A water-insoluble, dilute acid-soluble inorganic polyphosphate composition in solid form, the inorganic polyphosphate composition containing at least 15 wt.% calcium, magnesium or a combination thereof, 5 to 70 wt% orthophosphate, and optionally one or more micronutrients selected from the group consisting of boron, chromium, cobalt, copper, iodine, iron, manganese, molybdenum, selenium, and zinc, with the proviso that the inorganic polyphosphate composition contains no more than 3.5 wt% of such micronutrients, combined, based on the total weight of the polyphosphate composition, the inorganic polyphosphate composition having a number average chain length of greater than 2 but less than 50 repeat units when the orthophosphate content of the inorganic polyphosphate composition is excluded from the average chain length calculation and a number average chain length of at least 1.1 but less than 50 repeat units when the orthophosphate content of the inorganic polyphosphate composition is included in the average chain length calculation, the repeat units comprising phosphate, sulfate, borate, molybdate, or selenate units, or a combination thereof, provided the ratio of phosphate units to the combined total of sulfate, borate, molybdate and selenate repeat units comprised by the inorganic polyphosphate composition is at least 2:1, the water-insoluble, dilute acid-soluble inorganic polyphosphate composition having (i) a solubility in room-temperature (25 °C) deionized water such that the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 30 minute period in deionized water at room-temperature (25 °C) is less than 20% of the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 30 minute period in 0.1N HCl at room-temperature (25 °C), and (ii) a solubility in room-temperature (25 °C) dilute citric acid such that the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 20 minute period in 0.2 wt.% citric acid at room-temperature (25 °C) is at least 75% of the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 20 minute period in 0.1N HCl at room-temperature (25 °C). (i) a solubility in room-temperature (25 °C) deionized water such that the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 30 minute period in deionized water at room-temperature (25 °C) is less than 20% of the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 30 minute period in 0.1N HCl at room-temperature (25 °C), and (ii) a solubility in room-temperature (25 °C) dilute citric acid such that the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 20 minute period in 0.2 wt.% citric acid at room-temperature (25 °C) is at least 75% of the combined amount of boron, calcium, chromium, cobalt, copper, iodine, iron, magnesium, manganese, molybdenum, selenium and zinc that dissolves from the inorganic polyphosphate composition during a 20 minute period in 0.1N HCl at room-temperature (25 °C).