Agricultural-grade dicalcium phosphate (DCP) is a by-product from the production of feed-grade DCP and most of them were not utilized yet or even resulted in a second pollution.

• 肥料级磷酸氢钙是用二段中和沉淀法生产饲料级磷酸氢钙的副产品。大多数饲钙厂没有利用肥钙，甚至造成二次污染。