In my adventures on the social media interface, I often come in contact with people who have used a variety of terms in attempt to undermine the use of livestock on the landscape. One of those terms is "overgrazing."
Far too commonly the term "overgrazing" is over-used and abused so as to justify the means of attempting to demonize livestock for the world's increasing environmental problems, such as soil erosion, desertification, and "climate change."
It is ill-referred to as a matter of there being "too many animals" on a piece of land, no matter if it's tame pasture, native prairie, savannah veldt, forest meadows, etc. Overgrazing is also referred to as land that is "grazed too heavily" so that vegetation becomes damaged and land becomes "liable to erosion." (These are actually two common definitions that are maintained by today's online and hard-copy dictionaries. Both must be corrected!!)
All in all, the term is actually highly misunderstood and misinterpreted. Even the dictionaries have it wrong.
So, what IS overgrazing??
Overgrazing is actually a function of time, not number of animals.
It doesn't matter how many animals you have nor how many acres there are to graze. Overgrazing can occur with few animals on a lot of land, just as with a lot of animals on a small amount of land.
Overgrazing is a result of timing, largely because of mismanagement. The real definition for overgrazing is not what the standard dictionary says, but rather this: "To defoliate a plant before its energy stores have been fully restored." This is when that plant is trying to regrow after being defoliated (grazed, cut, or mowed). In other words, overgrazing is when a forage plant is bitten more than once during its growth period, or when it is trying to regrow and must use its energy reserves in order to do so. This second bite pushes the plant further back to the point where its recovery period will be significantly longer, and it requires more energy than before to regrow. If the plant is not given sufficient time to recover, it will become more stunted both above and below-ground, or it will die.
This is all a matter of timing.
Plants require time to regrow after being defoliated. Defoliation is done by either by grazing, mowing, or even burning.
Just think of a lawn. A lawn is covered in living green plant matter called "grass" that regrows after mowing.
Here's the mind-blowing part: It takes time for that cut lawn to grow back before needing to be mowed again!
Let's go back to the pasture, because I find mowing lawns a rather unfair comparison. The pasture is largely composed of grasses, often with at least four different species. There may be some legumes in the stand. But let's focus on grasses for now.
I already mentioned that it takes time for grass to grow. Grass has a growth curve that is in the form of a face-down S curve (forage yield is the exact opposite), and this growth curve is broken up into three phases.
Overgrazing occurs at three primary timing points (some call it the Three Cardinal Sins of Grazing, as from the grazing schools of Jim Gerrish):
Again, all three of these can and will occur no matter the size of the pasture or the size of the herd. Animals that are allowed to stay too long in the pasture will take too much: They will take the "second bite" of grass that they grazed a day or two ago.
Often the reason for returning for that second bite is because they are allowed to select what plants they want to eat. Selectivity by all livestock is primarily based on taste and smell, and somewhat past teachings and experience by Momma Cow or the School of Hard Knocks. If a plant tastes good the first time, chances are that animal will return to that plant once it has been able to taste most of the rest of the plants in that pasture.
I've turned out our steers onto a 50 acre piece of pasture--only 60 animals--and what they do when they smell a tasty plant is to take a bite, then move on. They move on because of their strong herd instinct, and because they feel they need to peruse the pasture to taste and smell what's out there. Until they've gone over most of the pasture, will they come back to eat those plants they found quite tasty again.
This is what I've found in raising cattle the conventional way of selective, set-stock, continuous grazing.
In coming back again for that second bite, those animals are returning too soon. The bite they take can remove about half or more the leaf area of a plant (sometimes an entire plant)--if you don't believe me, find a decent stand of grass (again, not lawn) and pull up, with your hand, 10 grabs of grass. See how much is left in that spot you've picked from. One hand grab of grass is typically the same amount of grass and similar force required by the cow to graze.
So when cattle or any grazing animal is allowed to come back too soon for whatever reason, that means that plant isn't allowed enough rest to recover. Leaf area is needed for a plant to generate photosynthesis to replenish energy stores and generate energy to regrow. Not enough leaf area could mean that plant needs to rely on its energy stores for regrowth.
And when the plant is grazed when those energy stores are already depleted, means that the plant is either going to be growing much, much slower through the season, or it will die.
