Optimizing Pasture Health: A Practical Guide to Implementing "Take Half, Leave Half" Grazing ▶️
When making changes to your beef cattle operation, starting with simple manageable steps is the key to long-lasting improvements. This is the case when it comes to the concept of “take half, leave half,” which is a basic rule of thumb for grazing management that can be effectively implemented in any region, in good weather years and bad.
In a recent video from the BCRC, Dr. Breeanna Kelln, adjunct professor at the University of Saskatchewan and a farmer/cow-calf producer north of Regina, demonstrated two methods to determine available forage and how to estimate when 50% has been utilized. Kelln explains, “Leaving behind some green material is important to ensure that plant can still photosynthesize and take energy back down into those roots so the pasture can persist and overwinter.”
Take Half, Leave Half – Method 1
Method 1 uses height as a quick and easy strategy to estimate the forage volume available to graze. Simply measure the height of your desirable forage in approximately 20 different spots, record the average height and then move cattle off that stand once that average height is cut in half.
Take Half, Leave Half – Method 2
Method 2 uses weight, which is more labour-intensive but more accurate to assume when 50% of the plant material is utilized. This entails cutting a few samples of forage from the pasture as close to the ground as possible, binding the bottom with an elastic band, and then finding the middle point by balancing the sample on your finger until the forage rests even and straight. Finally, cut off the plant material at the top, which allows for a visual representation of what the growing plants will look like once 50% of the plant material, based on weight, has been utilized.
Either method is an effective way to begin to recognize what you are starting with and what 50% utilization actually looks like.
Key Considerations
- Only look and measure the main nutritive forage in the pasture stand. Do not include undesirable or antinutritional weeds or plant material.
- Take measurements before cattle are let onto that field, ideally immediately before introducing them to the new piece.
- The more you graze, the more time that pasture needs to rest.
- Knowing the plant species in your pasture can help you to strategically graze throughout the season.
When taking these pre-grazing measurements, be sure you are only including the portion of the pasture that will be consumed by cattle. For example, if your pasture is half weeds and half forage, grazing the forage right down to the ground while the weeds remain untouched is not the “take half, leave half” principle. In this case, you would only consider the desirable forage portion of the pasture, which accounts for 50% of plant mass, meaning that 25% of the total plant mass on the field will be utilized to effectively apply “take half, leave half.”
While “take half, leave half” can be used as a guide, “the amount you graze is really determined by how long you’re able to rest that plant,” says Kelln. She adds that grazing 60%, 70% or 80% of top growth material can be okay as long as that pasture has time to regrow. “The more you take off the more time that pasture needs to rest.”
The University of Saskatchewan professor defines overgrazing as a function of time and not allowing pasture the time it needs to recuperate in order to be grazed again or survive the winter. “If we take off too much top plant and don’t allow adequate time to rest while it’s actively growing, then we are at risk of those plants dying off and having undesirable species coming into the pasture as well as productivity decline.”
Not allowing for adequate rest can also have animal health implications such as increased parasite loads and unideal selection behaviours, which impact the health and longevity of your pasture long-term.
Kelln goes on to say that if producers want to implement a heavier, more intensive grazing regime and have planned to do so, that can be very successful. But she stresses that it is important to “know what plants are out there, target them at the right time and allow for that rest at the right time.” Grazing a stand harder than intended in a pinch, during a drought, when forage is minimal is when things can get messy.
When it comes to grazing management, know what you have, have a plan, execute that plan to the best of your ability and always have a plan B . . . maybe even a plan C.
Want more grazing management videos? Check out the BCRC Grazing Management Playlist on Youtube.
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