"Designer" Composts To Fight
Rainwater falling on the Beltsville Agricultural Research Center's
77,000-square-foot composting pad drains into an orchardgrass field
(foreground) that filters out nutrients in the runoff.
The Agricultural Research Service officially opened its composting center
for organic byproducts in Beltsville, Maryland, this past falljust as the
debate over Pfiesteria in some Chesapeake Bay tributaries captured national
Pfiesteria piscicida and other Pfiesteria-like microscopic organisms
are dinoflagellates. These tiny, complex creatures sometimes behave like plants
and sometimes like animals. In one of two dozen or more life stages,
Pfiesteria and its cousins can produce a toxin that kills fish and harms
people who come in close contact with the toxin.
The new composting center offers a model for two recommendations made by a
Pfiesteria commission formed by Maryland's governor.
One recommendation is to compost chicken litter. The other: Install grass or
tree buffer zones around farm fields to filter out nutrients thought to be
responsible for Pfiesteria blooms.
The 2-acre composting site at the Beltsville Agricultural Research Center
(BARC) is surrounded on three sides by an 8-acre field of orchardgrass. This
buffer zone sits between the compost pad and the tree-lined banks of Beaver Dam
Creek, which teems with beavers, turtles, and other wildlife. The creek flows
into Indian Creek, which in turn feeds the Anacostia River, a tributary of the
Chesapeake Bay. Near Beaver Dam Creek is a bird-watcher's paradise, a wetlands
that even plays host to great blue herons. Canada geese fly over the compost
center to feed in BARC's grain fields or swim in its ponds.
"We harvest the orchardgrass for hay four times a year and feed it to
cattle. Then we recycle their manure and hay bedding back here again,"
says BARC director Phyllis E. Johnson.
The two-way street is a mark of the facility. The composts it produces will
go to the farm's researchers for testing in next year's sustainable and organic
farming projects. Even its vehicular traffic is two-way: Almost daily, dump
trucks arrive carrying manure, livestock bedding, landscape trimmings,
greenhouse discards, wood chips, and leaves. The trucks depart with loads of
finished compost to use as mulch in landscaping and farm research.
Last October 21, for example, a front-end loader filled a truck with 6 cubic
yards of finished compost, and the truck headed off to deliver it as
landscaping mulch around a nearby Agricultural Research Serviceoffice
building. The truck made five more return trips to complete the job.
The same day, according to a hauler's daily log, incoming trucks arrived
with 30 cubic yards of wood shavings--used livestock bedding--and 67 cubic
yards of dairy and poultry manure.
At any one time, the 77,000-square-foot composting pad between the shed and
the orchardgrass buffer holds about 900 tons of composting materials. These are
stacked in about 20 neat rows, each 160 feet long, 5 feet wide, and 40 inches
The windrows, as they're called, represent a simple method of composting,
which relies on regular turning so that heat generated by decomposition can
"cook" compost from the inside out. Frequent turning makes for a
uniform mixture. The finished product shows no sign of the compost's origins:
woodchips, manure, used animal bedding, or plant residue such as cornstalks and
Compost site operator Randy Townsend turns
the windrows as necessary to replenish oxygen
and mix the organic material for efficient composting.
Lawrence J. Sikora, the ARS microbiologist in charge of the composting
research center, says the 8-inch-thick composting pad has held up well under
all this weight during its first year. He's especially proud because the pad
itself is made partly of recycled materials: coal ash from area power plants
and cement kiln dust. It was built by working these materials, along with
quicklime and cement, into the existing clay subsoil.
Designing Composts for Special Uses
Sikora and his colleagues will use the facility to find better ways to make
composts from a blend of farm, industrial, and urban materials.
"We call them designer composts because we will tailor-make them in
hopes of solving particular problems such as vegetable diseases," he says.
"Compost has an inherent ability to control certain diseases--an
ability we can enhance with the right ingredients, such as manure type and the
right age or maturity. We can also add disease-fighting microorganisms. Liquids
leaching from the compost pile can be used as a liquid disease-control spray.
