % to 0.2 wt. % or at least any one of, equal to any one of, or between any two of 0.01 wt. %, 0.05 wt. %, 0.1 wt. %, 0.15 wt. % and 0.2 wt. % of the urease inhibitor, such as NBPT. In some aspects, the fertilizer granule can contain NBPT and MgO at a weight ratio of 0.005:1 to 0.1:1 or at least any one of, equal to any one of, or between any two of 0.005:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1 and 0.1:1.

[0070] The coat can contain one or more coating layers. In some aspects, the urease inhibitor and the base can be contained in the same coating layer. In some aspects, the coat can contain at least two coating layers, a base containing alkaline coating layer and a urease inhibitor containing inhibitor coating layer. The alkaline coating layer and the inhibitor coating layer can form separate coating layers on the core. The coat overall can cover 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the outer surface of the core. In certain aspects, the alkaline coating layer can further contain a micronutrient. A micronutrient is a botanically acceptable form of an inorganic or organometallic compound such as boron, copper, iron, chloride, manganese, molybdenum, nickel, or zinc. In certain aspects, the inhibitor coating layer can further contain a nitrification inhibitor. In some aspects, the nitrification inhibitor can be 3,4-dimethylpyrazole phosphate (DMPP), thio-urea (TU), dicyandiamide (DCD), 2-Chloro (trichloromethyl)-pyridine (Nitrapyrin), 5-Ethoxy-3-trichloromethyl-1, 2, 4-thiadiazol (Terrazole), 2-Amino-4-chloro-6-methyl-pyrimidine (AM), 2-Mercapto-benzothiazole (MBT), or 2-Sulfanimalamidothiazole (ST) or any combination thereof, preferably DCD. In some aspects, the fertilizer particle can include 0.1 wt. % to 5 wt. % of the nitrification inhibitor such as DCD.

[0071] In some aspects, the alkaline coating layer can form a coating over at least a portion of an outer surface of the core to form a base coated core and the inhibitor coating layer can form a coating over at least a portion of an outer surface of the base coated core to form the fertilizer granule. In some aspects, at least a portion of the alkaline coating layer can be positioned between the core and the inhibitor coating layer. In some aspects, the inhibitor coating layer can form an outer coating layer of the fertilizer granule. The alkaline coating layer can cover 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the outer surface of the core. The inhibitor coating layer can cover 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the outer surface of the base coated core.

[0072] In some other aspects, the inhibitor coating layer can form a coating over at least a portion of an outer surface of the core to form an inhibitor coated core and the alkaline coating layer can form a coating over at least a portion of an outer surface of the inhibitor coated core to form the fertilizer granule. In some aspects, at least a portion of the inhibitor coating layer can be positioned between the core and the alkaline coating layer. In some aspects, the alkaline coating layer can form an outer coating layer of the fertilizer granule. The inhibitor coating layer can cover 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the outer surface of the core. The alkaline coating layer can cover 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, or 100% of the outer surface of the inhibitor coated core.

[0073] Referring to FIG. 1A a fertilizer granule 100 according to an example of the present invention is shown. The fertilizer granule 100 contains a core 101, urease inhibitor containing inhibitor coating layer 102 coating an outer surface of the core, and alkaline coating layer 103 containing micronized particles containing a base, such as MgO, coating an outer surface of the inhibitor coating layer coated core, e.g., inhibitor coated core. The inhibitor coating layer 102 is represented as covering the entire outer surface of the core 101, although fertilizer granules with the inhibitor coating layer 102 covering a portion of the outer surface of the core can readily be made. The alkaline coating layer 103 is represented as covering the entire outer surface of the inhibitor coating layer coated core, although fertilizer granules with alkaline coating layer 103 covering a portion of the outer surface of the inhibitor layer coated core can readily be made.

