Step 2: Identify land management units (LMUs) and farm resources
Under the Code the identification of land management units (LMU’s) is optional. However, the concept is strongly recommended for pastoral and arable properties. Failure to identify LMU’s and manage them differently could lead to some significant production losses and adverse environmental impacts. Understanding differences in the way parts of the property respond to nutrient management and different land management practices is an important step in achieving production goals as well as recognising and understanding the environmental risks associated with nutrient management activities. The risks associated with nutrient management activities may vary on different parts of the property, so we need to consider each of these areas separately.
The method described below is one means of assessing land management units. In some areas alternative methods such as land use capability mapping may be used. General background is provided in Fact Sheet 1.
A land management unit (LMU) is defined as:
“A homogeneous block of land that responds in a similar way under similar management.”
Areas that need different management or that will show different responses need to be separated for good planning. For example, is all of the area managed in the same way? Will all parts of the property or block respond to nutrients in the same way? Do they share the same environmental risks?
LMUs are best assessed using a combination of physical factors (e.g. soil type, slope, aspect), major management factors (e.g. dryland versus irrigated areas, different arable or horticultural crops, dairy effluent disposal areas, etc.) and history of previous use and management. Some producers will find that their property has several land management units while others can treat their entire property as a single LMU.
Mark the different LMUs on a farm map, and the paddock number, with a note about what each unit represents – e.g. different soil types, aspect, flat and steep areas, different horticultural crops, etc.
Note also any significant environmental features within each LMU – e.g. waterways, wildlife habitat, wetlands, native bush or areas subject to frequent flooding. An example of a LMU map is shown below.
Figure 2: Example of Land Management Unit map
Collect information about the LMUs that will influence nutrient management decisions. Some things to think about:
- Do you have soil or herbage test results for these areas? What is the current soil nutrient status? If there are no recent test results then you should consider testing to establish background soil nutrient levels.
- Are nutrients other than fertiliser applied? For example, is dairy effluent spread on the land? Is conserved feed brought in from other land?
- Do you have information about factors that may alter the environmental risk in any of these areas? For example, are there any irrigated areas where the water table is naturally high?
Mark on your LMU map all potential nutrient ‘hot spot’ sites. (e.g. silage pits, offal pits, stock handling facilities, feedpads, effluent ponds, effluent spray areas, fertiliser storage areas etc)
Farm resources are interlinked and will influence the nutrient management plan.