Inorganic nutritive iron composition

An inorganic nutrient composition comprising at least one aqueous phase, at least one polyphosphate selected from the group consisting of sodium and potassium alkaline polyphosphates and at least one source of iron as micronutrient, wherein said nutrient composition has a Ppoly/Fe molar ratio of between 8 and 32 where Ppoly is a total number of moles of phosphorus in polyphosphate form and where Fe is a total number of moles of iron, wherein said inorganic nutrient composition comprising at least one aqueous phase is in the form of an aqueous solution in which the iron of the said iron source is complexed to the said at least one polyphosphate, and wherein the composition also has a molar ratio N/Ptotal of 0.2 or lower, where N is the number of moles of ammonium and where Ptotal is the number of moles of total phosphorus and an iron content of between 0.02% and 3% by weight relative to a total weight of said nutrient composition.