Someone won a Nobel Prize because of their work on ammonia. So what was it they did and what use, in practice, was their work that made it so significant? (This is what happens when I half- hear an answer on University Challenge a popular but highbrow TV quiz here The team got the man's name and what he studied but left me wondering what was so important about his ammonia ! )

That was Fritz Haber, who got the prize in 1918. Basically, he invented a method (the Haber process) for making ammonia out of nitrogen and hydrogen gases. The ammonia was, and still is, used in fertilizer.

An excerpt from the Nobel presentations speech:

In accordance with Nature's plan of economy, soil fertility under normal circumstances is maintained at an even level if the waste products from the crop are returned to the soil; if, however, substantially increased productivity is required from the soil, then additional fertilizer must be used. Since meanwhile a large proportion of the annual harvest is consumed by the yearly increasing population of towns, and since the towns' waste products are returned to land under cultivation only to a very incomplete extent, the inevitable consequence is that the soil becomes exhausted and the harvest yield diminishes. This has, in turn, led to the manufacture of artificial fertilizers which has also increased year by year in importance to such an extent that, at least in Europe, hardly a country exists which can do entirely without them.

Thanks.To a layman in Britain 'ammonia' suggests only the stuff that we used to use to disinfect floors