SiO2-coated N-P-Ca-Mg complex nutrients

Abstract

A slow release fertilizer composition containing a mixture of calcium ammonium phosphate and magnesium ammonium phosphate is disclosed. The fertilizer may also include silica that contributes to a slow release function by acting as a scaffold in which calcium ammonium phosphate and magnesium ammonium phosphate are provided. Methods of making and using the slow release fertilizer compositions are also disclosed.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to European application No. 22188754.0 filed on August 4, 2022, the contents of which are incorporated herein by reference in their entirety. Background of the Invention I. Technical field

[0004] The present disclosure relates generally to slow-release fertilizer compositions. In particular embodiments, the present disclosure relates to fertilizers containing calcium ammonium phosphate and magnesium ammonium phosphate. II. Background Technology

[0005] Fertilizers have been used for centuries to replenish soil with nutrients required for plant growth. Traditional non-coated fertilizers are known to be ineffective due to the rapid release of soluble nutrients into the soil. Therefore, the control of fertilizer nutrient release rate has become an area of ​​intensive research.

[0006] In some cases, controlled release fertilizers (CRFs) control the release of water-soluble nutrients by providing a coating on the surface of the fertilizer. A variety of CRFs use synthetic polymers to coat or encapsulate fertilizers. Typically, synthetic polymer coatings are difficult to degrade, which limits the amount of nutrients released into the soil. In addition, releasing the polymer material itself into the soil will lead to contamination of the soil and surface and groundwater.

[0007] With the global population expected to continue to grow and arable land decreasing, farmers will need to use the land they have available more efficiently. The increasing demand for crop production has a direct impact on the need for improved fertilizers and more efficient fertilizers. Summary of the invention

[0008] Disclosed herein are solutions to at least some of the problems associated with fertilizer effectiveness, including fertilizer compositions having slow and sustained nutrient release characteristics. Certain aspects of the disclosure relate to the production and use of fertilizers that exhibit slow and sustained nutrient release characteristics in the absence of a polymer coating. In some aspects, the fertilizer composition includes a non-polluting framework that helps release nutrients to the soil over an extended period of time. Slow-release fertilizers disclosed herein can reduce labor costs and application costs by eliminating the need for multiple fertilizations. Slow-release fertilizers disclosed herein provide more uniform plant nutrients, better growth, and improved plant performance. In addition, the slow and extended release characteristics provided by the fertilizers disclosed herein help reduce fertilizer losses due to leaching.

[0009] In one aspect, slow-release fertilizers include magnesium ammonium phosphate and calcium ammonium phosphate. In some cases, the magnesium ammonium phosphate and calcium ammonium phosphate are encapsulated in silicon dioxide. In some aspects, the silicon dioxide is a dehydrated silica gel. In some aspects, the silicon dioxide is used as a binder to impart structural integrity to the fertilizer and serves as a support for providing fertilizer nutrients therein. Silicon dioxide is present in many soils, and silicon dioxide provides a harmless, non-polluting support for the fertilizer composition. In some aspects, the slow-release fertilizer composition is prepared in the form of a powder, a prill, a granule or a pellet. In some aspects, the fertilizer composition also includes ammonium ferric phosphate. In other aspects, the fertilizer includes magnesium ammonium phosphate and calcium ammonium phosphate on the fertilizer surface or on the silicon dioxide surface. In some aspects, the fertilizer includes magnesium ammonium phosphate and calcium ammonium phosphate encapsulated in a dehydrated silica gel.

[0010] In some embodiments, the method for preparing the slow-release fertilizer comprises (a) reacting olivine and calcium oxide with phosphoric acid to produce a reaction mixture comprising calcium hydrogen phosphate, magnesium hydrogen phosphate and silicon dioxide, and (b) reacting an ammonia source with calcium hydrogen phosphate and magnesium hydrogen phosphate to produce magnesium ammonium phosphate and calcium ammonium phosphate, wherein the slow-release fertilizer composition comprises the magnesium ammonium phosphate and calcium ammonium phosphate. In some aspects, the fertilizer composition also comprises silicon dioxide. In some aspects, step (a) and step (b) are carried out in the same container. In some aspects, step (a) and step (b) are carried out in independent containers. In some aspects, the method also comprises drying the fertilizer composition. In some aspects, wherein the reaction mixture also comprises ammonium iron phosphate.

[0011] In some aspects, the step of reacting olivine and calcium oxide with phosphoric acid is carried out at a temperature of 20° C. to 75° C. The reaction of olivine and calcium oxide with phosphoric acid can be carried out at any of the following temperatures, temperatures below the following temperatures, temperatures above the following temperatures, temperatures between the following temperatures, or any range thereof, or any range of temperatures derivable therein: 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., 26° C., 27° C., 28° C., 29° C., 30° C., 31° C., 32° C., 33° C., 34° C., 35° C., 36° C., 37° C., ℃, 38℃, 39℃, 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃. In some aspects, the silica in the reaction mixture is silica gel. Therefore, drying the fertilizer composition provides a silica gel fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate encapsulated in dehydrated silica gel. In some aspects, the slow-release fertilizer composition also comprises magnesium ammonium phosphate and calcium ammonium phosphate on the surface of the fertilizer.

