20
Nov
Study Reinforces the Importance of Soil Management Practices on Ecological Effects
(Beyond Pesticides, November 20, 2024) The perpetual use of pesticide coated seeds and tillage changed the composition of various beetle, spider, and other epigeal arthropod communities on New Hampshire farmland, according to a recent study published in Agriculture, Ecosystems, and Environment. Researchers fell short of finding conclusive results about the multi-variable impacts of both practices on biodiversity but raise notable issues on the impact of treated seeds. This research builds on the existing peer-reviewed scientific literature that highlights the threats of toxic pesticides and pesticide-coated seeds. Environmental and public health advocates are in agreement with organic and agroecological farmers who reject chemical-intensive land management practices.
“At the root of the cascading crises of public health collapse, biodiversity loss, and the climate crisis is a reliance on petrochemical-based toxic products, rather than public policy and investments that strengthen consumer and institutional trust of nature-based, organic systems,†says Max Sano, organic program associate at Beyond Pesticides. “This is consistent with various interactions I have had with advocates across New England who are demanding action to stymie the impending biodiversity collapse enabled by government inaction.â€
Background and Methodology
This study was coauthored and led by environmental researchers at the Department of Natural Resources and the Environment at the University of New Hampshire. The report authors are specialized in plant biology, conservation, and entomology with numerous studies in peer-reviewed publications.
The goal of this three-year field study was to “quantify the effects of pesticide seed treatment (crops grown from seeds coated with pesticides versus uncoated seeds) and tillage system (full-tillage with a moldboard plow, strip-tillage, and no-tillage) on epigeal arthropod communities in a long-term conventionally managed annual feed grain rotation experiment.â€
The study itself was conducted between 2017 and 2019 growing seasons at the University of New Hampshire Kingman Research Farm. On this site, tillage system experiments began in 2013 and pesticide seed treatment experiments began in 2016 as part of a separate long-term study. Corn and soybeans were the crop of choice for previous experiments, as well as the focus of this study. Tillage treatments were applied for three years before adding treated seeds as an additional variable, and by the end of the study (2019) the treated seed versus no treated seeds component had been in place for four growing seasons.
All plots were sprayed with the weed killer glyphosate pre- and post-planting. The research plots included the following: full-tillage treated with glyphosate and then tilled with two different devices (moldboard plow and industrial-scale plow); strip-tillage treated with glyphosate and then tilled with one industrial-scale plow; and no-tillage sprayed but no plowing occurred.
The epigeal arthropod (including insects that decompose organic matter and other ecosystem services) communities sampled for this study include approximately “1669 individual arthropods, representing 47 species.†The researchers go on to list the various species from the collection periods in both 2018 and 2019. “In 2018, carabid beetles, including P. melanarius, H. erraticus, H. fuscipalpis, H. pensylvanicus, Stenolophus ochropezus Say, S. lecontei (Chaudoir), and Anisodactylus sanctaecrucis (Fabricius) accounted for 34.8 % of the total captures, while other arthropods, including individuals from Gryllidae, Formicidae, Lygaeidae, Scolytidae, Curculionidae, Meloidae, Cydnidae, and Araneae accounted for the remainder (65.2 %). In 2019, carabid beetles (P. melanarius, H. pensylvanicus, B. quadrimaculatum, Chlaenius tricolor, S. lecontei, C. tricolor, Zuphium sp.) represented 12.2 % of total captures, while the remainder (87.8 %) included individuals from Orthoptera, Gryllidae, Formicidae, Coccinellidae, Scolytidae, Curculionidae, Meloidae, Cydnidae, and Araneae.”
Results and Discussion
Researchers find the four following discoveries from this experiment:
- “Tillage and pesticide seed treatments affected epigeal arthropod community composition.
- Activity-density was lower in full-till compared to strip-till and no-till.
- Spider abundance in strip-till was reduced by pesticide seed treatment.
- Weed seed predation was higher in strip-till compared to full-till.â€
Weed seed predation refers to the ecosystem service that wildlife provides in consuming seeds of weeds that would otherwise be treated with pesticides in chemical-intensive agriculture. The main variable in 2018 was pesticide seed treatment, whereas the main variable in 2019 was the degree of tillage. The “activity densities of Pterostichus melanarius (Illiger) [rainbeetles] were higher in the strip-till compared to full-till treatment in 2018.†The authors conclude, “These data provide evidence that both pesticide seed treatments and tillage systems can influence the communities of epigeal arthropods that inhabit annual row crop agroecosystems relatively late in the growing season, when the majority of pesticide residues have likely dissipated, and that the weed seed predation services provided by members of this community can be strongly negatively impacted by intensive tillage.â€
The researchers also find that arthropod diversity was higher in full-till versus no-till plots in 2019, however they do acknowledge that “it is possible that had sampling of the epigeal arthropod community occurred earlier in the growing season a stronger pesticide treatment effect would have been detected.†The researchers remain unclear on why treated seeds did not impact spider abundance in the no-till and full-till plots. The variability can be attributed to other factors as well, including the corn-soybean crop rotation model used for this study.
