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Horse manure, why gardeners love this sh*t over all others

Horse manure
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Among all types of manure, horse manure certainly has the most balanced mix of nutrients. It’s perfect for spreading in both the vegetable patch and the garden, in flower beds and along borders.

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Composition of horse manure

Like all other types of manure, horse manure (and also pony or donkey!) consists of dry matter (straw), urine and feces (dung). It’s a hot manure that quickly heats up as it breaks down. It contains more woody matter (hence cellulose) than others (about 54%).

Horse manure nutrients
Near-neutral, but poorer in phosphorus than other manures

It’s a manure well balanced in carbon, potassium, and nitrogen, fairly neutral in terms of acidity. However, it’s poorer in phosphorus than other manures. Calcium and magnesium contents are also very interesting. This ideal composition makes horse manure a very good soil amendment and a quality organic fertilizer.

Horse manure can be found in different forms:

  • Fresh, but it may contain medicinal treatments, germs and bacteria. It is typically heavily loaded with ammonia.
  • Mature or aged because it has been exposed to open air, ideally on planks or atop branches, for 3 to 4 months. Since horse manure heats up quickly, bacteria, germs, and traces of treatments are usually destroyed. At this stage, it is precisely balanced in nitrogen, phosphorus, and potassium.
  • Composted, when integrated into compost. You can make it yourself or get it in a bag from gardening stores or specialized stores.
  • Dehydrated into pellets is perfect for gardeners who do not have access to fresh manure. It blends in very easily with soil.

The four forms of horse manure compared

Horse manure reaches the garden in four different states, and each one is handled differently. Use this table to match the form you can get hold of to the season and the job in hand.

The four forms of horse manure compared
Form How it is prepared When to use it Point to watch
Fresh Straight from the stable, straw and dung together Autumn only, spread on bare ground May carry treatments, germs and heavy ammonia
Mature or aged Left in the open air on planks or branches for 3 to 4 months Once aged, on beds and borders Heat destroys germs; balanced in N, P and K
Composted Mixed into a compost heap, home-made or bought by the bag Spring, just before planting or sowing Ready to use, no burning risk
Dehydrated pellets Dried and pelleted, sold in garden stores Any time soil is being worked Blends into soil very easily

Whichever form you choose, one application every two to three years is plenty.

Benefits of horse manure

Advantages of horse manure
Woody matter lightens clay and lets water and air through
  • Because of its high woody matter content, horse manure is recommended to improve heavy and clay soil, lighten and aerate it. This addition will help promote water and air penetration.
  • It provides a good amount of minerals and trace elements like nitrogen or potash and is a good organic fertilizer.
  • This manure decomposes quite quickly and quickly provides soil with quality humus.
  • It heats up more quickly than other types of manure.
  • That same heat can be put to work: a thick bed of fresh horse manure under a cold frame gives weeks of bottom warmth, the classic hotbed for early salads and melons.
  • Horses digest seed poorly, so heap manure hot rather than using it cool if you want to avoid a flush of weeds.

When and how to spread it?

Fresh manure is spread only in the fall. Thus, it will have time, during winter, to decompose. Earthworms and other soil microorganisms, assisted by the weather, will take care of decomposing it and integrating it into the soil. As spring returns, soil will be richer and naturally amended.

How do you spread your horse manure in autumn?

How to spread horse manure
Spread on bare ground, or over cartons on grass
  • Spread the dried manure on the bare ground (or atop a layer of cartons if you have grass underneath) in the garden in a thick layer at a rate of 6 pounds per square yard (3 kg per square meter) the first year. Every two-3 years after that, it’s enough to just add 2 pounds per square yard (1 kg per square meter).
  • Cover your manure with a layer of dead leaves.
  • Put a net in place to prevent these layers from flying away with the wind.

It is also possible to simply spread a layer of manure, without adding anything on top.

→ But don’t forget that fresh horse manure can burn plants. It’s got too much nitrogen and ammonia. So, never lay it fresh at the foot of your plants.

Decomposed or composted manure is spread in spring, just before planting or sowing vegetable plants:

  • Ideally, in early spring, spread a layer of 2 inches of horse manure (5 cm) on the ground
  • Two weeks later, rake the soil to partially bury the horse manure.
  • Plant or sow directly.

In spring, you can also add some at the base of your trees, shrubs, and perennial garden plants.

→ It is useless, even discouraged, to integrate manure into your garden or vegetable garden soil every year. This contribution can be made every two to three years.

Crops that love horse manure

Horse manure for vegetables
Hungry crops such as tomato and squash love it

In the vegetable garden, many plants are especially fond of horse manure. Especially nutrient-hungry vegetables such as tomato, squash, pumpkin and zucchini, eggplant, bell pepper and chili, melon…

Potato will also appreciate this manure for the significant supply of potash. Finally, don’t hesitate to provide it to lettuce and all vegetables that like rich soils. Fruit trees and roses will also love being supplied with horse manure.

→ Only alliums like onion, garlic and shallot are better off without it.

How to compost horse manure

  • Mix fresh horse manure you’ve gathered with straw and let it sit out in the open air for a month. The temperature will rise to at least 122 °F (50 °C), thus killing off bacteria.
  • Turn it over several times
  • Add organic waste such as vegetable or fruit peelings
  • Stir it up once more
  • Lightly water it if you find your manure is too dry.

After six weeks, you can use this decomposed horse manure.

→ To learn more: Everything to know about manure and its usefulness

  • Ask the stable what bedding they use, because manure mixed with wood shavings or sawdust rots far more slowly than straw-based manure and ties up nitrogen as it breaks down.
  • Cover the heap during prolonged or heavy rain, chiefly to stop it becoming waterlogged and anaerobic, though a cover also limits nutrients being leached out by water draining through the material.

Smart Tip

Don’t hesitate to walk into riding clubs and stud farms to ask for a few buckets of horse manure. They are generally quite happy to get rid of it!


Images: CC BY-NC 2.0: Jen, Ryan, CC BY-NC-ND 2.0: Carl F. Bagge, CC BY-NC-SA 2.0: Hayes Valley Farm; Pixabay: Manfred Richter

Written by Gaspard Lorthiois | Loves helping out, especially when it comes to growing things. Worked in herbal medicine, runs a farm, and dabbles in tech. Master's degree and engineer.

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