U.S. farmers plant more stacked corn and cotton
Adoption of genetically engineered (GE) crops by U.S. farmers has increased steadily the past 15 years, according to a 2014 USDA–Economic Research Service report.
Farmers planted about 170 million acres of GE crops in 2013—mainly corn, cotton and soybeans, representing about half of the U.S. farmland used to grow crops.
Yield quest. Average Bt corn yields have increased as new insect resistance traits have been incorporated into seed and stacked traits (seeds that contain several GE traits) have become available.
Most experimental field tests and farm surveys show that Bt crops produce higher average yields than conventional crops. USDA’s Agricultural Resource Management Survey (ARMS) data shows Bt corn yields were 17 bu. per acre higher than conventional corn yields in 2005 and 26 bu. per acre higher in 2010. Moreover, there was a 10% increase in the rate of Bt corn adoption associated with a 1.7% increase in yields in 2005 and a 2.3% increase in yields in 2010.
Evidence showing the impact of herbicide-tolerant seeds on corn, soybean and cotton yields is mixed. Some researchers have found no significant difference between the yields of adopters and non-adopters of herbicide-tolerant seed. Others have found that herbicide-tolerant adopters had higher yields, while still others have found that adopters had lower yields.
An analysis of ARMS corn data indicates stacked seeds have higher yields than conventional seeds or seeds with only one GE trait. In 2010, ARMS data showed conventional corn seeds had an average yield of 134 bu. per acre. Seeds with two types of herbicide tolerance (glyphosate and glufosinate) and three types of insect resistance (corn borer, corn rootworm and corn earworm) had an average of 171 bu. per acre.
Not surprisingly, adoption of stacked seed varieties have increased quickly, from 1% of planted acres in 2000 to 71% in 2013. Varieties with three or more traits are now common.
U.S. farmers are increasingly planting corn and cotton hybrids with stacked traits, rather than insect- or herbicide-only seed products.