News | May 6, 2017
Do GM Crops Increase Yield?
Since the advent of biotechnology, there have been a number of claims from anti-biotechnology activists that genetically-modified (GM) crops don’t increase yields. Some have claimed that GM crops actually have lower yields than non-GM crops.
Both claims are simply false.
In agriculture, desirable crop characteristics are known as traits. One of the most important traits is yield. Improving crop yield can be accomplished through both breeding and biotechnology. GM crops generally have higher yields due to both breeding and biotechnology.
Germplasm is the basic genetic information in a seed that influences the growth and development of the plant. For example, germplasm for different varieties of tomatoes may vary in pest and disease resistance, drought tolerance, color, size, yield potential and many other characteristics.
Starting long before modern biotechnology, plant breeders have worked to improve germplasm--for example, to develop seeds with the best mix of characteristics to deliver the best yield possible for the soil and climatic conditions where they will be grown.
Today, plant breeders use a mix of both traditional and modern methods to improve plants. Modern methods include marker assisted breeding, which enables breeders to use a blueprint of the genome to select seeds with the most desirable properties. Marker assisted breeding in effect helps speed up the time it takes to do traditional breeding--breeders can better select whether to cross tomato A with tomato B, or C, or D, or E, or F, or …--you get the idea--to get the desired improvement.
Biotechnology is a more direct approach than breeding since it allows you to incorporate genetic material directly into the germplasm. This allows you to create plants with traits that would be difficult or impossible to achieve through breeding. In some GM crops, the genetic material originates from another species. The most common traits in GM crops are herbicide tolerance (HT) and insect resistance (IR). HT plants contain genetic material from common soil bacteria. IR crops contain genetic material from a bacterium that attacks certain insects.
Yield can be increased by breeding and through the addition of GM traits.
Germplasm improvements from traditional breeding have contributed to modest but steady increases in yield. Marker-assisted breeding has nearly doubled the rate of yield gain when compared to traditional breeding alone.
GM traits, such as insect and herbicide tolerance, help to increase yields by protecting the yield that would otherwise be lost due to insects or weeds. The degree to which a farmer enjoys increased yields because of insect and herbicide tolerance traits will in large part be determined by how effective the farmer’s weed and insect control programs were before planting a crop with these traits. If weeds and insects had been controlled well, then the insect and herbicide tolerance traits will not be the primary factor in increasing yield.
In developing countries, where resources to effectively control weeds and insects are often limited, these traits have increased yield substantially. The same is also true for developed countries where there are particular pests that are hard to control--such as the corn rootworm complex or some perennial weeds.
The introduction of GM traits through biotechnology has led to increased yields independent of breeding. Take for example statistics cited by PG Economics, which annually tallies the benefits of GM crops, taking data from numerous studies around the world:
- Mexico - yield increases with herbicide tolerant soybean of 9 percent.
- Romania – yield increases with herbicide tolerant soybeans have averaged 31 percent.
- Philippines – average yield increase of 15 percent with herbicide tolerant corn.
- Philippines – average yield increase of 24 percent with insect resistant corn.
- Hawaii – virus resistant papaya has increased yields by an average of 40 percent.
- India – insect resistant cotton has led to yield increases on average more than 50 percent.
Even where insect and herbicide tolerance are not the primary factors in increasing yield, they provide many other benefits. Analysis by PG Economics also show that GM crops are credited with decreasing pesticide and fuel use, and with facilitating conservation tillage practices that reduce soil erosion, improve carbon retention and lower greenhouse gas emissions. Decreased inputs aren’t just a savings and convenience for farmers; they offer significant environmental benefits for everyone:
- The reduction in greenhouse gas emissions associated with GM crops for 2006 is estimated to be equal to removing more than half a million cars from the road.
- On average, the volume of herbicide used on corn has dropped 20 percent since herbicide tolerant corn was introduced in 1996.
Approximately 95 percent of the soybeans and 75 percent of the corn in the United States are GM. More than 95 percent of the soybeans in Argentina and half the soybeans grown in Brazil are GM. Where given the choice, farmers have consistently adopted GM crops quickly and widely because they see the improvement these products deliver. Whether it is increases in yield, or other benefits, farmers clearly see value in GM crops.
Misinformation and Setting the Record Straight
Irresponsible journalists and activists continue to misrepresent data and claim that GM crops actually reduce yields. For example, Geoffrey Lean recently published a story in the UK newspaper The Independent entitled Exposed: the Great GM Crops Myth. Lean concluded that yields were lower with GM crops based in large part on a study published by Dr. Barney Gordon of Kansas State University. Lean failed to understand or explain that the purpose of Gordon’s research was not to examine yields, but to look at how certain GM soybean varieties respond to manganese levels. Dr. Gordon has since published a response which characterizes the article as “a gross misrepresentation of my research and a good example of irresponsible journalism”.
Despite Dr. Gordon’s clarification and statements, some anti-GMO activists continue to reference the Gordon study and the Lean article as evidence of lower yields with GMOs. Dr. Mae Wan Ho of the Institute for Science in Society cited the Gordon study as evidence that biotech crops do not increase yields. The Center for Food Safety also referenced the study as evidence of decreased yields.
Monsanto and other agricultural technology companies continue to improve germplasm, and to develop GM traits that are designed to directly increase yield, and more. In 2009, Monsanto released a line of soybeans in the US that has been shown in field trials to increase yields by 7-11 percent. We’ve made a public commitment to double yields in key crops by 2030. Equally important to increasing yield, we’ve committed to doing so with one-third fewer resources, such as fertilizer and water, per unit of output.
Last Updated: 11/26/2012