Biotech Revolution on the Farm Yields Mixed Results

July 16,1999

A new USDA study shows that most of the time, differences in yields are statistically insignificant for herbicide-tolerant crops compared to traditional varieties. For the Bt crops, the results are more spectacular.

"Most of the time," the study says, (four of five cases for corn, nine of 13 for soybeans and three of five for cotton) "differences in yields are statistically insignificant" with herbicide-tolerant crops. "Only for a few regions and in some years are yields higher for adopters."

However, farmers who use herbicide-tolerant varieties find statistically significant reductions in herbicide treatments in half the cases across all crops, mostly for soybeans.

Farmers who adopt Bt cotton, however, "appear to obtain statistically significant higher yields than" those who do not adopt the technology. "Although less prevalent, similar results (two of five cases) were observed for Bt corn," the study adds.

"Despite environmental concerns about increased weed and insect resistance resulting from the use of herbicide-tolerant and insect-resistant crops, farmers believe that the use of these crops will offer many benefits, such as increased yields, decreased pest management costs and greater cropping practice flexibility," says the study.

"Benefits and performance of these crops are expected to vary greatly by region, pest infestation levels, seed and technology costs, irrigation and other factors," the report continues. "Performance may improve after development of popular regional varieties containing these genes to ensure yield advantages. For many farmers, expected benefits appear to have outweighed expected costs, as evidenced by the rapid adoption rates."

In 1997, the effect of adopting herbicide-tolerant soybean seeds created a very small yield increase. The effect on variable profits was not statistically significant as slightly higher adopters' revenues and lower herbicide costs "were not able to compensate for the higher adopters' seed costs and technical fees," according to the study.

The web site for the report is www.econ.ag.gov/whatsnew/issues/biotech/index.htm.