Bay Journal

Animal waste causes too great a share of Bay’s pollution to ignore

  • By Lynton S Land on March 01, 2010
Improving agricultural fertilization efficiency is necessary if we want to improve Bay water quality.  (Dave Harp)

In "Call for complete ban on land application of manure is unfounded," (December 2009) Chase Tanner disagreed with my advocacy that the land application of animal waste must be banned. He still does not quantitatively comprehend how the practice of disposing huge amounts of waste far from where the animals are grown causes about one quarter of the Bay's nutrient pollution.

Conventional chemical fertilization, used on the vast majority of farm fields in the Bay, accounts for about one quarter of Bay nutrient pollution. As an actual example, using averaged data published in the 2004 and 2005 Virginia On-Farm Corn Test Plots, 162 pounds of conventional nitrogen fertilizer were applied per acre to yield an average of 174 bushels of corn grain. The "Nitrogen Use Efficiency" (NUE = pounds of nitrogen harvested with the grain / pounds nitrogen applied) was 72 percent, assuming 56 pounds/bushel at 15 percent moisture and 1.4 percent nitrogen in the dry grain. Conventional chemical fertilization of one acre released about 46 pounds of nitrogen into the environment (162 - 116, where 116 = 174* 56* 0.85* 0.014*), most of which is pollution.

Acid raid deposits about one tenth of that amount of nitrogen per acre. When fertilizer is applied only at the time of planting, large amounts of nutrients wash out before they benefit the growing plants. Nitrogen retained in the soil for the next crop is balanced by nitrogen in the soil from the last crop.

How can pollution be reduced without impacting farm productivity? Applying fertilizer as the crop grows (side-dressing or split fertilizer application) uses less fertilizer but takes time, fuel and causes soil compaction. Growing a cover crop is additionally costly in seed. The development and mandated use of slow- or timed-release fertilizers is the best way to widely achieve increases in the efficiency of conventional chemical fertilization.

The land application of animal waste, about half of which is poultry litter, constitutes another quarter of the Bay's nutrient pollution, as the director of EPA's Chesapeake Bay Program Office states in a letter I received on March 25, 2009. The letter is also posted on the "Correspondence" page at www.VaBayblues.org).

About 250,000 tons of sewage sludge are applied on about 50,000 acres annually in Virginia, and about 550,000 tons of poultry litter are disposed of, probably on about twice that acreage. Litter application is still not meaningfully regulated in Virginia and nutrient management plans are still not required, despite recent regulatory changes. At least 4 million acres are farmed in Virginia, so a very small fraction of farm acreage causes a disproportionate amount of pollution.

Sewage sludge is the least efficient of the animal waste "fertilizers" and is legally applied in Virginia assuming that 30 percent of the nitrogen will be available to the succeeding crop. To supply the equivalent of 162 pounds of conventional nitrogen fertilizer, 540 (162/0.3) pounds of nitrogen are applied on each acre. The NUE is reduced to 21 percent (116/540), meaning that nearly 80 percent of the applied nitrogen (424 pounds per acre, or 540 minus 116) is not sequestered in the grain and is released to the environment.

Contrary to Tanner's assertion, there are only tiny amounts of inorganic nutrients in sewage sludge. Acid rain deposition is about 1 percent of 424 pounds of nitrogen per acre.

Tanner is incorrect in touting animal waste as a useful form of "timed-" or "slow-release" fertilizer. A spring crop fertilized with animal waste and drying in the field prior to harvest in late summer is no longer taking up nutrients, but the microbes are still active in the warm soil, decomposing the organic particles and releasing the nutrients to the environment. Most of the nutrients are wasted, especially in polluting the shallow groundwater, which U.S. Geological Survey studies show contributes about half of the nitrate load to the Bay.

Runoff is not the only source of pollution from agricultural fields. The Virginia Department of Conservation and Recreation recommends that chemical fertilization be reduced for three years after the land application of sewage sludge and assumes that an additional 25 percent of the applied nitrogen could become crop-available.

Even if farmers reduce chemical fertilization accordingly, and there is no evidence that they do so, the NUE would still be only 39 percent (116 / (162 / 0.55)), not too much lower than the NUE for poultry litter of 43 percent (116 / (162 / 0.6)) if recommended-but not required-disposal rates of the largely unregulated waste are followed.

After quoting some of his victories, Gerald Winegrad, the former Maryland state senator who was instrumental in legislating the ban on phosphate detergents stated: "Also notable are defeats, including my most regrettable failure, my repeated attempts to require mandatory controls on agricultural pollution, the largest single factor causing the Bay's decline. This legislative push (1989-94) could not overcome the opposition from the farm community, the agricultural lobby and their supporters in the government, and from the Schaefer [state] administration. These mandatory controls are still lacking and are pivotal to Bay restoration." (Emphasis is mine from his "Guest Entry" in Howard Ernst's book, "Fight for the Bay.") Truer words were never spoken.

Agricultural fertilization efficiency must be enhanced and pollution from urban sources must be reduced if Bay water quality is to improve. There are no alternatives. Forget acid rain, septic systems, landscape fertilization, etc. These sources of pollution are tiny compared to "the big two" and thus just waste limited resources and distract the public from understanding that there are only two major sources of pollution: agriculture, which constitutes half of the Bay's pollution, and urban infrastructure, which contributes one-third of the Bay's pollution.

The cumbersome total maximum daily load process touted by the EPA will merely "budget" actions among watersheds and is certain to lead to litigation as entities attempt to reduce the inflicted economic "pain" by challenging EPA's numbers. TMDLs have evolved from a simple ranking "based on a total maximum daily load or other waste limit allocation" (my emphasis) to quote the Clean Water Act, to an indefensibly overquantified bureaucratic nightmare.

A far simpler, more equitable and faster approach is to mandate a few undeniably meaningful actions watershedwide, now. Ban the land application of animal waste disposed out of trucks immediately and tax conventional, but not timed-release, fertilizer by some reasonable date. Upgrade the most polluting urban infrastructure now, creating badly needed jobs at the same time. Municipal bonds can provide the capital for infrastructure upgrades, along with secure investments, ensuring that the cost is spread as widely and equitably as possible and that "the polluter pays."

Nobody advocates dumping raw sewage into the Bay to save the money needed to build or expand a wastewater facility. It is a small step to recognize that we must spend money to avoid dumping excess nutrients into the Bay.

There are no alternatives to improving agricultural fertilization efficiency and upgrading urban infrastructure if we want to improve Bay water quality and "establish a clear path to meeting, as expeditiously as practicable, water quality and environmental restoration goals for the Chesapeake Bay" (Executive Order of 05/12/09, Part 3, Sec. 301a).

If President Obama is serious about restoring our "National Treasure," he must force the entrenched bureaucracy of the "Economy Protection Agency" (EPA) to take immediate and meaningful action and spend our tax dollars on changes we know will be effective rather than on more of the same old cumbersome, slow and costly bureaucratic wheel-spinning as advocated by the Bay Program in "Draft Bay strategy outlines plans for clean water, restoration, climate change," (December 2009). There is absolutely no excuse to wait until 2025 for "all practices needed to restore the Bay and its local waterways" to be in place. We've heard it all before.

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About Lynton S Land

Dr. Lynton S. Land is emeritus professor of geological sciences at the University of Texas in Austin, and now lives in Virginia.

Read more articles by Lynton S Land

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