Pasture Management
on Small Holdings
Ian N. Morrison Faculty
of Agriculture, Forestry and Home Economics, University of Alberta
CR wishes to note this was a paper for specific a location. It
is suggested that you contact your local agriculture specialists
as to specific forages for your area once you understand
what to ask.
Introduction
W hile most horse owners might imagine themselves living on a
farm or ranch with lush pastures or wide open expanses of range
land, the reality is that most of us live close to towns or cities
and keep our horses on hobby farms or acreages. Our 'wide open
spaces' typically range from 3 to 5 acres up to 20 or 40 acres.
These are what are defined as 'small holdings'.
Few acreage owners are experienced
pasture managers, and many are mis-managers, largely because
of over-stocking. While the quickest solution to this might be
to sell one or more horses, or to swap the Trakehner for a miniature
pony, this is probably 'not on' for most of us.
So the question becomes "
How do I do a better job of managing my pasture(s) to increase
forage production, provide my horse(s) with high quality feed;
decrease expenses associated with buying hay and concentrates;
and keep my property looking attractive, productive and free
of weeds?"
My intent in this presentation
is to answer these questions by providing some practical information
on the growth characteristics of pasture grasses and legumes;
some advice on which grasses and legumes thrive best, particularly
under heavy grazing; and a few tips on how to manage your pastures
to improve productivity and maintain healthy stands (relatively)
free of weeds.
Pasture Composition
Desirable pasture species include grasses as well as legumes
like alfalfa and clovers, which generally are more palatable
and have higher nutrient value than grasses and help maintain
fertility by fixing nitrogen in the soil.
Forage grasses can be classified
into two distinct groups: bunchgrasses, which form clumps and
don't spread very far laterally, and rhizomatous grasses, which
are spreading or "creeping" and form sods. On the one
hand, bunchgrasses have fibrous roots and distinct crowns, with
new shoots or tillers arising from crown buds. They reproduce
mainly by seed. Common bunchgrasses are crested wheatgrass, timothy
and meadow brome grass. On the other hand, rhizomatous grasses
grow out in patches with new shoots arising from terminal buds
on rhizomes that resemble roots but actually are a form of underground
stem. They also reproduce from seed and vegetatively from rhizome
nodes, which are small swellings along the length of the rhizomes
that can sprout new shoots and roots. Smooth brome grass, creeping
red fescue and Kentucky bluegrass belong in this group; as does
quack grass. Most people can easily visualize quack grass rhizomes
and know its ability to regenerate from rhizome fragments after
gardens are rototilled or fields are disced or cultivated. The
rhizomatous grasses are generally more aggressive in their growth
habit and typically can withstand heavier grazing and trampling
than bunchgrasses.
Forage legumes are herbaceous
forbs, mostly with tap roots and well-developed crowns which
produce new shoots produced from crown buds. Tap roots generally
penetrate deeply into the soil (in the case of alfalfa up to
1 metre or more) with primary and secondary lateral roots branching
off the main tap root. Most forage legumes either do not spread
laterally, e.g. red clover, sweet clover and most alfalfa cultivars,
or, if they do, their spread is quite limited, e.g. rangelander,
alfagraze or "Spredor" type alfalfas. One legume that
does spread laterally, however, is common white clover which
frequently grows wild in tame pastures and is a valuable forage
legume. It is relatively shallow rooted and spreads laterally
by horizontally growing, above-ground stems called stolons, the
same as a strawberry. New shoots and roots develop from nodes
at leaf axils along the stolons in much the same way as new shoots
are produced from the underground nodes of rhizomatous grasses.
The ability of forages to withstand
grazing is related to their growth habit, with grasses normally
being able to withstand heavier grazing than legumes. This is
because the growing points of grasses are typically closer to
the ground and more protected than the growing points of legumes
which are often more exposed (Table 1). However, for both perennial
grasses and legumes, regrowth after grazing is related to the
vigour of the plant which, in turn, is related to the amount
of foliage remaining and the storage reserves in the roots and
crowns or rhizomes. These reserves consist of sugars that are
produced in the leaves and transported to the below-ground parts
where they are converted to starch and other carbohydrates. Depletion
of these reserves by grazing too early in the spring, repeated
close grazing throughout the summer, or late fall grazing not
only reduces regrowth but leads to winter kill.