[0074] Referring to FIG. 1B a fertilizer granule 200 according to a second example of the present invention is shown. The fertilizer granule 200 contains a core 201, an alkaline coating layer 202 containing micronized particles containing a base, such as MgO, coating an outer surface of the core, and an urease inhibitor containing inhibitor coating layer 203 coating an outer surface of the alkaline coating layer coated core, e.g., base coated core. The alkaline coating layer 202 is represented as covering the entire outer surface of the core 201, although fertilizer granules with the alkaline coating layer 202 covering a portion of the outer surface of the core can readily be made. The inhibitor coating layer 203 is represented as covering the entire outer surface of the alkaline coating layer coated core, although fertilizer granules with inhibitor coating layer 203 covering a portion of the outer surface of the alkaline coating layer coated core can readily be made.

[0075] In some aspects, the fertilizer granule can contain a) a core containing i) 47 wt. % to 79.5 wt. %, or at least any one of, equal to any one of, or between any two of 47 wt. %, 50 wt. %, 55 wt. %, 60 wt. %, 65 wt. %, 70 wt. %, 75 wt. %, and 79.5 wt. %, of urea in total, present freely and/or within the UCS adduct, ii) 20 wt. % to 45 wt. %, or at least any one of, equal to any one of, or between any two of 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, 40 wt. %, and 45 wt. % of CaSO.sub.4 in total, present freely and/or within the UCS adduct and iii) 0.1 wt. % to 3 wt. %, or at least any one of, equal to any one of, or between any two of 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt. %, 0.6 wt. %, 0.7 wt. % 0.8 wt. %, 0.9 wt. %, 1 wt. %, 1.2 wt. %, 1.4 wt. %, 1.6 wt. %, 1.8 wt. %, 2 wt. %, 2.2 wt. %, 2.4 wt. %, 2.6 wt. %, 2.8 wt. %, 3 wt. % of phosphoric acid, wherein wt. % of i), ii) and iii) are based on the total weight of the core, and b) a coat containing iv) 0.5 wt. % to 5 wt. % or at least any one of, equal to any one of, or between any two of 0.5 wt. %, 1 wt. %, 2 wt. %, 3 wt. %, 4 wt. %, and 5 wt. % of MgO and v) 0.01 wt. % to 0.2 wt. % or at least any one of, equal to any one of, or between any two of 0.01 wt. %, 0.05 wt. %, 0.1 wt. %, 0.15 wt. % and 0.2 wt. % of NBPT, wherein wt. % of iv) and v) are based on the total weight of the fertilizer granule.

[0076] In some aspects, the core and/or coat contains a filler, binder, talc, pH buffer, and/or anticaking agent. In some aspects, the core and/or coat contains, based on total weight of the core and/or coat respectively, less than 0.5 wt. %, or less than 0.1 wt. %, or is substantially free, or is free of a filler such as each of silica, dried distillers grains with solubles (DDGS), bone mill powder, and rice husk. In some aspects, the core and/or coat contains based on total weight of the core and/or coat respectively less than 0.5 wt. %, or less than 0.1 wt. %, or is substantially free, or is free of a binder such as each of flour, bleached wheat flour, starch, gluten, kaolin, bentonite, and colloidal silica. In some aspects, the core and/or coat contains, based on total weight of the core and/or coat respectively, less than 0.5 wt. %, or less than 0.1 wt. %, or is substantially free, or is free of talc. In some aspects, the core and/or coat contains, based on total weight of the core and/or coat respectively, less than 0.5 wt. %, or less than 0.1 wt. %, or is substantially free, or is free of a pH buffer. In some aspects, the core and/or coat contains, based on total weight of the core and/or coat respectively, less than 0.5 wt. %, or less than 0.1 wt. %, or is substantially free, or is free of an anticaking agent.

