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 modelling from northern Australia and assesses the extent to which current recommendations to manage for these issues are supported. Overall, stocking around the safe long-term carrying capacity will maintain land condition and maximise 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 water-points and in some cases patch-burning, although the economics of infrastructure development are extremely context-dependent. Overall, complex multi-paddock 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.

Burning of savanna is a globally important source of greenhouse gas (GHG) emissions. In Australia, burning of savanna contributes between 2% and 4% annually of the nation’s reportable emissions. Complete removal of this source of emissions is unrealistic because fire is a ubiquitous natural process and important land-management tool. In the rangelands of northern Australia, fire is used to manage habitat for conservation, control woodland thickening, manipulate pastures for grazing and is an essential component of indigenous cultural and land-management practice. There has been a concerted attempt in recent times to move away from complete fire suppression and its consequence: frequent, extensive and high intensity wildfires occurring late in the dry season. In fire-adapted vegetation types, prescribed early dry season fires help reduce the incidence of late season wildfires and consequently the amount of GHG emissions produced. The emergence of a carbon economy affords a potential opportunity for land managers to diversify their livelihoods by adopting fire-management practices that reduce GHG emissions and increase carbon sequestration. However, in order to realise benefits from this emerging economy, there is a need to identify and address a range of barriers affecting community participation. The papers in this Special Issue document current scientific knowledge, policy issues and pathways to participation, with particular reference to Australia’s savanna rangelands. This introductory paper outlines how northern Australia has both the opportunity and requirement to develop a diversified rangelands economy to realise multiple conservation, economic and emissions outcomes.

A ‘safe’ pasture utilisation rate is defined as the proportion of annual forage growth that can be consumed by domestic livestock without adversely affecting land condition in the long term. Pasture utilisation rates are thus a cornerstone of a sustainable grazing industry because they directly determine livestock carrying capacity. Until now, it has only been possible to determine utilisation rates in the Northern Territory via expensive and time-consuming grazing trials. Reliance on this method has limited the validation of safe utilisation rates for the range of land types used for pastoral production. This study tested an alternative cost-effective method for calculating utilisation rates based on an approach used previously in Queensland. The method retrospectively calculates utilisation rates using cattle records and modelled pasture growth from commercial paddocks in good land condition. The assumption underpinning the method is that paddocks in good land condition, with a long history of grazing, must have been managed in such a way as to achieve a safe level of pasture utilisation. Utilisation rates were calculated for 10 commercial paddocks on three properties in the Barkly Tableland region of the Northern Territory from 1999 to 2009. Animal intake for each paddock was calculated from detailed cattle records held in property databases. Pasture growth was estimated using simulation models and cross-checked with field measurements. An average utilisation rate of up to 25% of annual pasture growth was found to be safe on highly uniform, grey cracking-clays supporting Mitchell grass (Astrebla F. Muell. spp.) pastures. However, this level of utilisation had negative impacts on land condition on less resilient and preferentially grazed pasture communities in paddocks with a mix of land types. The implications of the results for carrying capacity, animal productivity and seasonal risk management are explored in this paper.

The grazing lands of northern Australia contain a substantial soil organic carbon (SOC) stock due to the large land area. Manipulating SOC stocks through grazing management has been presented as an option to offset national greenhouse gas emissions from agriculture and other industries. However, research into the response of SOC stocks to a range of management activities has variously shown positive, negative or negligible change. This uncertainty in predicting change in SOC stocks represents high project risk for government and industry in relation to SOC sequestration programs. In this paper, we seek to address the uncertainty in SOC stock prediction by assessing relationships between SOC stocks and grazing land condition indicators. We reviewed the literature to identify land condition indicators for analysis and tested relationships between identified land condition indicators and SOC stock using data from a paired-site sampling experiment (10 sites). We subsequently collated SOC stock datasets at two scales (quadrat and paddock) from across northern Australia (329 sites) to compare with the findings of the paired-site sampling experiment with the aim of identifying the land condition indicators that had the strongest relationship with SOC stock. The land condition indicators most closely correlated with SOC stocks across datasets and analysis scales were tree basal area, tree canopy cover, ground cover, pasture biomass and the density of perennial grass tussocks. In combination with soil type, these indicators accounted for up to 42% of the variation in the residuals after climate effects were removed. However, we found that responses often interacted with soil type, adding complexity and increasing the uncertainty associated with predicting SOC stock change at any particular location. We recommend that caution be exercised when considering SOC offset projects in northern Australian grazing lands due to the risk of incorrectly predicting changes in SOC stocks with change in land condition indicators and management activities for a particular paddock or property. Despite the uncertainty for generating SOC sequestration income, undertaking management activities to improve land condition is likely to have desirable complementary benefits such as improving productivity and profitability as well as reducing adverse environmental impact.

This paper evaluates three decades of innovation by a leading beef producer in the Barkly region of the Northern Territory. The case study represents a rare published analysis of changes in production, greenhouse gas emissions and land condition metrics for a commercial livestock business. Thirty years ago the property was under-developed and had poor livestock productivity by today’s standards. Between 1981 and 2013, the business has increased carrying capacity through water point development, and achieved a >50% increase in herd size, a 46% improvement in weaning rate, an 82% reduction in breeder mortality rate and an improvement in land condition. Annual liveweight turn-off has increased from 75 kg to 128 kg per adult equivalent (AE) carried. All of this has been achieved while using recommended stocking rates. In contrast, two additional analyses reflecting other management approaches being taken by some north Australian beef businesses resulted in poor productivity, economic, emissions and land condition outcomes. Total greenhouse gas emissions have increased on the case study property since 1981 as a result of increasing herd size. However, the intensity of emissions per tonne of liveweight sold has declined by 43% due to the improvements in livestock productivity. The potential for generating carbon revenue from this emissions intensity improvement was explored. We found that for >95% of northern beef enterprises, current project transaction costs would entirely negate carbon revenue at a carbon price of < $25 tCO2e–1. At $5 tCO2e–1, the minimum herd size needed to cover the project transaction costs would be in excess of 35 000 AE. Although substantial carbon profits appear unlikely at present, the management practices evaluated can deliver substantial economic, emissions and land condition benefits to individual businesses and the wider industry. The paper concludes that cost-effective investment to concurrently increase herd size and livestock productivity per head, in conjunction with safe stocking rate management, is a proven path to economic and environmental sustainability in the north Australian beef industry.