Manure use is a dirty habit


Pollution: Management of animal waste needs to be a priority in the watershed for a healthy bay.

April 30, 2004|By Tom Horton | Tom Horton,SUN STAFF

MARYLAND'S governor and legislature, by passing the "flush tax," have taken a bold new step to clean up sewage. But now's no time to smell the roses.

It's time now to tackle manure - the back side of foamy white milk and luscious golden chicken - flowing bounteously from farms throughout the bay's six-state watershed.

I have nothing against manure. It smells like home to me. Mom would corral me as a toddler in the feed bin as she pushed it through our chicken houses.

When we cleaned the houses out, the dog and I reveled in the fragrant piles outside our log cabin (yes, log cabin - it's still on Spearin Road near Salisbury - and no, I'm not 100 years old).

The time was when greenies and aggies alike could agree manure was a good basis of farm production - animal wastes spread back on the fields that fed the cows - an ecologically satisfying recycling of nutrients.

But the modern reality is a bay watershed whose farms produce tens of billions of pounds of manure annually, part of the reason farming is the largest source of bay pollution.

The problem isn't just the amount of manure. It's the concentration. Modern agriculture has packed cows, hogs and poultry onto farms at average densities up to 100 times greater than when I was a kid in the 1950s.

To feed them all, farmers import grain, and the nitrogen and phosphorus in it, from across the bay watershed, nation and globe.

With no way to send the excesses of these nutrients in manure back where they came from, they've spread them lavishly on fields around animal production centers like the Delmarva Peninsula, Lancaster County, Pa., and Virginia's Shenandoah Valley.

Maryland and other bay states, to remedy the pollution this causes, are requiring farmers to use no more manure than it takes to fulfill a crop's nitrogen and phosphorus needs. This "nutrient management" is a good start. Manure remains, as the farm community likes to say, "a valuable resource." It's cheap and provides good yields.

But manure's got some bad habits, and unless we recognize them, we're going to be disappointed in our attempts to restore the bay to health.

Many farms, for example, need lots of nitrogen annually, but little or no phosphorus. With commercial fertilizers, you can buy these nutrients separately. But manure has lots of both, and you can't separate them.

Hauling manure to fields that need both nitrogen and phosphorus is only a partial solution. Years of study by Ken Staver, a University of Maryland agricultural researcher, show that using poultry manure on such fields, instead of commercial fertilizer, significantly increases water pollution.

That's because manure quickly loses nitrogen to the air - from which it ultimately ends up in the water - unless the manure is worked into soils almost immediately.

No "nutrient management plan" requires working manure into soils, and it's hard to do on a lot of farmland, where plowing has been eliminated or minimized to cut soil erosion and save energy. Even where manure was tilled under, Staver found nitrogen and phosphorus were bigger pollution problems than with commercial fertilizers.

In Pennsylvania, the problem is especially tough. Manure there is predominantly from cows, very heavy and mostly water, and therefore harder to ship to far-flung fields than poultry manure.

Farmers there seldom work manure into the soil when spreading, even on hilly land. And they often spread it even when crops can't use it. Manure spread on frozen slopes last winter in Pennsylvania washed off in storms, closing a town water supply in Perry County and badly polluting a creek in Adams County.

Staver and other agriculture experts concede that manure probably can never be as good for water quality as commercial fertilizer, but argue that there's nonetheless huge room for improvement. They're right, but there are only token movements around the watershed toward that sort of progress. Nor are we giving much urgency to finding alternative uses for manure, given its inherent water-quality drawbacks as a fertilizer.

Some alternatives exist. Perdue, the poultry company, is making manure into an organic soil supplement, some of it marketed cleverly as Cockadoodle DOO. But markets for this remain small.

University of Maryland researchers say manipulating chickens' feed is significantly reducing the amount of phosphorus in their manure. Pennsylvania has pilot projects to use cow manure for on-farm energy. The process still leaves the nutrients, but in a more transportable, less smelly form. A long-shot alternative is to talk potting soil companies into using composted manure in place of peat moss.

All these, however, won't turn the corner on ag pollution soon, given the magnitude of the problem.

There is a mindset to reject alternatives for manure that would require a subsidy, such as burning it for electricity, or transporting it long distances for reclaiming strip mines. A "valuable resource" shouldn't be a money loser, the thinking goes. But who expects a profit from sewage sludge, a "valuable resource" we all pay to spread on farm fields?

Given the size of the bay's problem and the challenges in resolving agriculture's piece of the puzzle, we can't afford years of muddling with halfway, piecemeal solutions to manure.

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