Most of the time, changes in forage production are not considered in grazing management, and herd size is kept constant rather than adjusted to match the amount of produced forage. Consequently, pastures tend to be overgrazed in hot and dry years and undergrazed during wet and temperate years.
Contrary to expectations, overstocked pastures decrease animal gain and forage production. Grazing forages close to the ground (i.e., less than 3 inches stubble height) decreases the amount of sugars and other nutrients left for pasture regrowth, thus reducing forage production in subsequent years. This situation can be aggravated if there is an absence of fertilization in introduced pastures intended to replenish animal forage extraction.
Even though the worst consequences to pastures occur during overstocking, understocking also has its negative effects. The excess forage will mature, resulting in low forage quality, livestock consumption and animal gains. Mature forage will substantially reduce, even cease, leaf and stem growth to invest its energy in seed production.
Moreover, undergrazed pasture may need to be burned early in the next season, which is an extra cost for removing the top deteriorated forage layer and allowing sunlight into the canopy for initiating new shoot growth. For that reason, matching correct herd size and grazing time with pasture production every year is crucial for maintaining long-term pasture productivity and profitable animal production.
Madness in the methods
Forage production can be measured, estimated or simply guessed from experience. Forages can be accurately measured by clipping and weighing, which is labor-intensive and time-demanding. Consequently, pasture managers who need fast and reliable tools to deal with the complexity of livestock production systems will not do it.
On the other hand, the fastest and least labor-demanding method to estimate forage yield is via web-soil survey, which can be done in the comfort of one’s office. However, this method is the least accurate because it takes into account relatively outdated survey data which does not reflect the current condition of pasture soils nowadays.
In between those two extreme methods, there are indirect methods to estimate forage quality, such as grazing sticks, which allow managers to estimate forage production based on readings of forage height and canopy cover. However, the user still needs to go through several tables and equations to calculate proper stocking rate after performing pasture measurements. Most of the time, forage producers have several pastures to manage at once, making it impossible to calculate stocking rates for all pastures promptly.
The app
Thinking about speeding up the process, a team at Oklahoma State University and I developed the GrazeOK app. The app allows forage managers to input plant height and canopy cover readings straight to their smartphones, where the app will estimate stocking rate in the fraction of a second.
When using the GrazeOK app, the grazing stick can be replaced by a simple yardstick because the app will already have all grazing stick tables and formulas built in. However, more important than using either a grazing stick or a yardstick to take the measurements is knowing how to take them.
Keep in mind, the GrazeOK app results will be as good as the measurements are. Therefore, it is essential to know how to take proper plant height and forage cover measurements. In this case, the GrazeOK app contains a video tutorial that explains how to use it step by step.
After taking proper measurements, the user will need to describe his or her pasture. Using drop-down menus, the user will select the pasture’s forage type, grazing stubble height, livestock, number of animals, grazing days and grazing system. Finally, the app will calculate forage yield, grazing days, stocking rate and other important values for producers to take the most from their pastures without any productivity loss.
The GrazeOK app contains forage estimates from the Southern Great Plains. Therefore, its results will better represent pastures within Oklahoma, northern Texas, southern and central Kansas, western Arkansas and eastern New Mexico. For other locations, the app will also work; however, we ask the producer to be more conservative when using GrazeOK results.
For other locations, we recommend producers slightly decrease GrazeOK results by 5 to 10 percent when using for the first time. This slight reduction may protect your pasture from potential overgrazing if your location tends to be less productive than the Southern Great Plains.
Evaluate how the app performed during the first year and make your own adjustments for the next year. Keep in mind, tools like the GrazeOK are not flawless; they are a good start and, perhaps, you will need to tune its results to your location. We expect to expand the GrazeOK app in the near future to precisely cover more locations with an expanded forage database. 
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Alexandre Caldeira Rocateli
- Forage Systems Extension Specialist
- Oklahoma State University
- Email Alexandre Caldeira Rocatelik
Additional resources
- Estimating forage with the Oklahoman grazing stick
(Estimating forage with the Oklahoman grazing stick )
Note: Even though this tutorial was developed primarily for Oklahoma producers, the instructions within this video are applicable to all producers regardless of their location. Grazing sticks may vary slightly from state to state, but the model that best fits your location can be found by contacting your local extension educator, NRCS office, your local affiliate of the American Forage and Grassland Council (if your state has one) or the National Grazing Lands Conservation Initiative.
- GrazeOK: Manage pastures on your phone
GrazeOK: Manage pastures on your phone
