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. In South Africa, GM white maize has been grown for direct human consumption, whereas GM yellow and conventional hybrid maize have been cultivated primarily for livestock feed. Across 106 locations, 28 years, 491 cultivars, and 49,335 dryland and 9,617 irrigated observations in South Africa, GM maize showed increased mean yields over conventional hybrid maize, and GM white maize showed higher increased yields than GM yellow maize.