Written by Tom Gotsch ‘26
Edited by Josephine Chen ‘24
Humans need food. That’s no secret—but as the global human population grows, and as our unsustainable farming practices continue to damage ecosystems with the runoff and intrusion of artificial pesticides and fertilizers into natural habitats, it becomes increasingly clear that we need a way to sustainably produce a larger quantity of food (Aktar et al., 2009). What if a little worm could help us? Meet the nematode.
Found in the soil on every continent, nematodes are microscopic organisms that often resemble small transparent worms (Hoogen & Geisen, 2020). While they might not seem like much at first (magnified) glance, these little creatures are absolutely essential to biogeochemical cycles and soil ecosystems. And they might just be a key player in the transition to more sustainable farming techniques!
A research team at West Virginia University found that the presence of one species of fungi-eating nematode, Aphelenchus avenae, increased the concentration of ammonium, a molecule containing nitrogen, in a sample of soil (Kane et al., 2022). Nitrogen, often pumped into the soil on farms via synthetic fertilizers, is vital for plant growth and development. Thus, it is logical to conclude that incorporating A. avenae into soil ecosystems on farms could decrease the necessary amount of synthetic fertilizer (and therefore the artificial energy-intensive processes that create it).
Beyond increasing nutrients in the soil, nematodes are capable of improving plant health. According to Zhang et al. (2020), a research team from Yunnan University, certain fungi-eating nematodes can consume fungi that cause diseases in crops; for example, the aforementioned A. Avenae has been found to potentially decrease the number of pathogens from two root-rot fungi in corn (Nickle & McIntosh, 1968). Many other species are capable of improving crop health, as well, by diminishing fungal pathogens. This means that on some farms, the application of chemical pesticides and fertilizers, known to damage local ecosystems (as in the case of the pesticide DDT in the 1960-70s), could be at least partially replaced by promoting beneficial nematode populations in the soil (Gupta et al., 2022).
There are some important considerations to this relatively recent area of research, though. Not all nematodes are beneficial—while some simply have no effect on pathogenic soil organisms, other nematodes are known to eat plants and inhibit crop growth, so it is necessary for farmers to have a very clear understanding of which kinds of nematodes they can incorporate into their farming techniques (Zhang et al., 2020). Furthermore, the matter of incorporating nematodes into farming is not always straightforward: doing so requires knowledge of soil ecosystems—made up of microbes, fungi, microscopic organisms like nematodes, and various nutrients—in an area, and then helping steward an environment that promotes nematode health. Different farms will likely differ in their soil ecology; thus, farmers may not be able to apply the same techniques for promoting beneficial nematode populations to all areas. This would require farmers to learn about the unique soil ecologies on their farm if they wished to start farming with a greater focus on nematode population health. And, of course, if farming practices incorporating nematodes are implemented, they should be as sustainable as possible—farms should not have to rely on the continuous import of nematodes into their soil and may need to rework their farming practices if they wish to create soil ecosystems that support thriving nematode populations. This is, of course, a complex process and could be too expensive for many farmers.
Moreover, it’s important to note that the option of implementing nematodes as a sustainable farming technique is not equally distributed around the globe. Researchers at Swiss university ETH Zürich found that nematode abundance varies across different biomes: they’re most abundant in the soil of temperate broadleaf forests (Northeastern US, central Europe, central China) and boreal forests (Canada, Russia), and less abundant in the soil of tropical dry forests (central South America, southern Asia, Mexico) and flooded grasslands (South America and central & southern Africa) (Hoogen & Geisen, 2020). This disadvantages countries in the Global South, which, on average, already have less access to resources; the effort of incorporating nematodes into farming is not a technique that is equally accessible to all.
That being said, the recent research on nematode-soil interactions introduces new ways to consider farming sustainably. While more research is needed to fully determine how effective nematodes are in the broader environment of agriculture, as well as how to make incorporating nematodes more widely accessible, nematodes are a beneficial part of any soil ecosystem, and we ought to start thinking about the ways in which we can work with them to grow more food for us both.
References
Aktar W, Sengupta D, Chowdhury A. Impact of pesticides use in agriculture: their benefits and hazards. Interdisciplinary Toxicology. 2009 Mar 1;2(1):1–12.
Gupta A, Singh UB, Sahu PK, Paul S, Kumar A, Malviya D, et al. Linking Soil Microbial Diversity to Modern Agriculture Practices: A Review. IJERPH. 2022 Mar 7;19(5):3141.
Hoogen J van den, Geisen S, Wall DH. Metadata record for: A global database of soil nematode abundance and functional group composition [Internet]. figshare; 2020 [cited 2022 Oct 31]. p. 5372 Bytes. Available from: https://springernature.figshare.com/articles/Metadata_record_for_A_global_database_of_soil_nematode_abundance_and_functional_group_composition/11925843
Nickle W., McIntosh P. Studies on the feeding and reproduction of seven mycophagous nematodes on Rhizoctonia, Fusarium, and Verticillium. 1968;14:11–12.
Zhang Y, Li S, Li H, Wang R, Zhang KQ, Xu J. Fungi–Nematode Interactions: Diversity, Ecology, and Biocontrol Prospects in Agriculture. JoF. 2020 Oct 4;6(4):206.
[IMAGE] Are nematodes a turfgrass problem? [Internet]. The Turfgrass Group Inc. 2022 [cited 2022 Nov14]. https://theturfgrassgroup.com/uncategorized/are-nematodes-a-turfgrass-problem/