Managing established horse pastures

Start grazing horses when:

• Tall cool-season forages (e.g. smooth bromegrass and orchardgrass) are 8 to 10 inches tall.

• Short cool-season forages (e.g. Kentucky bluegrass and perennial ryegrass) are 4 to 6 inches tall.

Remove horses from the pasture when:

• Tall cool season forages are 3 to 4 inches tall.

• Short cool season forages are 1 to 2 inches tall.

Adequate rest and recovery periods are essential to maintaining desirable pasture plants with good productivity.

A sacrifice paddock is a designated area where you can keep your horse when pastures:

• Don’t have enough forage.

• Are resting.

• Are too wet.

Because a sacrifice paddock usually turns to dirt, it’s also termed a dry lot or holding area. Many owners feed hay and grain in the sacrifice paddock. This area usually has a water source and shelter for the horse.

The sacrifice paddock should be large enough for comfortable, long-term housing for horses.

Generally, grass growth potential is higher in spring, lower in summer, and moderate in fall. If you have only a few paddocks or if it’s during the summer, you may need to keep your horses in a sacrifice paddock while the paddocks rest and regrow.

You must allow adequate rest and regrowth periods for pastures when using rotational grazing. Rest is key to pasture productivity. It provides pasture recovery and flexibility based on the season.

For example, you may need:

• Only 2 weeks of rest and regrowth per paddock in the spring or during rainy periods.

• 6 weeks of rest and regrowth per paddock in the summer or during dry spells.

• 4 weeks of rest and regrowth per paddock in the fall.

Remember resting the pasture is key to vigorous forage regrowth.

Often, horses pick an area to defecate in and not graze. Dividing the pasture into smaller paddocks can help solve this problem. Instead of two large dropping areas, there will be a few small ones. Smaller manure piles dry and break up faster than large piles. This reduces fly numbers and odor. 

Dragging the paddock a few times each year during hot and dry periods can help break up and dry out manure piles while distributing nutrients back to the pasture. It also can kill parasites found in manure.

Mowing can help pasture productivity by:

• Evening out pasture growth.
• Controlling weeds.

Mowing your pastures to a height of 4 inches three to four times a year will keep the grasses less mature. Young plants are more desirable and palatable for horses. 

Make sure to mow weeds at or before flowering to prevent seeding. You can apply herbicides selectively and carefully as necessary. Always follow the directions and restrictions provided on the herbicide label. Applying herbicides in the spring or summer will help control annual and biennial weeds. However, mowing three to four times each year can also control most annual weeds.

For effective perennial weed control, keep mowing throughout the growing season to prevent seeding. Apply herbicides in early fall (around September 1st) for the most effective control. Follow any grazing restrictions listed on the herbicide label.

A well-managed pasture will outcompete most weed species. But since horses are such picky grazers, you can’t completely eliminate all weeds.

As forage, weeds are generally:

• Less palatable.

• Less nutritious.

• Lower yielding.

• Less dependable for forage.

Weed types

There are three types of weeds:

• Annuals: complete their life cycle in one growing season.

• Biennials: complete their life cycle in two growing seasons.

• Perennials: can live for three or more years.

Some common pasture weeds are also poisonous, harmful or on the Minnesota Noxious Weed List, including:

• White snakeroot

• Hoary alyssum

• Thistles

Mowing

Make sure to mow weeds at or before they flower. This will prevent new seeds from entering the soil.

Mow pastures to a height of 4 inches three to four times a year or after rotating horses to control most annual weeds. Never mow below 3 inches and avoid overgrazing.  

For effective perennial weed control, mow throughout the growing season and keep the plants in an immature growth state before applying herbicide in the fall.

Herbicides

Only use herbicides if you need to. Apply them selectively and carefully.

• Always read and follow the herbicide label.

• Applying herbicides in spring or summer will help control annual and biennial weeds. You can also mow for control.

• Apply herbicides in early fall (around September 1) for the best control of perennials.

• You can’t use herbicides for selective weed control in legume-grass mixed pastures. The herbicide will injure or kill the legumes (e.g. alfalfa, clover, etc) or grass.