[0012] In some aspects, the phosphoric acid is provided in the form of an aqueous solution with a concentration of 50% to 86% by weight, such as 85% to 86% by weight, or 50% to 60% by weight, or 60% to 70% by weight, or 80% to 86% by weight, or any weight % or any range derived therefrom. In some aspects, olivine and calcium oxide are provided in a weight ratio of 1:5 to 5:1. The weight ratio of olivine to calcium oxide can be any one of the following ratios, less than any one of the following ratios, greater than any one of the following ratios, or a ratio between the following ratios, or any range of ratios derived therefrom: 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1. In some aspects, the phosphoric acid, olivine, and calcium oxide are provided in a solid weight to liquid weight ratio of 1:5 to 5:1, wherein the solid weight is the combined weight of olivine and calcium oxide, and the liquid weight is the weight of phosphoric acid. The solid weight to liquid weight ratio can be any one of the following ratios, less than any one of the following ratios, greater than any one of the following ratios, or a ratio between the following ratios, or any range of ratios that can be derived therefrom: 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1. In some aspects, the ammonia source is a solution of ammonium hydroxide, ammonium, ammonium carbonate, ammonia, succinimide and / or phthalimide. In some aspects, the source of calcium oxide is limestone. In some aspects, the ammonia source and phosphoric acid are provided in a weight ratio of 1:1 to 1:10. The weight ratio of the ammonia source and phosphoric acid can be any one of the following ratios, less than any one of the following ratios, greater than any one of the following ratios, or a ratio between the following ratios, or any range of ratios that can be derived therefrom: 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10. The compositions and methods described herein can use olivine as a source of magnesium, silicon, and iron. Olivine is a magnesium-iron silicate mineral with a chemical formula of (Mg,Fe)2SiO4. The ratio of Mg2SiO4 to Fe2SiO4 is generally greater than 1:1, for example, from about 0.9 to about 0.1.

[0013] In some aspects, the fertilizer comprises at least one additional nutrient selected from potassium, chloride, sulfate, superphosphate, phosphate rock, potash, sulfate of potash (SOP), chloride of potash (MOP), kieserite, carnallite, magnesite, dolomite, boric acid, boron, copper, iron, manganese, molybdenum, zinc, selenium, silicon, free calcium, elemental sulfur, neem oil, seaweed extract, biopromoter, charcoal, ash from burning animal waste or burning animal tissue, or any combination thereof. Additional aspects of the present disclosure relate to a method for fertilizing agricultural soil, comprising applying to the soil a slow-release fertilizer composition disclosed herein.

[0014] The following Aspect 1 to Aspect 25 of the present invention are also disclosed.

[0015] Aspect 1 is a method for preparing a slow-release fertilizer composition comprising nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg), the method comprising the following steps:

[0016] a. reacting olivine and calcium oxide with phosphoric acid to produce a reaction mixture comprising calcium hydrogen phosphate, magnesium hydrogen phosphate and silicon dioxide; and

[0017] b. reacting an ammonia source with calcium hydrogen phosphate and magnesium hydrogen phosphate to produce magnesium ammonium phosphate and calcium ammonium phosphate,

[0018] The slow-release fertilizer composition comprises magnesium ammonium phosphate and calcium ammonium phosphate.

[0019] Aspect 2 is a method according to aspect 1, wherein the fertilizer composition further comprises silicon dioxide.

[0020] Aspect 3 is a method according to any one of aspects 1 to 2, wherein step a and step b are performed in the same container.

[0021] Aspect 4 is the method according to any one of aspects 1 to 3, further comprising drying the fertilizer composition.

[0022] Aspect 5 is a method according to aspect 4, wherein the reaction mixture comprises ammonium ferric phosphate.

[0023] Aspect 6 is a method according to any one of aspects 1 to 5, wherein the step of reacting olivine and calcium oxide with phosphoric acid is performed at a temperature of 20°C to 75°C.

[0024] Aspect 7 is a method according to any one of aspects 1 to 6, wherein the silica in the reaction mixture is silica gel.

[0025] Aspect 8 is a method according to any one of aspects 1 to 7, wherein drying the fertilizer composition provides a dehydrated silica gel fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate encapsulated in dehydrated silica gel.

[0026] Aspect 9 is a method according to any one of aspects 1 to 8, wherein the slow release fertilizer composition comprises magnesium ammonium phosphate and calcium ammonium phosphate on the surface of the fertilizer.

[0027] Aspect 10 is a method according to any one of aspects 1 to 9, wherein phosphoric acid is provided in the form of an aqueous solution having a concentration of 50 wt % to 86 wt %.

[0028] Aspect 11 is a method according to any one of aspects 1 to 10, wherein phosphoric acid is provided in the form of an aqueous solution having a concentration of 80 wt % to 86 wt %.

[0029] Aspect 12 is a method according to any one of aspects 1 to 11, wherein the olivine and calcium oxide are provided in a weight ratio of 1:5 to 5:1.

[0030] Aspect 13 is a method according to any one of aspects 1 to 12, wherein the phosphoric acid, olivine and calcium oxide are provided in a solid weight to liquid weight ratio of 1:5 to 5:1, wherein the solid weight is the combined weight of olivine and calcium oxide, and the liquid weight is the weight of phosphoric acid.

[0031] Aspect 14 is a method according to any one of aspects 1 to 13, wherein the ammonia source is ammonium hydroxide or ammonia.

[0032] Aspect 15 is a method according to any one of aspects 1 to 14, wherein the ammonia source and phosphoric acid are provided in a weight ratio of 1:1 to 1:10.

[0033] Aspect 16 is a method according to any one of aspects 1 to 15, wherein the slow-release fertilizer composition is prepared in the form of powder, pellets, granules or pellets.

[0034] Aspect 17 is a slow-release fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate encapsulated in silica.

[0035] Aspect 18 is the slow-release fertilizer composition according to aspect 17, wherein the composition further comprises ammonium ferric phosphate.

[0036] Aspect 19 is a slow-release fertilizer composition according to any one of aspects 17 to 18, wherein the silica is a dehydrated silica gel.

[0037] Aspect 20 is a slow-release fertilizer composition according to any one of 17 to 19, wherein the fertilizer composition is provided in the form of powder, pellets, granules or pellets.

[0038] Aspect 21 is a slow-release fertilizer composition according to any one of aspects 17 to 20, wherein the slow-release fertilizer composition comprises magnesium ammonium phosphate and calcium ammonium phosphate on the surface of the fertilizer.

