In his letter to the editor, “Serious solution needed for excess manure,” (February 2007), Tom Weiland asked me to address the question “If the land application of animal waste is banned, what should be done with it?” based on my commentary, “Bay cleanup a waste of time unless we seriously address manure” (December 2006).
There is absolutely no doubt that agricultural fertilization practices are the largest source of nitrogen and phosphorus pollution in the Chesapeake Bay. There is absolutely no doubt that animal waste is the least efficient method of fertilization in common use.
Banning land application would be simple. Although poultry litter causes the most pollution, sewage sludge is the form of animal waste that is the most dangerous from a human health perspective. What would be the cost of a ban on the land application of municipal sewage sludge and how would the sludge otherwise be disposed?
The often-touted economic benefit of land application for farmers is miniscule. In Virginia, municipal sewage sludge is spread on 50,000 acres annually, out of about 4,300,000 acres farmed. The vast majority of Virginia farms are obviously profitable without using sewage sludge in lieu of chemical fertilizer. According to the Virginia Joint Legislative Audit and Review Commission report #89, the average savings, about $56/acre, means the total savings for farmers, statewide, is about $3 million each year. The recreational value of Chesapeake Bay and citizen’s “willingness to pay” to improve water quality vastly exceeds $3 million each year by any estimate (e.g., Rebecca Hanmer’s commentary “Chesapeake’s value worth more than the sum of its parts,” October 2004).
In Virginia alone, banning the land application of municipal sewage sludge would keep about 4.4 million pounds of nitrogen that have no benefit to crops from being disposed on fields. As reported in the February 2007 Bay Journal, the cost of upgrading the Blue Plains wastewater treatment plant to eliminate a similar amount of nitrogen pollution is between $500 million and $1 billion!
Two alternatives to land application are obvious—landfilling and incineration.
Take landfilling, for example. The Blue Plains wastewater facility generates about 1000 (wet) tons of sludge each day, lime-stabilizes it and land applies it. If the 365,000 tons per year were landfilled at a cost of $30/ton for tip fees, the cost to the 2.2 million customers would be about $11 million. Each customer would see their annual bill increase by no more than $5, the equivalent of two bags of junk food, each year.
Landfilling “wastes a valuable resource” according to sludge advocates. That is true, albeit less important than it is for aluminum cans and many other non-renewable resources our society refuses to recycle.
But land application also wastes a valuable resource. Animal waste, especially poultry litter, is phosphorus-rich. Phosphorus is a nonrenewable resource that is obtained by mining. The reserves of high-grade phosphorus ore will be consumed in the lifetimes of children being born today at current rates of extraction.
Because animal waste contains nitrogen and phosphorus in sub-equal amounts, and plants require much more nitrogen than they do phosphorus, nutrient management plans based on nitrogen overapply (wastefully dispose of) phosphorus.
Most (85 percent) poultry litter is land-applied in Virginia with no nutrient management plan at all. According to Dr. A. N. Sharpley, (editor of “Agriculture and Phosphorus Management: The Chesapeake Bay”, 1999, CRC Press, p. 66). “much of the crop land in the Chesapeake Bay watershed is now considered “optimum” or “excessive” in phosphorus from an agricultural perspective and hence needs little additional phosphorus, from any source, to ensure that economically optimum crop yields are attained.”
In my December commentary, I documented the amount of nitrogen in sewage sludge that was disposed in March of 2004 on 72.4 acres in Northumberland County, to no benefit of crops. For that same example, the soil in five fields, encompassing 55.9 acres, tested “very high” in phosphorus. This acreage should have received no phosphorus, according to Virginia Statute 12VAC5-585-550.A “The applied nitrogen and phosphorus content of biosolids shall be limited to amounts established to support crop growth.” and the Department of Conservation and Recreation’s “Crop Nutrient Recommendations.” According to the Virginia Department of Conservation and Recreation’s “Nutrient Management Standards” (p. 59) the remaining 16.5 acres, based on soil tests for phosphorus, should have received no more than 1,151 pounds of phosphorus. In fact, 10,912 pounds of phosphorus were disposed of, the equivalent to nearly 2,000, 50-pound bags of 10-10-10 in excess of crop needs, enough to fertilize 100 acres “low” in soil phosphorus.
The Virginia Department of Health ignored the Virginia Administrative Code statute (See my correspondence with State officials posted at www.VaBayBlues.org.) so as not to restrict land application, resulting in the massive over-application of phosphorus, unnecessary pollution by both nitrogen and phosphorus and a waste of a non-renewable resource.
The incineration of the animal waste, or the residue after methane extraction, is another disposal practice readily available and already in use. Incineration of a “biofuel” does not contribute to global warming because the carbon is already part of the biosphere and no “fossil” carbon is added to the atmosphere.
Charles Wachsmuth advocated another use for animal waste, “Manure digestion could provide chicken farmers with power, income” (February 2007), which would precede incineration. Anaerobic (in the absence of oxygen) digestion yields methane gas. Even a properly designed landfill can be “harvested” for methane, and some landfills flare the gas for safety reasons and to keep it out of the atmosphere (Methane is a more potent greenhouse gas than is carbon dioxide.) The microbial processes that produce methane can be enhanced by thermal and chemical manipulation.
Are methane extraction, incineration and phosphorus recovery economic? I suspect if the land application of animal waste were banned by 2010, the year we will fail to meet the long-touted nutrient reduction goals for Chesapeake Bay, and TMDL caps are supposed to be imposed, market forces will rapidly demonstrate the economic viability of alternatives to land application. As the price of fossil fuel rises and as the environmental costs of pollution are honestly cost-accounted, using animal waste as biofuel, and recovering the phosphorus, will prove cheaper than land application.
Does society prefer marginally higher profits for a very few farmers ($1,173 per farm according to the JLARC report) and inconsequentially lower wastewater bills for citizens of municipalities, or improved water quality in Chesapeake Bay?
The sooner the least efficient method of fertilization—the land application of animal waste—is banned, the sooner we will begin to meaningfully reduce pollution of Chesapeake Bay by agricultural fertilization practices, and the sooner market forces will provide alternative means of disposal.