Livestock animals eat a lot. In the grasslands around the Sonoita area the conversion is about 42 acres of pasture needed for a cow per year and 75–120 acres per horse. Because of their teeth and digestive system, horses are much tougher on range land than are cattle. Supplemental feeding on smaller acreage is a necessity but is not a cure-all. They will still spend their time grazing on native forage. The question is how to keep livestock healthy and, at the same time, prevent land mismanagement. This is what some folks refer to as overgrazing. 

“Overgrazing” is an overused and emotional term. To some folks overgrazed land is anything that shows any sign of use. To others it doesn’t even exist because “it all comes back with the summer rains.” Of course, the truth is somewhere in between. True overgrazing (I prefer the term mismanagement) occurs when the native plant community has been degraded by livestock to the point where it cannot recover, over time, on its own. This is the result of compaction, and root and seed loss. The result will be erodible ground, weeds, and potentially invasive species taking over. The real question is how do we prevent this from happening?

Timing of grazing is a critical factor. Our native grasses are dormant for a long period of the year. In spring, depending on the temperature and winter moisture, there may be a small amount of greening and growth. Grasses then go dormant again with days of near triple digit temperatures, double-digit winds, and single digit humidity. Dormant usage, within reason, does not lead to overgrazing. The real damage can occur during the summer growing and fall seeding seasons.

With the arrival (hopefully) of the summer rains grasses begin to grow. This growth period is important for two reasons. The full growth of its leaves allows the plants to take in enough resources to go to seed which ensures that further generations can grow. Also, it allows the individual grass plants to take in nutrients, which are stored in the roots to come back the next year. If these two factors don’t happen, the long-term survival of the grass plants is in doubt. Graze VERY lightly or not at all once the seeding process has started.

The question here is what to do with livestock when the late summer growth is happening. No answer is perfect but the best one for limited acreage is the creation of a small, sacrificial pasture. This area would be under .25 acre and would the main holding area of your livestock until the seed maturation process is complete on the native grasses. That would be marked by the grasses turning brown and the seeds coming off the heads easily by hand. 

Other problems go hand in hand with grazing mismanagement and contribute to land degradation. Weeds and invasive species top that list. Tumbleweed (AKA Russian thistle, Sasola tragus ) and pigweed (AKA carelessweed, Amaranthus palmeri) are very common in our area. Pigweed, especially, can be a problem as it can be very toxic and lethal to livestock. Both these species like disturbed ground, so the best policy is to disturb as little as possible. Since both these species are annual (they complete their life cycles in one year) the best control for them is mowing. This needs to be done before they go to seed. Plan on mowing for several years to be effective.

Unfortunately, dealing with invasive species is not as straight forward. The worst offenders in our area are Lehmann’s Lovegrass (Eragrostis lehmanniana), Yellow Bluestem (Bothriochloa ischaemum), and Johnsongrass (Sorghum halepense). Invasive species will out-compete native vegetation and change the local ecosystems. Most are far less desirable for grazing purposes, and, once established, are very difficult to eliminate in a large scale. The most effective treatment involves herbicides. Unfortunately, even if you spray and eliminate every visible invasive plant it won’t solve the problem, as there is a seed bank in the ground that can germinate in the future. Plan on some retreatment. 

I have seen a tremendous increase in invasive species in recent years. Invasive species are a huge and costly problem. There has also been in increase in the amount of so called “native grass hay” being cut and sold locally. I am not saying that this is responsible for the overall increase in invasives. It is not. However, several of the areas I have inspected, where this hay was being cut, have been full of invasive species, mainly Lehmann’s lovegrass and yellow bluestem. Just because grass is growing in our area doesn’t mean it is native. Using this hay or allowing it to be baled contributes to the spread of invasive species. Before feeding this hay, you should know exactly what is in it and where it came from. 

Weeds, invasive species and erosion are all problems directly related to poor land management. The best and least expensive solutions to these issues is to avoid them before they get started. Remember folks, taking care of the land… it’s not just for hippies anymore. 

Editor’s note: Jim Koweek is the author of several books and the owner of Arizona Revegetation & Monitoring