Earthworms are gross but they’re just harmless — in fact, forget the “yuck” factor. Earthworms are actually unsung heroes beneath our feet. According to a new study, earthworms are responsible for a staggering 6.5% of all grain yield and 2.3% of legumes produced each year worldwide, according to a new study. To put it in perspective, that’s a whopping 140 million metric tons of food, or more than Russia produces.

Researchers at Colorado State University crunched the numbers and estimated the contribution of earthworms to food production by cross-referencing maps showcasing earthworm hotspots with data on soil quality, fertilizer use, and crop yields. Although we’ve long known that these slimy soil dwellers are good news for a garden, their exact impact on our global food supply has been a bit of a mystery—until now.

“This is the first effort that I’m aware of that’s trying to take one piece of soil biodiversity and say, ‘OK, this is the value of it; this is what it’s giving us on a global scale,” Steven Fonte, associate professor of agroecosystem ecology in the Department of Soil and Crop Sciences at CSU, and the study’s lead author, said in a news release.

The Earthworm effect

Earthworms play a crucial role in fostering robust soil health and promoting plant growth. They enhance soil structure, aiding in efficient water retention, and facilitating the beneficial breakdown of organic matter. As earthworms burrow through the soil, they create channels that allow air to circulate. This aerated environment helps plant roots to access oxygen more efficiently, which is essential for growth. Earthworms can also contribute to natural pest control by breaking down soil organic matter that might otherwise serve as a habitat for harmful pests and diseases, and they help recycle nutrients in the soil. Additionally, they can stimulate the production of plant-growth-promoting hormones.

But not all worms have the same impact.

In their study, the researchers found that earthworms had a bigger impact on grain production in the Global South – 10% of grain yield in Sub-Saharan Africa and 8% in Latin America and the Caribbean. Earthworms likely contributed more to those areas as farmers have less access to fertilizers and pesticides, relying instead on manure.

“Earthworms are contributing a lot in these areas where we have fewer chemical inputs,” Fonte said. With his colleagues, they analyzed earthworm impacts on four crops (rice, maize, wheat and barley) and legumes (soybeans, peas, chickpeas, lentils and alfalfa, among others). They found that for all these plants, earthworms are important for food production.

This is part of a growing number of studies that show how important our soil systems are and how we don’t give them the attention they deserve.

Fonte pointed out that recent studies indicate soils harbor up to half of the world’s biodiversity, marking a big rise from earlier estimates of around 25%. He emphasized the intricate nature of soils as a habitat, expressing concern over the limited research to comprehend the significance of this biodiversity for overall global crop yields.

However, the researchers emphasized that they are not promoting the introduction of earthworms into environments where they are not naturally present. Instead, they aspire for this research to underscore the potential benefits of enhancing the management of soil biology in regions where earthworms already reside.

This enhancement could lead to higher agricultural productivity and a lower dependency on agrochemicals. “Soils are still this huge, big black box that we don’t fully understand. This work helps show that there’s a lot of opportunity that we’re just ignoring. There are probably other soil organisms that are even more important,” Fonte said.

So, the next time you see an earthworm, give it the respect it deserves—it might just be helping to put dinner on your table.

The study was published in the journal Nature.