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There's little chance that land managers will
rid grasslands in the Northern Plains of the weedy annual grass called Japanese
brome, also known as Bromus japonicus. So
ARS researchers in Miles City, Montana,
are helping ranchers live with it.
The scientists are correlating rainfall and other environmental factors with
the amount of the weed available for grazing, to help ranchers make the best
use of both the weed and the native grasses.
Japanese brome can make up as much as 40 percent of the forage available on the
mixed-grass prairies of Montana, Wyoming, and the Dakotas.
"When the plants are young, they make nutritious, palatable forage for
cattle," says ARS range scientist Marshall R. Haferkamp. "They also
don't develop seedheads as prickly as cheatgrass, a relative of Japanese brome
that's pervasive in other western states."
The problem is that the amount of forage annual grasses produce varies greatly,
ranging from as low as 20 pounds per acre to more than 600 in the spring.
Annual bromes contribute over 60 percent of this production. That makes using
brome as food for a cattle herd unpredictable.
"Ideally, livestock would graze brome-infested pastures during early
spring and then move to other pastures," says Haferkamp. "But we
don't always know how much brome forage will be produced each spring. Grazing
these pastures when brome forage is scarce may hinder development of the
associated perennial grasses."
The goal is to help ranchers better balance the use of various rangeland
resources. To do that, the scientists need to understand what controls the
growth rate of Japanese brome. They're measuring soil moisture, soil nitrogen,
and precipitation to find out how well each factor predicts brome productivity.
They're also looking at how the weed affects production of preferred perennial
grasses. They plan to produce a decision-support system to help farmers plan
grazing strategies based on each year's variable environmental
conditions.—By Kathryn Barry
Stelljes, Agricultural Research Service Information Staff.
Marshall R. Haferkamp is
with the USDA-ARS Fort Keogh Livestock and
Range Research Laboratory, Route 1, Box 2021, Miles City, MT 59301-9202;
phone (406) 232-8211, fax (406) 232-8209. |
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