Earthworms are the fourth largest global grain producer: Study

Earthworms have emerged as the fourth-largest global grain producer, contributing approximately 6.5% to the world's grain (maize, rice, wheat, barley) production, according to a recent study published in Nature Communications.

This amounts to 140 million tonnes of food a year, researchers have said.

A Guardian report underscores the significance of this finding by likening earthworms' production scale to that of Russia, a major grain-producing nation. Russia produced 150m tonnes in 2022 and expects to produce 120m tonnes this year.

Earthworms also contribute to the growing of 2.3% of legumes, which include soya beans, peas, chickpeas and lentils. This is probably smaller because legumes can fix their own nitrogen, which makes them less dependent on worms, researchers said.

The study, led by Steven Fonte from Colorado State University, highlights the critical role of earthworms as soil ecosystem engineers.

Operating beneath the surface, these creatures perform essential functions—moving, feeding, excreting, and reproducing—that break down organic matter, aerate soils, and enhance fertility. Their contribution extends to the creation of a soil carbon sponge, capable of retaining significant amounts of water and sequestering carbon.

"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,'" said lead researcher Steven Fonte from Colorado State University.

"Soils are just such an intricate habitat but there has really been very few efforts to understand what that biodiversity means to our global crop yields," he added

The study emphasises the intricate role of soil biodiversity in global crop yields, an aspect often overlooked.

While agricultural intensification has traditionally been credited with feeding a growing population, the study challenges this narrative. It points out that earthworm populations, adversely impacted by intensive farming, are poised to play a crucial role in the impending shift to agroecological food production.

The research team estimated the impacts of earthworms on global crop production by analysing maps of earthworm abundance, soil properties, and crop yields, along with data on earthworm-yield responses.

The findings indicate that earthworms play a pivotal role in global food production, particularly in the global South, contributing 10% of total grain production in Sub-Saharan Africa and 8% in Latin America and the Caribbean.

Although the impact of earthworms is notable, other soil organisms may be "equally as important" but further study is needed, the paper said, and only a fraction are believed to have been identified.

"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 kind of ignoring," Steven Fonte noted.