Biotech Reduces Pesticide Use
Hunter, Beatrice Trum, Consumers' Research Magazine
The possibility of reducing pesticide use through modern biotechnology, popularly known as genetic modification (GM) is attractive to farmers and consumers. In a poll taken of both groups in August 1999, 73% of consumers reported that they were willing to accept gentically modified crops as a means of reducing pesticide use in food production. Also, 68% of the respondents regarded pollution of ground and surface water from chemicals as a major problem. Has the adoption of GM crops resulted in reduced pesticide use?
Gathering the Facts. Information exists on pesticide use, both by farmers who opt to plant GM crops and those who choose to continue raising non-GM crops. Characteristics that affect this decision may influence pesticide use choices as well. Thus, simply comparing the two groups does not yield a satisfactory answer. Also, the changing mix of pesticides involved in the GM or non-GM choice complicates the analysis, because characteristics such as toxicity and persistence of pesticides in the environment varies, depending on which pesticides are used. (See sidebar on page xx.)
In attempting to estimate the changes in pesticide use resulting from choosing to plant GM or non-GM crops, agricultural researchers from the U.S. Department of Agriculture (USDA) used three different statistical methods. They measured the differences within the same year, differences from year to year, and estimated differences of pesticide use between two years using an econometric model that controlled factors other than GM crop adoption that might influence pesticide use.
The researchers used national data from the 1996-1998 Agricultural Resource Management Study, conducted by two divisions within the USDA; the National Agricultural Statistics Service, and the Economic Research Service. The data included information on adopting GM with major crops (varieties of corn, soybeans, and cotton), as well as the number of pesticide applications, and the amounts of specific pesticides used.
Interpreting the Facts. The same-year differences between the average pesticide use by GM and non-GM crop growers were measured. In 1997, the combined numbers of GM crop growers of corn, soybeans, and cotton used 7.6 million fewer pesticide acre-treatments than non-GM crop growers. (An acre-treatment represents the number of acres treated, multiplied by the number of pesticide treatments.) The following year, the differences increased to nearly 17 million fewer acre-treatments by the GM crop growers.
The year-to-year differences were measured between 1997 and 1998 by acre-treatments. Collectively, in 1997, the GM crop growers used 7.6 million fewer pesticide acre-treatments than non-GM crop growers. By 1998, the difference more than doubled, with nearly 17 million fewer acre-treatments by GM crop growers. This was achieved mainly by planting herbicide-tolerant GM soybeans. In 1997, in terms of active ingredients used in pesticides, GM crop growers used 331,000 pounds fewer than non-GM crop growers. This represented less than 0.1% of the total number of pounds of chemical treatment applied. By 1998, the difference narrowed still further, to only 153,000 fewer pounds applied. (The reduction of active ingredients applied in 1997 was related to Bt cotton and herbicide-tolerant soybeans, restricted to the Southern Seaboard area of the United States. In 1998, herbicide-tolerant cotton and Bt corn accounted for most decreases, nationwide.)
The year-to-year differences in total pesticide use between 1997 and 1998 (adjusted for changes in acres planted, and including both GM and non-GM crops) totaled 9 million fewer pesticide acre-treatments. Although GM crops lead to less pesticide use, acre-treatments by GM crop planters collectively increased by 49 million between 1997 and 1998, whereas acre-treatments by the shrinking number of non-GM crop planters decreased by 58 million. This change resulted in 3.2 million fewer pounds of active pesticide ingredients applied. …