Take soil samples every three years to determine if your pasture needs additional fertilizer. When applying fertilizer, apply half of the amount in early spring and the other half in the middle of June. Grass pastures will usually require about 90 pounds of nitrogen per acre each year. Keep horses off the pasture until the fertilizer is no longer visible.

Soil nutrients and pH

A soil test will provide the information you need to manage soil fertility and pH. For test kits and further information see the Soil Testing Laboratory.

Often, pastures only need nitrogen. Minnesota soils tend to be naturally higher in P and K, and manure adds additional P and K. Neglected pastures may need K and P.

Apply lime if soil pH is below 6.0. For legumes, lime the soil to pH 6.8.  It is best to till in or incorporate the lime several months before establishing a new pasture.

Splitting nitrogen (N) fertilizer applications in two (spring and mid-summer) provides the best yield distribution over the season. Applying N during a dry spell can burn the grass. Apply phosphorus (P) and potassium (K) if needed, based on the soil sample. These can be applied once in the spring.

Avoid fertilizing right before a large storm event to prevent the fertilizer from washing away. The ideal time to fertilize is right before a gentle, soaking rain. Keep horses off the pasture until you can no longer see the fertilizer pellets.

Spreading manure

• Only spread manure on your pastures if you have more than 2 acres per horse.
• Spreading additional manure (other than what the horse naturally leaves behind) can increase the risk of parasite exposure.  
• Manure spread on pastures should be mostly free of bedding (e.g. shavings and straw) and dragged to encourage faster break-down.   

When to seed

• The best time to seed or reseed pasture in Minnesota is August 1 to September 15.
• You can seed in the spring if you missed the fall deadline. April 1 to May 15 is the best time in the spring to reseed your pastures, but is depends on weather conditions.

Seeding

• If you overseed into existing pastures, 12 to 15 pounds per acre is a typical rate.
• Keep your horses off newly seeded pastures until the grasses have established and you have mowed two to three times.
• A no-till drill works best for seeding. You may also rough up the area and broadcast seed. Soil disturbance can increase weed emergence.

Commonly seeded grasses 

• Orchardgrass

• Timothy

• Smooth bromegrass

• Turf-type lawn grasses (e.g. Kentucky bluegrass)

  • Good for high traffic areas

  • Serves as a good pasture base

• Endophyte free fescues

  • Don’t use turf-type tall fescues. These can be harmful to horses.

• Annual ryegrass, used as a nurse or cover crop (2 to 3 pounds per acre)

  • Its high seedling vigor makes it easy to establish and compete with weeds.

Grass pasture seeding rates

• LaCrosse BLM #4 at 25 pounds per acre.

• Agassiz CHS #4 at 25 pounds per acre.

• University of Minnesota research found that seeding either LaCrosse BLM #4 or Agassiz CHS #4 seed mixtures resulted in a high yielding, persistent and preferred grass pasture for horses.  

• Both commercially available mixtures include tall fescue, perennial ryegrass, Kentucky bluegrass and timothy.

Toxic tree leaves

Some deciduous leaves can be deadly after a frost. Eating dried or wilted, but not fresh, maple leaves can cause toxicosis in horses. Dried leaves are not generally believed to be toxic the following spring. Horses are the only species for which maple leaf toxicity has been reported. Fence horses out of areas where wilted maple leaves are plentiful.

Remove any Prunus species containing cyanide (species in the cherry family) from horse pastures. Cyanide is released after chewing the plant or seed, or when the plant material wilts (after a frost). Animals are often found dead within minutes to a few hours after eating the plant.

Frost

Frost-damaged pastures can have a higher nonstructural carbohydrate (or sugars) content. This can lead to increased risk for founder and colic, especially for horses diagnosed with obesity, laminitis or Equine Metabolic Syndrome. To reduce the chance of adverse health effects, wait up to a week before turning horses back onto a pasture after the first killing frost. Subsequent frosts aren’t a concern as the first frost kills pasture plants.

Winter pasture access

During the winter, keep your horses in a dry lot with hay, water and shelter.

We don’t recommend keeping your horse on pasture over winter. There’s little nutritional value in dormant/dead grass and legumes. Hoof traffic and continuous grazing can cause great damage. The damage can result in weak plants or bare spots in the pasture the following spring and summer.