A ranch is only as good as its grass. Without a continual cover of grass, most beef cattle operations are not sustainable, which makes grazing management a very important rancher responsibility.
“An acre of leafy grass equals 43,560 square feet of solar panel,” says Dr. Wayne Hanselka, Professor and Extension Range Specialist Emeritus, Texas A&M AgriLife Extension Service. “Energy from the sun causes green pigment (chlorophyll) in plant leaves to produce carbohydrates through a process called photosynthesis. The carbohydrates are stored in the stem bases, roots and rhizomes. If a plant is continually grazed too close to the ground, it tries to re-grow foliage using its carbohydrate reserves. If it is unable to replenish the reserves due to lack of leaves to manufacture more carbohydrates, the plant will die once the supply is depleted. That is why it is important to allow pastures an opportunity to rest and give forage a chance to recover from grazing.”
Appropriate Grazing Stubble Heights
“Measuring grass stubble height can provide the land manager with important information such as when to move livestock to another pasture,” says Dr. Robert Lyons, Professor and Extension Range Specialist, Texas A&M AgriLife Extension Service. “Managing for sufficient grass stubble height can also provide long term range sustainability and watershed protection benefits, such as healthy plant root system maintenance, greater rainfall infiltration, runoff and erosion reduction, and lower soil temperatures. Soil moisture evaporation is reduced by lower soil temperatures, which in turn promotes plant growth and reduces invasion by less desirable species.”
Lyons continues, “Many livestock managers ‘take half, leave half’ in their forage management. They should realize that almost 25 percent of the grass is susceptible to trampling and insect consummation, therefore leaving only 25 percent of the forage for livestock – not 50 percent. The following table gives minimum stubble heights to maintain for various types of grasses:”
Type of Grass
Grass Species Examples
Minimum Stubble Height (inches)
|Tall Grasses||Little Bluestem, Big Bluestem, Indiangrass, Switchgrass||
12 – 14
6 – 8
|Introduced Grasses||Bermudagrass, Bahiagrass||
3 – 4
|Introduced Grasses||Kleingrass, Old World Bluestems||
4 – 6
Pasture Rotation Systems
To be able to give pastures rest, you must have ungrazed areas in which to move cattle. A grazing plan should be designed with a goal to keep key grass species in the vegetative stage and at or above recommended minimum stubble heights. This goal can be accomplished with a pasture rotation system.
Pasture rotation system can be implemented by dividing a pasture into as few as two paddocks, but more divisions make it easier to give grass the necessary number of days for full recovery from grazing. There are many different rotation grazing systems in use and a few of them will be discussed in this article.
Hanselka describes deferred grazing as a rotation system where grazing animals are removed for an adequate period of time to give desirable plant species an opportunity to regain vigor and reproduce. Animals are moved from one pasture to another when proper use of the key forage species has been obtained. Pastures are also deferred to allow forage to re-establish following seeding or brush control.
A four pasture deferred rotation program was developed in 1949 by Dr. Leo Merrill at the Texas Agricultural Experiment Station near Sonora, and it is known as the Merrill System. This system requires four pastures near equal size to avoid overgrazing in a smaller pasture, causing the system to fail. Total proper stocking rate of all four pastures is calculated and stock is divided into three herds. Three pastures are grazed while one is deferred.
“High intensity-low frequency grazing (HILF) systems concentrate livestock into one herd and allow them to graze a pasture until proper use is obtained,” explains Hanselka. “They are then moved to another pasture and the process is repeated. Multiple pastures are necessary so that significant time may elapse before the original pasture is re-grazed.”
The rancher should determine the months in which maximum growth and forage production can be expected and when little growth can be expected. The system should be designed to promote maximum production in all possible pastures during the growing season, and allow for standing forage to remain for use during dormancy periods.
“Short duration grazing (SDG) involves a cell system where fencing radiates from a central watering and working facility like spokes on a wheel,” continues Hanselka. “This arrangement reduces livestock handling stress and the need for developing a water source in each pasture. Livestock are usually grouped into one herd for each cell and moved through the paddocks in such a manner that they select a high quality diet and don’t overuse the plants. The livestock are off the paddocks long enough for the grazed plants to recover sufficiently to withstand another grazing period.”
Planning and Management
In planning rotation grazing systems, determine the necessary rest periods first and then let them dictate average grazing periods. An example of a cell design is shown in the Holistic Management® Grazing Planning notebook on page 53. The cell has a wagon wheel design and is divided into six paddocks. A grazing period of twelve days in each will allow every paddock 60 days to recover. The herd will cover the whole cell in 72 days.
“Rotation grazing plans should be flexible and not managed strictly by calendar dates,” says Hanselka. “During dry periods, you may need to slow down the rotation to allow paddocks more time to rest. When you receive rainfall, shorter rest periods may be feasible which allows each paddock to be grazed for shorter periods. Slow forage growth equals slow moves and a longer recovery period. Fast forage growth equals fast moves and shorter recovery periods.”
For any type of rotation system to be successful, you must begin with pastures in good condition. The soil must be covered with vegetation revealing minimal bare ground. Remove cattle and other livestock from pastures in poor condition so the grass can re-establish itself. Do not restock these pastures until the vegetation has fully recovered.
If all pastures are in poor condition, animal demand must be reduced by early weaning, culling and/or relocating to lease pastures. It may be necessary to sacrifice a small trap and use it to drylot feed the cattle. The trap will be sacrificed because it will take many years for it to recover without reclamation efforts.
Remember that a ranch is only as good as its grass, so we need to keep our pastures in good condition