ROTATIONAL grazing, where livestock are periodically rotated and paddocks rested, according to research in north western NSW rangeland areas, can achieve healthier environments and associated improved productivity benefits compared to set stocking.
Well managed rotational grazing systems can also result in similar healthy environments to locking up country with no domestic animal stocking.
This is especially significant research as it challenges common practise in many semi-arid environments of more or less set stocked grazing management, as well as the alternative of closing off these lands from sheep and cattle production.
Dr Sarah McDonald of NSW Department of Primary Industries led the research as part of her doctorate, 'Implications of grazing management systems incorporating planned rest for biodiversity conservation and landscape function in rangelands', through the University of New England.
The research was undertaken in the Mulga Lands and Darling Riverine Plains bioregions of north-western NSW where average annual rainfall varies from 400 millilitres in east to 275mm west across the study region. Thirteen grazing contrasts comparing different grazing treatments were sampled on heavy clay and sandy-loam soils. Each grazing contrast compared at least two different grazing treatments in adjacent paddocks in the same land system and vegetation community.
Grazing treatments included (1) areas currently managed for conservation where domestic livestock were excluded; (2) rotational grazing on commercially grazed properties where paddocks were strategically rested for periods of generally four months or more per annum, to maintain ground cover and pasture biomass; and (3) continuous grazing where paddocks were grazed for most or all of the year.
Properties were selected where grazing treatment had been in operation for at least five years before sampling. Significantly, areas managed for nature conservation (domestic animals excluded), did contain a variable presence of native (kangaroos) and feral unmanaged animals (goats and rabbits), as is common in public nature conservation reserves.
Although highly variable, average annual stocking rates were 0.45 dry sheep equivalents (DSE) per hectare for rotationally grazed systems compared to 0.34 DSE/ha for set stocked grazing.
From a biodiversity conservation perspective, rotationally grazed areas registered similar levels of understorey floristic diversity and native species richness to conservation management areas across a variety of scales. They were also not associated with an increased proportion of exotic, annual or unpalatable species.
Rotationally grazed sites also had greater floristic richness, diversity and ground cover than continuous grazing management. These results are consistent with a growing body of literature suggesting potential for rotational grazing management to conserve biodiversity in commercially grazed semi-arid rangelands.
This study supports that careful rotational grazing has the potential to improve both ecological and socio-economic outcomes in rangeland environments by reducing selective grazing (thereby avoiding overgrazing of patches and desirable species), resting to maintain plant vigour and increasing control over grazing pressure, resulting in increased abundance and cover of perennial species and increased plant diversity compared to traditional set-stocking or continuous grazing.
The research is published in CSIRO The Rangeland Journal, 2019, 41, 135-145, titled "Rotational grazing management achieves similar plant diversity outcomes to areas managed for conservation in a semi-arid rangeland" and in the journal Agriculture, Ecosystems and the Environment, 2018, 298, 8-14, titled "Improving ground cover and landscape function in a semi-arid rangeland through alternative grazing management". Other authors of the research are Prof. Nick Reid, Dr Rhiannon Smith, Dr Cathy Waters, Dr John Hunter and Dr Romina Rader.
This research was supported by the UNE, NSW DPI and Western Local Land Services. Contact email@example.com
Next week. Monitoring soil water for better crop and pasture decisions.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email firstname.lastname@example.org or phone 0428 752 149.