The results of this experiment highlight the compounding impacts of chemical-intensive agricultural practices on biodiversity. Farmers who acknowledge the interconnected systems of agriculture and ecosystems understand the long-term impacts of soil disturbance through tilling disrupts microbial life and biodiversity, not to mention the impacts of glyphosate applications and pesticide-treated seeds can have on soil and human health.
Rise of Organic No-Till Farming
Beyond Pesticides has reported on organic no-till as a potential solution to the issue of toxic inputs and practices. Rodale Institute’s 40-year comparative field study on organic versus non-organic farming finds that, “No-till and organic no-till are not created equal. Conventional no-till utilizes herbicides to terminate a cover crop, whereas organic systems use tools like the roller crimper. We have found that organic no-till practices year after year do not yield optimal results, so our organic systems utilize reduced tillage, and the ground is plowed only in alternating years.†The Rodale Institute’s website adds that, in order to model standard agricultural approaches, GM (genetically modified) crops and no-till were introduced to the conventional plots in 2008 when those techniques became common in the U.S. (See Daily News here.)
The Institute’s Farming Systems Trial (FST) on its 12-acre Pennsylvania parcel uses 72 experimental plots, with three broad approaches:
- Organic manure, representing a typical organic dairy or beef operation, featuring long rotations of annual feed grain crops and perennial forage crops, fertilized through legume cover crops and periodic applications of composted manure, and using diverse crop rotations as primary defenses against pests;
- Organic legume, representing a typical cash grain operation, featuring mid-length rotations of annual grain crops and cover crops, deploying leguminous cover crops as the sole fertilizers, and using only crop rotations as pest defense;
- Conventional synthetic, representing a typical U.S. grain-producing enterprise, using synthetic nitrogen fertilizer, and controlling weeds with synthetic herbicides (according to recommendations of Penn State University Cooperative Extension).
As reported, each of those three is further divided into “no-till†and “tillage†strategies (tillage being the practice of digging up, turning over, or otherwise agitating the soil with mechanical tools — typically a plow or disc). This yields six different systems in the FST.
The FST finds:
- Organic systems achieve 3–6 times the profit of conventional production;
- Yields for the organic approach are competitive with those of conventional systems (after a five-year transition period);
- Organic yields during stressful drought periods are 40% higher than conventional yields;
- Organic systems leach no toxic compounds into nearby waterways (unlike pesticide-intensive conventional farming;
- Organic systems use 45% less energy than conventional; and
- Organic systems emit 40% less carbon into the atmosphere.Â
See Beyond Pesticides’ National Forum session, Tackling the Climate Emergency (see November 29, Session 3 recording), with presentation by Rodale Institute’s Andrew Smith, PhD and coauthor of several landmark reports on soil biology and carbon sequestration — including the just-released Farming Systems Trial — 40-Year Report.
Call to Action
Advocates view both pesticide-treated seeds and high-tillage farming systems as extensions of the chemical-intensive agriculture and land management systems that perpetuate public health crises, undermine biodiversity integrity, and amplify the climate emergency.
Various studies indicate the failure of chemical-intensive no-till farming systems, including a 2022 study published in Nature which finds widespread herbicide resistance on pesticide-intensive corn and soybean farms leads to an increase in greenhouse gas emissions due to need for more tillage. Conversely, reporting from Vermont Public Radio in 2021 highlights the perspective of a retired state scientist, Nat Shambaugh, who found “regenerative†no-till farms increase use of toxic herbicides that ultimately run off into surrounding waterbodies, undermining ecosystem health.
A 2023 study published by American Bird Conservancy finds “a single corn kernel coated with a neonicotinoid can kill a songbird. Even a tiny grain of wheat or canola treated with the oldest neonicotinoid, imidacloprid, can poison a bird.†This report builds on previous studies, including a 2022 study published in Environmental Pollution finding that parents’ ingestion of pesticide-treated or contaminated seeds results in chronic exposure that adversely impacts offspring health, even at “sublethal†doses. (See additional Daily News coverage on neonicotinoid insecticide impacts on wildlife here and here.) With neonicotinoid insecticides in particular, a recent study published this year in Frontiers in Toxicology uncovered serious flaws in the pesticide registration process for five neonic insecticides (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) in terms of potential adverse effects on human health. The issue of pesticide-treated seeds continues to surface in various state legislatures, with New York and Vermont passing the first laws in the nation to restrict the use of pesticide-treated seeds beginning in 2029, pending rulemaking. (See Daily News here and here.)
Earlier this year, advocates across the nation called on EPA to not exempt pesticide-treated seeds and paint from thorough risk assessment and examination. (See Action of the Week here.) To learn more on how to engage in strengthening USDA organic standards, see Keeping Organic Strong.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
