Group Title: Research report - University of Florida Agricultural Research and Education Center ; RC-84-5
Title: Response of Ona stargrass to different grazing pressures
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 Material Information
Title: Response of Ona stargrass to different grazing pressures
Series Title: Research report ;
Physical Description: 2 p. : ; 28 cm.
Language: English
Creator: Pitman, William Don, 1949-
Agricultural Research and Education Center, Ona
Publisher: Agricultural Research and Education Center,
Agricultural Research and Education Center
Place of Publication: Ona, FL
Publication Date: 1984
Copyright Date: 1984
Subject: Grasses -- Varieties -- Florida   ( lcsh )
Pastures -- Florida   ( lcsh )
Grazing -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: W.D. Pitman.
General Note: Caption title.
General Note: "September, 1984."
 Record Information
Bibliographic ID: UF00074297
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 85895016

Full Text

SAgricultural Research and Education Center
Research Report RC-84-5 September, 1984

Response of Ona Stargrass to Different
Grazing Pressures

W. D. Pitman

The stargrasses have proven to be productive pasture grasses on many
flatwoods sites in peninsular Florida. However, their high requirement for
nitrogen fertilization must be met each year. Stand deterioration and
invasion by weedy species can occur in stargrass pastures with depletion of
soil nitrogen. Knowledge of this dependence of stargrass on fertile o
has led to a tendency to credit deterioration of stargrass kaac
of soil fertility rather than to evaluate the overall 5 ement
program. In an effort to determine the effects o g pressuree on
stargrass stands, pastures of Ona stargrass were s b ected to a rg of
stocking rates during the 1982 and 1983 growing se ons. \\


Three stocking rates were imposed on Ona stargra :ures with 3 head
of yearling steers per 1.25 acre pasture (2.4 head/acre) at the heavy
stocking rate, 2 head per 1.25 acre pastures (1.6 head/acre) at the medium
stocking rate, and 2 head per 2.5 acre pasture (0.8 head/acre) at the light
stocking rate. The experimental design was a randomized block design with
three replications of each grazing treatment. All pastures were fertilized
in March and August of 1982 and in May of 1983 with 450 pounds per acre of a
16-8-8 fertilizer.


The accompanying table shows that the greatest total beef gains were
obtained at the high stocking rate during the first year. However,
progressively higher average daily gains were obtained at the two lower
stocking rates. During the second year, total beef gains at the highest
stocking rate were not greater than total gains at the medium stocking rate.
Total gains at the low stocking rate were still lower in the second year
despite the high average daily gains. Differences in animal condition were
obtained at the end of each grazing period reflecting the differences in
average daily gains. The differences in animal condition were more distinct
at the end of the second grazing period.

Although body condition and daily gain reflected the increased grazing
pressure at the higher stocking rates, the lowest average daily gain figures
obtained at the highest stocking rate are quite acceptable levels for summer
gains for yearling cattle. The initial impact of continuous grazing at the
high stocking rate on these stargrass pastures was stargrass stand reduction,
even though individual animal performance was only moderately reduced and
total pasture gains were still as high as or higher than total gains at the
lower stocking rates. Initial stands at all three stocking rates were
approximately 85% stargrass with common bermudagrass scattered throughout the

Performance of yearling steers
three stocking rates.

grazing Ona stargrass

Stocking Animal days Average Total
rate of grazing daily gain gain

head/acre days/acre pounds/head/day pounds/acre


0.8 134 1.79 240
1.6 269 1.52 406
2.4 403 1.43- 574

0.8 84 1.75 147
1.6 168 1.42 238
2.4 252 0.94 236

pastures and comprising most of the other 15% of the pasture canopy.
Following two years of continuous grazing at the low and medium stocking
rates, pasture compositions were very similar to the initial pasture
compositions. At the high stocking rate stand reductions occurred with a
range of 70% to 20% stargrass remaining in the pasture canopy. In addition
to common bermudagrass, vasey grass and bahiagrass invaded the heavily grazed
stargrass pastures.


At high grazing pressures that predisposed stargrass pastures to
invasion by less palatable and more competitive species such as common
bermudagrass, bahiagrass, and vasey grass, performance of grazing steers
remained at acceptable levels. This is in direct contrast to the ability of
bahiagrass pastures to withstand heavy grazing pressures that produce
detrimental effects on grazing cattle before substantial pasture damage
occurs. However, stargrass is much more persistent under heavy grazing
pressure than is limpograss (Hemarthria).

Stargrass pastures grazed for extended periods of time at heavy stocking
rates should be closely monitored to allow adjustments to be made in length
of the grazing period or in stocking rate before damage to the grass stand

pastures at

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