Economic and Environmental Impacts of First Generation Genetically Modified Crops

The report examines the deployment of first-generation GMO crops in the US and Argentina. It finds that while RR soybeans facilitate no-till farming and replace more toxic herbicides, they often result in a 5-10% yield drag and increased total herbicide volume. The author warns that high selection pressure, particularly in Argentina, risks accelerating weed resistance and shifts. Additionally, the paper highlights emerging concerns regarding glyphosate's impact on soil microbial communities, specifically the buildup of Fusarium fungi, and potential impairments to plant immune responses and nitrogen fixation.

• Roundup Ready (RR) soybeans generally exhibit a 'yield drag,' producing 5% to 10% fewer bushels per hectare or acre compared to identical conventional varieties grown under similar conditions.
• Contrary to biotechnology industry claims, RR soybeans require more herbicides by volume than conventional soybeans in both the US and Argentina. In the US, they require 5% to 10% more herbicide-active ingredient per acre.
• The adoption of RR soybeans in Argentina is more extensive and intensive than in the US, with 90% adoption by 2000 and an average of 2.3 glyphosate applications per year compared to 1.3 in the US.
• High levels of glyphosate use in RR soybean systems are linked to an increase in Fusarium fungi in the soil, which can lead to crop diseases and livestock issues such as swine pseudopregnancy.
• Glyphosate applications on RR soybeans can impair root development, nodulation, and nitrogen fixation, with yield losses of up to 25% observed under drought stress or in infertile soils.
• The genetic transformation for glyphosate tolerance may depress the production of aromatic amino acids like phenylalanine, which are critical for triggering a plant's systemic acquired resistance (SAR) and immune response.
• The impact of Bt crops on insecticide use is mixed: Bt cotton has significantly reduced insecticide use in several US states, but Bt corn has had little to no impact on corn insecticide use.
• Excessive reliance on a single weed management strategy, such as the RR system, creates high selection pressure that leads to weed shifts and the emergence of glyphosate-resistant weeds, such as horseweed.

APA

Benbrook, C. (2003). Economic and Environmental Impacts of First Generation Genetically Modified Crops. International Institute for Sustainable Development. https://www.iisd.org/system/files/publications/tkn_firstgen_gmo_us.pdf

Chicago

Benbrook, Charles. Economic and Environmental Impacts of First Generation Genetically Modified Crops. International Institute for Sustainable Development, 2003. https://www.iisd.org/system/files/publications/tkn_firstgen_gmo_us.pdf.

Wikipedia

{{cite report |last1=Benbrook |first1=Charles |title=Economic and Environmental Impacts of First Generation Genetically Modified Crops |publisher=International Institute for Sustainable Development |date=2003 |url=https://www.iisd.org/system/files/publications/tkn_firstgen_gmo_us.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{benbrook2003economic, author = {Benbrook, Charles}, title = {{Economic and Environmental Impacts of First Generation Genetically Modified Crops}}, institution = {International Institute for Sustainable Development}, year = {2003}, url = {https://www.iisd.org/system/files/publications/tkn_firstgen_gmo_us.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }