Tapping Manure's Rich Resources

Jerry Hatfield takes exception to the view that hogs generate tremendous amounts of toxic wastes. In fact, Hatfield's line of work generally proves hogs generate quite the opposite. He calls animal manure "the most undervalued natural resource that exists."Hatfield is laboratory director of USDA's National Soil Tilth Laboratory in Ames, IA. He has become a big proponent for capturing manure's high

Jerry Hatfield takes exception to the view that hogs generate tremendous amounts of toxic wastes. In fact, Hatfield's line of work generally proves hogs generate quite the opposite. He calls animal manure "the most undervalued natural resource that exists."

Hatfield is laboratory director of USDA's National Soil Tilth Laboratory in Ames, IA. He has become a big proponent for capturing manure's high value instead of merely discarding it.

"Our pitch over the last few years is manure is a great source of organic nutrients and inorganic nutrients," he says. "It has a value going on that soil that is much more than just the nitrogen, phosphorus and potassium of manure."

Manure can help improve certain characteristics of soil from water-holding capacity to nutrient cycling capabilities. Hatfield cites research that shows manure will even bring productivity back to eroded land, creating topsoil.

So the popular attitude of viewing manure as waste frustrates Hatfield. "Manure has become a disposal problem, not a utilization problem," he says. "That attitude has pervaded the public. When they look at livestock operations, they envision mountains of toxic waste."These "mountains" don't exist. All solid and liquid swine manure produced in the U.S. can only cover one-eighth of the nitrogen requirements for the U.S. corn crop, according to Hatfield. The U.S. is far from an oversupply of manure.

Toxic Label Misplaced Plus, the toxic waste label should instead be pinned on human waste. The nutrients in animal manure are not hazardous wastes, Hatfield states.

"There is nothing in animal manure that is a toxic substance," he claims. "While animals generate volumes more than humans, human waste is closer to a toxic material. The components of human waste are heavy metals, volatile hydrocarbons, oils and greases. Obviously, these don't all come from human excrement, but they are in the pool of stuff in waste-handling systems."

Manure's bad image today is a far cry from the role and image of manure throughout most of history. "Until the 1940s, manure was the source of nutrients (for crops)," Hatfield says. "A farmer had animals and crops. He moved manure out to the field. The original site-specific management was done with manure."

During those times, Hatfield says farmers possessed a basic understanding of manure management and crops. "Then we got into commercial fertilizers and manure changed from being a resource to a waste," he says.

Undoubtedly, commercial fertilizer was and is much easier to handle than manure. Farmers know exactly how many nutrients are in a tank of anhydrous ammonia compared to what is in a tank of manure. But the extra equipment and time to handle the manure will pay off. "Manure can help sustain our soil resource over time," he says.

Manure Improves Soil Properties Research Hatfield has reviewed shows that applying hog manure will produce similar yields to commercial fertilizer. But over time, the variation of yield from year to year is much less, about half. "Farmers are guaranteed to get that same yield, and they don't go through the extremes," he adds. "It is a much more stable system."

Manure changes soil property in terms of organic matter. "If you look at fields that have long-term manure application, they are much better in terms of their soil structure," Hatfield says. "They are much better in terms of organic carbon content. The soil is much more tilthy, has a much better crumbly structure at the surface so it doesn't crust over. That allows more water to infiltrate, more water to be stored within the profile, and better utilization of nutrients within it."

In fact, manure can rebuild topsoil as found in some recent Canadian research, Hatfield reports. Yields from hog manure applied to plots with no topsoil yielded just as good as plots with topsoil. This effect occurred even the first year of the three-year study. Manure and residue were incorporated into the soil in a one-time application.

Manure can enhance organic matter when combined with a reduced-tillage system. Hatfield says research is showing manure will help reduced-tillage systems restore organic matter in soil faster than intensively cultivated systems.

"There is a whole litany of positive aspects we can bring to bear on this that have just been set aside," he adds. Much literature from years ago exists on this topic, but farmers and scientists seem to have forgotten it.

In a recent paper on manure and cropping research, he writes, "Organic materials contained within manure increase the plant availability of nitrate and phosphorus, increase soil organic matter, decrease the carbon:nitrogen ratio, and increase infiltration rate and soil water-holding capacity through changes in soil organic matter. These changes vary among soils in the absolute degree of change. However, almost all studies show these trends."

Air, Water Quality These benefits extend to less runoff of nutrients in subsurface drainage. Hatfield says drainage water from fields with manure applied as fertilizer tend to have lower nitrate concentrations than fields with commercial fertilizer. This is due to the higher organic matter in the soil and to the slower release of organically bound nitrogen in manure.

