Sustainable Grazing Management for Temporal and Spatial Variability in North Australian Rangelands–A Synthesis of the Latest Evidence and Recommendations

Rainfall variability is a major challenge to sustainable grazing management in northern Australia, with management often complicated further by large, spatially heterogeneous paddocks. This paper presents the latest grazing research and associated bio-economic modeling from northern Australia and assesses the extent to which current recommendations to manage for these issues are supported. Overall, stocking at around the safe long term carrying capacity will maintain land condition and maximize long term profitability. However, stocking rates should be varied in a risk-averse manner as pasture availability varies between years. Periodic wet season spelling is also essential to maintain pasture condition and allow recovery of overgrazed areas. Uneven grazing distributions can be partially managed through fencing, providing additional waters and in some cases patch burning, although the economics of infrastructure development are extremely context dependent. Overall, multipaddock grazing systems do not appear justified in northern Australia. Provided the key management principles outlined above are applied in an active, adaptive manner, acceptable economic and environmental outcomes will be achieved irrespective of the grazing system applied

Do Multi-Paddock Systems Increase Evenness of Grazing at the Paddock Scale?

There is ongoing debate about the benefits of multi-paddock rotationally grazed systems compared to continuous grazing (Briske et al. 2008). One of the purported benefits of high density short duration grazing is more spatially uniform defoliation. A commercial-scale trial in northern Australia (Hunt et al. 2013) compared continuously grazed paddocks to cell grazed and wet season spelled systems in newly developed paddocks. This paper reports the effect of grazing system on defoliation with distance to water through time

Impacts of Projected Climate Change on Pasture Growth and Safe Carrying Capacities for Three Extensive Grazing Land Regions in Northern Australia

The northern beef industry is a major component of the regional economies of Queensland, Northern Territory and northern Western Australia, and has contributed an estimated $5 billion to Australia’s economy in 2009-10. Projected climate change will have an adverse impact on Australia’s agricultural production (McKeon et al. 2008) with an expected 3.5% decline in beef production in northern Australia by 2030 (Heyhoe et al. 2008). The GRASP pasture production model (McKeon et al. 2000) has been used to evaluate impacts of climate change in Australia’s rangelands (Crimp et al. 2002, McKeon et al. 2008), with the positive effects of higher carbon dioxide (CO2) on pasture growth likely to be offset by reductions in pasture productivity and digestibility due to lower rainfall and higher temperatures (Crimp et al. 2002). The impacts of three projected future climates on livestock carrying capacity of grazing lands in Fitzroy, Maranoa-Balonne and Victoria River District regions were assessed using GRASP

Systematic Management of Stocking Rates Improves Performance of Northern Australian Cattle Properties in a Variable Climate

The risks for extensive cattle properties in the rangelands of northern Australia arising from high inter-annual rainfall variability are predominantly managed through adjustments in stocking rates (SR). This modelling study compared the performance of SR strategies that varied considerably in the extent that they adjusted SR annually at three locations in northern Australia. At all locations, land types and pasture condition states, the SR strategies that achieved the best pasture condition were those that least increased and most decreased SR annually in response to changes in forage availability. At Donors Hill (Qld), these conservative strategies also achieved the highest cattle live-weight gains per hectare (LWG/ha). While conservative strategies produced the highest percent perennials at Fitzroy Crossing (WA), strategies which allowed larger increases and decreases in SR also performed well, enabling them to also achieve high LWG/ha with little deterioration of pasture condition. A similar trend occurred at Alice Springs (NT), although at this location the strategies with even larger annual increases and decreases in SR achieved relatively high percent perennials and the highest LWG/ha. While systematic management of SR appears to perform better than a constant SR strategy when rainfall variability is high, it is unclear if the magnitude of annual adjustments in SR needs to increase with increasing rainfall variability

Resting pastures to improve land condition in northern Australia: guidelines based on the literature and simulation modelling