Table 1.
|
Grasses |
Legumes |
1.New shoots from crown buds or rhizome nodes
2,Growing points close to ground during vegetative growth
3.Stem elongation (jointing) => flowering
4.Can generally withstand heavy grazing pressure |
1. New shoots from crown buds; branches from axillary meristems
2.Growing points exposed at tips of shoots
3.Flowers borne on terminal shoots or in leaf axils
4.May succumb to intensive grazing |
Forage Selection
In establishing a new pasture, the choice of the most suitable
pasture mix will depend on the site, including soil type and
texture, internal drainage, slope, winter snow cover, intended
grazing intensity, etc. etc. On very dry sites on the brown and
dark brown soils, crested wheatgrass or Russian wild ryegrass
are good choices, but on the moister black and grey wooded soils
of central and west-central Alberta, timothy and creeping red
fescue are better adapted. Timothy especially survives well where
surface drainage is poor as long as the soil is not completely
waterlogged for periods of more than two to three weeks. ( CR
note: Over 13 counties see our show and site visitors around
the world so please consult on your local conditions)
Species type and varieties that
are most suited for hay crops may not be the best choice for
pastures. Whereas hay varieties are selected for high production
and rapid regrowth after one or two cuttings, they may not be
able to withstand the repeated grazing common to pastures. On
small holdings where persistence is of premier importance, it
is wiser to choose hardier, less productive species than ones
that will yield more under less severe conditions. For example,
smooth brome grass is an excellent choice in mixtures for hay
crops, but is less able to recover after grazing than meadow
brome grass which increasingly is becoming the species of choice
for pastures. Not only does meadow brome grass regenerate better
than smooth brome grass after grazing, it continues to grow well
into the summer months when smooth brome growth is very slow.
Under intensive grazing on small
holdings, creeping red fescue and Kentucky bluegrass are good
choices on both grey wooded and black soils where there is good
moisture. These grasses have fine leaves and do not produce as
much forage as smooth brome grass or timothy under low grazing
pressure. But, because they are sod forming and can withstand
close clipping they stand up very well to both heavy grazing
and trampling. Commercial forage mixtures commonly contain 4-5%
creeping red fescue and about 10% Kentucky bluegrass, along with
other grasses like meadow brome and timothy. Over time the proportion
of fescue and bluegrass will increase in the stand providing
good groundcover and suppressing weeds.
On productive, well-drained sites,
alfalfa is the most common forage legume in pastures. It is highly
palatable, has a high protein content, and grows more uniformly
throughout the season than most grasses. It is widely adapted
over a very broad range of soil types (except those with low
pH), and is relatively drought tolerant. Properly managed it
can be grazed into the late summer as long as there are 'rest
periods' from time to time to allow for regrowth. On continuously
grazed sites, under moderate to heavy grazing pressure, alfalfa
stands will eventually thin, becoming displaced by grasses and
weeds. It is susceptible to waterlogging and will die out in
low spots and other sites where drainage is poor. The "creeping
rooted" kinds of alfalfa are notably more grazing tolerant
and winter hardy than the hay types.
  Both red clover and dutch white
or wild white clover are good pasture species, especially well
suited for production on moister soils and in areas where the
pH is too low to support vigorous alfalfa stands. Red clover
and white dutch clover are short- to medium-lived clovers that
reproduce by seed. Neither is very persistent on heavily grazed
pastures. Where these clovers die out after three or four years,
they are often replaced by wild white clover which is extremely
tolerant of grazing. As such it frequently becomes the dominant
legume in overgrazed pastures on small holdings. In fact, its
presence is a good indicator of heavy stocking rates and declining
pasture productivity.
 Alsike
clover thrives across a wide range of conditions in cool, moist
climates and is particularly well adapted to grow on poorly drained
soils and in the grey wooded soil zone of west central and northern
Alberta. However, alsike clover is not recommended for horse
pastures as it is considered toxic. The evidence for this
is somewhat inconclusive, and it is not even known for certain
if it is the alsike clover itself, or some other factor like
an associated bacteria, that causes the problem (Nation, 1989
and 1991).
Nevertheless, there appears to
be a link between alsike clover and occurrences of photosensitization
and/or liver dysfunction in horses, and so it is recommended
that horses should not be grazed on alsike over long periods
of time. Alsike clover has been observed growing in many areas
where horses are pastured.. Because of it's 'low' toxicity rating
(and on the assumption that poisoning occurs only after horses
have been feeding on alsike clover for extended periods of months,
or even years) horse owners need not be alarmed if there is some
alsike on their properties. Nevertheless, good judgment dictates
that alsike be avoided wherever possible.
