The old style super phosphate 0-18-0 or 0-20-0 made by treating rock phosphate with an equal amount of sulfuric acid was a good source of phosphate in low acid or high alkaline soils because it became calcium sulfate and calcium phosphate which are two natural products found in nature. However, little if any is still made. Triple superphosphate (0-46-0) is a more concentrated source of phosphorus. It is made by using phosphoric acid and is extremely destructive to soil fertility. It is so bare that it quickly combines with various trace minerals making them unavoidable to plant roots.