[0077] In some aspects, additional fertilizer substances besides urea can be included or excluded in the core of the fertilizer granules. If included, additional fertilizers can be chosen based on the particular needs of certain types of soil, climate, or other growing conditions to maximize the efficacy of the fertilizer granule in enhancing plant growth and crop yield. Additional additives may also be included or excluded in the fertilizer granules. Non-limiting examples of additives that can be included or excluded from the fertilizer granules of the present invention include micronutrients, additional nitrogen nutrients, and/or secondary nutrients. A micronutrient is a botanically acceptable form of an inorganic or organometallic compound such as boron, copper, iron, chloride, manganese, molybdenum, nickel, or zinc. An additional nitrogen nutrient is a nutrient other than urea can deliver nitrogen to a plant. In some aspects, the additional nitrogen nutrient can include ammonium nitrate, ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea-formaldehyde, ammonium chloride, and potassium nitrate. A secondary nutrient is a substance that can deliver calcium, magnesium, and/or sulfur to a plant. In some aspects, the secondary nutrients may include lime, gypsum, superphosphate, or a combination thereof.

[0078] The core of the fertilizer granules can have desirable physical properties such as desired levels of abrasion resistance, granule strength, pelletizability, hygroscopicity, granule shape, and size distribution, which are important properties for the fertilizer core.

[0079] The fertilizer granules described herein can be comprised in a composition useful for application to soil. In addition to the fertilizer granules, the composition may include other fertilizer compounds, micronutrients, primary nutrients, additional urea, additional nitrogen nutrients, insecticides, herbicides, or fungicides, or combinations thereof.

[0080] The fertilizer granules described herein can also be included in a blended composition comprising other fertilizer granules. The other fertilizer granules can be granules of urea, monoammonium phosphate (MAP), diammonium phosphate (DAP), muriate of potash (MOP), monopotassium phosphate (MKP), triple super phosphate (TSP), rock phosphate, single super phosphate (SSP), ammonium sulfate, and the like.

B. Method of Making a Fertilizer Granule

[0081] One aspect of the present invention is directed to a method for making a fertilizer granule, such as a fertilizer granule disclosed herein. In certain aspects, the method can include forming or providing a core containing phosphoric acid and an urea adduct containing urea and calcium sulfate; and coating an outer surface of the core with an urease inhibitor, a base, and optionally a nitrification inhibitor and/or a micronutrient to form a coat. In some aspects, the coat can be formed by contacting the outer surface of the core with the urease inhibitor and optionally the nitrification inhibitor to form an inhibitor coated core, and contacting an outer surface of the inhibitor coated core with particulate solids containing the base and optionally a micronutrient. In some aspects, the coat can be formed by contacting the outer surface of the core with particulate solids containing the base and optionally a micronutrient to form a base coated core, and contacting an outer surface of the base coated core with an urease inhibitor and optionally a nitrification inhibitor. In some aspects, the coat can be formed by contacting the outer surface of the core with a combination of particulate solids containing the base and an urease inhibitor and optionally a micronutrient and/or a nitrification inhibitor. In certain aspects, a solution containing the urease inhibitor can be contacted with, such as sprayed on, the outer surface of the core or base coated core. In some aspects, the solution can be an aqueous solution containing 15 wt. % to 40 wt. % or at least any one of, equal to any one of, or between any two of 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, and 40 wt. % of the urease inhibitor.

[0082] In some aspects, the core or based coated core can be coated with 0.3 kg to 3 kg or at least any one of, equal to any one of, or between any two of 0.3, 0.5, 1, 1.5, 2, 2.5, and 3 kg of the urease inhibitor such as NBPT per ton of urea e.g. present freely and in the UCS adduct, in the core. In some aspects, the core or inhibitor coated core can be coated with 2 kg to 30 kg or at least any one of, equal to any one of, or between any two of 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, and 30 kg of the base such as MgO per ton of urea e.g. present freely and in the UCS adduct, in the core.

[0083] FIG. 2A shows a flow chart of a method 300 for making a fertilizer granule according to one example of the present invention. Referring to FIG. 2A, a core 301 can be coated with a solution containing an urease inhibitor 302 to form an inhibitor coated core 303, the inhibitor coated core 303 can be coated with micronized particles containing a base 304 to form a coated fertilizer granule 305. FIG. 2B shows a flow chart of a method 400 for making a fertilizer granule according to another example of the present invention. Referring to FIG. 2B, a core 401 can be coated with micronized particles containing a base 402 to form a base coated core 403, the base coated core 403 can be coated with a solution containing an urease inhibitor 404 to form a coated fertilizer granule 405.

