Biotechnology 'No Sure Fix' for World's Nitrogen Fertilizer Pollution Problem, New Report Finds
WASHINGTON (December 9, 2009) – After more than a decade of effort, the biotechnology industry has yet to produce any commercial crops engineered to reduce nitrogen fertilizer pollution, while traditional breeding and other methods have improved the nitrogen use efficiency of wheat, rice, and corn by about 20 percent to 40 percent, according to a report released today by the Union of Concerned Scientists (UCS).
"Nitrogen pollution is among the world's worst environmental problems," said Doug Gurian-Sherman, a senior scientist in UCS's Food and Environment program and author of the report. "A number of very promising solutions have begun addressing the problem, but so far genetic engineering has yet to make a contribution."
Plants, including commodity farm crops, need large amounts of nitrogen to thrive and grow. Soils often do not contain enough nitrogen for plants to attain optimal productivity, but many farmers apply far more synthetic nitrogen fertilizer to their soils than what the plants can use. More than half of the nitrogen fertilizer applied on U.S. farms, for instance, is not absorbed by crops, and much of it becomes a pollutant.
Nitrogen pollution causes harm in multiple ways. Chemical fertilizers from farms, for example, are the largest contributor to the Gulf of Mexico's "dead zone"—an area the size of Connecticut and Delaware combined where excess nutrients indirectly rob the region of oxygen, making it uninhabitable for commercially valuable fish and other marine life for much of the year. In addition, nitrogen in the form of nitrate can seep into drinking water and become a health risk, especially to pregnant women and children. Nitrogen entering the air as ammonia, meanwhile, contributes to smog, respiratory diseases and acid rain, which damages forests and other habitats.
Nitrogen overuse in agriculture also is the largest domestic, human-caused source of nitrous oxide, a global warming gas that is nearly 300 times more potent than carbon dioxide. According to the Environmental Protection Agency, agricultural soil management accounts for two-thirds of the nation's human-induced nitrous oxide emissions.
One solution to the nitrogen overload problem is to develop crops that use nitrogen more efficiently, which would reduce the amount of nitrogen fertilizer farmers apply to their fields. Traditional breeding methods have already proven successful at doing this. Meanwhile, the biotechnology industry has identified genes that have the potential to reduce nitrogen pollution and have tested them in laboratories and field trials, but none are commercially available. The UCS report, "No Sure Fix: Prospects for Reducing Nitrogen Fertilizer Pollution through Genetic Engineering," evaluated the new genes and concluded that the prospects for their commercial use are uncertain due to the complexity of nitrogen metabolism and genetics in crops.
The report documents a number of practices that can complement nitrogen-efficient crops in reducing nitrogen fertilizer pollution. Precision farming, for instance, times fertilizer applications to match crop growth, which reduces the amount of nitrogen applied to fields. Farmers also can grow cover crops—plants grown between cash crop growing seasons—to protect the soil, add organic nitrogen and other nutrients, and remove excess nitrogen. Even if genetically engineered crops were commercially viable, they would not be able to reduce the large amount of nitrogen pollution that occurs when farmers are not growing cash crops.
"We need to pursue all reasonable approaches to solve the nitrogen overload problem," said Margaret Mellon, director of UCS's Food and Environment Program. "We should focus first on making the necessary public investment in traditional crop breeding, cover crops, precision farming, and other proven approaches to boost nitrogen efficiency. Our nitrogen pollution problem will only worsen as global food demand increases, which makes it all the more critical that we invest in technologies and methods we know work."