Grass-Based Farming: A Demo Dairy
Cove Mountain Farm operator Glenn Moyer (left), agricultural engineer Al Rotz,
and animal scientist Kathy Soder review data generated by meteorological and
other instruments. The data are stored in a computer model that simulates the
whole farm operation.
The Cove Mountain Project has a neat, top-secret military ring to it. In
reality, it's the name for a demonstration dairy farm owned by the American
Farmland Trust (AFT) in Franklin County, south-central Pennsylvania.
Each month, Cove Mountain is besieged by a small army of agricultural
researchers tending to various experiments on the 300-plus-acre farm. Data
generated there by meteorological and other instrumentation are helping the
scientists gauge the economic and environmental merits of an alternative
approach to dairying.
In short, it calls for grazing dairy cows on intensively managed grass and
legume pastures instead of confining the animals indoors and feeding them hay,
grain, or cut forage.
Dairy farmer Glenn Moyer first began operating the farm in March 1998 as
both an AFT demo project and a commercial dairy.
"It should be recognized there's more than one way to dairy," says
Bryan Petrucci, AFT's Cove Mountain Farm project director. "Our aim is to
use the farm as a place where people can learn about the economic and
environmental benefits of grass-based farming."
According to several estimates, grazing-based systems on small to
medium-sized dairies can boost net income by $50 to $100 per cow. Computer
simulations on ARS' Dairy Forage System
Model generally bear this out, say agricultural engineer C. Alan Rotz and
animal scientist Kathy J. Soder, who are at the ARS Pasture Systems and
Watershed Management Research Laboratory (PSWMRL) in University Park,
Preliminary analyses with the model have shown that this low-input approach
at Cove Mountain may increase net income up to twice this amount.
Cows in full-confinement operations generally produce higher milk yields
than those that graze. The benefit of grazing comes from lower production costs
and less labor.
For those who try it, the secret to success isn't hiking milk production,
but rather decreasing operating costs associated with growing, harvesting, and
storing crops like corn as year-round feeda standard practice for
full-confinement operations. There's also less capital investment than is
associated with managing and housing large dairy herds, says Petrucci.
Holstein and Jersey crossbreeds graze on American Farm Land Trust's Cove
Mountain Farm in south-central Pennsylvania.
Still, some northeastern dairy farmers remain skeptical, he acknowledges.
"To Glenn's credit, he's a leader and not afraid to try new things,"
For researchers, the Cove Mountain farm is a unique opportunity to collect
scientifically defensible data on the economics and sustainability of
grazing-based systems from a commercial operation. Thanks in great part to
Moyer and AFT, visiting scientists can carry out their experiments to that end
in a controlled manner.
Monitoring Animal Wastes
A chief interest of the scientists is determining the extent to which waste
from grazing animals contributes to nitrate leaching or phosphorus runoff. Both
can diminish water quality. Consider that on average, an adult cow excretes 2
to 3 quarts of urine a dozen times daily and defecates 4 pounds of manure about
as oftenand that's 7 days a week, 52 weeks a year.
"Only about 15 percent of the nutrients contained in pasture herbage
leave the pasture as milk or meat. The remaining 85 percent are recycled onto
the pasture in urine or manure," says PSWRML soil scientist William L.
And because "85 percent of the nutrients are recycled onto only about
15 percent of the pasture," he adds, "the concentrations beneath
urine or manure patches are very high."
The challenge, then, is improving management of these pasture wastes.
Under certain conditions, wasteborne nutrients can outpace what pasture
plants, soil microbes, and other biological processes can recycle or convert
into forms less damaging to water quality. For example, excess phosphorus in
runoff can harm recipient streams, lakes, or reservoirs by triggering algal
To address these concerns, Stout and colleague ARS soil scientist Stephan R.
Weaver closely monitor various instruments set up at the farm. One site is a
10-acre paddock where they can monitor nutrients from the cow's urine and
manure. Unbeknownst to the placid animals, the paddock is home to roughly
10,000 feet of underground piping.