[0039] Aspect 22 is a slow-release fertilizer composition according to any one of aspects 17 to 21, wherein the fertilizer comprises at least one additional nutrient selected from potassium, chloride, sulfate, superphosphate, phosphate rock, potash, sulfate of potash (SOP), chloride of potash (MOP), kieserite, carnallite, magnesite, dolomite, boric acid, boron, copper, iron, manganese, molybdenum, zinc, selenium, silicon, free calcium, elemental sulfur, neem oil, seaweed extract, biostimulant, charcoal, ash from incinerated animal waste or incinerated animal tissue, or any combination thereof.

[0040] Aspect 23 is a slow-release fertilizer composition according to any one of aspects 17 to 22, which is prepared by the method according to any one of aspects 1 to 16.

[0041] Aspect 24 is the method according to any one of aspects 1 to 16, wherein the slow-release fertilizer composition prepared is the slow-release fertilizer composition according to any one of aspects 17 to 22.

[0042] Aspect 25 is a method for fertilizing agricultural soil, comprising applying the slow-release fertilizer composition according to any one of aspects 17 to 23 to the soil.

[0043] The term "fertilizer" is defined as a substance applied to soil or plant tissue to provide one or more plant nutrients necessary or beneficial to plant growth, and / or a growth promoter or enhancer that promotes or enhances plant growth.

[0044] The term "granule" may include solid materials. Granules may have a variety of shapes, non-limiting examples of which include spheres, spheres, ovoids, rods, ellipses, or random shapes.

[0045] The term "particle" may include solid material having a largest dimension less than a millimeter.

[0046] The term "particulate" or "powder" may include a plurality of particles.

[0047] The term "about" or "approximately" is defined as close to what one of ordinary skill in the art understands. In a non-limiting embodiment, the term is defined as within 10% deviation, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0048] The terms "wt %, "volume %" or "mole %" refer to the weight percent, volume percent or mole percent of a component based on the total weight of the material including the component, the total volume of the material or the total moles of the material, respectively. In a non-limiting example, 10 grams of a component in 100 grams of material is 10 wt %.

[0049] When used in conjunction with the term "includes", the indefinite quantifier preceding an element may mean "a", but is also consistent with the meaning of "one or more", "at least one", and "one or more than one".

[0050] The phrase "and / or" means "and" or "or". For example, A, B, and / or C includes: A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. In other words, "and / or" is used as an inclusive or.

[0051] The words "comprising," "having," "including," or "containing" are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0052] Compositions and methods of use thereof may "comprise," "consist essentially of," or "consist of" any ingredient or step disclosed throughout the specification. Compositions and methods that "consist essentially of" any disclosed ingredient or any step limit the scope of the claims to the specific materials or steps that do not materially affect the basic and novel characteristics of the claimed invention.

[0053] It is contemplated that any embodiment discussed in this specification can be implemented with respect to any method or any composition of the invention, and vice versa. In addition, the compositions of the invention can be used to implement the methods of the invention.

[0054] Other objects, features and advantages of the present invention will become apparent from the following detailed description. However, it should be understood that the detailed description and specific examples, although indicating specific embodiments of the present invention, are given by way of illustration only, because various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art based on the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The following drawings constitute part of this specification and are included to further demonstrate certain aspects of the present invention. The present invention may be better understood by referring to one or more of these drawings in conjunction with the detailed description of specific embodiments given in this specification.

[0056] Figure 1 : Schematic diagram of a system and method for producing fertilizer according to a non-limiting example of the systems and methods disclosed herein.

[0057] Figure 2 : Schematic diagram of a system and method for producing fertilizer according to another non-limiting example of the systems and methods disclosed herein. DETAILED DESCRIPTION

[0058] Certain aspects of the present disclosure provide a slow-release fertilizer composition comprising nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg). In some aspects, the fertilizer composition comprises dehydrated silica gel. The dehydrated silica gel (silicon dioxide) can be used as a binder to impart structural integrity to the fertilizer. The dehydrated silica gel can also serve as a support in which fertilizer nutrients are provided. In some aspects, additional nutrients are also provided. In some aspects, the additional nutrients are provided on the outer surface of the fertilizer composition.

[0059] The fertilizer composition utilizes olivine as a source of magnesium, iron and silicon, and the olivine is an abundant and relatively cheap mineral. Acid is used to dissolve and / or react with a combination of calcium oxide and olivine to obtain a mixture comprising calcium, magnesium, silicon dioxide, possibly iron and possibly any nutrient derived from acid. In some embodiments, phosphoric acid is used to contact olivine and calcium oxide to produce a first mixture comprising calcium hydrogen phosphate, magnesium hydrogen phosphate and silicon dioxide, wherein the phosphate component is derived from phosphoric acid. One or more than one additional nutrient can be added to the first mixture to provide a second mixture. In some embodiments, an ammonia source is added to the first mixture to produce a second mixture comprising magnesium ammonium phosphate and calcium ammonium phosphate, wherein the ammonium component is derived from an ammonia source. Drying the second mixture removes water and converts colloidal silicon dioxide into dehydrated silica gel. The dehydrated silica gel helps maintain the structural rigidity of the fertilizer composition and serves as a framework for providing fertilizer nutrients therein. In some aspects, additional fertilizer components can be provided in the fertilizer and / or on the surface of the fertilizer composition.

[0060] I. Fertilizer

[0061] Certain embodiments described herein relate to a slow-release fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate. Certain aspects relate to a method for preparing the slow-release fertilizer composition using olivine, calcium oxide, phosphoric acid and an ammonia source. The fertilizer can be a fertilizer granule, which can contain a uniform mixture comprising nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg). In some aspects, the magnesium ammonium phosphate and calcium ammonium phosphate are encapsulated in or dispersed in silicon dioxide, such as dry silicon dioxide gel.

