Nitrogen fixation is the process of producing ammonia.

固氮是产生氨的过程。

For example, how many news articles have been written about nitrogen fixation, the process by which plants can be made to fix their own nitrogen, thus reducing the need for fertilizer?

例如， 关于固氮作用的新闻文章有多少，植物可以通过该过程固定自身的氮，从而减少对肥料的需求？