Can Composted Cow Manure Burn Plants? | How to Prevent Burning

Composted cow manure will not burn plants if it has been properly broken down. Breaking down cow manure in a hot composting system will break down weed seeds and any leftover ammonia to stop it burning plant roots. Buy composted cow manure in bags from garden centers or age it at home in your compost bin for at least 6 months.

You can buy aged manure in bags which is the easiest way to use it at home without burning your plants. You can add this mild fertilizer straight into your soil, as a top dressing for plants or add a few handfuls to your potting mix to give it an extra boost.

This article will explore if composted cow manure burns plants, how to choose the best manure for your garden and the easiest ways to age manure at home.

How to prevent cow manure burning plants

To prevent cow manure from burning plants, avoid using fresh manure on your garden. Fresh cow manure can contain higher levels of ammonia which can burn plant roots.

Fresh manure can also contain weed seeds that have not been fully broken down. These can sprout in your garden and become a real problem.

Cow manure is considered a ‘cold’ manure, it is higher in carbon and lower in nitrogen than ‘hot’ manures like chicken or horse manure. It breaks down fast and is ready to add to your garden in 6 months to improve your soil, feed soil bacteria and worms.

What is composted cow manure?

Composted cow manure is aged manure, broken down with other organic material and will be ready to add straight to your garden. Cow manure is a mild fertilizer once it has been aged but what it contains will depend on what the animal was fed, how old it is, how dry it is and what it is mixed with.

1. What the animal was fed

What the cow was fed will affect the type of manure it makes. Cows that have been grazing on grass including weeds can ingest weed seeds and they can end up in the manure. If you are picking up bags of manure from farms on the side of the road, check out the pasture to see what the cows are eating.

If the cows are feeding on weed seeds it is essential that the manure is composted. This will help to break down the weed seeds. Hot composting is the best way to break them down fully so they won’t grow in your garden.

I am using aged cow manure to set up my new no-dig garden so I can plant in it straight away.

2. How old the manure is

Old manure that has been sitting around in bags for months will be partly broken down. It will be well on the way to being ready to add to your garden. Fresh cow manure picked up from a paddock or farm gate can be strong smelling, higher in ammonia and can burn plant roots.

3. How dry the manure is

If manure has been left to dry out in bags then it will have a different bacterial balance than fresh or composted manure. If the manure is dry good bacteria levels can decrease making it less bioactive when you add it to your soil.

Wetting down dry cow manure with your hose and mixing it through your compost bin or is essential to stop dust particles from entering the air. Wear a face mask when handling dry cow manure to avoid breathing it in.

Wet the cow manure down if it is dry.

4. What the manure is mixed with

Often cow manure that is picked up on local farms will be mixed with hay or straw. This is used in cow yards to absorb moisture particularly on small farms. The extra hay and straw is a great extra ingredient to boost the cow manure. It will add extra organic matter and help to improve soil structure and drainage.

How to age cow manure

Here are a few easy ways to age cow manure at home. If you have picked up a bag of fresh cow manure from the side of the road, here are some great ways to age it ready for your garden.

1. Leave it out on a tarp

You can put aged cow manure out on a tarp, seeds will sprout and you can then dig the manure and the sprouts into your compost.

2. Dig it through compost

Digging fresh cow manure through your compost pile is the best way to age the manure. Soil bacteria living in your compost pile will break down the components making the nutrients available to plants and mixing the organic matter through.

Leave manure to break down in your compost pile for around 6 months to let it fully break down and incorporate into the ingredients. Mix through extra dry ingredients such as hay, straw or fall leaves to help to balance out the moisture content of the fresh manure.

3. Add it to your worm farm

Worms in my worm farm are happy to eat manures including cow.

Fresh cow manure can be broken down in your worm farm. You can add it straight into the worm farm or mix it together with some sugar cane mulch or hay and add it as a top layer. Worms will love to digest the cow manure and will break it down in a few months.

Start with small amounts if you have a small worm farm and add more as the first lot is broken down.

4. Leave it in a pile

The simplest way to age cow manure is to leave it in a pile on its own in an open area of your garden. A large pile of cow manure will naturally break down on its own. Turning the pile every few weeks will help it to break down faster. Soil bacteria and worms will find their way to the pile and will digest it for you.

How to use composted cow manure at home

Here are my favorite ways to use composted cow manure at home.

  • Dug into soil – Mix it into new garden beds or before planting vegetables
  • Added to potting mix- Add a few handfuls to your potting mix to add extra nutrients
  • Top dressing for citrus and established trees – Mix aged cow manure with compost and sprinkle it around the root zone of your plants.
I am adding aged cow manure to refresh my strawberry bed in the fall.

Can Composted Cow Manure Burn Plants? | Summary

Composted cow manure will not burn plants but fresh manure can. Age fresh cow manure by digging it through compost or leaving it in a large pile to break down on its own. Turn the pile every few weeks and in 6 months you will have aged manure that is ready to dig through your garden or top dress your citrus.

Happy growing.