Scientists find that less tilling means more earthworms

Anecic earthworms live deep in the soil and emerge at night, providing a helpful mixing of soil in agricultural fields. (The Earthworm Society of Britain)

Jenna Ladd | May 16, 2017

Wriggly earthworms are the unsung heroes of agricultural fields around the world. Their tiny bodies make it easier for water and air to enter the soil, transform organic matter into nutrients that is available to plants and can improve crop productivity by more than 50 percent.

A study recently published in the journal Global Change Biology sought to better understand which agricultural conditions are optimal for worms. Dr. Olaf Schmidt and Dr. Maria Briones analyzed 215 studies from over 40 countries that explored the relationship between tilling practices and worm population health.

The meta-analysis showed that disturbing the soil less (i.e. no-till farming, conservation agriculture) resulted in significantly more abundant earthworm populations. For example, no-till farmland saw a 137 percent increase in worm populations and a nearly 200 percent increase in soil biomass. Those areas of land in reduced-till for more than ten years saw the most earthworms return to the soil. In contrast, those field that were heavily plowed lost half of their original worm population.

Researchers observed the affect of tilling on 13 species of worms and found that the largest species were most heavily impacted. These creatures, called anecic earthworms, live deep down in the soil. At night-time they wriggle up a single channel, grab food, such as plant matter or manure, and then slide back down the same permanent burrow.

The researchers write that restoring earthworm populations through practing reduced-till or no-till farming “will ensure the provision of ecosystem functions such as soil structure maintenance and nutrient cycling by “nature’s plow.””