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Keep an Eye on Your Keys

Posted Mar. 1, 2002

Losing your keys can put a damper on the beginning of a beautiful spring day. If you've simply misplaced them, but know they're around somewhere, the worst that usually happens is you have to put other things on hold while you locate them. If the search reveals that you have truly lost your keys, the next step is to get some new keys made. An extra bonus when this happens is the frustration you experience, wasted time, and an outlay of cash for some new keys.

Did you ever think of the same thing happening with your pastures? Think about it if you run livestock on rangeland, what happens when key forage species get overgrazed? Gradually, livestock will selectively graze out the key species, and before you know it, forbs (weeds) or less desirable species have replaced the good stuff and left you wondering what happened to your "keys!"

If you recognize this problem early, you can adjust your stocking rate and/or grazing management to sustain your key species and maintain or gradually increase pasture productivity. However, failing to recognize this situation, or recognizing it but not adjusting grazing management, often leads to frustration, finger pointing at the weather man, and, for the impatient, thoughts of converting native grass to bermudagrass or the latest wonder grass on the market (making new keys).

Many times with tame pasture, such as bermudagrass, we suggest stocking rates based on the total amount of production we expect combined with the level of utilization that we believe corresponds to a producer's grazing management skills and which also sustain plant vigor. For an experienced producer with a fertilized stand of bermudagrass that will yield an estimated 2.5 tons of forage per growing season, we might suggest a seasonal stocking rate based on grazing 70 percent of the grass that he grows over a seven month period. In this case, the stocking rate would be 1.8 acres per 1,100 pound cow. We often suggest stocking rates on native grass in the same manner, but if we are not conservative in doing so, or if the producer does not monitor his pastures, this method can lead to "losing your keys." So, while we may stock based on utilizing 25 percent on native grass, the knowledge of, and use of key forage species as a management tool, enables us to adjust stocking rates in order to keep desirable forages and avoid reducing the productivity of native grass pastures.

To find out what your key forage species are, you have to know your major plants and a little about what livestock like to eat. Key forage species are normally perennial plants. They should be well distributed and provide a significant proportion of the plant composition in a pasture. They should also be relatively well preferred by the livestock species that you are managing. This is where knowing what livestock like to eat proves valuable. Several years ago, an old friend of mine from Louisiana and I were looking around on a ranch when he asked me, "If you had the choice of eating a steak or a hotdog, which would you eat?" It was close to dinner so I said, "I'd eat my steak first and then if I was still hungry, I'd eat the hotdog." He asked, "Then, why do you think the cattle are hammering the little bluestem in this pasture." Before I could reply, he said, "The cattle figure they don't know how long they'll be in this pasture, so they're eating their steak first, too!" His message to me was that cattle have preferences for different plants just like people have preferences for different foods. The cattle preferred the little bluestem over the rest of the forages in the pasture and therefore ate a higher percentage of it than the other forages.

In this case, little bluestem was the key species and, if grazing management were not addressed, the abundance of this important plant would be reduced and gradually replaced by less desirable species, which most likely would reduce the carrying capacity of the pasture. The picture on the left depicts three native grasses (left to right), which are indiangrass, three-awn (ticklegrass), and silver bluestem. If you had a pasture that contained all three of these plants, it is highly likely that cattle will apply the "Steak / Hotdog Principle" when grazing these plants. Most often, cattle will prefer indiangrass over silver bluestem, and silver bluestem over three awn. There are times, such as early spring, when all of these forage species are preferred and you can't discern much difference in grazing preferences. However, as the growing season progresses, you will almost always see the indiangrass grazed harder than the other two grasses by cattle. If indiangrass was abundant enough and distributed fairly well in this pasture, we would consider it the key species.

Now, go back to the discussion on stocking native grass pastures based on a percentage of grass utilization. If we stocked this pasture based on 35 percent utilization and had enough information to tell us that this pasture should produce 3,000 pounds over a year's time, the suggested yearlong stocking rate would be about 10 acres per 1,100 pound cow. But, if we don't monitor the grazing use of our key species, the cattle may overgraze the indiangrass, resulting in under-use of the other grasses. With no attention paid to this matter over several years, the composition of plants in the pasture will likely shift to the point that indiangrass is no longer abundant enough to be considered a key species. Weeds or less desirable grasses replace indiangrass, and pasture production is reduced. To alleviate this problem, allow the livestock that you are managing to graze no more than 50 percent of the key species. By not overgrazing your key species, the remaining forages are much less likely to be overgrazed, and pasture productivity is easier to sustain. It's easy to talk about using no more than 50 percent of a particular grass than doing it. Obviously, this will take some monitoring, or "looking for your keys." The most practical method of doing this is to locate a key area in every pasture. A key area obviously contains the key species, has a high amount of available forage, average topography relative to the whole pasture, and the grazing distribution of livestock is not biased by distance to water (too close or too far). A key area should also not be close to feeders, mineral or salting locations, or the lone grove of shade trees in the pasture.

It's not hard to find a key area in each native grass pasture, but another key is to get out of the pickup and walk through the area so that you can determine the grazing use of the key species. You will get a different perspective by looking down on the grass than you do from looking across the grass. For most tall native grasses, a good rule of thumb is to graze them no lower than six to eight inches in the growing season and then rotate cattle to another pasture. Key species that are considered tall grasses should be allowed to recover to a height of 10-14 inches before first frost. If your key species is a shorter grass such as sideoats grama, rotate pastures during the growing season when the grazed stubble is no lower than four inches. Generally, short grasses should be allowed to recover to a height of six to eight inches prior to first frost.

The concept of key species and key areas is a proven grazing management tool that has been used on native grass pastures for many years. It is also one of the easiest monitoring methods available. Ranchers spend a lot of time on their land. Use the spring wisely by learning your plants and utilizing this simple method. Also, it's probably not a bad idea to keep another set of keys in the barn.

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