Plant fertirrigation method comprising the formation of a series of mother solutions, the feeding of each of the mother solutions into a dilution system in order to form a fertirrigation solution, the supply to a fertirrigation device by means of a transfer device, supplying said fertirrigation device with said fertirrigation solution, and an addition of iron and of at least one polyphosphate.

Plant fertirrigation method comprising the formation of a series of mother solutions, the feeding of each of the mother solutions into a dilution system in order to form a fertirrigation solution, the supply to a fertirrigation device by means of a transfer device, supplying said fertirrigation device with said fertirrigation solution, and an addition of iron and of at least one polyphosphate.

A method of calcination includes providing a raw material including whitlockite Ca.sub.9(Mg,Fe.sup.2+)[PO.sub.3(OH)|(PO.sub.4).sub.6], and/or iron phosphate FePO.sub.4, and/or aluminum phosphate AlPO.sub.4 and/or fluorapatite Ca.sub.5(PO.sub.4).sub.3F; providing an alkaline-sulfuric compound as an additive; and calcining a mixture of the raw material with the additive to obtain a product, including a citrate soluble phosphate compound.

A method of calcination includes providing a raw material including whitlockite Ca.sub.9(Mg,Fe.sup.2+)[PO.sub.3(OH)|(PO.sub.4).sub.6], and/or iron phosphate FePO.sub.4, and/or aluminum phosphate AlPO.sub.4 and/or fluorapatite Ca.sub.5(PO.sub.4).sub.3F; providing an alkaline-sulfuric compound as an additive; and calcining a mixture of the raw material with the additive to obtain a product, including a citrate soluble phosphate compound.

A water insoluble micronutrient fertilizer, methods of producing, and methods of using the same are provided. The fertilizer may comprise at least one first micronutrient selected from the group consisting of chromium, cobalt, copper, iron, manganese, and zinc; a polyphosphate; and optionally at least one second micronutrient selected from the group consisting of boron, chlorine, iodine, molybdenum or selenium. The fertilizer compounds are preferably water insoluble, dilute acid soluble, and free-flowing powders.

A water insoluble micronutrient fertilizer, methods of producing, and methods of using the same are provided. The fertilizer may comprise at least one first micronutrient selected from the group consisting of chromium, cobalt, copper, iron, manganese, and zinc; a polyphosphate; and optionally at least one second micronutrient selected from the group consisting of boron, chlorine, iodine, molybdenum or selenium. The fertilizer compounds are preferably water insoluble, dilute acid soluble, and free-flowing powders.

A method of calcination includes providing a raw material including whitlockite Ca.sub.9(Mg,Fe.sup.2+)[PO.sub.3(OH)|(PO.sub.4).sub.6], and/or iron phosphate FePO.sub.4, and/or aluminium phosphate AlPO.sub.4 and/or fluorapatite Ca.sub.5(PO.sub.4).sub.3F; providing an alkaline-sulfuric compound as an additive; and calcining a mixture of the raw material with the additive to obtain a product, including a citrate soluble phosphate compound.

A method of calcination includes providing a raw material including whitlockite Ca.sub.9(Mg,Fe.sup.2+)[PO.sub.3(OH)|(PO.sub.4).sub.6], and/or iron phosphate FePO.sub.4, and/or aluminium phosphate AlPO.sub.4 and/or fluorapatite Ca.sub.5(PO.sub.4).sub.3F; providing an alkaline-sulfuric compound as an additive; and calcining a mixture of the raw material with the additive to obtain a product, including a citrate soluble phosphate compound.

Plant fertirrigation method comprising the formation of a series of mother solutions, the feeding of each of the mother solutions into a dilution system in order to form a fertirrigation solution, the supply to a fertirrigation device by means of a transfer device, supplying said fertirrigation device with said fertirrigation solution, and an addition of iron and of at least one polyphosphate.

There is provided a method for producing ferrous sulphate and phosphoric acid comprising treating ferrous phosphate with sulphuric acid for obtaining ferrous sulphate and phosphoric acid. Additionally, there is provided a use of sulphuric acid for treating ferrous phosphate for obtaining ferrous sulphate and phosphoric acid.