An old gardening trick is being used to help scientists study land, climate change, drought and possible famine.
A team of European Union funded scientists are spreading a mix of water and mustard on fields in Leicestershire to force earthworms to the surface.
This will let them count the worms more easily, and then judge the quality of the land and its use for farming.
Worms holes mix soil and improve drainage so rainwater can be better absorbed into the earth.
Good soil aeration is thought to help protect land against flooding and droughts.
The technique works by means of the mustard irritating a worm's skin - forcing it to escape to the surface, but not harming it in any way.
Mike Lane, European Project director, said: "The essence of the project is to preserve soil and water in the farmer's field.
"These are two of the most precious commodities and one of the ways of seeing if a farmer has a healthy field is to look to see what the earthworm population is."
Dr Heidi Cunningham, one of the researchers, said: "Earthworms play a vital role in the soil. They bring in organic matter and aid the aeration of the soil.
"As well as helping crops to grow, the worm holes help to keep the water in the soil which makes it less likely to erode."
The experiments are being carried out at the 830-acre (336 hecatre) Allerton Farm, managed by the Game Conservancy Trust, where various forms of agriculture will be tested to gauge the effect on the worm population.