A study of England’s farmland has found key earthworm types are rare or absent in two out of five fields.
Carried out by farmers, the #60minworms project was the first comprehensive worm survey concentrating solely on farmland and has led to 57 per cent of farmers that took part saying they would change their soil management practices.
Dr Jackie Stroud, a NERC soil security fellow, Rothamsted Research, who led the study said: “Earthworms are sensitive and responsive to soil management which makes them an ideal soil health indicator. The aim of this research was to find a baseline of farmland earthworm populations that would be useful and used by farmers to assess soil health now and in the future.”
Biologists categorise earthworms by ecological role - with surface dwelling and deep burrowing worms the types most sensitive to farming practices, whilst the topsoil worms are generally unaffected by over-cultivation. High numbers of earthworms have been linked to enhanced plant productivity.
The study revealed 42 per cent of fields had poor earthworm biodiversity – meaning either very few or no surface dwelling and deep burrowing worms were seen.
The absence of deep burrowing worms on 16 per cent of fields is concerning, says Dr Stroud, because they are ’drainage worms’ with vertical burrows that aid water infiltration and ultimately helps combat waterlogging.
“The deep burrowing worms have slow reproduction rates so recovery in their populations could take a decade under changed management practices. In fact, we know very little about earthworm recovery rates.”
More than 1300 hectares were surveyed from all over England for the project, including fields managed under arable, potatoes, horticulture and pasture.
Dr Stroud said: “Decisions made above the ground, whether by farmers or policy makers, influence the billions of earthworms that are engineering the soil ecosystem below the ground.
“Earthworms influence carbon cycling, water infiltration, pesticide movement, greenhouse gas emissions, plant productivity, the breeding success of birds and even the susceptibility of plants to insect attack.
“However, as earthworms are sensitive to various farming practices, including tillage, rotations, cover cropping, organic matter additions, and pesticides, we need to do more to look after them.”