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Yield gains larger in GM maize for human consumption than livestock feed in South Africa


The majority of genetically modified (GM) crops are produced for livestock consumption, whereas minimal attention has been given to GM crops for direct human consumption. In South Africa, GM white maize has been grown for direct human consumption alongside GM yellow maize and conventional hybrid (CH) maize for livestock feed since 1999. Here we investigate yield differences between GM white, GM yellow and CH maize across 106 locations, 28 years, 491 cultivars, and 49,335 dryland and 9,617 irrigated observations in South Africa. GM maize increased mean yields over CH by 0.42 metric tons (Mt) ha−1 and reduced yield risk. We show that GM white maize increased yields by 0.60 Mt ha−1 and GM yellow maize by 0.27 Mt ha−1 compared with CH maize. GM yield gains were similar for dry and irrigated production. Our study highlights the potential impacts of growing GM grain crops for human consumption in African countries.

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Fig. 1: Comparison of maize yields for South African trial data for 1980–2009.

Data availability

The data that support the findings of this study were provided by the South Africa ARC and are available from the corresponding author upon request and with approval from the ARC.

Code availability

The Stata v.15 code that supports the findings of this study is available from the corresponding author upon request.


  1. Smyth, S. J., Kerr, W. A. & Phillips, P. W. B. Global economic, environmental and health benefits from GM crop adoption. Glob. Food. Sec. 7, 24–29 (2015).

    Article  Google Scholar 

  2. Brookes, G., Taheripour, F. & Tyner, W. E. The contribution of glyphosate to agriculture and potential impact of restrictions on use at the global level. GM Crops Food 8, 216–228 (2017).

    Article  Google Scholar 

  3. Klümper, W. & Qaim, M. A meta-analysis of the impacts of genetically modified crops. PLoS ONE 9, e111629 (2014).

    ADS  Article  Google Scholar 

  4. Xu, Z., Hennessy, D. A., Sardana, K. & Moschini, G. The realized yield effect of genetically engineered crops: US maize and soybean. Crop Sci. 53, 735–745 (2013).

    Article  Google Scholar 

  5. Lusk, J., Tack, J. & Hendricks, N. Heterogeneous Yield Impacts from Adoption of Genetically Engineered Corn and the Importance of Controlling for Weather (National Bureau of Economic Research, 2017).

  6. Qaim, M. Bt cotton, yields and farmers’ benefits. Nat. Plants 6, 1318–1319 (2020).

    Article  Google Scholar 

  7. Ahmed, A., Hoddinott, J. F., Abedin, N. & Hossain, N. Z. Economic and Health Impacts of Genetically Modified Eggplant: Results from a Randomized Controlled Trial of Bt Brinjal in Bangladesh (IFPRI, 2019).

  8. Ahmed, A. U., Hoddinott, J., Abedin, N. & Hossain, N. The impacts of GM foods: results from a randomized controlled trial of Bt eggplant in Bangladesh. Am. J. Agric. Econ. (2020).

    Article  Google Scholar 

  9. Zilberman, D., Holland, T. & Trilnick, I. Agricultural GMOs—what we know and where scientists disagree. Sustainability 10, 1514 (2018).

    Article  Google Scholar 

  10. Gastrow, M., Roberts, B., Reddy, V. & Ismail, S. Public perceptions of biotechnology in South Africa. S. Afr. J. Sci. 114, 2017–0276 (2018).

    Google Scholar 

  11. Qaim, M. & Zilberman, D. Yield effects of genetically modified crops in developing countries. Science 299, 900–902 (2003).

    ADS  CAS  Article  Google Scholar 

  12. Global Status of Commercialized Biotech/GM Crops: 2018 ISAAA Brief 54-2018 (ISAAA, 2018).

  13. Shew, A. M. et al. Are all GMOs the same? Consumer acceptance of cisgenic rice in India. Plant Biotechnol. J. 14, 4–7 (2016).