[0062] The ratio of elements present in the fertilizer can be adjusted according to the specific application. In some aspects, the weight ratio of calcium oxide and olivine can be adjusted from 1:5 to 5:1. By adjusting the weight ratio of calcium oxide and olivine, the weight ratio of calcium to magnesium in the slow-release fertilizer composition can be adjusted. In some aspects, the weight ratio of olivine to calcium oxide can be any one of the following ratios, less than the ratio in the following ratios, greater than the ratio in the following ratios, or the ratio between the following ratios, or any range of ratios that can be derived therefrom: 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1. In some aspects, the weight ratio of the solid to liquid of the material used to generate the fertilizer can be adjusted. The solid weight is the combined weight of olivine and calcium oxide, and the liquid weight is the weight of phosphoric acid. In some aspects, the solid weight to liquid weight ratio can be any one of the following ratios, less than the following ratios, greater than the following ratios, or a ratio between the following ratios, or any range of ratios derived therefrom: 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1.

[0063] In some aspects, the fertilizer composition comprises N, P, Ca and / or Mg, wherein i) the N content in the slow-release fertilizer composition can be at least any one of the following contents, at most any one of the following contents, equal to any one of the following contents, or between any two of the following contents: 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt% %, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, %, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, %, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.5 wt % and 100 wt %, ii) the P content in the slow-release fertilizer composition can be at least any one of the following contents, at most any one of the following contents, equal to any one of the following contents, or a content between any two of the following contents: 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt % %, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 2wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt%, 82wt%, 83wt%, 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, 99.5 wt % and 100 wt %, iii) the Ca content in the slow-release fertilizer composition may be at least any one of the following contents, at most any one of the following contents, equal to any one of the following contents, or a content between any two of the following contents: 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, %, 16 wt %, 17 wt %, 18 wt %, 19 wt %, 20 wt %, 21 wt %, 22 wt %, 23 wt %, 24 wt %, 25 wt %, 26 wt %, 27 wt %, 28 wt %, 29 wt %, 30 wt %, 31 wt %, 32 wt %, 33 wt %, 34 wt %, 35 wt %, 36 wt %, 37 wt %, 38 wt %, 39 wt %, 40 wt %, 41 wt %, 42 wt %, 43 wt % %, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 2wt%, 73wt%, 74wt%, 75wt%, 76wt%, 77wt%, 78wt%, 79wt%, 80wt%, 81wt%, 82wt%, 83wt%, 84wt%, 85wt%, 86wt%, 87wt%, 88wt%, 89wt%, 90wt%, 91wt%, 92wt%, 93wt%, 94wt%, 95wt%, 96wt%, 97wt%, 98wt%, 99wt%, 99.5 wt % and 100 wt %, and iv) the Mg content in the slow-release fertilizer composition may be at least any one of the following contents, at most any one of the following contents, equal to any one of the following contents, or a content between any two of the following contents: 1 wt %, 2 wt %, 3 wt %, 4 wt %, 5 wt %, 6 wt %, 7 wt %, 8 wt %, 9 wt %, 10 wt %, 11 wt %, 12 wt %, 13 wt %, 14 wt %, 15 wt %, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt% %, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt %, 74 wt%, 75 wt%, 76 wt%, 77 wt%, 78 wt%, 79 wt%, 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 99.5 wt%, and 100 wt%. In some aspects, the ratio of Ca to Mg is 2:1 to 1:2. The ratio of Ca to Mg can be at least any one of the following ratios, at most any one of the following ratios, equal to any one of the following ratios, or a ratio between any two of the following ratios: 2:1, 3:2, 1:1, 2:3, and 1:2, for example, about 1:1. .

[0064] The moisture content of the dried fertilizer composition can be less than 1 wt %, such as 0.1 wt % to 0.9 wt %, or any one of the following, or any two of the following, or any range thereof: 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 % or 1 wt %, based on the weight of the fertilizer granules. As a non-limiting example, the moisture content can be determined by drying the sample at 50° C. for 25 minutes and measuring the mass loss of the fertilizer after drying.

[0065] The slow-release fertilizer composition can be any suitable shape. Non-limiting shape includes sphere, cube, cylinder, spherical, ovate and oblong. In some respects, the fertilizer granules can be cylindrical, and it has a cross section that is circular, elliptical, ovate, triangle, square, rectangle, pentagon or hexagon, but can also be made into a cylindrical core that the cross section is other shapes. In some respects, the widest dimension of the fertilizer granules can be 0.5mm to 6mm, or 0.5mm to 5mm, preferably 1mm to 4mm, or any one size of the following size at least, any one size of the following size at most, any one size equal to the following size or any two following sizes between the size: 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm and 6mm. In some particular aspects, the fertilizer granules may be substantially spherical, with an average diameter of 0.5 mm to 6 mm, or 0.5 mm to 5 mm, preferably 1 mm to 4 mm, or at least any one of the following diameters, at most any one of the following diameters, equal to any one of the following diameters, or a diameter between any two of the following diameters: 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm and 6 mm.

[0066] The slow release fertilizer composition can be water dispersible and / or soil dispersible. In some aspects, at ambient temperature, under stirring at a rate of 90 rpm to 110 rpm, within 1 minute of adding the granules to water having a pH of 7, the fertilizer granules having a size of 2 mm to 4 mm before being added to the water can be broken into particles having a size of less than 1 mm, less than 0.9 mm, less than 0.8 mm, less than 0.7 mm, less than 0.6 mm, less than 0.5 mm, less than 0.4 mm, or less than 0.3 mm.

[0067] The slow-release fertilizer composition can have a substantially uniform composition. In some cases, the composition of a 1 mm×1 mm×1 mm cube at any location in the mixture can be similar to the composition of a 1 mm×1 mm×1 mm cube at any other location in the mixture (within ±20%, or ±10%, or ±5%, or ±3%, ±2%, or ±1%, or ±0.5%).

