The research, led by Dr. Steven Fonte and his team, reveals that earthworms contribute to about 6.5% of global grain yield and 2.3% of legumes produced each year.
The researchers found that earthworms account for an estimated 140 million metric tons of food produced annually.
This figure is comparable to the cereal grains produced annually by Russia, the world’s fourth-largest producer.
“This is the first effort that I’m aware of that’s trying to take one piece of soil biodiversity and say, ‘this is the value of it; this is what it’s giving us on a global scale,'” said Dr. Fonte, the study’s lead author.
Earthworms promote healthy soils in different ways. They enhance soil structure, optimize water retention, and enrich the soil by churning organic matter, making essential nutrients more accessible to plants.
In fact, the presence of earthworms has been linked to a surge in plant productivity by an estimated 25 percent.
The impact of earthworms on food production is more pronounced in the global south, accounting for up to 10% of grain yield in sub-Saharan Africa and 8% in Latin America and the Caribbean.
The greater impact in certain regions is attributed to the reliance on earthworm-rich organic matter, as opposed to chemical fertilizers and pesticides.
“Earthworms are contributing a lot in these areas where we have fewer chemical inputs,” said Fonte.
The team, including Nathan Mueller and Marian Hsieh (supported by a U.S. National Science Foundation Graduate Research Fellowship), conducted their analysis by overlaying maps of earthworm abundance with data on soil properties, fertilizer rates, and crop yields.
The study focused on four grain crops (rice, maize, wheat, barley) and a range of legumes, including soybeans, peas, chickpeas, lentils, and alfalfa.
Dr. Fonte noted that soil biodiversity has historically been undervalued, and he hopes this work will bring more attention to how healthy soils can have positive, tangible impacts on crops.
“If we manage our soils in a more sustainable way, we can better harness or leverage this biodiversity and produce more sustainable agroecosystems,” said Dr. Fonte. “This work highlights that potential.”
Dr. Fonte also noted that other recent research has shown that soils contain as much as half the world’s biodiversity, a significant increase from previous estimates of approximately 25 percent.
“Soils are just such an intricate habitat,” he said. “But there’s really been very few efforts to understand what that biodiversity means to our global crop yields.”
According to Dr. Fonte, insights from this study could also have implications in future efforts to mitigate drought and erosion. For example, he said, earthworms can improve soil porosity, aiding in the beneficial capture and retention of water.
The researchers emphasized that they are not advocating for anyone to transplant earthworms into places they do not already exist.
Dr. Fonte hopes this work shows how improved management of soil biology in places where earthworms already call home has the potential to enhance agricultural productivity and reduce our reliance on agrochemicals. He said the study marks an important first step.
The study is published in the journal Nature Communications.
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