47 BURDEKIN DRY TROPICS NATURAL RESOURCE MANAGEMENT PLAN 2016-2026
When soils become strongly acid their productivity is compromised. Factors that accelerate acidification include: excess ammonium-based nitrogen fertilisers and continued removal of plant, animal and waste products. Treating surface acidity can be simple such as matching fertiliser inputs to crop demand; efficient irrigation management and early sowing after fallow.
managing grazing lands with fire information packages; and
• Tropical Savannas Cooperative Research Centre’ s satellitebased fire scar mapping. This mapping can be found on the North Australia Fire Information( NAFI) website. The live maps allow graziers to monitor fires on large properties, better protect infrastructure and fodder from wildfire, improve native pastures and woodland structures, and improve fire management planning( Felderhof & Jacklyn, 2011).
Within our region’ s grazing area there are thirty-three land types( listed in Appendix E, p 92), which are mostly characterised by phosphorus poor and highly-erodible soils. Two documents- the Sustainable Management of the Burdekin Grazing Lands and Land Condition Photo Standards for the Burdekin Dry Tropics Rangelands, identified these land types from collating previous regional and local soil mapping data, to better understand the interconnected nature of regional land types, their soils and pasture condition requirements. They highlight each land type’ s preferred 3P grasses( productive, perennial and palatable), susceptibility to erosion, and safe utilisation rate( maximum rate of average annual use to maintain and encourage good land condition)( McIvor, 2012). Examples of land condition photo standards for a land type are shown on pages 47 and 48.
LAND
Example of‘ A’ conditon land has:
• good coverage of 3P grasses;
• > 50 % coverage at the end of dry season;
• few weeds and no significant infestations;
• good soil condition: no erosion, good surface condition;
• no sign, or only early signs, of woodland thickening;
• minimal run-off and high
infiltration rates.
Example of‘ B’ condition land has:
• some decline of 3P grasses;
• increase in other species( less favoured grasses, weeds);
• 40 – 50 % coverage at the end of the dry season;
• some decline in soil condition;
• some signs of previous erosion and / or current susceptibility to erosion is a concern;
• some thickening in density of woody plants.
In recent years there have been significant improvements in grazing practices, and reductions in the rate of fine sediment loss from the Burdekin catchment, however, the overall health of soils in rangeland areas remain weak due to erosion and a significant loss of soil carbon as a legacy from past land practices( Hook, 2011). Assessment of our region for the Water Quality Improvement Plan( WQIP)( Refer to Part B – Water) has identified substantial areas of the Burdekin to be in very poor‘ D’ and poor‘ C’ land condition.‘ D’ condition land has significantly reduced groundcover and exposed soils, which erode more readily during high-intensity rainfall events that are a common feature in the Dry Tropics.
The proportion of our region with less than 50 per cent groundcover fluctuates substantially with rainfall; after multiple wet years only five per cent of our region has reduced ground cover and after several dry years this can increase to over 40 per cent of our region( Queensland Government, 2010).
The Upper Burdekin and Bowen subcatchments have the highest rate of erosion derived from exposed subsoils, highlighting a significant loss of topsoil into the waterways as indicated by tracing data( Lewis, et al., 2015). Studies into gully erosion in the Upper Burdekin have also identified that long-term catchment runoff may be greater than 30 per cent higher from degraded catchments than from those in good condition( Wilkinson, et al., 2013)( Meat Livestock Australia, 2015).