[0084] In some particular aspects, a core in a form of prills and/or granules of size 1 mm to 5 mm can be provided in a container, such as a drum coater or a granulator. An aqueous solution containing 15 wt. % to 40 wt. % of an urease inhibitor such as NBPT can be sprayed on the core prills and/or granules in the container to form an inhibitor coated core, e.g., NBPT coated core. Micronized particles containing a base such as MgO can be added to the container to coat the NBPT coated core with the micronized particles to form the fertilizer granules.

[0085] In some other aspects, a core in a form of prills and/or granules of size 1 mm to 5 mm can be provided in a container, such as a drum coater or a granulator. Micronized particles containing a base such as MgO, can be added to the container to coat the core prills and/or granules in the container to form a base coated core, e.g., MgO coated core. An aqueous solution containing 15 wt. % to 40 wt. % of an urease inhibitor such as NBPT can be sprayed on the MgO coated core to form the fertilizer granules.

[0086] In certain aspects, the core can be formed by contacting urea with phosphogypsum to form a slurry containing a UCS adduct, drying the slurry to form a dried UCS adduct and granulating the dried UCS adduct. The UCS adduct can be formed by an adduct forming reaction between calcium sulfate present in the phosphogypsum and urea (equation 1).

CaSO.sub.4.Math.2H.sub.2O+4CO(NH.sub.2).sub.2.fwdarw.CaSO.sub.4.Math.4CO(NH.sub.2).sub.2+2H.sub.2O  (1)

[0087] The urea and phosphogypsum can be contacted in presence of water to form the slurry. In certain aspects, urea in form of an urea solution, urea particles, urea granules, or urea prills, or any combination thereof can be contacted with the phosphogypsum to form the slurry. In some aspects, the urea solution contacted with the phosphogypsum can contain 10 wt. % to 40 wt. % or at least any one of, equal to any one of, or between any two of 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, and 40 wt. %, of water. In some aspects, a phosphogypsum having 2 wt. % to 30 wt. % or at least any one of, equal to any one of, or between any two of 2 wt. %, 5 wt. %, 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. % and 30 wt. % of moisture can be contacted with urea to form the slurry. In some aspects, the slurry can contain 10 wt. % to 40 wt. % or at least any one of, equal to any one of, or between any two of 10 wt. %, 15 wt. %, 20 wt. %, 25 wt. %, 30 wt. %, 35 wt. %, and 40 wt. %, of water. Urea can be contacted with phosphogypsum at molar ratio of 3:1 to 5:1 or at least any one of, equal to any one of, or between any two of 3:1, 3.5:1, 4:1, 4:5 and 5:1 of urea to calcium sulfate contained in the phosphogypsum. In some aspects, the urea and phosphogypsum can be contacted at 40° C. to 90° C., or at least any one of, equal to any one of, or between any two of 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., and 90° C. In certain aspects, the slurry can be dried at 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C. or greater, or any temperature or range thereof or there between to form the dried UCS adduct. The amount of water, e.g., moisture, in the dried UCS adduct can be less than 0.6 wt. %, 0.5 wt. %, 0.4 wt. %, 0.3 wt. %, 0.2 wt. %, 0.1 wt. %, or less, or any amount or range thereof or there between. The amount of UCS adduct in the core can be 40 wt. %, over 40 wt. %, over 45 wt. %, over 50 wt. %, over 55 wt. %, over 60 wt. %, over 65 wt. %, over 70 wt. %, over 75 wt. %, over 80 wt. %, over 85 wt. %, or any amount or range thereof or there between. The dried UCS adduct can be granulated at 65° C. to 95° C., or at least any one of, equal to any one of, or between any two of 65, 70, 75, 80, 85, 90 and 95° C. The core can be formed from the dried UCS adduct and the core can be coated in the same or in a different granulator. In certain aspects, the granulator used for granulating the dried UCS adduct and/or coating the core can be a granulation drum, pugmill, pan granulator, etc.