    Article  Google Scholar 

  14. Gonsalves, C., Lee, D. R. & Gonsalves, D. The Adoption of genetically modified papaya in Hawaii and its implications for developing countries. J. Dev. Stud. 43, 177–191 (2007).

    Article  Google Scholar 

  15. Gouse, M., Pray, C. E., Kirsten, J. & Schimmelpfennig, D. A GM subsistence crop in Africa: the case of Bt white maize in South Africa. Int. J. Biotechnol. 7, 84–94 (2005).

    Article  Google Scholar 

  16. Gouse, G. GM maize as subsistence crop: the South African smallholder experience. AgBioForum 15, 163–174 (2012).

    Google Scholar 

  17. Shi, G., Chavas, J.-P. & Lauer, J. Commercialized transgenic traits, maize productivity and yield risk. Nat. Biotechnol. 31, 111–114 (2013).

    Article  Google Scholar 

  18. Genetically Engineered Crops: Experiences and Prospects—New Report (NASEM, 2016).

  19. Adenle, A. A., Morris, E. J. & Parayil, G. Status of development, regulation and adoption of GM agriculture in Africa: views and positions of stakeholder groups. Food Policy 43, 159–166 (2013).

    Article  Google Scholar 

  20. Lobell, D. B. et al. Prioritizing climate change adaptation needs for food security in 2030. Science 319, 607–610 (2008).

    CAS  Article  Google Scholar 

  21. Serdeczny, O. et al. Climate change impacts in sub-Saharan Africa: from physical changes to their social repercussions. Reg. Environ.Change 17, 1585–1600 (2017).

    Article  Google Scholar 

  22. Rippke, U. et al. Timescales of transformational climate change adaptation in sub-Saharan African agriculture. Nat. Clim. Change 6, 605–609 (2016).

    ADS  Article  Google Scholar 

  23. Travis, W. R. Mapping future crop geographies. Nat. Clim. Change 6, 544–545 (2016).

    ADS  Article  Google Scholar 

  24. General Household Survey (STATSA, 2016).

  25. Walker, N. J. & Schulze, R. E. Climate change impacts on agro-ecosystem sustainability across three climate regions in the maize belt of South Africa. Agric. Ecosyst. Environ. 124, 114–124 (2008).

    Article  Google Scholar 

  26. Kruger, M., Van Rensburg, J. B. J. & Van den Berg, J. Perspective on the development of stem borer resistance to Bt maize and refuge compliance at the Vaalharts irrigation scheme in South Africa. Crop Prot. 28, 684–689 (2009).

    Article  Google Scholar 

  27. Chavas, J.-P., Shi, G. & Lauer, J. The effects of GM technology on maize yield. Crop Sci. 54, 1331 (2014).

    Article  Google Scholar 

  28. Greyling, J. C. & Pardey, P. G. Measuring maize in South Africa: the shifting structure of production during the twentieth century, 1904–2015. Agrekon 58, 21–41 (2019).

    Article  Google Scholar 

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We acknowledge and thank the South Africa Agricultural Research Council–Grain Crops Institute (ARC-GCI) for providing access to the data used in this study. All opinions expressed in this paper are the authors’ and do not necessarily reflect the policies and views of ARC-GCI.

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Authors and Affiliations



A.M.S., J.B.T., L.L.N., P.C. and S.M. conceptualized the study and performed research. P.C. and S.M. collected and synthesized data. A.M.S., J.B.T. and L.L.N. designed the study. A.M.S. and J.B.T. analysed data. A.M.S., J.B.T. and L.L.N. wrote the manuscript. A.M.S., J.B.T., L.L.N., P.C. and S.M. revised the final manuscript.

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Correspondence to Aaron M. Shew.

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The authors declare no competing interests.

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Peer review information Nature Food thanks G. Slafer, S. Smyth and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary Tables 1–3 and Fig. 1.

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Shew, A.M., Tack, J.B., Nalley, L.L. et al. Yield gains larger in GM maize for human consumption than livestock feed in South Africa. Nat Food 2, 104–109 (2021).

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