To humans, earthworms are among the most vital creatures on the planet. Beyond serving as a food source for many animals, they act as original ecosystem engineers and play a foundational role in agricultural productivity and global matters. Data leaves little doubt: earthworms underpin about 6.5% of world grain production including corn, rice, wheat, and barley, and they contribute roughly 2.3% of legume output.
These figures translate to more than 140 million tons of food each year. Earthworms rank fourth in global production, a figure comparable to Russia’s agricultural output. Their influence is especially pronounced in the southern hemisphere, where they account for about 10% of total grain production in sub-Saharan Africa and around 8% in Latin America and the Caribbean.
Lumbricidae, the worm family, impacts plant growth in several ways. Yet until now, their global contribution to agricultural production had not been fully quantified.
A team of researchers from Colorado State University undertook a comprehensive analysis of how these annelids affect crop outcomes. The study mapped earthworm abundance, soil properties, and crop yields, and integrated findings from the broader scientific literature on worm performance.
The researchers identified, for the first time, the measurable contribution of a beneficial soil organism to global agricultural production. Although the worms have a substantial impact, the team cautions that other soil biota may also be important. More studies are needed, according to the authors of the study published in Nature Communications.
Sustainability and durability
To be clear, the researchers do not advocate broad inoculation of worms into areas where they are not already present, as this could cause ecological consequences in neighboring natural regions.
Instead, they urge further investment in research and the promotion of agroecological management practices that support entire soil biological communities. This approach would sustain a wide range of ecosystem services that contribute to worm-driven sustainability and durability in agriculture over the long term.
The study clarifies that worms help build healthy soil by fostering structure, capturing and retaining water, and recycling organic matter. This makes nutrients more accessible to plants.
Other studies have noted that earthworms promote hormone production that stimulates plant growth and helps defend crops against pathogens. Some estimates suggest worms can improve overall plant efficiency by about 25%.
Three researchers, including the lead author, estimated the global contribution of earthworms by overlaying maps of worm abundance, soil properties, fertilization rates, and crop yields. They found the strongest impact in sub-Saharan Africa, Latin America, and the Caribbean. The lead author notes that earthworm contribution in these regions is likely higher where farmers have limited access to synthetic fertilizers and pesticides, relying more on organic matter such as manure and crop residues to boost worm benefits for crops.
Reduce drought and erosion
Worms contribute so much that chemical inputs can be reduced in some contexts, the lead researcher emphasizes. The analysis covered four grain crops—rice, corn, wheat, and barley—and a variety of legumes including soybeans, peas, chickpeas, lentils, and alfalfa.
The researcher argues that soil biodiversity has historically been undervalued and hopes the study will highlight how healthy soils can yield tangible crop benefits. If lands are managed more sustainably, that biodiversity can be leveraged to create more robust agricultural ecosystems. This study underscores that potential, and aligns with other recent findings showing soils host a large share of global biodiversity, with significant increases over earlier estimates.
Soil is a complex habitat, and actual understanding of what biodiversity means for global crop performance remains incomplete. The researcher explains that there are many opportunities that current farming practices may be missing.
The findings point to practical implications for future efforts to reduce drought and erosion. For example, earthworms improve soil porosity, aiding in water capture and retention.
Advocates call for better management of soil biology to raise agricultural productivity and reduce dependence on chemical inputs. Soils remain a vast, partially understood system. The study suggests there are multiple opportunities that are being overlooked, with microbial communities also playing a crucial role.
Reference work: Nature Communications article on soil biodiversity and crop production.
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