1. Construct a plan that defines grazing land into pasture and cropping zones based on the limits set to determine the best options for establishing and managing pasture for optimum growth, quality and sustainability. There are a number of methods for classifying land capability and these attempt to rank the ability of the natural resource using land class as the basis to sustaining production over time. The features and options for the various land classes are shown in the following table adapted from NSW Agriculture.
• Base the initial description of zones on physical properties of the landform and soil type that cannot be altered over time through management.
• Further demarcate the zones based on major pasture growth or management limiting factors, such as occasional cropping, that can be changed over time but need to be factored into pasture species and fertiliser decisions. This includes saline affected areas or acid soils with high aluminium content.
• Identify zones that are not adjoining but have similar characteristics and group them for farm planning purposes. However, their identity should be preserved to assist utilisation practice and analysis to ensure balanced growth, quality and species diversity across pasture based grazing lands.
2. Use the following observations and previous table to define changes in land class and capability. A new zone should be created whenever maximum acceptable limits are exceeded.
• Soil texture class in A and B horizons. Create a new zone when texture changes more than one class, for example from sand to loam.
• Depth to impermeable layer and/or to sub-soil layers with low soil pH as an indicator of potential rooting depth. Base initial assessments of soil depth on existing knowledge gained from digging post holes or soil pits and the presence of perched water tables. Then assess current pasture species and growth potential to identify shallow soils.
• Slope as an indicator of the risk of excess run-off and soil erosion. When available use contour maps for precise measurement. Initially map out all land that you regard as steep and prone to higher rates of run-off. Look for evidence of soil erosion.
• Aspect as a measure of ambient temperature and its impact on grazing patterns, exposure to sunlight and degree of evapotranspiration. Separate north facing slope land from all others. South facing slopes can also have lower pasture production potential especially in combination with steep slopes and shading.
• Location of streams and naturally confined watercourse drainage lines.
• Soil salinity (EC) and acidity (low pH).
• Indicators of saline discharge areas and salt affected land . This enables you to map out areas for reclamation for special stabilisation or reclamation treatment.
• Cropping or specialty fodders, such as lucerne, as the primary land use.
3. Use the mapped results to guide the development of infrastructure and to allow differential management of pasture zones. If the cost of changes to infrastructure is likely to be significant, conduct an economic assessment. Give highest investment priority to the management of identified fragile zones to ensure environmental protection is not compromised. The following are examples of fragile areas with recommended management approaches:
• Riparian areas. Maintain a minimum of 5 metres of thickly grassed and unfertilised land along stream banks where water flows are likely to enter, and a minimum of 10 metres where periodic flows are likely.
• Problem aspects and slopes. Develop the capacity to differentially manage aspect to avoid overgrazing of warmer north facing slopes, undergrazing of cold south facing slopes, and land classes 3, 4 and 5 to maintain high levels of ground cover, litter and pasture mass, especially during expected periods of high evapotranspiration, low soil moisture and risk of high intensity rainfall.
• Factors that limit pasture growth. Use species that are tolerant of any limiting factors. For example, use salt-tolerant species in saline discharge areas. Use species that tolerate long periods of soil saturation in zones prone to water logging as identified from indicator species and avoid grazing these areas while water logged.
• Natural features will affect grazing patterns and mustering ease.
4. Sources of planning assistance.
• Whole farm planning packages are available from various agencies. Visit state agency websites (see Tool 1.4), or contact your nearest planning office.
• Mapping software is available from agricultural software suppliers (usually as part of farm database packages).
• Aerial photos (scanned if using computer mapping software). Use clear plastic
overlays on aerial photos when the cost of mapping software is not justified.
• Commercially available contour maps of local area district (1:25,000 or better).
• Maps and photos are available from state planning and mapping authorities: NSW – Land and Property Information, (02) 6332 8123 Victoria – Information Victoria, 1300 366 356 Tasmania – Service Tasmania, (03) 6233 3382 South Australia – Mapland, (08) 8226 4919 Western Australia – Department of Land Administration, (08) 9273 7373
