Explain one key difference between the industrial production of ammonia in the Haber process and the subsequent manufacturing of NPK fertilisers.

The Haber process produces ammonia (NH₃) by reacting nitrogen and hydrogen over an iron catalyst at high temperature and pressure, whereas NPK fertiliser manufacture uses that ammonia (and other raw materials such as phosphate rock and mined potassium salts) to produce a range of ammonium, phosphate and potassium salts that are blended into fertiliser formulations.

A strong answer should directly address the approved learning objective to distinguish NPK fertiliser manufacture from the Haber process that produces ammonia. This question belongs to Production and uses of NPK fertilisers within The Haber process and the use of NPK fertilisers, so the response should use that exact curriculum context rather than a generic statement. The answer is correct when it names the key idea, explains the link to NPK fertiliser, and keeps the wording specific to AQA GCSE revision.