No Financial Benefits from GM Crops, Says Study

January 24, 2002

Michael Duffy, associate director of the Leopold Center for Sustainable Agriculture at Iowa State University, says there are no financial benefits to farmers planting genetically modified corn or soybeans. Duffy repeated a study he conducted two years ago and again found that the use of genetically modified seed did not appear to have an impact on a farmer's bottom line for either corn or soybean production.

About 350 Iowa farmers were asked what crops they grew, and whether the seed they planted contained a GM organism. The survey covered all aspects of crop production including yields, pesticide and fertilizer use, seeding rates and the type and nature of machinery operations performed. The herbicide-tolerant soybeans averaged 43.4 bushels per acre while the non-tolerant soybeans averaged 45 bushels per acre. The percentage difference in yields was identical to the difference found in the 1998 crop year. In 1998, the yields were 49.2 and 51.2 bushels per acre for herbicide-tolerant and non-tolerant soybeans, respectively, according to Duffy.

The seed cost for herbicide-tolerant soybeans averaged $5.69 per acre more than the non-tolerant fields. In 1998, the difference was $7.53 per acre. The expense for non-tolerant soybeans was lower in 1998 while the expense for the tolerant varieties was slightly higher.

Average yield for GM corn was 152 bushels per acre. The average yield for the non-GM corn was 149 bushels per acre, Duffy said, less than the difference found in the 1998 study-160.4 bushels per acre for GM corn and 147.7 bushels per acre for non-Bt corn. The GM corn fields had slightly higher total fertilizer costs per acre. The GM fertilizer cost was $53.30 versus $48.67 for the non-GM fields, quite similar to the results found in 1998. Although no production reason exists for the higher fertilizer costs, it is believed that the GM fields are managed more intensively which leads to the increased fertilizer costs, said Duffy.

"If returns are not significantly different, why have we seen such an increase in the use of GMO technology?" asks Duffy. For herbicide-tolerant soybeans, "farmers answer that question by saying they can cover more acres more quickly and that they do not have to worry about weed management as they did in the past. For GM corn, farmers view use of GM seed as an insurance policy if there's an insect infestation. There are many such non-quantifiable benefits and costs associated with using GMO seeds."

Other observers note the widespread adoption of genetically modified crops by cotton, corn and soybean farmers. If farmers did not find GM crops economically advantageous, these observers argue, adoption rates would not be as high as they are. Farmers' actual behavior is the best indicator of whether GM crops are profitable, according to this viewpoint.