[0068] In some respects, the fertilizer may include or exclude other fertilizer materials. If included, other fertilizer nutrients may be selected according to the special needs of certain types of soil, climate or other growth conditions to maximize the effectiveness of fertilizer in promoting plant growth and crop yield. Other additives may also be included or excluded in the fertilizer. Non-limiting examples of additives that the fertilizer of the present invention may include or exclude include other nitrogen nutrients, other phosphorus nutrients, other potassium nutrients, other trace element nutrients and / or other secondary nutrients. Trace element nutrients may be copper, iron, chloride, manganese, molybdenum or nickel or a combination thereof. The nitrogen nutrient may be urea, ammonium nitrate, ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea-formaldehyde, ammonium chloride and potassium nitrate. In some respects, the other secondary nutrients may include lime and / or superphosphate. In some cases, the other fertilizer materials and / or other additives are included in the optional fertilizer coating.

[0069] In some cases, the inhibitor includes a nitrification inhibitor and / or a urease inhibitor. Suitable nitrification inhibitors include, but are not limited to, 3,4-dimethylpyrazole phosphate (DMPP), dicyandiamide (DCD), thiourea (TU), 2-chloro-6-(trichloromethyl)-pyridine (Nitrapyrin), 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole, 2-amino-4-chloro-6-methylpyrimidine (AM), 2-mercaptobenzothiazole (MBT) or 2-sulfathiazole (ST) sold herein and any combination thereof. In some aspects, the nitrification inhibitor may include DMPP, DCD, TU, nitrapyrin, 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole, AM, MBT, or ST, or a combination thereof. In some embodiments, the fertilizer composition may include NBTPT, DMPP, TU, DCD, PPDA, nitrapyrin, 5-ethoxy-3-trichloromethyl-1,2,4-thiadiazole, AM, MBT, ST, or a combination thereof.

[0070] In some cases, the adhesive includes phosphate, polyphosphate, biodegradable polymer, or wax or a combination thereof. Suitable waxes include, but are not limited to, vegetable wax, high melting point wax, ethylene bis stearamide wax, paraffin, polyethylene wax, and olefin wax. Suitable phosphates include, but are not limited to, diammonium phosphate and monoammonium phosphate. Suitable polyphosphates include, but are not limited to, ammonium polyphosphate. Suitable biodegradable polymers include, but are not limited to, polyacrylamide, polyacrylic acid, polyacrylonitrile, biodegradable polylactic acid, and other biodegradable polymer materials, such as polylactic acid, poly(3-hydroxypropionic acid), polyvinyl alcohol, poly-e-caprolactone, poly-L-lactide, polybutylene succinate, and biodegradable starch-based polymers. The adhesive may include plaster of Paris, flour, starch, gluten, kaolin, bentonite, colloidal silicon dioxide, or a combination thereof. Suitable flour includes, but is not limited to, rice flour, wheat flour, and bleached wheat flour. Suitable starch includes, but is not limited to, dextrin-modified starch.

[0071] In some cases, the pH buffer comprises MgO, KH2PO4, NaHCO3, chalk powder, aluminum hydroxide, magnesium hydroxide, aluminum hydroxide / magnesium hydroxide coprecipitation, aluminum hydroxide / sodium bicarbonate coprecipitation, calcium acetate, calcium bicarbonate, calcium borate, calcium carbonate, calcium bicarbonate, calcium citrate, calcium gluconate, calcium hydroxide, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dipotassium phosphate, disodium hydrogen phosphate, magnesium acetate, magnesium borate, magnesium bicarbonate, magnesium carbonate, magnesium hydroxide, magnesium lactate, magnesium oxide, magnesium phosphate, magnesium silicate, magnesium succinate , magnesium tartrate, potassium acetate, potassium carbonate, potassium bicarbonate, potassium borate, potassium citrate, potassium metaphosphate, potassium phthalate, potassium phosphate, potassium polyphosphate, potassium pyrophosphate, potassium succinate, potassium tartrate, sodium acetate, sodium bicarbonate, sodium borate, sodium carbonate, sodium citrate, sodium gluconate, disodium hydrogen phosphate, sodium hydroxide, sodium lactate, sodium phthalate, sodium phosphate, sodium polyphosphate, sodium pyrophosphate, sodium tartrate, sodium tripolyphosphate, synthetic hydrotalcite, tetrapotassium pyrophosphate, tetrasodium pyrophosphate, tripotassium phosphate, trisodium phosphate and tromethamine and combinations thereof.

[0072] Slow-release fertilizer compositions as described herein can be included in compositions for application to soil. In some respects, except fertilizer as described herein, compositions can also include other fertilizer compounds, trace element nutrients, major nutrients, urea, other nitrogen nutrients, pesticides, herbicides or fungicides or its combination. Fertilizer as described herein can also be included in mixed compositions comprising other fertilizers. Described other fertilizers can be urea, monoammonium phosphate (MAP), diammonium phosphate (DAP), potassium chloride (MOP), monopotassium phosphate (MKP), triple superphosphate (TSP), phosphate rock, superphosphate (SSP), ammonium sulfate etc.

[0073] The fertilizer formed into granules can have desired physical properties, such as a desired degree of abrasion resistance, granule strength, granulation, hygroscopicity, granule shape, and particle size distribution. In some aspects, the compressive strength of the fertilizer granules can be higher than 1.5 kgf, such as higher than 1.8 kgf, such as 2 kgf to 6 kgf, or at least any one of the following compressive strengths, equal to any one of the following compressive strengths, or between any two of the following compressive strengths: 2 kgf, 2.5 kgf, 3 kgf, 3.5 kgf, 4 kgf, 4.5 kgf, 5 kgf, 5.5 kgf, and 6 kgf. The bulk density of the fertilizer granules can be between 1 g / cm3 and 1.2 g / cm3, or at least any one of the following densities, at most any one of the following densities, equal to any one of the following densities, or between any two of the following densities: 1 g / cm3, 1.02 g / cm3, 1.04 g / cm3, 1.06 g / cm3, 1.08 g / cm3, 1.1 g / cm3, 1.12 g / cm3, 1.14 g / cm3, 1.16 g / cm3, 1.18 g / cm3, and 1.2 g / cm3. In some aspects, 10 mg or more, for example 10 mg to 40 mg, or at least any one of the following masses, at most any one of the following masses, equal to any one of the following masses, or between any two of the following masses of fertilizer granules can be dissolved in 1 ml of water at pH 7 under stirring at a speed of 90 rpm to 110 rpm and at ambient temperature within 5 minutes of adding 100 mg of the fertilizer granules to the water. In some aspects, the fertilizer granules can lose less than 0.13 wt%, such as 0.02 wt% to 0.12 wt%, or up to any one of the following wt%, equal to any one of the following wt%, or between any two of the following wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.11 wt%, and 0.12 wt% in an attrition loss test. The following attrition loss test can be used to measure attrition loss.

