An April 2022 study published by researchers at Iowa State University is the latest example, revealing another layer to the agrichemical-dependent dilemma of the most widely grown crops in the U.S.^{4 5} The key takeaway of the Iowa study is that farmers who grow GE corn and soybean are increasing their use of tillage, which is significantly increasing their greenhouse gas emissions (GHG)—and the trend is strongly correlated with the rise of herbicide-resistant weeds, following the widespread adoption of herbicide-tolerant GE crops.^{6 7}

But to understand why it matters first requires some context about the practice of tilling. Repeat tillage is destructive to soil structure, facilitating the escape of greenhouse gases like carbon dioxide from the soil into the atmosphere.⁸ A 2014 study, for example, comparing conventional till systems to zero-till found that the global warming contributions were 20 percent greater from tilled soil. It also concluded that conversion to zero-till practices could help mitigate climate change within five to 10 years.⁹

When GE crops first came on the market, they were promoted as a no-till game-changer because the herbicide-tolerant seed technology would allow farmers to manage weeds without tillage by simply treating already planted fields with chemicals, namely, glyphosate.¹⁰

According to the Iowa study, the no-till claims held true as GE corn and soy began to overtake U.S. farmland during the first decade of use. From 1998 to 2008, the acreage of no-till corn and soybeans significantly increased by 12 million and 17 million acres, respectively, and as expected, there was also a reduction in associated GHG emissions.¹¹ However, the pattern shifted after 2008, at the same time that a plague of glyphosate-resistant weeds overtook farms across the country. By 2016, the researchers found that millions of corn and soybean acres under no-till or conservation tillage had reverted to prior levels, and the intensifying tillage completely offset the greenhouse gas mitigation benefits accomplished between 1998 and 2008.^{12 13} Meanwhile, U.S. farmers were also paying a steep price for crops lost to "superweeds," estimated at one billion dollars by 2014.¹⁴

As climate change intensifies, agriculture plays a significant role, accounting for roughly 10 percent of GHG emissions in the U.S. and 25 percent worldwide.¹⁵ And this begs the question: if the most widely grown crops in the U.S. are trending in the wrong direction, what are the alternatives?¹⁶ The Rodale Institute estimates that we could sequester more than 100 percent of current annual CO2 emissions if we converted all global croplands and pastures to no-till regenerative organic agriculture.¹⁷ Their rationale is based on data from more than 30 years of field trials and collaborations with soil scientists doing similar research worldwide.¹⁸

Additionally, it’s important to note that organic farms, in general, have superior soil health metrics compared to conventional ones. A 2017 study found that, on average, organic soils contain 13 percent more soil organic carbon than conventional soils and that the potential for long-term carbon sequestration was 26 percent higher in organic soils.¹⁹

Our food choices are loaded with impact, one way or another. Let’s choose those that nurture the soil, because when it comes to the future of this planet, these four letters—F-O-O-D—make a loaded word.

References

1. 21, Caren Baginski | Jul. “What's the Difference between GE and GMO?” New Hope Network, 31 May 2017, https://www.newhope.com/non-gmo/whats-difference-between-ge-and-gmo.
2. “The Rise of Superweeds.” Union of Concerned Scientists, https://www.ucsusa.org/resources/rise-superweeds.
3. Bain, Carmen, et al. “'Superweeds' or 'Survivors'? Framing the Problem of Glyphosate Resistant Weeds and Genetically Engineered Crops.” Journal of Rural Studies, Pergamon, 14 Mar. 2017, https://www.sciencedirect.com/science/article/abs/pii/S0743016716304983….
4. Lu, Chaoqun, et al. “Emerging Weed Resistance Increases Tillage Intensity and Greenhouse Gas Emissions in the US Corn–Soybean Cropping System.” Nature News, Nature Publishing Group, 21 Apr. 2022, https://www.nature.com/articles/s43016-022-00488-w.
5. Jeff. “Top 10 Produce Crops Grown in the U.S.” AgAmerica, 21 June 2022, https://agamerica.com/blog/power-of-10-top-10-produce-crops-in-the-u-s/.
6. “Chemical No-till Failure Due to Herbicide Resistance Increases Greenhouse Gas Emissions.” Beyond Pesticides Daily News Blog, 9 May 2022, https://beyondpesticides.org/dailynewsblog/2022/05/chemical-no-till-fai….
7. Lu, Chaoqun, et al. “Emerging Weed Resistance Increases Tillage Intensity and Greenhouse Gas Emissions in the US Corn–Soybean Cropping System.” Nature News, Nature Publishing Group, 21 Apr. 2022, https://www.nature.com/articles/s43016-022-00488-w.
8. “Chemical No-till Failure Due to Herbicide Resistance Increases Greenhouse Gas Emissions.” Beyond Pesticides Daily News Blog, 9 May 2022, https://beyondpesticides.org/dailynewsblog/2022/05/chemical-no-till-fai….
9. Mangalassery, Shamsudheen, et al. “To What Extent Can Zero Tillage Lead to a Reduction in Greenhouse Gas Emissions from Temperate Soils?” Nature News, Nature Publishing Group, 4 Apr. 2014, https://www.nature.com/articles/srep04586.
10. “Chemical No-till Failure Due to Herbicide Resistance Increases Greenhouse Gas Emissions.” Beyond Pesticides Daily News Blog, 9 May 2022, https://beyondpesticides.org/dailynewsblog/2022/05/chemical-no-till-fai….
11. “Intense Tillage on US Farm Fields Boosts Greenhouse Emissions.” Futurity, 29 Apr. 2022, https://www.futurity.org/tillage-agriculture-greenhouse-emissions-27324….
12. “Intense Tillage on US Farm Fields Boosts Greenhouse Emissions.” Futurity, 29 Apr. 2022, https://www.futurity.org/tillage-agriculture-greenhouse-emissions-27324….
13. “Chemical No-till Failure Due to Herbicide Resistance Increases Greenhouse Gas Emissions.” Beyond Pesticides Daily News Blog, 9 May 2022, https://beyondpesticides.org/dailynewsblog/2022/05/chemical-no-till-fai….
14. Bain, Carmen, et al. “'Superweeds' or 'Survivors'? Framing the Problem of Glyphosate Resistant Weeds and Genetically Engineered Crops.” Journal of Rural Studies, Pergamon, 14 Mar. 2017, https://www.sciencedirect.com/science/article/abs/pii/S0743016716304983….
15. “Chemical No-till Failure Due to Herbicide Resistance Increases Greenhouse Gas Emissions.” Beyond Pesticides Daily News Blog, 9 May 2022, https://beyondpesticides.org/dailynewsblog/2022/05/chemical-no-till-fai….
16. Jeff. “Top 10 Produce Crops Grown in the U.S.” AgAmerica, 21 June 2022, https://agamerica.com/blog/power-of-10-top-10-produce-crops-in-the-u-s/.
17. “Carbon Sequestration.” Rodale Institute, 25 Sept. 2020, https://rodaleinstitute.org/why-organic/issues-and-priorities/carbon-se….
18. Regenerative Agriculture - Rodale Institute. https://rodaleinstitute.org/wp-content/uploads/Rodale-Soil-Carbon-White….
19. “Organic Better than Chemical-Intensive Agriculture at Fighting Climate Change.” Beyond Pesticides Daily News Blog, 19 Sept. 2017, https://beyondpesticides.org/dailynewsblog/2017/09/organic-better-chemi….