Scientists have from the University of Vigo in Spain and University College Dublin in Ireland discovered the population of earthworms around the world has been decreasing due to the severe activity of tillage farming. Tillage farming is the activity of digging, stirring, and overturning of soil through conventional ploughing.
In the findings published in the scientific journal Global Change Biology titled "Conventional tillage decreases the abundance and biomass of earthworms and alters their community structure in a global meta-analysis," it shows that there has been a systematic decline of earthworm population in soils that are often plowed every year. The study also shows that the deeper the soil is disturbed, the more harmful it is for the earthworms.
In order to arrive at this conclusion, the scientists analyzed 215 field studies from across 40 countries dating back as far as 1950. These studies have investigated earthworm populations under conventional tillage and other forms of tillage that were reduced.
"What we see is a systematic decline in the earthworm population in the soil after continued plowing and a significant increase in the abundance of earthworms in a less disturbed soil, although some soils would need more than 10 years to show good signs of recovery" Olad Schmidt of the University College Dublin has said.
In an article published in Phys.org, the "anetic earthworms" or larger earthworm that move between layers of soil and create permanent burrows between them are the most vulnerable of all earthworm population to tillage farming. On the other hand, "epigeic earthworms" or earthworms living in the top layers of soil and convert debris topsoil were also found to be highly vulnerable.
Earthworms are considered to be important in maintaining soil functions and ecosystem services people expected from them. Charles Darwin even called earthworms " nature's plow" since they continually consume and defecate soul enhancing its fertility in the process.