[0074] Wear loss test: weigh single particles with a size of 2 mm to 4 mm and a total volume of 100 cm 3 A plurality of sieved fertilizer granules (W1) were placed in a test drum together with 50 stainless steel balls with a total weight of 100 grams. The test drum was sealed and rotated at 30 rpm for 10 minutes. The balls were then separated from the sample and the material was sieved on a 2 mm sieve using a vibrating sieve. The total weight of the granules on the 2 mm sieve was then reweighed (W2). The results were calculated as weight loss % using the following formula:

[0075]

[0076] II. Methods of Using Slow-Release Fertilizer Compositions

[0077] The slow-release fertilizer composition of the present disclosure, including fertilizer granules, compositions containing the fertilizers, and fertilizer mixtures containing the fertilizers, can be used in methods for increasing the amount of one or more plant nutrients in soil and in methods for promoting plant growth. These methods may include applying an effective amount of a composition and / or mixture containing the fertilizer of the present invention to the soil. The method may include increasing the growth and yield of crops, trees, ornamental plants, etc., such as the growth and yield of palm, coconut, rice, wheat, corn, barley, oats, and / or soybeans. The method may include applying the fertilizer composition of the present invention to at least one of soil, organisms, liquid carriers, liquid solvents, etc. One or more compositions and / or one or more fertilizer mixtures containing fertilizers can be applied to plants and / or soil as topdressing fertilizers, base fertilizers, and / or by any suitable application method.

[0078] Non-limiting examples of plants that can benefit from the fertilizer of the present invention include lianas, trees, shrubs, culms, ferns, etc. The plants may include orchard crops, lianas, ornamental plants, food crops, trees, and harvested plants. The plants may include gymnosperms, angiosperms, and / or ferns.

[0079] The effectiveness of a composition comprising the slow-release fertilizer composition of the present invention can be determined by measuring the content of phosphorus and optionally other nutrients in the soil at different times after the fertilizer composition is applied to the soil. It is understood that different soils have different properties, which may affect the stability of nitrogen in the soil. The effectiveness of a slow-release fertilizer composition can also be directly compared to other fertilizer compositions by making a side-by-side comparison in the same soil under the same conditions.

[0080] III. Methods for Preparing Slow-Release Fertilizer Compositions

[0081] refer to Figure 1 , a schematic diagram of a system and method for preparing fertilizer according to one embodiment of the present invention is depicted. System 100 may include a granulator 102 and a dryer 104. A feed mixture 106 may be granulated in the granulator 102 in the presence or absence of water to form a wet granular mixture 108. If water is present, the water may be provided with the feed mixture 106, and / or the water may be added to the granulator 102 separately. The wet granular mixture 108 may be dried in the dryer 104 to obtain a dry granular mixture 110 containing fertilizer.

[0082] refer to Figure 2 , a schematic diagram of a system and method for preparing fertilizer according to another embodiment of the present invention is described. System 200 may include a mixer / reactor 212, although the mixer and the reactor may be two components, three components, four components, or more than four components, such as two reactors and a mixer or one reactor and a mixer. System 200 may include a granulator 202, a spheronizer 214, one or more particle size screens 216, and a dryer 204, or any combination thereof. Feed mixture components 218 may be added to the mixer / reactor 212 independently and / or in any possible combination. In the mixer / reactor 212, the feed components may react and / or mix to form a feed mixture 206. Feed mixture 206 may be granulated in the granulator 202 in the presence or absence of additional water to form a wet granular mixture 220. Granules in the wet granular mixture 220 may be spheronized in the spheronizer 214 to form a wet granular mixture 222 containing substantially spherical granules. The wet granular mixture 222 can pass through one or more particle size screens 216 to separate granules having a particle size less than a desired particle size or greater than a desired particle size from the wet granular mixture 222 and obtain a wet granular mixture 224 containing granules of the desired particle size. At least a portion of the granules 226 separated from the granulated mixture 224 containing granules of the desired particle size can be recycled to the granulator 202. The wet granular mixture 224 containing granules of the desired particle size can be dried in the dryer 204 to obtain a dry granular mixture 210 containing fertilizer granules. In some aspects, the mixer / reactor 212 can include a ribbon mixer.

[0083] The feed mixture composition 218 may include i) a Ca source, such as calcium oxide, a Mg source, such as olivine, iii) a N source, such as NH4 +In some cases, the mixture components provide more than one Ca, Mg, N and / or P. In some cases, the mixture components provide additional nutrients and / or trace element nutrients, such as Fe and / or Si. In some aspects, one or more components as aqueous solutions may be added. In some cases, the mixture components are provided in the form of powders. In some cases, one or more components as gases may be added. In some cases, NH3 is provided at a pressure higher than 1 bar, for example, at a pressure of the following pressures, or between the following pressures, or at a pressure of any range of the following pressures: 1.2 bar, 1.3 bar, 1.4 bar, 1.5 bar, 2 bar, 2.5 bar, 3.5 bar, 4 bar, 4.5 bar, 5 bar, 5.5 bar, 6 bar, 6.5 bar, 7 bar, 7.5 bar, 8 bar, 9 bar, 10 bar, 15 bar, 20 bar, 25 bar, 30 bar, 35 bar and 40 bar. In some cases, some of the mixture ingredients are provided in powder form.

