Implementing a system using sacrifice paddocks, rotational grazing and proper maintenance can improve pasture quality and provide more forage for grazing horses.
Well-managed horse pastures can contribute significant forage to the diet, as well as providing necessary horse health benefits, fulfilling the horse’s psychological need to graze and minimizing the risk of poisonous weeds. Over-grazed horse pastures filled with weeds and bare patches are the result of a lack of enough pasture acres; a general thumb rule is at least two to three acres per horse. Also, horses will typically overgraze some areas of a paddock, which weakens and eventually kills forage plants, with weeds becoming established in their place. Horses also prefer not to graze grass that is too tall.
A sacrifice paddock is an area where horses are fed hay during conditions that are unsuitable for turnout on pasture. This includes wet periods such as spring and fall, where horse hoofs will turn wet pasture soils to mud and destroy plant growth. Sacrifice paddocks should also be used when there is not enough pasture forage available to avoid over-grazing, such as during dry summer months.
Confining horses to a sacrifice paddock for part of the day provides them with a chance to get exercise without ruining the pastures. It may seem counter-intuitive, but feeding hay to horses in a sacrifice paddock rather than letting them overgraze actually saves hay in the long run – providing they are fed using a well-designed hay feeder. Research shows that more than half the hay is wasted when fed on the ground.
The sacrifice paddock should be close to the barn and connected to the pasture fields. It may include a run-in shelter, and water and hay should be provided; sometimes a crushed stone base and specialized footings around waterers is recommended. Proper drainage is extremely important in sacrifice paddock design to minimize mud and health issues, such as thrush and mud fever.
Rotational grazing is the practice of moving horses from pasture to pasture to allow forage plants time to rest and re-grow. If pasture stands are overgrazed, the leaf area of the grass will be greatly reduced so the plant will be less able to photosynthesize solar energy into re-growth. Overgrazing will also lower carbohydrate stores in the roots, further limiting re-growth and plant health. Overgrazed, stressed grasses store more sugars as fructans, which can lead to founder or other metabolic diseases in some horses.
Pastures should be about 6-8” tall before horses are allowed to graze and they should be removed when the pasture stand is grazed to about 3-4” in height. (If it is predominately bluegrass, 5-6” at move-in and 2-3” at move-out.) Mowing at 4-6” to remove seed heads and weeds, and harrowing to spread manure piles, should be done shortly after the horses are rotated out of the pasture.
The paddock “rest period” will depend on plant growth. In the spring, with rapid growth, it might take about 2-3 weeks for pastures to regrow, while in the hot, dry summer it may take 4-6 weeks or more. A good setup has four paddocks that are rotated on a weekly basis. While this may not be possible on farms with limited paddocks, keep in mind that some rest and rotation of paddocks is better than none at all. Consider whether temporary interior electric fencing can be used to create more paddocks, although exterior fences and sacrifice paddock fences need to be more substantial.
If rotational grazing is not practical, successful continuous grazing can still be achieved through the use of sacrifice paddocks, regular mowing, and having sufficient acreage per horse.
Horses are often turned out on pastures too early in the spring, resulting in a lot of damage to wet soils and immature pasture plants. This severely reduces the amount of pasture growth available for the rest of the year. Also, early spring grass growth is typically very high in non-structural carbohydrates that can increase the risk of colic, laminitis, and insulin resistance. Reintroducing spring pasture to horses after winter should be done for brief periods of time and then gradually increased once the ground is firm and grass growth is about 6” tall.
The mixture of forage species present in a horse pasture quickly adapts to the level of management. Species that we use for hay such as timothy, smooth bromegrass, and alfalfa that cannot tolerate frequent, close grazing will weaken and eventually disappear. Bluegrass and white clover tolerate frequent, close grazing, so they tend to become dominant, along with ungrazed weeds. Grass species with a good balance of persistence, yield and palatability in horse pastures include orchardgrass, Kentucky bluegrass, and endophyte-free tall fescue.
Kentucky bluegrass, while very palatable, is lower-yielding and goes dormant during the hot, dry summer, but spreads with rhizomes and creates a turf that is fairly resistant to horse traffic.
Orchardgrass is a bunchgrass that readily produces new shoots and can be very productive, but requires clipping in the spring to remove seed heads. Like most grasses except timothy, once the seed head is clipped, subsequent growth is vegetative leaf.
Tall fescue is a good choice where overgrazing and traffic damage can be an issue. It can sometimes be less palatable, but grows well in the summer and fall. Only endophyte-free tall fescue varieties should be used.
