What is phosphate rock treated with before it can be used as a fertilizer?

Phosphate rock is typically treated with acid before it can be effectively used as a fertilizer. This process involves the reaction of phosphate rock, which largely contains calcium phosphate, with sulfuric acid or phosphoric acid. The treatment converts the insoluble calcium phosphate present in phosphate rock into soluble forms that plants can easily absorb, such as monoammonium phosphate or diammonium phosphate. This solubility is crucial for the nutrient to be accessible to plants, thus enhancing the effectiveness of the fertilizer.

Using base solutions or water would not effectively convert the phosphate into a usable form for plant nutrition. Additionally, while natural gas is utilized in various chemical processes, it is not directly involved in the treatment of phosphate rock for fertilizer production. Therefore, acid treatment is the required step to make phosphate rock a viable fertilizer option.