Monthly All-Breed Horse Magazine
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2003, I have helped landowners understand and manage their resources by
promoting sustainable practices and conservation-minded weed and grazing
For over eight years, I have managed two to four horses on my ten
acres north of
In this article, I want to share some concepts that have allowed me to balance my horses’ needs and my land’s limitations. To put it simply, if you don’t manage your horses’ time on pasture, you’re asking for weeds. Below, I will go into more detail, but first I need start with the big picture.
Why Manage Grazing?
Improves use of
forage supply throughout the year
flexibility in management
order to ensure your land and its resources remain healthy, you need to
have a plan. For example, when horses are left on pastures 24/7, they
quickly overgraze because of their close and uneven grazing patterns.
Horses prefer sweet, young grass, and in confined pastures will literally
eat down those “sweet” spots to the soil surface, often killing the
grass and creating bare spots while more coarse forage goes untouched.
horses’ high-impact movements, especially those of shod horses, uproot
tender plants and dig long furrows in the soil, leaving welcome mats for
result, desirable forage will decrease, weeds will increase, and
management costs will skyrocket.
properties benefit from a rotational grazing system. Pastures are
subdivided into smaller areas or paddocks, and a portion of the pasture is
grazed, while the other paddocks rest. This allows the rested grasses to
renew energy reserves, rebuild plant vigor, and compete against weeds,
ultimately improving the sustainability of the pasture resources. A
rotational grazing system mimics nature by allowing our animals to move to
a new area.
The foundation of a
rotational grazing system is a drylot or sacrifice area. This area is
“sacrificed” so the rest of your land can grows grass. These areas
keep animals off pastures to avoid overgrazing, soil compaction, and
damage during wet (or very dry) weather. The drylot is also used to keep
horses off pastures when you are fertilizing or using herbicides. Take
into consideration how many animals you have and what their management
needs are when setting up a drylot.
pastures into several smaller areas and rotating among them helps avoid
overgrazing, because a good portion of your land’s grass is growing
while one pasture is being utilized.
Allowing your animals to graze grass down to four-inch stubble and
then moving them to another section encourages plant growth, limits soil
compaction, and discourages parasite infestation. Most parasites
congregate between the soil surface and two inches up the forage plant.
Removing animals before plants are grazed too low helps keep your herd
Grazing Systems Keep Horses
& Land Healthy
Pastures are subdivided into smaller areas or paddocks
A portion of the pasture is grazed, while the other paddocks rest
type of animal?
When planning for a
grazing system, the first consideration is what type of animal you have.
Each species of animal has its on
characteristics, needs, and grazing habits. I’m going to use cows and
horses to illustrate my points, but know that all animals have unique and
individual impacts on the land.
Cows are creatures of
habit, and they notice and respond to any unusual change in their routine.
They are heavy animals and can inflict damage to pastures, especially wet
Cows graze eight hours and ruminate for twelve hours, and due to
the design of their lips, teeth and jaw, they can’t get closer than two
inches from the soil. They are cloven-footed animals, meaning their hoof
consists of two digits.
Cows are known to camp
out in riparian zones, but behavior can be modified with herding and
placement of water and minerals.
Horses are large,
active, playful animals. Horses can quickly overgraze a property and
damage resources when not managed properly.
Horses tend to spot graze, overgrazing some areas and ignoring
others. They eat smaller amount per session, with more sessions per day
than cows. Their top and bottom teeth allow them to graze down right to
soil surface, destroying the growing points of grasses.
Horses tend to section
pasture into eating and spoiling areas, leaving a lot of quality forage
untouched. Their close and uneven grazing patterns coupled with
high-impact movements, especially those of shod horses, can quickly stress
the grass resources.
The goal is to create a
grazing system that complements your property.
Above is a map of my property. You can see I have five
pastures, a drylot with two shelters,
and a perimeter shelterbelt. It would be ideal to have all pastures the
same size, but irrigation ditches and the location of the house made it
is an Animal Unit Month (AUM)?
An AUM represents the
approximate amount of forage consumed by one 1,000 lb cow in one month.
AUMs were developed to
help land managers determine the stocking rate or the number of animals
that can be effectively grazed on an area of land. The stocking rate will
vary greatly depending both on the type of livestock, the fertility of the
land, and the climatic conditions.
Many agencies use AUMs to help landowners determine the carrying
capacity of their property.
Notice that the last row in the table
shows that a cow represents 1 AUM,
The AUM concept is based on a cow grazing 24 hours a day, not a horse. Recall
that horses behave very differently in pastures than cows, and
allowing 24 hour access to horses will have fundamentally different
impacts on the land and horse health (more on that later).
Even though it’s not
perfect, calculating the carrying capacity of your land is the starting
point of sustainable land management.
can your land sustain?
To help explain AUMs, I’ll use my place as an example. Hang in
there with me through these calculations, because at the end of this I
will discuss the limitations I find in the AUM method and explain the
method I use that yields great results.
many horses can I graze on my 6.5 acres and for how long?
acres of pasture. Even though my property is 10 acres, I have only 6.5
acres of pasture.
Since I have water rights, I am able to irrigate. I will calculate
both dryland and irrigated numbers to illustrate the difference between
them – it’s amazing!
Soil AUMs: 0.5 for dryland and 3 for irrigated (note: numbers used
are for ideal conditions)
To find the AUMs for your property, contact your local NRCS office
or look up soil reports on line at the Web Soil Survey (http://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx).
Table 2: Calculating carrying capacity
Tips on Resource Conservation for Landowners Who Manage Smaller Tracts of
what does this mean?
acres of dryland pasture can carry…
horses for 1 month, or
horse for 2.6 months, or
horses for 1.3 months
acres of irrigated pasture can carry…
horses for 1 month, or
horse for 15.6 months, or 2 horses 7.8 months
What a difference water makes! According to the math, with
irrigation I can easily manage 4 horses for 3.9 months - right? Not with
24/7 access! Remember, horses are highly selective when grazing and can
quickly change the composition of species to favor weeds and unpalatable
grasses. For two years, I had 4 horses and found I could graze for 6
months and still have healthy grasses at the end of the year.
maintain a sustainable system, I follow two simple rules:
the time horses are grazing/out on pasture to 5 hours per day.
grazing with 4 inches of stubble left.
Next month, Part 2 of the article — Limiting a horse’s time
spent grazing and the four-inch of stubble rule.
© Jennifer Mohler 2003-2008
Jennifer Mohler of Bridger
is a resource conservationist specializing in holistic and sustainable
land management. Jennifer has worked with a diverse group of public,
private, and non-profit entities to conserve natural resources by
promoting sustainable practices and conservation minded weed and grazing
management plans. As a horse specialist, she assists landowners in finding
a balance between the horse’s needs with the land’s limitations and
offers creative options to reduce costs, increase forage yields, manage
weed populations, and improve animal health. You can reach Jennifer Mohler
at 406-388-5668 or email@example.com.
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