New Zealand Journal of Agricultural Research abstracts
Populations of soil organisms under continuous set stocked and high
intensity–short duration rotational grazing practices in the
central tablelands of New South Wales (Australia)
Nisha Tom
Soil Research Group
The University of Sydney
P.O. Box 883
Orange, NSW 2800
Australia
Anantanarayanan Raman*
Dennis S. Hodgkins
Helen Nicol
Soil Research Group
The University of Sydney/Charles Sturt University
*Author for correspondence: araman@csu.edu.au
Abstract Grazing management practices modify soil
structure, which, in turn, alters the behaviour and population dynamics
of soil-inhabiting organisms. Monitoring of changes in abundance and
richness of soil organisms is vital in determining the sustainability
of grazing regimes. In this paper, populations of soil organisms were
compared—using abundance and population trends as an indicator of
diversity—in two different grazing practices (a) conventional,
set stocked (SS) grazing regime and (b) high intensity–short
duration (HI–SD) grazing regime) and an ungrazed control (C). A
thorough sampling of earthworms and arthropods, and an assay of soil
microbial biomass and respiration was made in Spring 2004
(September–November), after a pilot sampling of earthworms and
arthropods in Autumn 2004 (March–May). Earthworm numbers were
found to be unaffected by grazing regimes, however, microarthropod
abundance at 0–10 cm soil depth was significantly higher in
soil of the HI–SD grazing regime and in the ungrazed control,
when compared with set stocking. Microbial biomass and respiration did
not differ across treatments. Overall, our results indicate that
arthropod abundance reflects the changes impacting on soil structure as
a consequence of grazing practice. Evaluation of earthworm populations
was not found to be useful in discriminating between the two grazing
regimes, because the earthworm numbers were principally affected by
rainfall.
Keywords earthworms; high intensity–short
duration grazing; microarthropods; microbial biomass and respiration;
set-stocked grazing
A05056; Received 3 November 2005; accepted 5 May 2006; Online publication date 10 July 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 261–272
0028–8233/06/4903–0261 © The Royal Society of New Zealand 2006
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