Pasture rest is a possible strategy for improving land condition in the extensive grazing lands of northern Australia. If pastures currently in poor condition could be improved, then overall animal productivity and the sustainability of grazing could be increased. The scientific literature is examined to assess the strength of the experimental information to support and guide the use of pasture rest, and simulation modelling is undertaken to extend this information to a broader range of resting practices, growing conditions and initial pasture condition. From this, guidelines are developed that can be applied in the management of northern Australia’s grazing lands and also serve as hypotheses for further field experiments. The literature on pasture rest is diverse but there is a paucity of data from much of northern Australia as most experiments have been conducted in southern and central parts of Queensland. Despite this, the limited experimental information and the results from modelling were used to formulate the following guidelines. Rest during the growing season gives the most rapid improvement in the proportion of perennial grasses in pastures; rest during the dormant winter period is ineffective in increasing perennial grasses in a pasture but may have other benefits. Appropriate stocking rates are essential to gain the greatest benefit from rest: if stocking rates are too high, then pasture rest will not lead to improvement; if stocking rates are low, pastures will tend to improve without rest. The lower the initial percentage of perennial grasses, the more frequent the rests should be to give a major improvement within a reasonable management timeframe. Conditions during the growing season also have an impact on responses with the greatest improvement likely to be in years of good growing conditions. The duration and frequency of rest periods can be combined into a single value expressed as the proportion of time during which resting occurs; when this is done the modelling suggests the greater the proportion of time that a pasture is rested, the greater is the improvement but this needs to be tested experimentally. These guidelines should assist land managers to use pasture resting but the challenge remains to integrate pasture rest with other pasture and animal management practices at the whole-property scale

How hot? How often? Getting the fire frequency and timing right for optimal management of woody cover and pasture composition in northern Australian grazed tropical savannas. Kidman Springs Fire Experiment 1993-2013

Abstract. A long-term (1993-2013) experiment in grazed semiarid tropical savannas in northern Australia tested the impact of varying the frequency (every 2, 4 and 6 years) and season (June -EDS versus October -LDS) of fire compared with unburnt controls on woody cover and pasture composition, in grassland and open woodland. Over an 18-year period, woody cover increased by 4% (absolute) in the woodland even with the most severe (i.e. frequent, late dry season) fire treatments. With less severe or no fire, woody cover increased by 12-17%. In the grassland, woody cover remained static when subjected to LDS fires every 2 or 4 years, but increased by 3-6% under other fire treatments, and by 8% when unburnt. Major shifts in understorey species composition occurred at both sites regardless of fire regime. The effect of fire on herbage mass and composition was compounded by higher grazing after fires. The herbage mass of perennial grasses declined and that of annual grasses and forbs increased following early or frequent fires. Brachyachne convergens, Gomphrena canescens and Flemingia pauciflora increased in response to fire while Aristida latifolia and Heteropogon contortus decreased. Four-yearly LDS fire provided the most effective management of woody cover and pasture composition. Although EDS fire is recommended for biodiversity management and reducing greenhouse gas emissions in wet tropical savannas, on grazed pastoral land, it can promote woodland thickening and pasture degradation. Optimal fire management, therefore, depends on vegetation type, land use and the prevailing seasonal timing and frequency of fire. Additional keywords: fire management, fire season, rangeland management, time since fire

Northern grazing carbon farming – integrating production and greenhouse gas outcomes 1 : Climate Clever Beef Final Report

This project targeted three large and diverse regions across northern Australia: the Queensland Gulf, the Queensland Fitzroy Basin and the Northern Territory (Victoria River District, Douglas Daly and Barkly Tableland regions). Eleven grazing businesses across three broad regions were engaged as case studies to undertake demonstrations and evaluations within their businesses. These businesses manage more than 1,281,000 ha and 97,600 cattle. The project provided an excellent opportunity to capitalize on established networks and genuine producer interest and participation built up in recent initiatives (e.g. CCRP Climate Clever Beef (Bray et al. 2014), Northern Grazing Systems project (Phelps et al. 2014), RELRP, SCaRP, SavannaPlan, CQ Beef). The project team included research and extension professionals with decades of combined experience working with northern beef producers. The knowledge and analytical tools developed during previous projects identified practices to: reduce the greenhouse gas emissions impact of beef businesses, manage climate variability, improve land condition and increase business profitability