The present disclosure concerns a method for producing fertilizer particles comprising an alternative source of boron. It is found that certain colemanite and ulexite powders can be supplied to a fertilizer melt shortly before granulation essentially without dissolving into the melt. Accordingly, the fertilizer particles produced from the melt may contain negligible amounts or non-detectable levels of sodium borates or boric acid. Furthermore, the fertilizer particles can be homogeneous which is desirable for boron supplying fertilizers. It is also found that the fertilizer particles can supply boron to plants at a rate comparable to borax pentahydrate.

The present disclosure concerns a method for producing fertilizer particles comprising an alternative source of boron. It is found that certain colemanite and ulexite powders can be supplied to a fertilizer melt shortly before granulation essentially without dissolving into the melt. Accordingly, the fertilizer particles produced from the melt may contain negligible amounts or non-detectable levels of sodium borates or boric acid. Furthermore, the fertilizer particles can be homogeneous which is desirable for boron supplying fertilizers. It is also found that the fertilizer particles can supply boron to plants at a rate comparable to borax pentahydrate.

The present disclosure concerns a method for producing fertilizer particles comprising an alternative source of boron. It is found that certain colemanite and ulexite powders can be supplied to a fertilizer melt shortly before granulation essentially without dissolving into the melt. Accordingly, the fertilizer particles produced from the melt may contain negligible amounts or non-detectable levels of sodium borates or boric acid. Furthermore, the fertilizer particles can be homogeneous which is desirable for boron supplying fertilizers. It is also found that the fertilizer particles can supply boron to plants at a rate comparable to borax pentahydrate.

The invention relates to a coated granular fertilizer, preferably wherein granules are sulfate-based or phosphate-based. When sulfate based granules, as in ammonium sulfate, the coating substance is an inorganic salt of alkaline earth elements, preferably calcium, such that when applied to the surface of fertilizers, forms calcium sulfate, preferably a calcium sulfate-dihydrate, as a protective coating. For a reactive coating of a thiosulfate, free sulfuric acid present on the granule reacts to provide an elemental sulfur coating. For ammonium phosphate-based granules, coatings may comprise compounds of Ca.sup.++, Al.sup.+++ and/or Fe.sup.+++ salts thereby forming a calcium, an aluminum, an iron, or mixed cation phosphate protective coating. Thiosulfate is also effective with phosphate based granules which are manufactured with sulfuric acid. Granules coated according to the disclosure have advantageous properties as the coating can be applied in a specified and sparing manner due to its tendency to adhere to surfaces during the reaction. Coated fertilizer granules of the disclosure are also advantageous in that, with regard to the applied amount of coating, they provide increased resistance to dusting in long term warehouse storage, to moisture uptake and to oxidative heating. Coating components also add nutrients to plants that can provide nutrients over a longer period of time such as a slow-release characteristic.

The invention relates to a coated granular fertilizer, preferably wherein granules are sulfate-based or phosphate-based. When sulfate based granules, as in ammonium sulfate, the coating substance is an inorganic salt of alkaline earth elements, preferably calcium, such that when applied to the surface of fertilizers, forms calcium sulfate, preferably a calcium sulfate-dihydrate, as a protective coating. For a reactive coating of a thiosulfate, free sulfuric acid present on the granule reacts to provide an elemental sulfur coating. For ammonium phosphate-based granules, coatings may comprise compounds of Ca.sup.++, Al.sup.+++ and/or Fe.sup.+++ salts thereby forming a calcium, an aluminum, an iron, or mixed cation phosphate protective coating. Thiosulfate is also effective with phosphate based granules which are manufactured with sulfuric acid. Granules coated according to the disclosure have advantageous properties as the coating can be applied in a specified and sparing manner due to its tendency to adhere to surfaces during the reaction. Coated fertilizer granules of the disclosure are also advantageous in that, with regard to the applied amount of coating, they provide increased resistance to dusting in long term warehouse storage, to moisture uptake and to oxidative heating. Coating components also add nutrients to plants that can provide nutrients over a longer period of time such as a slow-release characteristic.

A controlled release fertilizer has been prepared comprising a nutrient core coated with one or more moisture barrier coatings, at least one of said moisture barrier coatings comprising: at least one polyethylene wax; and a thermoset polyurethane from the reaction of a polyol and a polyisocyanate. The weight ratio of thermoset polyurethane to polyethylene wax is from about 50:50 to about 98:2. The polyethylene wax is heated above the melt point of the polyethylene wax and mixed and dispersed into the polyol component of the thermoset polyurethane in a ratio of 90-70% polyol to 10-30% polyethylene wax before the thermoset polyurethane-forming mixture is applied to the surface of the nutrient core and cured. A coating of a high temperature microcrystalline wax can be applied prior to final curing of the thermoset polyurethane to the coated nutrient core particles.

A controlled release fertilizer has been prepared comprising a nutrient core coated with one or more moisture barrier coatings, at least one of said moisture barrier coatings comprising: at least one polyethylene wax; and a thermoset polyurethane from the reaction of a polyol and a polyisocyanate. The weight ratio of thermoset polyurethane to polyethylene wax is from about 50:50 to about 98:2. The polyethylene wax is heated above the melt point of the polyethylene wax and mixed and dispersed into the polyol component of the thermoset polyurethane in a ratio of 90-70% polyol to 10-30% polyethylene wax before the thermoset polyurethane-forming mixture is applied to the surface of the nutrient core and cured. A coating of a high temperature microcrystalline wax can be applied prior to final curing of the thermoset polyurethane to the coated nutrient core particles.

Method of forming an encapsulated fertilizer that includes the step of providing a core particle. The core particle includes a fertilizer and has an outer surface. The method further includes the step of applying an isocyanate component directly to the outer surface of the core particle. The isocyanate component has isocyanate functional groups. The method further includes the step of reacting the isocyanate component with ambient moisture to form a layer disposed about the core particle to form the encapsulated fertilizer. The layer includes polyurea linkages and may further include polyurethane linkages.

A controlled release granular fertiliser composition comprising a mixture of nitrogenous fertiliser, particulate silicate mineral filler and biodegradable ionic polyurethane.

A controlled release granular fertiliser composition comprising a mixture of nitrogenous fertiliser, particulate silicate mineral filler and biodegradable ionic polyurethane.