[0084] The feed mixture 106 and the feed mixture 206 may contain Ca, Mg, N, P, Fe and / or Si. In some aspects, the feed mixture 106 and the feed mixture 206 may contain i) metal oxides, ii) phosphoric acid, iii) ammonium hydroxide and iv) olivine, v) CaNH4PO4, vi) MgNH4PO4, vii) SiO2, viii) FeHPO4, ix) MgHPO4 and / or x) CaHPO4.

[0085] Water may be added to the feed mixture in the mixer / reactor 212 and / or the granulator 102, granulator 202. In certain aspects, water may be added (e.g., together with one or more feed mixture components and / or added independently) in a total amount of 5 to 20 grams, or at least any one of the following masses, at most any one of the following masses, equal to any one of the following masses, or between any two of the following masses per 100 grams of feed mixture: 5 grams, 6 grams, 7 grams, 8 grams, 9 grams, 10 grams, 11 grams, 12 grams, 13 grams, 14 grams, 15 grams, 16 grams, 17 grams, 18 grams, 19 grams, and 20 grams.

[0086] In some aspects, granulator 102 and granulator 202 can be drum granulator, stirring granulator, disc granulator, solid mixer, grinding drum, extruder, high shear mixing granulator, roller granulator, mycromix or round bottom flask. In granulator 102 and granulator 202, feed mixture 106 and feed mixture 206 can be granulated by agglomeration, spray granulation, compression, slurry granulation and / or high shear mixing granulator. In some special aspects, the feed mixture 106 and feed mixture 206 can be granulated by compression in granulator 102 and granulator 202. In some aspects, the granulator 102 and granulator 202 can include at least two rollers, and compression granulation can include using at least two rollers to compress the feed mixture. In some aspects, during the pressing process, two rollers can move in a countercurrent direction. In some aspects, the feed mixture can be compressed into a shaped granule, such as a cylindrical granule, by at least two rollers. In some aspects, the surface of one roller can have desired holes to press the feed mixture into the holes, and the surface of the other roller can push the feed mixture into the holes. The pressure during granulation, such as the pressure during compression granulation, can be 1 bar to 40 bar, or at least any one of the following pressures, at most any one of the following pressures, equal to any one of the following pressures, or between any two of the following pressures: 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 10 bar, 15 bar, 20 bar, 25 bar, 30 bar, 35 bar and 40 bar. In certain aspects, the feed mixture can be granulated in granulator 102, granulator 202 at ambient temperature to 50°C, or at a temperature of at least any of the following temperatures, at most any of the following temperatures, equal to any of the following temperatures, or between any two of the following temperatures: -20°C, -15°C, -10°C, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C and 50°C.

[0087] In some aspects, the reaction of the feed mixture components, mixing and granulation of the feed mixture can be carried out in different containers, for example, the mixer / reactor 212 and the granulator 202 can be different containers. In some aspects, the reaction of the feed mixture components, mixing and granulation of the feed mixture can be carried out in the same container, for example, the mixer / reactor 212 and the granulator 202 can be the same container (not shown). In some aspects, the mixer / reactor 212 and the granulator 202 can be more than two containers. In some cases, MgHPO4 and CaHPO4 are formed in two different containers. In some cases, MgHPO4 and CaHPO4 are formed in one container. In some cases, CaNH4PO4 and MgNH4PO4 are formed in two different containers. In some cases, CaNH4PO4 and MgNH4PO4 are formed in one container. In some cases, MgHPO4 and CaHPO4 are formed in two different containers, and CaNH4PO4 and MgNH4PO4 are formed in one container. In some cases, MgHPO4 and CaHPO4 are formed in two different containers, and CaNH4PO4 and MgNH4PO4 are formed in two different containers. In some cases, MgHPO4 and CaHPO4 are formed in one container, and CaNH4PO4 and MgNH4PO4 are formed in one container. In some cases, MgHPO4 and CaHPO4 are formed in one container, and CaNH4PO4 and MgNH4PO4 are formed in the same container as MgHPO4 and CaHPO4.

[0088] In some aspects, MgHPO, CaHPO, CaNH4PO, and / or MgNH4PO are formed at a temperature of at least, at most, at, or between any two of the following temperatures: 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, ℃, 2℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃, 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, for example, from 20℃ to 75℃, or from 30℃ to 75℃.

[0089] In some cases, the fertilizer can be extruded before drying. The extruder can extrude the fertilizer at a pressure of at least 1 bar, at most 1 bar, at a pressure of 4 bar, at 5 bar, at 6 bar, at 7 bar, at 8 bar, at 9 bar, at 10 bar, at 11 bar, at 12 bar, at 13 bar, at 14 bar, at 15 bar, at 16 bar, at 17 bar, at 18 bar, at 19 bar, at 20 bar, at 21 bar, at 22 bar, at 23 bar, at 24 bar, at 25 bar, at 26 bar, at 27 bar, at 28 bar, at 29 bar, at 30 bar, at 31 bar, at 32 bar, at 33 bar, at 34 bar, at 35 bar, at 36 bar, at 37 bar, at 38 bar, at 39 bar, and at 40 bar. The extruder can extrude the fertilizer at a temperature of at least -20° C., -15° C., -10° C., 0° C., 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., and 50° C. The extrudate can be sliced ​​or divided, for example, by a die, before drying.