C. Methods of Using Fertilizer Granules

[0088] The fertilizer granule(s) and fertilizer blend containing the fertilizer granule(s) of the present invention can be used in methods of increasing the amount of nitrogen in soil and of enhancing plant growth. Such methods can include applying to the soil an effective amount of a composition comprising the fertilizer granule(s) of the present invention. The method may include increasing the growth and yield of crops, trees, ornamentals, etc., such as, for example, palm, coconut, rice, wheat, corn, barley, oats, and soybeans. The method can include applying the fertilizer blend of the present invention to at least one of a soil, an organism, a liquid carrier, a liquid solvent, etc.

[0089] Non-limiting examples of plants that can benefit from the fertilizer of the present invention include vines, trees, shrubs, stalked plants, ferns, etc. The plants may include orchard crops, vines, ornamental plants, food crops, timber, and harvested plants. The plants may include Gymnosperms, Angiosperms, and/or Pteridophytes. The Gymnosperms may include plants from the Araucariaceae, Cupressaceae, Pinaceae, Podocarpaceae, Sciadopitaceae, Taxaceae, Cycadaceae, and Ginkgoaceae families. The Angiosperms may include plants from the Aceraceae, Agavaceae, Anacardiaceae, Annonaceae, Apocynaceae, Aquifoliaceae, Araliaceae, Arecaceae, Asphodelaceae, Asteraceae, Berberidaceae, Betulaceae, Bignoniaceae, Bombacaceae, Boraginaceae, Burseraceae, Buxaceae, Canellaceae, Cannabaceae, Capparidaceae, Caprifoliaceae, Caricaceae, Casuarinaceae, Celastraceae, Cercidiphyllaceae, Chrysobalanaceae, Clusiaceae, Combretaceae, Cornaceae, Cyrillaceae, Davidsoniaceae, Ebenaceae, Elaeagnaceae, Ericaceae, Euphorbiaceae, Fabaceae, Fagaceae, Grossulariaceae, Hamamelidaceae, Hippocastanaceae, Illiciaceae, Juglandaceae, Lauraceae, Lecythidaceae, Lythraceae, Magnoliaceae, Malpighiaceae, Malvaceae, Melastomataceae, Meliaceae, Moraceae, Moringaceae, Muntingiaceae, Myoporaceae, Myricaceae, Myrsinaceae, Myrtaceae, Nothofagaceae, Nyctaginaceae, Nyssaceae, Olacaceae, Oleaceae, Oxalidaceae, Pandanaceae, Papaveraceae, Phyllanthaceae, Pittosporaceae, Platanaceae, Poaceae, Polygonaceae, Proteaceae, Punicaceae, Rhamnaceae, Rhizophoraceae, Rosaceae, Rubiaceae, Rutaceae, Salicaceae, Sapindaceae, Sapotaceae, Simaroubaceae, Solanaceae, Staphyleaceae, Sterculiaceae, Strelitziaceae, Styracaceae, Surianaceae, Symplocaceae, Tamaricaceae, Theaceae, Theophrastaceae, Thymelaeaceae, Tiliaceae, Ulmaceae, Verbenaceae, and/or Vitaceae family.

[0090] The effectiveness of compositions comprising the fertilizer granule(s) of the present invention can be ascertained by measuring the amount of nitrogen in the soil at various times after applying the fertilizer composition to the soil. It is understood that different soils have different characteristics, which can affect the stability of the nitrogen in the soil. The effectiveness of a fertilizer composition can also be directly compared to other fertilizer compositions by doing a side-by-side comparison in the same soil under the same conditions.

