Carrying Capacity Considerations
Written By: Ross Bronson
You may have heard the saying Ranchers are grass farmers, and cattle are the tool for harvesting their crop! I personally love the animals and the life cycle exposure of raising them. However, the concept that our forage and the landscape we run on is the key to our product sustainably reaching the market is an important perspective. The way producers utilize their rangeland impacts its health and subsequent producer profitability in the long run. This makes decisions about how many animals our range can support, and the timing of grazing crucial to long-term success.
Many in the ranching industry have used Take Half, Leave Half as a rule of thumb. But what does that really mean, and how can we as producers know we are only taking half? Why do we only take half? In addition, what are we only taking half of—standing forage, total growth, or both?
This conversation starts with an accurate, and conservative estimate of long-term carrying capacity (LTCC). The ecological definition of carrying capacity, according to Oxford’s English Dictionary, is “the number of people, other living organisms (livestock or wildlife), or crops that a region can support without environmental degradation”. Long-term carrying capacity can be calculated using the following formula:
LTCC = (Total projected forage production * % utilization)/calculated intake/365
Research suggests that percent consumption for long-term productivity be set from 15-30%. This supports the 25% utilization rate used in many range management guidelines. By assuming livestock consume 25% of forage available to them, another 25% is left for trampling, waste through manure or urine, and “other disappearance”. Other disappearance is most often attributed to wildlife but can also include mechanical damage, erosion, or other causes.
Accurate calculation of animal consumption allows us to be more confident that we are only taking half of our forage. But what about the other half? The other half is left to support plant and soil health and productivity through an improved nutrient cycle. In seasonal climates, especially those where forage goes dormant for a time, some see leaving standing forage as a wasted resource. However, leaving appropriate residuals will support faster growth when forage begins its growth cycle again because rebuilding roots will not be necessary. This energy and time can be utilized for stem and leaf growth. This makes the landscape better at growing forage!
So, what are we only taking half of? Quality range and forage management is a dynamic system that merges time, animal numbers, projected forage growth, and residual. I was recently introduced to the concept of forage budgeting. Forage budgeting is a process by which projected growth is used to estimate the number of animals and duration of grazing for a certain pasture or landscape. This is then reconciled with what really happens. This process takes both standing forage and growth into consideration. A great tool for this is the Rangeland Analysis Platform which gives years of average growth data for projections as well as 16-day biomass information for actual growth. Just like balancing a checkbook, this process allows for producers to make timely decisions on the movement of livestock to preserve rangelands and avoid over-utilization of forage.
This process can be involved, but it can be implemented at varying levels. Just make sure your carrying capacity and the way you stock your individual pastures are based on educated calculations. Your effort will pay you back in the long run.
For those years when your forage budget dries up and you find your account overdrawn, PRF insurance through Redd Summit Advisors provides means by which producers can feed their livestock through the purchase of forage such as hay for feeding or crop residue for grazing.
If you aren’t sure where to start in calculating carrying capacity or would like more information on forage budgeting and the Rangeland Analysis Platform, Redd Summit Advisors can put you in touch with a qualified consultant.
About the Author: Ross was born and raised in Idaho and has managed ranches in Idaho, Montana, Colorado, and Hawaii. He has enjoyed the exposure to different operational practices these opportunities have given him. He is passionate about all things horses and will talk all day about them if you let him. Ross had the opportunity to start his own livestock operation in southwestern Colorado where, in his second year, he weathered severe drought conditions. It was only later that Ross learned about PRF and its benefits! He looks forward to helping ranchers incorporate PRF into their drought mitigation strategies and show how it can help their profitability. Ross’ two proudest achievements are his family which he adores, and successfully earning a master’s degree in Ranch Management through the King Ranch Institute for Ranch Management. He is excited to join the Redd Summit Advisors team and is looking forward to the long-term relationships he will form with producers.