Fire management at Ban Ban Springs station

By Tom Starr, former manager Ban Ban Springs
From Savanna Burning—Understanding and Using Fire in Northern Australia, Tropical Savannas CRC, Darwin 2001

My 14 years of experience at Ban Ban Springs about 130 km south-east of Darwin illustrate one way that a range of fire-related issues can be dealt with practically.

Ban Ban Springs receives an average 1200 mm rainfall. The topography varies between high, steep ridges in the east and west and the extensive flood plain along the Margaret and McKinlay rivers. The open savanna woodlands have a typical Top End overstorey of trees and shrubs over kangaroo grass (Themeda triandra), but with annual and perennial sorghums (Sorghum spp.). Cattle graze these native pastures at stocking rates of about one beast to 10 ha in relatively large paddocks (3000–15,000 ha).

Our fire management

Our burning regime revolves around extensive burning during the early to mid-dry season, coupled with selective wet season burning to control tree saplings and the Sorghum grasses. However, if stocking rates are too heavy (over 1:10 ha), repeated dry season burning can rapidly deplete pastures — within three seasons. High grazing pressure also favours growth of shrubs and trees as well as introduced weeds.

Ideally we burn about one-third of the grazed part of the property each year in the late wet season or early dry season (March-May) giving a three-year cycle.

Practically, it has been possible to burn about half of each paddock, although wildfires can upset the intended burning regime.

Burning on Ban Ban can be opportunistic and generally takes place before the ground has dried sufficiently to grade firebreaks. We make use of the Bushfires Council helicopter to drop incendiaries when access to the country is still limited. An aerial drip torch is used to ensure that secure burnt lines are established in areas that are too wet or green for effective incendiary ignition.

Fire and grazing

Grazing the breeding herd on this combination of burnt and unburnt pastures allows us to wean calves earlier in the dry season so that the breeding cows maintain better condition later into the season and so conceive earlier.

Fire used in this way also helps to even out the grazing pressure as cattle prefer to graze young, short, green pasture that is provided by burning and, to a lesser degree, by grazing. Grazing pressure is shifted dramatically within days to the burnt areas where it is common to find 90% or more of the stock. This provides another advantage; our stock are concentrated and so easier to muster.

Late dry-season fire is an effective means of controlling woody weeds, but the paddock should be lightly stocked (one beast to 30 ha) to build up grassy fuel loads for the high-intensity fire needed. These kinds of burn should take place after rainfall of at least 100 mm or at the onset of the full wet season to reduce the risk of total pasture depletion and to encourage rapid pasture regrowth.

Fire history maps from the Bushfires Council NT help us with planning and monitoring. Knowing where the burnt areas are saves time and resources when combating wildfire later in the dry season.