Worms are among the planet’s most influential animals for humans. They provide nourishment for a wide range of wildlife, act as original ecosystem engineers, and play a pivotal role in agricultural systems around the world. The data speak clearly: earthworms contribute to 6.5% of global grain production, including corn, rice, wheat, and barley, and 2.3% of legume production.
These figures translate to more than 140 million tons of food each year. They rank fourth in global production, with a volume comparable to Russia’s output. The earthworms’ impact is especially notable in the southern hemisphere, where their contribution reaches about 10% of total grain production in sub-Saharan Africa and around 8% in Latin America and the Caribbean.
Within the Lumbricidae family, worms influence plant growth in numerous ways. Yet their precise contribution to world agricultural output has not been fully quantified until now.
A team of researchers from Colorado State University in the United States carried out a comprehensive analysis of how these annelids affect crop production. The study mapped earthworm distribution, soil properties, and crop yields, and drew on extensive scientific literature about worm performance in soils.
This research represents the first attempt to quantify the contribution of a beneficial soil organism to global food production. The authors caution that, although the worms make a sizable impact, other soil biota may also be important and more studies are needed. The findings were published in Nature Communications.
Sustainability and durability
To be clear, the study does not advocate widespread worm inoculation in areas where worms are not already present, as that could lead to adverse ecological effects on neighboring natural areas.
Instead, the researchers emphasize the need for ongoing research and for promoting agroecological management practices that support entire soil biological communities. This approach helps sustain a broad range of ecosystem services that contribute to long-term soil health and agricultural resilience.
The study clarifies that worms help create healthy soil by improving structure, increasing water retention, and accelerating the turnover of organic matter, which makes nutrients more available to plants.
Other studies have found that worms can promote the production of plant hormones that aid growth and help defend plants against pathogens. Some estimates suggest that worm activity might boost overall plant efficiency by roughly 25%.
Three researchers, Steven Fonte (lead author), Nathan Muelle, and Marian Hsieh, estimated the contribution of earthworms to global food production by overlaying maps of earthworm abundance with soil properties, fertilization rates, and crop yields.
In sub-Saharan Africa, Latin America, and the Caribbean, Fonte considers the impact likely greater because farmers in these regions often have limited access to mineral fertilizers and pesticides. They rely more on earthworm-rich organic matter such as manure and crop residues, which enhances the beneficial effects of worms on crops.
Reduce drought and erosion
Worms contribute so much to these regions that chemical inputs can be reduced, according to the lead author. The researchers examined the effects of worms on four grain crops—rice, corn, wheat, and barley—as well as legumes such as soybeans, peas, chickpeas, lentils, and alfalfa.
Fonte notes that soil biodiversity has often been undervalued and hopes the study will spotlight how healthy soils positively influence crops. If lands are managed more sustainably, biodiversity can be harnessed to build more resilient farming ecosystems. This study underscores that potential and aligns with other recent work showing soils hold a large portion of the world’s biodiversity, with estimates indicating a substantial increase from earlier figures.
Soil is a complex habitat, and there have been relatively few efforts to understand what this biodiversity means for global crop performance, he adds.
The researchers’ findings point to implications for future work aimed at reducing drought and erosion. Fonte provides an example: earthworms improve soil porosity, helping to capture and retain water more effectively.
Advocacy centers on better management of soil biology to boost agricultural productivity and lessen dependence on chemical inputs. Soils remain a vast, partly understood frontier, and this study highlights many opportunities that are being overlooked. It is also noted that other soil organisms, particularly microbial communities, may be even more important.
Reference work: marked citation to Nature Communications 2023.
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