Charles Darwin once wrote of worms that “it may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures”. Darwin was not one to exaggerate; and, although written over 130 years ago, modern scientific evidence continues to lend credence to his words.
Abundant evidence exists to support the fact that earthworms play a dominant role in soil engineering. In agricultural systems, earthworms increase soil infiltration and aeration by digging elaborate tunnels. Earthworms also form a key link in soil food webs, acting as both predator and prey.
In addition, certain species of earthworm, such as the nightcrawler, actively incorporate surface residue into the soil, speeding up decomposition and the conversion of fresh residue into soil organic matter.
Farmers who have adopted no-till have seen substantial increases in worm populations. Cover crops combined with no-till may also go a long way towards increasing on-farm worm populations. Cover crops can encourage earthworms by providing additional surface residue, as well as additional below-ground food sources.
Although little scientific research has investigated the link between cover crops and worms, there is an abundance of observational data from farmers who claim more worms exist in places managed under cover crops and conservation tillage.
Earthworms are nature’s plow; if we create the right conditions for them to work, then we won’t need to spend time and money doing their job for them.