EXAMPLES

[0091] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

Example 1

Urease Inhibitor and Magnesium Oxide Coated Urea Calcium Sulfate (UCS)

[0092] Methods: Coated UCS containing fertilizer granules were prepared using a drum coating system with a batch process. The lab scale drum coating system had a capacity of 200 grams to 2 kilograms and had a drum interchanging facility based on the required volume. The drum contained four baffles 0.5 inch in height and 1 inch in width across the drum length. The drum coater system was worked in manual mode starting from feeding, pumping, spraying, exhausting, drying, and discharging the coated material. The urease inhibitor and the magnesium oxide used to coat the UCS granules were obtained from commercial sources. The UCS granules were made from urea and phosphogypsum. The UCS granules contained 0.2-1.2 wt. % of phosphoric acid.

[0093] Three parallel experiments were performed. In experiment 1, 199.54 g of granular UCS product was weighed and fed into the drum. 0.46 g of a solution containing 26 wt. % of urease inhibitor was pumped into the drum using a peristatic pump. The pump was connected to a spray nozzle with orifice design. The solution was atomized by compressed air and was sprayed onto the granular UCS adduct. An exhaust pipe line on top of the drum took off the compressed air. After completion of spraying the coating solution, the drum was rotated continually for five more minutes to ensure dispersion of the coating. Then rotation of the drum was stopped and the inhibitor coated UCS product was collected for packing.

[0094] In experiment 2, 195.54 g of granular UCS product was weighed and fed into the drum. 4 g magnesium oxide as a powder was added to the drum. Then 0.46 g of a solution containing 26 wt. % of urease inhibitor was pumped into the drum using a peristatic pump. The pump was connected to a spray nozzle with orifice design. The solution was atomized by compressed air and was sprayed on to the magnesium oxide coated granular UCS adduct. An exhaust pipe line on top of the drum took off the compressed air. After completion of spraying the coating solution, the drum was rotated continuously for five more minutes to ensure dispersion of the coating. Then rotation of the drum was stopped and the UCS coated first with 2% MgO and second with inhibitor product was collected for packing.

[0095] In experiment 3, 195.54 g of granular UCS product was weighed and fed into the drum. 0.46 g of a solution containing 26 wt. % of urease inhibitor was pumped into the drum using a peristatic pump. The pump was connected to a spray nozzle with orifice design. The solution was atomized by compressed air and was sprayed on to the granular UCS adduct. An exhaust pipe line on top of the drum took off the compressed air. After completion of spraying the coating solution, 4 g magnesium oxide as a powder was added to the drum, and the drum was rotated continuously for five more minutes to ensure dispersion of the coating. Then rotation of the drum was stopped and the UCS coated first with inhibitor and second with 2% MgO product was collected for packing.

[0096] Table 1 shows the process parameters for experiments 1, 2 and 3.

TABLE-US-00001 TABLE 1 process parameters for experiments 1, 2 and 3. Parameters Drum RPM 20 Urease inhibitor solution spray rate 2 ml/min Spray nozzle type orifice Spray nozzle distance from the coating bed 300 to 600 mm Atomizing air pressure 0.1 bar

[0097] Results: The coated UCS granules from experiments 1, 2, and 3 were stored and the urease inhibitor (NBPT) stability was monitored at room condition. The recovery of NBPT, e.g. concentration of NBPT remaining, after certain time intervals were quantified using an HPLC technique. Results shown in Table 2 demonstrate better stability of NBPT in the MgO coated UCS samples (experiment 2 and 3) compared to a granule without a MgO coating(experiment 1).

TABLE-US-00002 TABLE 2 Percentage NBPT recovery in blended samples stored at room condition. Concentration of NBPT remaining in storage Experi- Day Day Day Day Day Day ment Sample 3 15 45 75 120 180 1 UCS coated  66%  2%  0%  0%  0%  0% with inhibitor liquid 2 UCS coated 100% 100% 100% 92% 80% 74% first with 2 wt. % MgO followed by inhibitor liquid coating 3 UCS coated 100% 100% 100% 95% 72% 65% with inhibitor liquid followed by powder coating of 2 wt. % MgO