Stocking Rates
Horses are notoriously selective spot grazers, leaving some areas
untouched and completely overgrazing and trampling other areas.
For the most part, horses prefer grasses and tame legumes
over native forbs. When forage is sparse they will graze
between 14 and 17 hours/day, compared to cattle which typically
graze about 12 hours/day.
For the most part, the nutritional
needs of a horse can be met by grazing on good quality pasture,
providing they have access to salt and a mineral mix. However,
as pasture quality declines in late summer and fall, it is recommended
that mares with foals, and weanlings, be provided extra concentrates
or grain to ensure adequate intake of protein and energy.
A mature, 500 kg (1100 lb) horse
will consume about 10 kg (22 kg) of dry matter daily. Horses
require about 1.5 times as much pasture as cattle, with lactating
mares requiring half as much again. This means, that to pasture
a horse over the summer, about 4-6 acres of improved tame pasture,
or 8-12 acres of native pasture is required. This will be affected
by the condition of the pasture, with stocking rates being higher
on well-maintained pastures compared to those in poor condition
as illustrated in Table 3.
Stocking Rates (Acres/Horse/Month)
Range/Pasture Conditions
|
|
Good |
Poor |
|
Tame Pasture |
|
|
|
Brown Soil |
1.5 |
3.0 |
|
Grey Wooded/Black |
1.0 |
1.5 |
|
Native Range |
|
|
|
Dry South |
6.0 |
10.0 |
|
Parkland |
5.0 |
9.0 |
Overgrazing not only severely
decreases pasture productivity but leads to unsightly pastures
with bare spots and/or ugly weed infestations. The condition
of the pasture is largely dependent on how frequently it is grazed
and how much regrowth occurs between grazings. The cardinal rule
of thumb is:
Don't graze until regrowth
is at least 15-20 cm (6-8 in) tall Stop grazing when 5-10 cm
(2-4 in) tall.
Overgrazing seriously depletes
the root reserves of desirable perennial pasture species. This,
in turn, results in weakened plants, reduced regrowth and thinning
of stands. Not only does the overall productivity of pastures
decline rapidly with overgrazing, but the pasture becomes invaded
with weeds. .
Weed Control
Two herbicides that can be used with reasonable effectiveness
for spot treatment of tough-to-kill weeds are Banvel II (dicamba)
alone or mixed with 2,4-D, and Target (dicamba, MCPA, mecoprop
mix). These are hormone type herbicides that are generally safe
to use on established grasses but are very injurious to most
legumes and other broad-leaved plants, including shrubs and trees.
As with any herbicide, label instructions must be followed closely
and great care taken to avoid movement of the chemicals off target.
Areas that have been sprayed should not be grazed for at least
7 days after treatment.
Lontrel (clopyralid) is a very
potent (and expensive) herbicide that is highly effective in
controlling Canada thistle and some other weeds, including scentless
chamomile and, interestingly, alsike clover. It, too, is very
damaging to desirable forage legumes like alfalfa, and so must
be used sparingly only on established forage grasses. There is
no grazing restriction for Lontrel and so treated areas can be
grazed immediately after treatment.
Escort (metsulfuron) is a relatively
new herbicide specifically intended for use on pastures and rangeland.
It is active at very low dosages and will control a range of
weeds including Canada thistle, dandelion, sow thistle, and wild
rose. It must be measured out in very small quantities which
may be a deterrent for many owners of small holdings who are
not equipped to use products of this kind. There is no grazing
restriction applied to the use of Escort.
In cases where people either
don't want to use herbicides, or aren't sufficiently knowledgeable
or properly equipped to apply them as recommended, then the only
recourse is to control weeds like thistles by mowing them repeatedly.
Other weeds like dandelions can be kept partially in check by
maintaining a healthy, competitive pasture. This, in turn, implies
that the pasture is well managed, fertilized regularly and not
overgrazed.
Tips for Better
Pasture Management
In a continuous grazing system, horses are put into a pasture
and not moved throughout the season. This necessitates low stocking
rates and is really only suited to areas of low productivity
under dry conditions. On small holdings, continuous grazing generally
leads to a rapid decline in pasture productivity, a loss in forage
quality and the obvious necessity of providing additional hay
or concentrates to keep animals in condition. Forage grasses
and legumes don't get a chance to regrow, resulting in reduced
vigour and invasion by weeds.
Even on small holdings pastures
should be cross-fenced and horses moved from one paddock to another.
