In New Century, New Corn Could Cut Phosphorus Pollution

By Jim De Quattro
February 20, 1998

The water-quality threat from phosphorus in chicken and pig manure could be greatly reduced by a new type of feed corn that is low in phytic acid. Seed of the new corn could be available to farmers as soon as the year 2000.

The first license for using the technology was awarded this month by USDA's Agricultural Research Service, which developed and patented the new low-phytic-acid corn. Phytic acid, plentiful in regular corn, stores phosphorus in a form unusable by animals with one stomach, including poultry, pigs and fish. Instead, much phosphorus winds up in the animals' manure. Rain can carry the phosphorus to waterways, nourishing algae that consume the water's oxygen and choke out other aquatic life.

Phosphorus loss to manure is 25 to 40 percent less with the low- phytic acid corn discovered by ARS geneticist Victor Raboy in Aberdeen, Idaho. Research could lead to larger reductions in phosphorus loss to manure.

To enable wide use of the discovery, ARS is negotiating licenses with small and large companies that produce hybrid corn seed. The first license was signed two weeks ago with Pioneer Hi-Bred International, Johnston, Iowa. Pioneer and other companies are breeding the trait into elite corn plants. Commercial hybrids may be released next year, but only if the plants exhibit critical traits including desirable yield, nutritional qualities and pest and disease resistance.

Excess phosphorus pollutes many bodies of water such as the Chesapeake Bay. In some Bay tributaries, phosphorus is suspected-- though not proven--as one culprit in fish-killing bacterial blooms.

Click here to read a December 1996 story about Raboy's research on low-phytic acid corn.

The most promising new corn plants identified by Raboy and colleagues reduce phytic acid by two-thirds without reducing total phosphorus. In preliminary tests, low-phytic corn seeds have germinated well and in some cases yielded as well as regular hybrids. In other tests, low-phytic-acid corn fed to chickens resulted in less phosphorus in manure. Raboy has expanded the research to rice, barley and wheat, in which phytic acid also ties up phosphorus. He is based at ARS' Small Grains and Potato Germplasm Research Unit in Aberdeen.

Cattle and other animals with multiple stomachs have natural enzymes that break down phytic acid. Feed for one-stomached animals can be treated with similar enzymes. But hybrids with the low-phytic trait could be a less expensive, more sustainable strategy.

Scientific contact: Victor Raboy, USDA-ARS Small Grains and Potato Germplasm Research Unit, Aberdeen, ID 83210, phone (208) 397-4162, fax (208) 397-4165, vraboy@uidaho.edu.