A hundred years on from its invention, factory-made nitrogen fertiliser needs to be rationed or replaced, according to scientific advisers to both the European Union and the United Nations.

The scientists are paying respects to the anniversary of the breakthrough that led to the Haber-Bosch process for the synthesis of ammonia (NH3) from atmospheric nitrogen (N2) and hydrogen.

But they are also saying it is time to think of something else.

At the end of the 19th century, the world understood the importance of nitrogen but was running out of sources – mainly bird guano and saltpetre from South America.

Fritz Haber patented a way to produce it in the laboratory in 1908 and he and Karl Bosch went on to perfect a process which would work on an industrial scale.

It made possible the "green revolution", which kept food production ahead of population growth.

It also prolonged the First World War, by giving the Germans access to an essential ingredient of TNT and nitro-glycerine, when they were cut off from their usual sources.

Artificially-produced 'active nitrogen' – as opposed to the inert form which makes up nearly 80 per cent of the air we breathe – has killed millions and fed billions since.

But it has doubled the amount of 'loose' nitrogen in the environment, forming compounds which pollute water and increase the greenhouse effect of the atmosphere.

And it has been estimated that the manufacturing is alone responsible for up to one fiftieth of worldwide consumption of man-made energy.

Four of the world's leading environmental research centres worked together on an article in Nature Geoscience recently summing up the pros and cons of the Nobel-winning invention.

Lead author Jan Willem Erisman, from the Energy Research Centre of the Netherlands, says: "Haber-Bosch is perhaps the most significant invention of the 20th century, yet it has many side effects.

"Now we need a new invention that changes the world just as much but without the environmental impact."

Mark Sutton, a government scientist Edinburgh's Centre for Ecology and Hydrology, who contributed to the report, said:"Haber-Bosch nitrogen has transformed all our lives. Without it, half of us might not be alive today.

"Plants need nitrogen for all sorts of things – protein, amino acids, DNA. It is fairly well known that living things are 90 per cent carbon.

"It is less well known that nitrogen is also an essential part of the mix.

"It has been said that carbon is the quantity and nitrogen is the quality.

"There has been a lot of talk about the carbon explosion in the environment but the nitrogen explosion is even more important."