With all of the agronomic benefits that earthworms deliver, readers frequently ask the No-Till Farmer editors whether they should consider seeding fields with more earthworms, especially nightcrawlers.
Eileen Kladivko, a soil physicist at Purdue University and a world authority on earthworms, says the answer is usually no.
Kladivko initially became interested in earthworms in the early 1980s after seeing the benefits that they had on soil tilth and friability.
“It’s not something that I can as yet recommend,” she says. “I’ve tried seeding nightcrawlers in 14 fields in research projects over the years. It worked in a couple of fields and didn’t work in others. The cost is maybe a couple of hundred dollars an acre and is a one-time thing, so I might consider it if I had a field that should have nightcrawler populations but doesn’t.”
Most of the inquiries that she receives about seeding earthworms come from no-tillers. “I think that’s a result of two things,” she says. “One is that when growers switch to no-till, they’re aware that they should see more earthworms. And if they don’t, they call me.
“The second is that when they switch to no-till or minimum tillage, they become more interested in soil tilth and how earthworms can help improve soil quality.”
Rather than seeding fields with nightcrawlers, Kladivko recommends that no-tillers work on providing the conditions under which nightcrawlers flourish. Those include leaving plenty of residue on the soil surface, reducing tillage and rotating occasionally into…