Hatfield's goal is to devise the most efficient way to apply nitrogen, both commercial and in manure, for the least impact on water quality. Research projects involving entire watersheds and nitrogen applications are underway.

The other environmental concern facing farmers is air quality, he adds. Already, Hatfield and the center's scientists are conducting research to determine the gases emitted from hog buildings, manure storage and application.

"A watershed is well defined while air sheds are a little different," he says. "Where the air blows is more topographically driven. We're trying to determine what's coming through this imaginary plane."

Some of this research is conducted through the Soil Tilth Laboratory's 17 scientists in the Ames facility. The laboratory cooperates with land-grant universities and other groups to research all types of soil-related topics.

Ten years ago, Hatfield says they rarely looked at manure research. Today, they are heavily involved in manure-related research.

Education Research must also look at the best management tools for working with manure. He believes the pork industry must keep looking at better ways of storing, handling and applying manure to retain valuable nutrients.

Along with the research, he says farmers also need education about manure and good management practices. "Anybody handling manure is going to have to be very aware that if this is your field you're putting manure on, nothing must move through the boundary of the field. Period."

Nutrient plans for all farmers, and not just those applying manure, are vital for this work, Hatfield states.

Results are in from 80 different Iowa farms all recruited to demonstrate odor reduction plans. The demonstrations have been conducted over the past year on all species and sizes of livestock farms.

Iowa State University (ISU) coordinated and managed the demonstrations. Jeff Lorimor, ISU agricultural engineer, recently reported on the results of the demonstration projects. He emphasized that the projects are not research.

Nine different odor-reducing techniques were studied in the aggressive demonstration program. Each technique and results of the demonstrations follow:

1. Pit additives - Eight different pit additives for hog manure were used in the demonstrations. The pit additives were previously tested in labs at ISU.

Cost for the additives ranged from $.25-1.00/pig marketed. Lorimor said the odor tests yielded only variable effectiveness from the additives.

"I see pit additives have some ability to reduce odor a little," he said.

2. Biocovers - Manure storage biocovers made of straw, old hay and cornstalks were tested. The covers were put on manure storage basins, not lagoons or in-building pits.

The cost of the biocovers ranged from $.25-.40/pig. Some producers were concerned with the biocovers at pump out, however. A chopper pump was needed.

Odor panels sniffing the air from the biocovers indicated a well-defined advantage for the simple technique, Lorimor notes.

3. Plastic covers - Plastic covers did even better than biocovers. No odor was detected at 150 ft. from the manure storage by the odor panels.

Cost for the plastic covers ran $.35-.45/pig marketed, based on an 8- to 10-year life.

4. Soil injection - Injecting manure into the soil at time of application was cited as one of the most effective ways of cutting odors during application, Lorimor said.

Cost for the injection method was $.40-.50/pig, or about $.003/gal. Lorimor noted the extra nutrients gained from injection could pay for the process.

During ISU field days last year, farmers attending were asked to evaluate the odor from various manure application methods. Direct injection easily won the odor reduction contest over broadcast methods.

5. Aerobic treatment - Two farms demonstrated aerobic treatments. This treatment involved aeration of the stored manure. It very effectively reduced odors, Lorimor reported.

However, a high price tag was attached to the method. The aeration equipment cost $1.50-3.00/pig and variable costs (energy use, etc.) added another $1.20-1.50/pig.

6. Anaerobic treatment - Another very effective but very expensive method of reducing odor involved digesters. Lorimor estimated the cost between $5-12/pig.

7. Solid separation - Six dairy farms demonstrated solid separation for odor reduction. At a cost of $3/head, separation did show some reduction in odor, Lorimor said. However, proper management was critical for its success. And separation generally does not work with swine manure.

8. Composting - Eight dairy and poultry farms tested composting for cutting odors. It was considered an effective method. The cost ranged from $.20-.40/head marketed. 9. Landscaping - Several farms demonstrated landscaping as one way to reduce odors. Odors were not tested from these farms.

Lorimor says the cost can run from $.15/head on up for landscaping. Most of the landscaping involved trees and shrubs around the buildings and manure storage.

Conclusion "The biocovers, plastic covers and soil injection rose above the rest," Lorimor stated. "But there's not a silver bullet for odor control."

Often, proper site selection will reduce odors. ISU is developing a computer model to help engineers select the best sites for hog facilities. The model will assume an "acceptable" odor level used by the Europeans of neighbors smelling the hogs only 2% of the time. This amounts to seven days/year