Why does mulch smell like manure? (Cause and solutions)

Everything in this world is handy, but sometimes it can make you feel like it is one of the worst things. In the case of mulch, it has the same problems.

Generally, we know mulch is known to be the best friend of the gardeners. This helps keep your beautiful plants safe from insects and prevents the growth of unnecessary weeds. But do you wonder why does mulch smell like manure?

In my previous article, I have talked to you about some usefulness of the mulches, but today I will focus on the wrong sides of the mulches.

In this garden gild guides we’ll discuss the following:

  • Why does mulch smell like manure?
  • How do you get the manure smell out of mulch?
  • Why does the yard smell like manure?
  • Are mulch fumes toxic?
  • Are Mulch and Manure the same thing?
  • FAQs
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Why does mulch smell like manure?

I think it is one of the threatening components for the environment if it is not maintained correctly. So many people wanted to know what could be on the wrong side of the mulches. That is: mulch can smell like manure!!! But WHY???

The reasons for which the smell spreads from the mulch are:

  • When the microorganisms like bacteria and fungi decompose without oxygen(anaerobic respiration), mulch causes terrible odors. It produces strong smells like various gases such as methane, hydrogen sulfide gas, acetic acids. These types of gases have a stinky and sour smell like ammonia gas, sulfur, and vinegar. 
  • Mulch also smells terrible when it is not kept in a dry place and does not have plenty of oxygen. For example, in the rainy season, this can be seen.
  • Some of the organisms like actinomyces break mulch. At the time of decomposition, mulch releases chemicals which is the main reason for the bad smell.

Why does grass smell like manure?

Sometimes, grass can smell like manure if there is not enough oxygen, too much moisture, and bacteria or fungi decompose other parts of the grass. 

Also, it can create a smell like rotten eggs and hydrogen sulfide if it is not maintained correctly.

How do you get the manure smell out of mulch?

First, let me clarify that much does not contain any amount of manure. Mulches smell like manure when it becomes rotten due to water or during the decomposition of bacteria or fungi.

There are some ways in which you can get the manure smell out of mulch. They are:

  • Don’t allow bacteria to grow in mulch
  • Use odor spray 
  • Clean using water or add dry browns
  • Add something that contains a high amount of carbon

1. Don’t allow bacteria to grow in mulch:

Bacteria and fungi eat manure as food. There can be bacteria and fungi in mulches that spread the smell like manure when the mulches become rotten due to the uncleaned water or humidity. 

It is better to keep so that bacteria and fungi have no chance to dance happily on the manure.

2. Use odor spray or chemicals:

The smell of the rotten mulch, like manure, is malodorous. So you can buy some ready-made odor spray or chemicals from the shop. It will not work efficiently, but you can better for some time as these types of spray helps you to prevent the smell of the mulches for a while.

3. Clean using water or add dry browns:  

You can clean mulches using water to get rid of the smell of the mulches, but it can be very time-consuming.

It is vital to water the mulch every day in the summer season because it will clean and soak up dampness rapidly. On the other hand, you can add some dry browns because it helps to soak up unnecessary moisture and allow more oxygen to enter. 

4. Add something that contains a high amount of carbon:

To get rid of the stinky smell of the manure from mulches, you can use something that has a high amount of carbon, such as wood chips, shredded cedar, or paper.

For getting rid of the smell of manure in mulch from hands, there is an easy solution for you.

  • Vinegar and baking soda 
  • Lemon or citrus rub
  • Toothpaste
  • Salt 
  • Vicks vapor rub 
  • Grass

Why does the yard smell like manure?

The yard smells like manure when the soil is decomposed by various types of bacteria and fungi, at which time it becomes rotten.

Why does the yard smell like manure?

So, the rancid smell diffuses in the surroundings by releasing chemicals such as hydrogen sulfide and ammonia. These two compounds have a pungent smell. When it can’t get proper aeration, the awful smell diffuses. 

Are mulch fumes toxic?

Yes, mulch fumes can be toxic for plants from the particles of the vapors, but it is too harmful to humans and animals in general. It would be best to take care when working on something related to mulches because you sometimes may experience minor irritation. 

If you study broadly about the dangers of breathing mulch, you will get to how much the fumes of mulch can be dangerous for the plants.

These poisonous mulch fumes can cause different symptoms such as weakened lead, which turns yellow, torrefied leaves, and eventually, die.

 In humans, sometimes these mulch fumes can cause the flu-like syndrome, Organic Dust Toxic Syndrome, but it occurs in humans very rarely.

For this reason, you may fall sick due to the reactions to the airborne toxins from the fumes of the mulch and different types of harmful organic compounds in mulch. But death will not occur if you do not have any breathing or suffocation problems.

Are Mulch and Manure the same thing?

Mulch and manure are both used by gardeners. Many of you might think both are the same but do you know there are some differences between mulch and manure?

People are sometimes confused about where to use mulch and manure. If you apply to any of them in the wrong place, the growth of the plants and other determined organisms may be destroyed. 

So, Let’s get to know about the differences between mulch and manure!!!


  • We all know that there are many different types of mulch for the different types of uses of the plants, so their components must not be the same. They are mainly made of bark, grass, leaves, pebbles, rocks, gravel, landscape fabrics, plastic sheeting, cardboard, wood, hay, sawdust, etc.
  • It helps to protect what is kept on the soil around the plants.
  • It helps to reduce the number of unnecessary weeds growing in your garden.
  • It is beneficial for maintaining the moisture of the soil and preventing erosion.
  • The temperature for the mulch depends on the condition of the weather. For example, if the weather temperature is 100 degrees Fahrenheit, the suitable temperature for the mulch above the soil will be 80 degrees Fahrenheit.


  • Manure is mainly made of decomposed, organic materials that help to pile up and give the plants strength.
  • It is the process in which the organic materials decompose from the plants mainly.
  • It is beneficial because it helps decrease carbon from the atmosphere by increasing carbon in the soil. As a result, it improves the fertility of the ground and drops the process of nitrate leaching.
  • The best temperature for the manuring is 135 degrees Fahrenheit to 160 degrees Fahrenheit.

1. Why does my SCOTTS mulch smell like manure?

The pigmentation of the SCOTTS mulch is lovely and bright, but SCOTTS mulch can be very smelly if the proper care is not regulated. Again, the reason is the same as the regular mulch.

2. Can mulch be poisonous?

We all know that mulch is beneficial for plants and weeds but have you ever thought mulch could be venomous for some species?

Different types of mulch produce various risks for some species—for instance, dogs. If any dog consumes mulches, other symptoms can be seen, such as breathing difficulties, high blood pressure, vomiting, tumors, etc.  Humans are less affected by mulch compared to animals.

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Maintaining the mulch and manure is not rocket science, but you have to know the proper method for getting rid of the stinky smell, and it is not like that awful smell will remain forever.

After two or three days, the foul smell will be gone, so you don’t have to worry. You need to keep your garden fresh and clean.

If you are confused about any topics, feel free to ask me!

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