If a legume is desired to provide nitrogen for the grasses, only a very small amount of white clover should be used. White clover is very tolerant of overgrazing and competitive in horse pastures and can take over and dominate other grass species. The grazed leaves of white clover are very high in digestible energy, which can be an issue with high-risk laminitis and insulin-resistant horses.
Weeds proliferate in overgrazed pastures, so good pasture management goes a long way to controlling weeds, including annuals such as ragweed and wild mustard, biennials such as burdock and thistles, and perennials such as milkweed, Canada thistle, and goldenrod. It is very important that pastures be scouted for weeds that are potentially poisonous to horses, such as poison hemlock, horsetail, and buttercup.
Effective mowing removes seed heads before weeds develop viable seed. This prevents reproduction in species that reproduce only by seed, but is less effective in perennial species that can reproduce by underground roots and rhizomes. Low-growing, prostrate weeds are difficult to control by mowing, because they can grow and flower below the mowing height.
If using grass pasture herbicides, be sure to consult the product labels for directions, including the period of time to keep livestock out of treated areas. Broadleaf herbicides such as 2,4-D, dicamba, and MCPA can be used to control many broadleaf weeds. However, they will also injure or eliminate broadleaf legumes such as white clover, so they should be limited to straight grass pastures only. Small-boom 12 volt sprayers are commercially available that are suitable for smaller horse paddocks and gates, and can be used with an ATV or small tractor. Ontario farmers must be certified through the Grower Pesticide Safety Course to purchase and use class 2 and 3 pesticides on their own farms. Those in other provinces should check with their Ministry of Agriculture regarding regulations.
Spot spraying of glyphosate with a backpack sprayer can be done to control thistles, burdock, milkweed, etc. Glyphosate is non-selective, so will also kill desirable forage species. Where larger patches are inadvertently killed with glyphosate, weeds tend to germinate and regrow.
Horses are selective and prefer to graze younger, shorter growth and immature plants. They will avoid taller, more mature plants, which decrease even more in nutrient availability and palatability as they mature. Mowing at a height of 4-6” is a good strategy to “even out” grass growth, control many weeds, and encourage the tillering of forage grass species to thicken the stand. Mowing should be done a minimum of 2-3 times per year, and in rotational grazing situations after each grazing rotation (at the start of the rest period).
Grass growing around manure in pastures is usually left ungrazed. To eliminate this problem, pastures can be harrowed or dragged at the beginning of the rest period. This spreads the manure, which is then broken down by insects and microbes more quickly and nutrients are returned to the soil for plant availability.
A disadvantage of harrowing manure in horse pastures is the risk of increasing parasite contamination through ingestion of fecal matter containing parasite eggs and larvae. This is becoming more of an issue as equine internal parasites develop resistance to commercial dewormers. Parasite eggs and larvae can live for a considerable time in manure, soil and plants. Harrowing on hot, dry days at the beginning of the rest period to kill parasites in pastures will reduce the risk. Horses should be kept off pasture for at least a week to reduce the presence of parasites, but longer is better.
Soil Testing and Fertilization
Proper fertility improves yield and health of pastures. Taking a representative soil sample and sending it to a lab for analysis helps determine fertilizer requirements. A basic test includes phosphorous (P) and potassium (K) levels, and pH. There is not a useful soil test for nitrogen (N), but N as urea can be applied based on the potential productivity of the stand in split applications (early spring, June and possibly late summer). When applying urea, remove horses from the pasture for a few days, or until after a rainfall. P and K application levels are determined by the soil test results.
Pasture Renovation or Re-establishment
There will be times when pastures will thin and bare ground may start to appear in parts of the field. It may be possible to renovate or rejuvenate a poor pasture without ripping it up and starting over by re-establishment. Simply giving the pasture a rest by removing the horses, fertility and weed management, and mowing may help to some extent. Seeding poor areas with desired pasture species can be done to renovate them. Fall seedings are best done in late August or early September. Spring seedings should be done in late March or April. To prevent seedling damage, it is important to keep horses out of newly seeded pastures until the grasses are well established.
Pasture re-establishment will require a longer rest period that may eliminate horses from grazing that pasture for an entire season. Re-establishing a pasture usually means killing the existing stand and weeds using glyphosate, then reseeding and providing broadleaf weed control.
Proper horse pasture management requires more work and attention than just throwing horses out into the field. It ultimately provides horse owners with the economic benefits of reduced hay requirements and healthier horses.