This network, or drainage tile, captures water flowing beneath the paddock
and directs it to five, keg-size sampling devices. Each is located in a flume
house a few hundred yards from Little Cove Creek and about a mile or so from
the hulking green shoulders of Cove and Cross Mountains.
Ecological Benefits and Drawbacks
Walking from the flume house during a June visit to the farm, Stout notes
some pros and cons to grazing.
Without a corn crop to worry aboutunless grown for winter feeda
grazier doesn't have to spray chemical pesticides. This cuts the risk of drift
beyond the field and spares beneficial insects, like bees. What's more, it
minimizes erosion because the pasture's plants keep soil firmly anchored.
And by keeping herds out on pasture, rather than indoors, less fuel and
labor are spent spreading manure and harvesting feed. This minimizes offensive
odors and further cuts the grazier's expenses.
"But on the other hand," says Stout, "there's the potential
for greater nitrate loss to groundwater because of the concentrated deposition
of urine and manure."
Another concern is the impact of selective grazing and constant trampling by
cows on the habitat, diversity, and productivity of grasses like orchardgrass,
bluegrass, or tall fescue and legumes like clover and alfalfa.
Plant physiologist Howard Skinner (right) demonstrates the plant canopy
photosynthesis system to farm operator Glenn Moyer. It pumps carbon dioxide
into the Plexiglas chamber, which is placed over a selected area of pasture to
see how much is absorbed by pasture grasses. The grazing exclosures in the
background are used to study grazed and nongrazed pastureland.
Understanding these ecological changes, including their effect on pasture
productivity, is the focus of ARS scientists R. Howard Skinner, Matt A.
Sanderson, and Benjamin J. Tracy, all from University Park, about 2 hours north
of Cove Mountain.
About once a week, they visit the farm to examine the height, density, and
distribution of pasture plants. They also take root samples, along with
photosynthetic and carbon partitioning measurements.
Skinner uses a 3-foot-wide Plexiglas chamber to collect photosynthetic data.
During visits, he'll place the chamber over grassy patches inside and outside
each of the farm's six fenced exclosures.
According to farm records dating back to 1968, no livestock have grazed
inside the exclosures, a stroke of luck for scientists. Such virgin territory
allows them to compare the plants' health and productivity with those in other
pasture areas regularly grazed by the farm's 106 Jersey and Holstein cows.
Flipping a switch on the chamber's control panel, Skinner starts a motor
that draws in air and pipes it into the chamber. Of chief interest is the rate
at which pasture plants absorb carbon dioxide to drive photosynthesis. The rate
at which carbon is stored gives scientists a clue to the productivity of
"We want to see if there's a difference in pasture production levels
when it's cut for hay versus when it's grazed," says Skinner. In dairy
circles, "there's been some question as to whether it's better to graze,
or to cut a pasture for hay."
For Cambridge, New Zealand, graziers Ron Geck and his wife Willy, who
visited Glenn Moyer in June, there's no better alternative, because of high
feed costs and other prohibitive expenses.
Sitting at a picnic table in front of the farm's main home, Ron likens the
practice to playing chess. "When you're grazing, set your farm up so you
can still graze under difficult conditions," he says. Drawing on 30 year's
experience, he adds "grazing's a science and should be treated that
way."By Jan Suszkiw,
Agricultural Research Service Information Staff.
This research is part of Animal Production Systems (#102); Rangelands,
Pastures, and Forages (#205); and Water Quality and Management (#201), ARS
National Programs described on the World Wide Web at
Scientists mentioned in this article are at the USDA-ARS
Pasture Systems and
Watershed Management Research Laboratory, Bldg. 3702, Curtin Rd.,
University Park, PA 16802; phone (814) 863-0947, fax (814) 863-0935, e-mail
American Farm Trust hosts a Cove Mountain Farm web site at
"Grass-Based Farming: A Demo Dairy Project" was published
in the October 1999 issue of
Agricultural Research magazine.