Two forum pieces in the November 2010 Bay Journal-"NY Phosphorus Index may not be perfect, but has served state well" and "Do we want to save the Bay by destroying other ecosystems?"-extol the virtues of agricultural management of phosphorus in New York and complain about the economic consequences to global society of banning the land application of animal waste in the Chesapeake Bay watershed. The authors all ignore three undisputed facts:
1. Inefficient agricultural fertilization practices are responsible for half of the Bay's nutrient pollution. In Virginia, if all point source discharge from wastewater treatment plants was lowered to the "limit of technology," pollution from stormwater was halved and combined sewage overflow eliminated, nitrogen pollution would be reduced less than 3 million pounds per year, far short of the reduction of 20 million pounds per year being required by the EPA. We have gone about as far as we can go reducing urban pollution. A nitrogen reduction of 20 million pounds per year can only be achieved by significant improvements in agricultural fertilization efficiency.
2. The land application of animal waste causes half of agricultural pollution, the same amount of Bay pollution as is caused by all the wastewater treatment plants in the watershed. Reducing the discharge from wastewater treatment plants is expensive and the discharge cannot be reduced to zero unless the water is recycled. The land application of animal waste, which takes place on less than 10 percent of farm acreage, can be reduced to zero with the stroke of a pen, with minimal economic impact.
3. Bay water quality is not improving. Whether or not the EPA's goal of reducing Virginia's nitrogen pollution by 20 million pounds per year and phosphorus pollution by 2 million pounds per year will achieve a significant reduction in the volume of the dead zone in summer and a significant increase in submerged aquatic vegetation remains to be seen. But it is clear that "tweaking" around the edges of the huge agricultural pollution problem, as is proposed in Virginia's most recent watershed implementation plan, will not achieve sufficient pollution reduction to result in meaningful water quality improvement. The land application of animal waste causes so much pollution that banning the practice in Virginia would achieve all of the EPA's mandated nitrogen and phosphorus reduction goals for the state.
Four scientists from Cornell defend New York's Phosphorus Index and document progress in reducing phosphorus pollution, largely from dairy cow manure. The authors do not address the increased nitrogen pollution caused by using manure rather than conventional chemical fertilizer. A much better strategy than the index to protect water quality is to use common sense and apply only the amount of phosphorus needed to grow the crop, about 32 pounds per acre according to the authors.
As a geochemist, I reject their statement that "the phosphorus index...is a practical and much more scientifically defendable option than limits based on soil test phosphorus..." Science dictates that to minimize water pollution and protect crop productivity, one must "Get the right nutrients in the right amount at the right time in the right place." The soil test phosphorus method comes much closer to achieving that goal than does the index.
When I complained to Virginia's Department of Environmental Quality that Virginia's phosphorus index is not sufficiently protective of water quality, they defended its use because "... dairy, poultry, swine and biosolids sectors have all voiced a strong desire to have an option to use the phosphorus index." No wonder. The Virginia index permits more phosphorus to be disposed than would be true if the soil test phosphorus method were used.
Why doesn't Virginia protect water quality by restricting phosphorus application "to amounts established to support crop growth" as the law requires? Because more land would be needed to dispose of the waste if the application was phosphorus-based instead of being nitrogen-based. In addition, the waste would need to be supplemented with chemical nitrogen fertilizer because the lower application rate could not supply sufficient nitrogen for the crop. Current government policies, including use of the phosphorus index, protect the profits of a few waste generators and users, not water quality.
Jeff Stoltzfus addresses larger issues, and is also focused on manure and not poultry litter or sewage sludge. He asserts that "a portion of the animal manure in the urea/ammonia form is chemically identical to fertilizer." That is correct for poultry litter and manure as anyone's nose can attest. But the problem is that a great deal of ammonia escapes to the atmosphere during the accumulation, storage, transport and application of animal waste, where it is oxidized to nitrate and rains out as pollution. The loss of ammonia from chemical fertilizer is much more controllable, although still a problem.
He further states: "The remaining nitrogen is in the organic form, which is a controlled-release nitrogen." He seems to understand the time frame-years-over which organically bound nitrogen is released to the environment by microbes, but he ignores the pollution that results when the microbes are active but the crop is drying in the field or the field is fallow. An efficient controlled-release chemical fertilizer is consumed by the time the crop matures so there is little or no remaining fertilizer to cause pollution. But a considerable excess of nitrogen must be applied in the form of animal waste because the microbial release of nitrogen is so slow and unrelated to crop uptake. The unavoidable inefficiency in nitrogen availability to the crop is the primary reason animal waste must be replaced with more efficient fertilizers.
I disagree with Stoltzfus' qualitative, unsubstantiated statement that "The carbon footprint and the environmental footprint of replacing manure [litter and sludge] with fertilizer is unacceptably high." This is an example of "cherry-picking economics." I can play that game too, arguing that because less than 10 percent of fields are fertilized with animal waste in the Bay watershed, if controlled release fertilizers, which contain less nitrogen and phosphorus, were used and animal waste used as a biofuel to replace fossil fuels, energy consumption would be reduced, as would the cost of pollution.
Both commentaries-along with most politicians and proponents of continuing current agricultural practices-ignore honest economics. The 2004 Blue Ribbon Finance Panel concluded that Chesapeake Bay is worth "Perhaps in excess of a trillion dollars to an economist." The value of the Bay to Virginia, hundreds of billions of dollars, greatly exceeds the value of animal waste disposal because all of agriculture and the poultry industry are each worth only a few billion dollars. Increasing the efficiency of agricultural fertilization will not be free and the best we can do is spread the increased cost widely and equitably.
But if we continue on our current path, favoring farm profits over water quality, chipping away at small fertilization inefficiencies and crying about global economic issues, Bay water quality cannot possibly improve meaningfully.