What is Stocking Rate & Carrying Capacity?
Stocking rate is a measure of the stock carried (per area, per time period, per unit rainfall), while carrying capacity is the ability of the soil & pasture to provide this from below. Farms generate data, loads of it, whether we are aware of it, care or don’t care. Your average farm is a sausage machine generating numbers like a day at the races. There is rainfall, frosts, temperatures, water tank quantities, flow rates, livestock ins and outs. Plus, all the stock movements, drafting, inputs, treatments, admin and on it goes.
For most land holders, this annual rhythm of the property is understood. It’s part of the mental model for what/when/how/why we do what we do on this property throughout the year. The spring break comes then, the winter shutdown happens by this date, we join by that date, etc. If the season turns up on time, as per average, predictable and consistent, then your stocking rate is going to be about right for the simple reason that is what you’re good at.
You know this place.
So why does knowing my stocking rate matter?
When the season is not on time, is wetter/drier/hotter/colder than average, you will have too much or too little grass/forage. There will be opportunity cost now or in future. The proof is written in the landscape of damage done during droughts.
Why am I even bringing this up for that matter? Because it is critical to farm ecological and financial and personal resilience. Something we are seeing stretched and stressed in Australia this year.Stocking rate and carrying capacity are used interchangeably and incorrectly in conversation by a lot of people. They are actually two very different measures of how things are at a point in time.Stocking rate is how things are, good, bad or ugly. Carrying Capacity is how it should be, ideally.
Evidence suggests most graziers don’t really understand stocking rate & carrying capacity
Whenever I’m talking to a grazing group or event, I always ask who knows what these numbers are. I almost always see 8 out 10 people putting their hands up for yes. Yet the data suggests they don’t. Since 1996 the Australian federal government has spent a massive $5.8 Billion (and rising) in drought assistance. That is in the order of $48k per farm.
At any given point in time, the data within MaiaGrazing is evidence that farms are either over stocked or understocked. Those who minimise the variance to optimal have choices when it comes to buying, selling, agisting, contract grazing, or supplementary feeding when the market suits them.
Breaking down the numbers
It's important we clarify what stocking rate & carrying capacity is, for those not confident enough to say they don’t know but want to. Both are numbers, specific to paddocks, pastures, land types and properties, best viewed at a farm level. The units can be lb/ac, kg/ha or dse days or stockdays or a variety of other units of measure. These units ultimately don’t matter as much as the ratio they represent.
Stocking rate is the actual livestock (plus ferals!) the property has carried over a period. While also relative to the season that grew the grass consumed.
Carrying capacity is nominal, can change (slowly) over time, and is a function of the soil, forage and management. Both are single numbers on a given day or month. Both are simply the ratio of dry matter consumed per unit of precipitation that grew it. In MaiaGrazing we gather up all the yield per paddock and pasture, for the last 365 days for ever animal. Divided by the precipitation that grew it.
You can’t do this math in your head, which is why most people don’t know their stocking rate now. Hence, they realise too late they are running out of feed in a tightening market with prices for feed increasing and selling stock decreasing.
How to see the warning signs and adjust ahead of time
The ratio, of accrued feed consumed relative to the precipitation that grew it, rising indicates the need to reset the plan. Whether that plan is to sell some cull animals, maybe wean early, or look for opportunities to graze elsewhere on contract. Taking these steps takes confidence because they are obviously not trivial decisions and made all the harder when you are ahead of the market by 6 to 8 weeks.
Even better than knowing what stocking rate is and should be, is how simple it then becomes to forecast out a few months. Also, what it will look like given any assumptions you like. For folks who have been crunched by lack of feed or lost opportunity these are game changing tools. We built MaiaGrazing to meet this need and more. Whether it’s to better understand planning grazes, forecasting or understanding your carrying capacity, we are here to help.
FAQ
How do you work out stocking rate?
Stocking rate is “forage demand” which accounts for animal size, number of animals and the length of the grazing period. Calculate it using the Animal Unit Equivalents (AUE) and Animal Unit Months (AUM).
AUE (standard) = 1000 lb animal = 1.0 AUE (for every 100 lbs over 1000 lbs, add 0.1 AUE)
What is the carrying capacity of my farm?
As mentioned in this article, the carrying capacity is the maximum number of animals that a pasture can support without causing land degradation. Therefore, carrying capacity can change over time since it relies on changing variables such as soil type, management practices, etc.
In general, carrying capacity can be expressed in multiple ways. To calculate AUMs:
AUM/acre (for rangeland pastures only):
AUEM/ac = AUM ➗ total acres ➗AUE
Where AUM is based on the vegetation type and AUE is based on the livestock.
AUM/acre (for rangeland and tame grass pastures):
AUEM/ac = AUM ➗ total acres ➗ AUE
Tools such as MaiaGrazing can help automate these calculations by integrating real-time data on pasture conditions, forage growth, and livestock requirements.
How many cattle can you have per acre in Australia?
In Australia, the number of cattle per acre varies based on regional climate, soil fertility, and pasture management. On average, one acre can support between 0.5 to 1.5 head of cattle. However, these figures can differ significantly, so it's essential to use local data and grazing management tools to determine the optimal stocking rate for your specific conditions.
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