"By adding a specific benefit to compost, we add enough value that an
entrepreneur could justify shipping it hundreds of miles beyond the traditional
50- to 100-mile limit of today's commercial compost operations," says
The scientists will test composts in six concrete bins in the equipment
shed. Each bin, about twice the size of a typical backyard compost pile, has a
separate drainage system, so all compost "tea" drains into separate
containers. The scientists can analyze the liquids for nutrients, chemicals,
and disease organisms.
Sikora and his colleagues often seek feedback from regulatory agencies and
industries they invite to the composting center, such as the U.S. Food and Drug
Administration and a number of food associations.
Sikora says the first research projects will include finding better ways to
reduce chances of nutrient pollution of waterways, kill disease organisms such
as Escherichia coli O157:H7, and control odors.
"Composting stabilizes nutrients such as nitrogen and phosphorus,
making them less likely to leach into groundwater," he says.
While the composting center is a research facility, it also provides vital
recycling services for BARC's 7,000-acre research farm, which includes
greenhouses, animal barns, crop fields, pastures, and lawns and other
landscaped areas. The BARC "farm" produces manure from 650 head of
cattle, 600 pigs, 250 sheep, and 3,500 chickens and turkeys--along with their
used bedding--and plant residue from its greenhouse and landscape operations.
The compost facility recycles all this organic residue.
This helps the farm comply with voluntary state restrictions designed to
keep nitrogen and phosphorus out of the Chesapeake Bay and its tributaries.
Where There's Heat, There's Compost
The operational side of the compost facility is Randy Townsend's turf.
Townsend is an ARS employee who is certified as a compost operator by the
Maryland State Department of Agriculture.
Townsend says the signature BARC compost--a mixture of the same ingredients
produced year after year--will be a blend of dairy manure, shredded wood chips,
"We will use all of it on the research farm," Townsend says.
"Researchers require a steady and consistent supply for multiyear
Townsend has office space in a nearby trailer he shares with a mini-lab
equipped with an oven for drying compost to measure its moisture content. He
uses special vacuum bottles test the maturity of compost by monitoring its
reheating potential: If the temperature of a sample rises more than 35 degrees
above the ambient air temperature, the compost is not ready to use.
To speed up composting, Townsend runs a windrow turner over the rows once a
week. The turner has six rows of blades that rake through the piles, tossing
and reforming them while letting air in. He will turn the piles more often if
they're not getting enough air. He determines this with a 5-foot probe equipped
with sensors for oxygen, temperature, and carbon dioxide.
Townsend explains that a temperature of 131oF for more than 2
weeks is enough to kill all disease organisms and weed seeds. When the
temperature in a pile drops to about 115oF to 120oF, the
compost is ready to be used on the farm.
"That usually occurs in 12 weeks," Townsend says. He occasionally
verifies the compost's readiness with the vacuum bottle test.
Even Townsend's neat operational piles are useful to Sikora. "We are
keeping careful records of various mixtures to see which work best, in terms of
speedy compost," he says. He points to three windrows, each containing a
different combination of animal manure, bedding, and tomato and other vegetable
With over 20,000 cubic yards of BARC organics expected to be trucked in
before the year ends, Sikora will have plenty of opportunities to fine-tune
designer recipes.--By Don
Comis, Agricultural Research Service Information Staff, 6303 Ivy Lane,
Greenbelt, Maryland 20770, phone (301) 344-2748.
Lawrence J. Sikora is at the
USDA-ARS Soil Microbial
Systems Laboratory, Bldg. 318, 10300 Baltimore Ave., Beltsville, MD
20705-2350; phone (301) 504-9384, fax (301) 504-8370, e-mail
Randall K. Townsend is at the USDA-ARS Compost Research Facility, Bldg.
218-P, 10300 Baltimore Ave., Beltsville, MD 20705-2350; phone (301) 504-6762,
fax (301) 504-8403.
"Designer" Composts To Fight Farm Pollutants was published
in the May 1998 issue of Agricultural Research magazine. Click here to see this issue's table of