New Zealand Journal of Agricultural Research abstracts
Managing the composition of native and naturalised pastures
with grazing
D. R. KEMP
P. M. DOWLING
D. L. MICHALK
NSW Agriculture Pasture Development Group
Cooperative Research Centre for Weed
Management Systems
Agricultural Research & Veterinary Centre
Forest Road, Orange, NSW 2800
Australia
Abstract Many native, naturalised, and low-input pastures
have a low proportion of desirable species. Under the prevailing economic
conditions, it is unlikely that these pastures would be replaced with sown
native species as there may not be seed of suitable cultivars available and
costs would exceed returns. Better management is a preferable strategy to
improve the proportion of desirable components. Grazing tactics are central to
any improved management strategies for these pastures as they offer a lower
cost option for land managers. Additional tactics, which will vary depending
upon specific circumstances, include some use of fertiliser (to increase the
rate of change), herbicides (where weed problems are particularly severe and
animals are unlikely to eat the "weeds"), and fire (to reduce dead material and
seed numbers and produce green leaf for grazing). Several examples of
manipulating pasture composition are considered. In situations where the
desirable species are C3 perennial grasses (e.g., Danthonia spp.,
Microlaena, and Dactylis), and the less desirable are C3 annual
species (e.g., Vulpia), rests over the summer period, especially
in wetter years, improved the perennial grass content. In addition, extra
grazing pressure in spring limits seed set by annual grasses. Where the
undesirable species are C4 perennial grasses (e.g., Bothriochloa and
Aristida), heavy summer grazing is more important. In some instances,
the timing of a heavy grazing period will depend upon monitoring the plant
community to find the "window of opportunity" when the desirable species have
completed flowering and seed set but when the less-desirable species are
starting to flower. Further development of improved management systems will
require knowledge of the ecology of the principal species. Any release of new
cultivars of native and low-input species should be supported by knowledge of
the better management practices to maintain those species in the pasture.
Keywords pasture; composition, management; grazing; native
grasses
New Zealand Journal of Agricultural Research, 1996, Vol. 39: 569-578
0028-8233/96/3904-0569 $2.50/0 (c) The Royal Society of New Zealand
1996
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