Do you see how the concept of time in regards to the subject of overgrazing is applied? Here it is in regards to phases discussed above:
One bite to a grass plant that is in late Phase 2 pushes it back to either early Phase 2 or late to mid Phase 1. Two bites pushes that same plant back to early Phase 1.
This is a result of staying too long, coming back too soon, and taking too much.
How do you mitigate overgrazing then?
Control animals using temporary and permanent electric fence. Divide a big pasture into many smaller paddocks, and move the animals quickly enough that they are not going to selectively graze and take that second bite.
Doing so ensures plants get adequate rest, and there is plenty of residue left behind until the next grazing period.
The amount of rest a pasture needs depends on the stage of growth and time of year. Plants growing quickly will require you to graze quickly. Slow growing plants means you graze slower. Tighten up your paddocks when grasses are growing quickly, and make them bigger when plants are growing slower.
Rest can be anywhere from 3 weeks to 18 months. Native grassland requires longer rest periods than tame forage stands. Fast growing tame grass stands can be returned fairly frequently, unlike most native grass stands.
And do not be afraid to "waste grass." Wasting grass is a good thing because it covers the soil surface and slows the rain drops from impacting the soil surface. It also gives the soil flora something to eat and convert into organic material, topsoil, and sequesters carbon.
Good grazing practices that involve more management and less selective grazing also means mitigating soil erosion and desertification.
It all sounds counter-intuitive, but when you put the puzzle pieces together, it should all make sense.
A Few Exceptions: Dormant-Season/Stockpile Grazing
Much of what I talked about above was in direct reference to the green, and often growing plants of the pasture. Overgrazing during the point in time when these plants are growing and putting down energy root reserves as they do so is certainly something that must be taken into account in grazing management.
But there are some exceptions to the rule as mentioned above. These exceptions go right into the aspects concerning dormant-season grazing.
The basic concept is that, for dormant season grazing (or what others [myself] call stockpile grazing), you are putting animals on a pasture stand that has received an extended amount of rest during the growing season, and with plants that have accumulated more than enough energy root stores to withstand some heavy grazing treatment and that may get cows to take more than just one bite per plant; not to mention, with the desired herd effect (mobbing), a good bit of trampling as well.
During the dormant season, plants can take a whole lot more "abuse" than if those same plants were grazed while they were still recovering energy reserves from spring growth, or as I hoped to communicate above, after the first defoliation event. Of course that doesn't necessarily mean that you can push those to eat the grass plants right down to the nubs during the dormant season, as you still need some residue left behind to protect the soil, especially on a regular basis! No, that wouldn't be good at all. But, this kind of "abuse" (for lack of better terms) certainly opens up the canopy, gets rid of a lot of dead plant material from previous years and turns it into meat, milk, and fertilizer (manure), and encourages vigorous plant regrowth and biodiversity when that area is allowed sufficient recovery time.
See, the whole concept of overgrazing, as I was harping on about above, is about TIME. Recovery time in particular.
It certainly would be considered overgrazing if a particular part of the pasture was dormant-season grazed, then the animals were turned back onto it when the plants energy root reserves were low. That in itself is strongly discouraged and considered poor management.
I also understand that I focused on grasses only and not on other species, nor biodiversity, nor soil health.
The thing is, the basic concepts are the same: Time to rest so that a plant stand has time to recover sufficiently is a crucial part of grazing management.
That time is going to depend what's in the pasture, other than just grass. Time will need to be allocated to accommodate for legumes in the stand, like alfalfa, trefoil, clovers, and even sainfoin. Legumes and other sensitive forbs can be easily chased out of a pasture if you're only managing for the grasses; Or, on the other hand, other species that are more sensitive to heavier grazing will start to move in. You need a balance of both with timing.
Manage for the soil as well; that should be priority. The principles are the same: Cover the soil, living roots in the soil at all times, manage for biodiversity by trying to be more biodiverse with your grazing "tools" (rather than just cows, use sheep, chickens, goats, etc.).
Manage for the whole system, or rather on a holistic context. Your land that you are the temporary steward of now, will thank you.
Range Nerd, Forage & Grazing Fanatic and a Bovine Enthusiast. A love for farming, and for the soil.
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