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| Titel |
Optimising stocking rate and grazing management to enhance environmental and production outcomes for native temperate grasslands |
| VerfasserIn |
Warwick Badgery, Yingjun Zhang, Ding Huang, Kim Broadfoot, David Kemp, David Mitchell |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104855
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| Publikation (Nr.) |
 EGU/EGU2015-4294.pdf |
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| Zusammenfassung |
| Stocking rate and grazing management can be altered to enhance the sustainable production
of grasslands but the relative influence of each has not often been determined for native
temperate grasslands. Grazing management can range from seasonal rests through to
intensive rotational grazing involving >30 paddocks. In large scale grazing, it can be difficult
to segregate the influence of grazing pressure from the timing of utilisation. Moreover,
relative grazing pressure can change between years as seasonal conditions influence grassland
production compared to the relative constant requirements of animals. This paper reports on
two studies in temperate native grasslands of northern China and south eastern
Australia that examined stocking rate and regionally relevant grazing management
strategies.
In China, the grazing experiment involved combinations of a rest, moderate or heavy
grazing pressure of sheep in spring, then moderate or heavy grazing in summer and autumn.
Moderate grazing pressure at 50% of the current district average, resulted in the better
balance between maintaining productive and diverse grasslands, a profitable livestock system,
and mitigation of greenhouse gases through increased soil carbon, methane uptake
by the soil, and efficient methane emissions per unit of weight gain. Spring rests
best maintained a desirable grassland composition, but had few other benefits and
reduced livestock productivity due to lower feed quality from grazing later in the
season.
In Australia, the grazing experiment compared continuous grazing to flexible 4- and
20-paddock rotational grazing systems with sheep. Stocking rates were adjusted between
systems biannually based on the average herbage mass of the grassland. No treatment
degraded the perennial pasture composition, but ground cover was maintained at higher levels
in the 20-paddock system even though this treatment had a higher stocking rate. Overall there
was little difference in livestock production (e.g. kg lamb/ha), because individual animal
performance was greater for continuous grazing than higher intensity grazing systems
(4-Paddock and 20-Paddock). Differences in SOC, CO2 flux and erosion were determined by
landscape position rather than grazing treatment. To remove the confounding influences of
stocking rate and grazing management, the Ausfarm biophysical model, calibrated to the
experimental treatments, examined the interaction between grazing management
and stocking rates. Ground cover and profitability were similar between grazing
systems at lower stocking rates (3 ewes per ha), but continuous grazing had higher
profitability and lower ground cover above the optimum stocking rate of 4 ewes per
ha.
The findings of these two studies suggest that optimising stocking rate is more important
than grazing management for a sustainable and profitable grazing system. Grazing
management can further enhance environmental outcomes for an optimal stocking rate, but
the findings from the Chinese study particularly highlight the need to look at multiple
ecosystem services, when optimising systems. The Australian study also suggests
the optimum stocking rate is dependent on the intensity of grazing management.
Further work is required to understand the influence of landscape on grassland
production and how stocking rates and grazing management can be sustainably
optimised for different landscape areas to utilise this variation more effectively. |
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