Reference: Stroud, J. L., & Goulding, K. W. (2022). Science and user‐based co‐development of a farmland earthworm survey facilitated using digital media: Insights and policy implications. Annals of Applied Biology. https://doi.org/10.1111/aab.12766
What do earthworms have to do with soil health?
Although they make look small and slimy, earthworms can play an important role in helping farmers understand the health of the soils they grow their crops in. If an agricultural soil is teeming with earthworms, you can bet it is also fairly healthy. As earthworms snack on plant scraps leftover in the soil, they help decompose and recycle nutrients (like nitrogen) so that those nutrients can be made available for use by plants again. Their movement through the soil creates channels that help air and water move through the soil more easily, too. Earthworms also require moist and fertile soil to begin with in order to survive, and so are more likely to be found in soils that are already relatively healthy. All these factors mean that the presence of earthworms can be a very useful indicator to farmers trying to figure out how healthy their soil is.
Beyond just determining if earthworms are present or not, we can learn even more about soil health by figuring out which specific types of worms are in the soil. It turns out there are three distinct types of earthworms that each impact soil in different ways: epigeic earthworms eat plant scraps on the surface of the soil; endogeic earthworms burrow and feast on organic materials in the top several centimeters of the soil; and anecic earthworms create deep, vertical burrows throughout the soil. Ideally, a healthy soil would have all three types of earthworms. The presence and abundance of each type can be very useful information to scientists trying to understand how different farming practices influence earthworm populations and soil health. However, it can be difficult for scientists to visit large numbers of farm fields to collect this information, and most people, including your average farmer, are not aware of these different types of earthworms, nor how to identify them. This is where a scientist-farmer partnership comes into play!
Collaboration is key
To learn more about relationships between farm management and soil health, a group of scientists and farmers partnered up to monitor earthworm populations on farm fields. This partnership was mutually beneficial – both parties were interested in figuring out which types of farming practices were most beneficial or detrimental for maintaining earthworm populations, and in turn, soil health. For example, many farmers use a practice known as tillage, where they churn and break up the soil with a plow to reduce weeds and prepare the soil for planting crops. However, tillage also disturbs the soil habitat where earthworms and other organisms live, and can negatively impact air and water movement through soil.
By reporting their management practices in an online survey along with observations they made about earthworms in their fields, participating farmers were able to provide scientists with the data needed to determine how different practices impact earthworm populations. However, many farmers did not initially know how to distinguish between the three different types of earthworms that could be present in their fields, so the researchers provided videos and identification guides to help them accurately report this information. Both sides – farmers and scientists – learned from and helped each other.
A win-win-win for farmers, scientists, and earthworms!
The effort started small in 2018, focused on farms in England, and then expanded to a global effort in 2019. The science-farming partnership revealed that most fields without tillage had more earthworms overall, and were more likely to have all three types of worms, compared to fields that were regularly tilled. Furthermore, epigeic (surface-dwelling ) worm populations were found to decline the most in response to tillage, and in general, the team found fewer anecic (deep-dwelling) worms than expected across all fields regardless of tillage status. This means there may be additional factors at play beyond tillage that are negatively influencing anecic worm populations, but further research is needed to determine exactly what those factors are.
Their findings still send a clear message, though: reducing soil disturbance is good for earthworms and soil health. The study and its results were advertised widely through social media networks, helping raise awareness in the farming community that earthworms can be useful indicators of soil health, and that reducing tillage is an important aspect of sustainable farm management. Although the study’s funding ended in 2019, numerous organizations are interested in continuing to use the earthworm survey in collaboration with farmers to better understand the state of soil health and how to improve it across the world.
Disclaimer: Earthworms may be great for farm fields, but can actually wreak havoc in many forested ecosystems because most earthworm species in North America are invasive and disturb the establishment and growth of native plant species. To learn more about this, check out this article on earthworms in forests: https://fpr.vermont.gov/sites/fpr/files/Forest_and_Forestry/Forest_Health/Library/EarthwormsInForests_final.pdf