Overstory-understory grass seedings on sagebrush-bunchgrass range
Hedrick, Donald W.
"Crested wheatgrass, beardless wheatgrass, and big bluegrass were
seeded as overstory grasses. Streambank wheatgrass, canby bluegrass,
bulbous bluegrass, and Ladak alfalfa were seeded as companion species.
Pure and mixed stands were seeded on sagebrush-bunchgrass
range in eastern Oregon to compare yield and competitiveness. The
grasses were planted in 1956, 1957, and 1958, and half of each plot
was fertilized with ammonium nitrate at 20 or 30 pounds of N per
acre. The plots were evaluated for seeding success, herbage production,
weed production, and brush establishment in four consecutive
years after planting.
Yields of overstory grasses in pure stands exceeded those in
mixed stands. Nitrogen fertilization increased yields about 45% but
did not increase seeding success on f allowed or burned seedbeds or
alter greatly either competitive status or plant composition.
Relative yields of individuals in mixed stands (yields expressed
in percent of that in a pure stand) were computed to indicate competitive
status and compatibility. Crested wheatgrass was highly competitive,
producing 90% with canby bluegrass and 82% with streambank
wheatgrass. Beardless wheatgrass and big bluegrass were about
equally, but weakly to moderately, competitive, and were suppressed
considerably more by streanibank wheatgrass than by canby bluegrass.
The sums of relative yields in mixed stands were near 100, indicating essentially direct competition, except for the mixture of
beardless wheatgrass and canby bluegrass. In this case, the sum of
relative yields averaged 120%, indicating reasonable compatibility
that improved with age of the stands.
Crested wheatgrass in either pure or mixed stands practically
eliminated all herbaceous weeds in the second growing season. All
grasses except bulbous and canby bluegrass provided effective weed
control by the fourth growing season. Crested and streambank wheatgrasses,
and mixtures including them, permitted the establishment of
fewer brush than other species. Beardless wheatgrass was least effective
in resfricting brush establishment. Brush became established in
the seeding years in greater numbers than in any single year thereafter,
but the counts in the fourth year were about twice that in the
first year. Except on plots seeded to crested wheatgrass, there was no
appreciable mortality of established brush seedlings. All seedings restricted
brush establishment when compared to unseeded plots.
Big bluegrass was continually and severely suppressed by companion
understory grasses and should be planted in pure stands. Un-i
derstory grasses with crested wheatgrass offered little advantage or
disadvantage, and would likely incur a small economic loss. Beardless
wheatgrass and canby bluegrass were reasonably compatible and provided
a mixed stand that could be recommended as preferable to
beardless wheatgrass in a pure stand. In areas of coarse-textured
soils where gray rabbitbrush is a problem, a closer row spacing of
crested wheatgrass would likely provide maximum resistance to brush
establishment."--Summary
Published December 1964. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
↧