[0090] In some aspects, the desired particle size of the final fertilizer product, such as granules, can be 0.5 mm to 5 mm, or 1 mm to 4 mm, and have a particle size of less than 0.5 mm or less than 1 mm, and / or a particle size greater than 4 mm or greater than 5 mm that can be separated from the wet granular mixture 222 using one or more particle size screens 216. In some aspects, the wet granular mixture can be spheronized and / or spheronized in a spheronizer. In some cases, the granular mixture is contacted with the spheronizer for at least any of the following times, at most any of the following times, equal to any of the following times, or a time between any two of the following times: 5 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 50 seconds, or 60 seconds. In some cases, the pelletizer has a rotating disk or a rotatable disk that can rotate at least any of the following speeds, at most any of the following speeds, equal to any of the following speeds, or at any two of the following speeds: 200 rpm, 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500 rpm, 4000 rpm, 4500 rpm, 5000 rpm. In certain aspects, the wet granule mixture can be dried in the dryer 104, the dryer 204 at 40°C to 85°C, or at least any of the following temperatures, at most any of the following temperatures, equal to any of the following temperatures, or between any two of the following temperatures: 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, and 85°C. In some aspects, dryer 104, dryer 204 can be a fluidized bed dryer, a rotary drum dryer, or an air flow dryer. In some aspects, the wet particle mixture can be dried in dryer 104, dryer 204 with a hot air flow having at least any of the following flow rates, at most any of the following flow rates, equal to any of the following flow rates, or between any two of the following flow rates: 100 cubic meters / hour, 150 cubic meters / hour, 200 cubic meters / hour, 250 cubic meters / hour, 300 cubic meters / hour, 350 cubic meters / hour, 400 cubic meters / hour, 450 cubic meters / hour, and 500 cubic meters / hour, and / or a hot air flow under rotation at at least any of the following speeds, at most any of the following speeds, equal to any of the following speeds, or between any two of the following speeds: 5 rpm, 10 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 40 rpm, 45 rpm, and 50 rpm.

[0091] Example

[0092] The present invention will be described in more detail by specific examples. The following examples are provided only for illustrative purposes and are not intended to limit the present invention in any way. Those skilled in the art will easily recognize various non-critical parameters that can be changed or altered to produce substantially the same results.

[0093] Example 1

[0094] Generation of slow-release fertilizer compositions

[0095] 160 g of olivine powder can be added to 78 g of 80 wt % phosphoric acid in a 1 liter glass beaker, and the reaction mixture can be stirred. The temperature of the reaction mixture can then be increased at a rate of 4° C. / minute until the temperature reaches 62° C. to 65° C. The reaction mixture can be stirred at this temperature for 45 minutes.

[0096] In a separate beaker, 80 g of CaO can be mixed with 140 g of 80 wt % phosphoric acid in a 1 liter glass beaker and stirred. The temperature of the reaction mixture can then be increased at a rate of 4° C. / minute until the temperature reaches 62° C. to 65° C. The reaction mixture can be stirred at this temperature for 30 minutes.

[0097] The contents of the two beakers can be combined and the temperature can be reduced to 40°C. 57 g of NH4OH solution can be added dropwise to the mixture. The resulting reaction mixture can be stirred at 40°C for 30 minutes. The temperature can then be raised to 74°C, at which point some water begins to evaporate and the mixture becomes colloid. The colloid mixture can then be dried to provide a solid fertilizer material. The dried solid material can then be ground into final fertilizer product particles of a particle size of 20 to 60 mesh.

[0098] ***

[0099] In light of the present disclosure, all methods disclosed and claimed herein can be carried out and implemented without undue experimentation. Although the compositions and methods of the present invention have been described according to preferred embodiments, it will be apparent to those skilled in the art that the steps or sequence of steps of the methods and methods described herein may be changed without departing from the concept, spirit and scope of the present invention. More specifically, it will be apparent that certain chemically and physiologically related reagents may replace the reagents described herein while achieving the same or similar results. All of these similar substitutions and modifications are apparent and are considered to be within the spirit, scope and concept of the present invention as defined by the appended claims.

Claims

1. A method for preparing a slow-release fertilizer composition comprising nitrogen (N), phosphorus (P), calcium (Ca) and magnesium (Mg), the method comprising the following steps: a. reacting olivine and calcium oxide with phosphoric acid to produce a reaction mixture comprising calcium hydrogen phosphate, magnesium hydrogen phosphate and silicon dioxide; and b. reacting an ammonia source with the calcium hydrogen phosphate and the magnesium hydrogen phosphate to produce magnesium ammonium phosphate and calcium ammonium phosphate, wherein the slow-release fertilizer composition comprises the magnesium ammonium phosphate and the calcium ammonium phosphate.

2. The method according to claim 1, wherein step a and step b are performed in the same container.

3. The method of claim 1 or 2, further comprising drying the fertilizer composition.

4. The method according to any one of claims 1 to 3, wherein the step of reacting olivine and calcium oxide with phosphoric acid is carried out at a temperature of 20°C to 75°C.

5. The method of any one of claims 1 to 4, wherein drying the fertilizer composition provides a dehydrated silica gel fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate encapsulated within dehydrated silica gel.

6. The method of any one of claims 1 to 5, wherein the slow release fertilizer composition comprises magnesium ammonium phosphate and calcium ammonium phosphate on the surface of the fertilizer.

7. The method according to any one of claims 1 to 6, wherein the olivine and calcium oxide are provided in a weight ratio of 1:5 to 5:

1.

8. The method of any one of claims 1 to 7, wherein the ammonia source is ammonium hydroxide or ammonia.

9. The method according to any one of claims 1 to 8, wherein the ammonia source and phosphoric acid are provided in a weight ratio of 1:1 to 1:

10.

10. The method according to any one of claims 1 to 9, wherein the slow release fertilizer composition is prepared in the form of a powder, a pellet, a granule or a pellet.

11. A slow release fertilizer composition comprising magnesium ammonium phosphate and calcium ammonium phosphate encapsulated in silica.

12. The slow release fertilizer composition of claim 11, wherein the composition further comprises ammonium ferric phosphate.

13. The slow release fertilizer composition according to claim 11 or 12, wherein the silicon dioxide is a dehydrated silicon dioxide gel.

14. A slow release fertilizer composition according to any one of claims 11 to 13, wherein the fertilizer composition is provided in the form of a powder, a pellet, a granule or a pellet.

15. A method for fertilizing agricultural soil, comprising applying the slow release fertilizer composition according to any one of claims 11 to 14 to the soil.

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