I have, over the last year, been engaged in a debate on these pages over the use of manure as a fertilizer. Several articles in the May Bay Journal prompt me to write again, and as long as I am doing so, I would like to set the record straight with respect to some comments Dr. Lynton Land has made in direct reference to me.
First, he stated that I don't "quantitatively comprehend how the practice of disposing of huge amounts of waste far from where the animals are grown" causes nutrient pollution. Actually, the problem is more that too much is disposed of too near where the animals are grown, and I certainly do understand. That is why in both of my previous commentaries-"Call for complete ban on land application of manure is unfounded," (December 2009) and "Throwing away manure is like throwing away money," (July-August 2009)-I have called for more options, including farm-scale and commercial biomass energy production as well as processing wastes into fertilizer products.
It is why, as a nutrient management consultant, I identify fields that should not receive manure and places where manure should not be stockpiled. And, it is why, as farmers, my husband and I maintain a stocking rate in balance with our land base; use a combination of perennials and double-cropping to keep the ground covered year-round; and in our first year of land ownership, planted trees in 32-foot buffer strips along ditch banks.
I have never claimed that pollution from animal manure isn't a problem, only that a total ban on land application isn't the solution.
Second, accord to Land, I asserted that sewage sludge contained significant amounts of inorganic nitrogen. I did not. My statement was that manure contains both organic and inorganic nitrogen. The ratios of organic to inorganic vary widely, depending not only on the source of the manure but also on the processing and storage. All of this must be accounted for when using manure as a nutrient source.
Third, manure, with its organic matter component and its ability to stimulate microbial activity in the soil, is, as I had stated, a useful form of slow-release fertilizer. The first-year mineralization of poultry manure occurs primarily in the first eight weeks after application, so good timing and appropriate rates can prevent the losses that might occur after the crop has finished growing. Also, as I have explained before, and as Kenneth Carter described in "Animal waste causes too great a share of Bay's pollution to ignore," (March 2010), double-cropping and cover-cropping can effectively use leftover nutrients, whether from manure or chemical fertilizers.
Livestock operations and crop rotations are many and varied. We can not write laws based on the assumption that every field is a cornfield and every spreader is loaded with broiler litter or sewage sludge.
Oversimplification of the issue has also led Land to be dismissive of split applications and cover crops and to propose the mandated use of chemical, slow-release fertilizers. These products certainly have a place, but they do not work in all situations and their performance, like that of other materials, is dependent on weather and soil conditions. They are another tool that we can use, not a silver bullet. Although split applications do require extra time and fuel, they also allow us to delay the decision on how much nitrogen to apply. This often results in a significant reduction in nitrogen use.
The recently developed Greenseeker technology uses sensors that read the nitrogen needs of the crop coupled with variable rate applicators for a precision fertilizer job that is far more efficient than what can be accomplished with timed-release products.
Likewise, cover crops, despite the expense of seed, should not be ruled out without the consideration of other benefits. They can prevent erosion, suppress weeds, build soil organic matter and supply nitrogen for ensuing crops.
The point is that cropping and fertilization decisions need to be made on the ground, field by field, not proclaimed across the region from some ivory tower.
The May Bay Journal featured an article and commentary on the problem of excess phosphorus in manure, bringing us back full circle to where I was a year ago when I wrote that while we have the knowledge and tools to deal with phosphorus, what we are missing is a market for the surplus manure.
The Watershed Stewardship report can be a positive force that will provide the impetus to get these alternative outlets going, or it can be a negative-just another excuse to condemn agriculture.
I found the article, "Scientists say phosphorus index allows too much of nutrient to go on on fields," (May 2010) to provide a good, objective look at the situation.
The commentary, "Pretending excess phosphorus doesn't exist won't make it go away," (May 2010) is both inaccurate and unfair. Manure has been overapplied in the past, and though to a lesser extent, is still overapplied today. But the assertion that farmers face "a stark dilemma" in that they must spread manure so heavily as to pollute the waterways with phosphorus to provide enough nitrogen to grow a crop is ridiculous. We don't attempt to supply all of the nitrogen with manure. We use manure at a rate that the latest science tells us is unlikely to cause phosphorus losses to runoff or groundwater and make up the rest of the nitrogen requirement with chemical sources, or sometimes a legume cover crop.
This brings us to the Phosphorus Site Index, the chief tool used in determining where manure application is environmentally responsible. Contrary to what the commentary says, the Phosphorus Site Index was specifically developed for water quality protection. In fact, it would make no sense at all as a fertility management tool because it is only used in situations where one already has a phosphorus level higher than is required for optimum crop production. The stated goals of the group that developed the index concept 20 years ago were: to create a system to rate fields according to their potential for phosphorus loss; to relate the index to the sensitivity of the receiving waters to eutrophication and degradation from phosphorus enrichment; and to minimize the buildup of soil phosphorus and the transport of phosphorus from soils to sensitive water bodies.
If someone wants to deride our efforts to curb nutrient transport, that's his or her prerogative, but the fact remains that agriculture is the one segment that has achieved significant success in reducing its impact. The Phosphorus Site Index is part of that story. True, the index is a work in progress-what in environmental science isn't?-but that's a moot point, really.
An extreme excess of soil phosphorus is agronomically, as well as environmentally, undesirable.
The problem isn't the index, it's the surplus of manure that puts us in the position of having to use the index in the first place, and in many cases causes producers to be operating on the edge of compliance. This is not just a farmer's problem. Modern agriculture is the creation of society as a whole, and the chicken-eating public bears a responsibility here as well.
The overwhelming majority of producers are not in denial. They are very much on board with putting manure to an alternative use, although they would need to be fairly compensated. The material is, indisputably, a valuable resource. The fact that we don't yet have an on-farm conversion of poultry litter to fuel for heating chicken houses is an inexcusable failure on the part of our agricultural research institutions and the poultry companies. The lack of litter-burning power plants is another story.
A few years ago, Delmarva poulty integrator Allen's proposed such a project for the mid-shore region but had to scrap it because of the public outcry.
More recently-despite strong support from the Virginia Poultry Federation and the Virginia Poultry Grower's Cooperative-Fibrowatt, a Pennsylvania-based company that already operates several plants in other parts of the country, was rejected by Virginia's Page County.
We could have more fertilizer facilities like Perdue's AgriRecycle, which enjoys the support of producers, if there weren't so many roadblocks to getting them built.
I suppose it is easier to rail against farmers than it is to confront the other 98 percent of the population, but it is not consistent with an honest acknowledgement of the problem.
As of early April, Fibrowatt was still interested in finding a location in the Shenandoah Valley. Perhaps that's an opportunity for environmental activists and the poultry industry to come together.