Electric fencing works well, provided the outside fences are
well-constructed and maintained, preferably from high tensile
wire or a similar fencing material that is non-injurious to horses.
"Fencing with Electricity" published by Alberta Agriculture,
Food and Rural Development offers good advice on proper installation
of electric fences.
In a rotational, or controlled,
grazing system, the animals are moved according to a schedule
which is adjusted through the season depending on the composition
of the pasture, the vigour of the stand, the number of horses,
and temperature and rainfall. As a rule, the animals should be
moved before they graze over the same area twice and when there
is still enough foliage to support rapid regrowth.
To promote uniform development
and maximum forage production, rough areas should be mowed and
the area harrowed to spread manure. Mowing delays maturity and
stimulates regrowth of palatable forage. Harrowing not only helps
to destroy the eggs of intestinal parasites, but it also encourages
more vigorous and uniform regrowth.
In pastures where legumes such
as alfalfa or clovers comprise less than 20% of the biomass,
productivity will be substantially increased from application
of a nitrogen fertilizer. Since there is also a reasonable probability
that other nutrients are also deficient, it is recommended that
a fertilizer like 20-10-10-5 be used. This blend contains 20%
nitrogen, 10% phosphorous; 10% potassium and 5% sulphur. A good
guideline is to add at least 50 to 60 kg of actual nitrogen per
hectare (45 to 55 lbs/ac). If the product is purchased in 25
kg bags, then each bag will contain just 5 kg of actual nitrogen
and so it will be necessary to spread 10-12 bags over 1 ha (~4-5
bags/acre) to get the desired amount of nitrogen. The other nutrients
will normally be in adequate supply. More precise fertilizer
recommendations can be obtained from private soil testing laboratories,
but for many small acreage owners this probably is unnecessary.
Conclusion
As indicated at the outset, pasture management on small holdings
is a particular challenge considering that oftentimes the number
of horses exceeds the 'carrying capacity' of the pasture. In
addition to practicing rotational grazing, in some cases it may
be possible to confine horses in corrals for part of the day
to limit the number of hours spent grazing. Not only will this
reduce pressure on the pasture, but it will help keep the horses
from getting too fat during the early summer when forage growth
is rapid. The trick is to extend the grazing period from spring
to fall by controlled grazing and to allow enough regrowth late
in the summer and early fall to ensure that the grasses and legumes
regain enough vigour to overwinter and resume growth in the spring.
This will necessitate getting winter hay supplies in early enough
to begin feeding in late September or early October before the
pasture is literally grazed to within an inch of its life. In
the spring, it will be necessary to keep horses off the pasture
until the 3rd week of May until such time as the grass is 5 cm
(2 in) or more above your ankles.
References
Alberta Forage Manual. 1981. Agdex 120/20-4 Alberta Agriculture,
Food and Rural Development. 86 pp. http://www.gov.ab.ca/crops/forage/species
Gramiak, G. 1996. Grazing alfalfa with horses. Canada-Manitoba
Agreement on Agricultural Sustainability. Manitoba Agriculture.
4pp. http://www.gov.mb.ca/agriculture/crops/forages
Grazing Tame Pastures Effectively. Alberta Agriculture, Food
and Rural Development. Agdex 130/53-1. 9pp. http://www.agric.gov.ab.ca/agdex/100/130_53_1.html
Guide to Crop Protection. 2000. Alberta Agriculture, Food and
Rural Development. 330 pp.
Kennedy, B. 1996. Fencing with Electricity. Alberta Agriculture,
Food and Rural Development. 43 pp..
McCann, J. S. 1996. Forage utilization by horses. Proceedings
of Horse Owners and Breeders Conference. 6pp. http://www.agric.gov.ab.ca/livestock/horses/hbo9601
Nation, N.P. 1989. Alsike clover poisoning; a review. Can Vet
J. 30: 410-414.
Nation, N.P. 1991. Hepatic disease in Alberta horses; A retrospective
study of "alsike clover poisoning" (1973-1988). Can
Vet J. 32: 602-607.
Pasture Management. Is your grass overgrazed? 1996. Quarter Horse
Journal.
Ian N. Morrison - Dr. Morrison
is the Dean of the Faculty of Agriculture, Forestry and Home
Economics at the University of Alberta. He was formally Head
of the Dept. of Plant Science, University of Manitoba. His specialization
is in agronomy and crop management with an emphasis on weed control
in forage and field crops.
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