A farm's carrying capacity is its ability to sustain animals. This capacity depends on both space and feed availability, where feed availability is a function of pasture composition, soil quality, climate, and the enterprise's ability to bring in supplementary feed.
In Australia, carrying capacity is typically measured according to a standardised methodology called the "dry sheep equivalent" (DSE). One DSE is the amount of feed required to maintain the weight of a 45 kg, two-year-old Merino sheep. It follows that carrying capacity is fundamentally a measure of energy produced over time, where one DSE is equivalent to roughly 7.6 megajoules (MJ) per day.
Using DAS, you can get a carrying capacity estimate for any farm in Australia, in units of either DSE or "adult equivalent" (AE) - the corresponding standardised measure for beef cattle. This measure is for a 450kg Bos Taurus steer maintained at that weight.
Read on below to find out how we generate these estimates.
How carrying capacity is calculated
When talking about carrying capacity, it's important to distinguish between potential and actual.
Potential measures the carrying capacity of a farm under best management conditions, which could include pasture composition, rotation rate, and fertiliser application. Potential measures allow farm scoring and like-for-like comparisons between farms by standardising these land management practices.
Actual on the other hand measures how many animals a farm has actually supported over time. Actual measures allow measuring of historical farm capacity and how this has changed over time.
At DAS, we're currently focussed on potential capacity, as it helps to best support the farm valuation and comparison process.
Potential carrying capacity
Traditionally there have been several; rules of thumb for quickly estimating potential carrying capacity, such as:
Dividing rainfall by evaporation
Measuring out a small grazing area on the farm, estimating the feed that could be grown in that area, then multiplying over the rest of the grazing area of the farm
One problem with these methods is they do not take into account many factors which contribute to carrying capacity, like climate projections, soil, and changes in feed availability across a typical growing season.
To help address this, we've partnered with CSIRO to build a model which estimates carrying capacity based on:
Actual climate data
Actual soil type data
Feed availability across a season
Typical pasture compositions (on a per area basis)
Economic models of grazing enterprises
You can find this measure on the Production tab for any property, cadastre, or custom farm, where you can also toggle between sheep (DSE) and beef cattle (AE). As always, you can get in touch with us with any feedback about this data using our chat box, or the "Report a data error" button.