Food production is affected by numerous factors, such as the amount of rain the crop receives, the quality of the soil, the number of weeds that compete for soil nutrients and moisture and the number of insects that feed on the crop. GMOs can’t address all of these factors, but they can address two important ones: weeds and insects.
Each weed that grows in a field takes soil nutrients and moisture away from a food plant. The more resources that are used by weeds, the less food that is able to be produced. Twenty-five years ago, South African researcher JN Marais argued that poor weed control was the single largest contributor to low crop yields. The genetic modification of plants to be tolerant to chemicals has improved weed control by the farmers that adopt GM crops. Fewer weeds in the fields, especially of small landholders in developing countries, results in higher yields as the soil nutrients and moisture are used by the food crop, rather than weeds.
Insects also feed on food crops by eating the plant, which stresses the plant, resulting in lower yields. The genetic modification of plants to be resistant to insects, results in less insect damage to plants and therefore higher yields. When plants are able to spend less energy defending against insects, they are able to devote most of these resources to producing seeds, resulting in higher yields.
Taken in combination, improved weed and insect control, strongly contribute to increase the yield of GM crops. In a 2014 analysis of 147 published articles, Klümper and Qaim estimate the yield of GM crops is 22 percent higher than the yield of conventional crops. The yield increases that result from fewer weeds and insects contribute to increased food production.
Klümper, W., Qaim, M., 2014. A meta-analysis of the impacts of genetically modified crops. PLOS One 9 (11), 1-7.
Marais J N, 1992. FSR-E Newsletter No. 4, November 1992. Southern African Association for Farming Systems Research- Extension, Development Bank of Southern Africa, Halfway House, South Africa. p8.