CHANGING THE DIETS of cows, pigs and chickens could help address the serious problem of runoff pollution from farms. Reducing animal manure, by altering livestock feeds, would mean less waste available to foul the Chesapeake watershed.
With agriculture accounting for nearly half the harmful nitrogen and phosphorus reaching the bay, that's no small factor. But the trade-off would be higher prices for consumers, as well as for the farmer.
The technology and policy that have provided Americans with low-cost food have also created a system that disrupts the natural agricultural cycle, overloading the environment with excess chemicals and manure that flow off the land into our waters.
Les Lanyon, a Pennsylvania State University soils scientist, explains that the use of cheap, efficient chemical fertilizers has reduced the need for animal manure to enrich croplands. And livestock feeds imported from other parts of the country reduce the need for farmers to grow their own crops to feed their #F animals. "Instead of a cycle (of crops to animals to fertilizer), there is actually the potential for nutrient accumulation on the animal farm," he warns.
While crop farmers have become more efficient in their use of chemical fertilizers, livestock farmers still struggle to find solutions for their animal waste. Holding tanks and other containments are the most common methods; there's a limit to how much can be assimilated by over-saturated farm fields.
Specialized feeds could reduce animal waste at the source, experiments show. Adding the enzyme phytase to pig feed, for example, can significantly decrease the amount of phosphorus excreted; it's used by hog farmers in the Netherlands, where strict manure regulations make it practical.
Specialized feeds are more expensive. Finding the right biological balance for a particular farm is a complex task, even with eventual economies in more efficient feeds. But agricultural researchers are looking harder at this approach, as the problem of farm runoff becomes more acute. The burden is not just on farmers; consumers must share the responsibility for reducing waste runoff in our waters.
Pub Date: 4/21/96