Why Does Mulch Smell Like Manure

One of the best garden additions any gardener can use is mulch. They help retain soil moisture when the weather is hot and add nutrients as it breaks down over time.

Another benefit is that natural mulch acts as a weed barrier and stops weeds from growing.

However, although entirely safe, you can find mulch smells like manure, or if you have rubber mulch, it also has a bad smell.

In our guide, you can learn why does mulch smell like poop because there are different reasons. By the end, you’ll find out how long does mulch smell and how to get rid of the smell if it is too bad around your home. (Read Best Mulch For Vegetable Garden)

Mulch Smell Like Manure

Why Does Some Mulch Smell Like Manure?

Good mulch may have an odor, but it is rarely very strong or unpleasant. Mulch that is good to plants is usually distinguished by the distinctive fragrance of newly cut wood or freshly composted organic matter.

Using your nose to identify the quality of mulch is an excellent way to determine whether or not it is useful to use on your plants; if it stinks, it is most likely harmful.

You can find two instances of why your mulch smells of manure.

Anaerobic Conditions

Organic mulch is made commercially on a massive commercial scale, and the way they store mulch often leads to the first reason it smells bad. The way manufacturers store mulch in heaps often leads to anaerobic conditions.

From here, they seal them in airtight bags ready for resale, and the anaerobic conditions continue until you get home and release them from the plastic. Here, you can smell rotten eggs from the gases that build up and are trapped by the plastic.

Mulch Decomposition

Decomposition occurs when you use organic mulch in your garden. The rotten smell comes from fungal and bacterial organisms in the soil.

The most prevalent organisms that break down mulch are actinomyces. In addition, it will release certain chemicals because of the breakdown, and these are the source of the odor in natural mulches.

Many nutrients are provided to plants, and most often, the best natural mulch won’t smell too much.

You can explain why mulch smells bad when using dyed mulch or black rubber mulch. Such mulches will be smelling for different reasons.

Rubber mulch or dyed mulch can be bad for your soil. Even worse, black rubber mulch heats in the summer and further water evaporation.

Why Does My Mulch Smell Like Cow Poop?

Mulch does not emit pungent scents, and typically, mulch that is normal and healthy only has an organic odor. If you use woody mulch, it will just smell like newly chopped wood chips.

You can detect whether mulch is helpful for your garden or harmful by sniffing it. These toxins are produced by anaerobic conditions and will hurt your plants.

Your plants are at risk of toxic mulch, which can lead to yellow or scorch blotches on leaves and harm the foliage. This is because of the chemicals your plants absorb as the old mulch decomposes.

It isn’t much you can do if you’re using black rubber mulch because it contains chemicals.

The good thing with organic mulches is the strong smell is caused by natural decomposition and too much moisture. Any bad smells from your sour mulch will stop smelling over a few days.

Here you can learn more about anaerobic mulch and decomposing mulch.

Anaerobic Mulch

It’s most likely because of anaerobic conditions in your mulch has the smell of manure. A definite toxic or sour odor can be detectable. It smells like rotten eggs, silage, cow manure, ammonia, or strong vinegar most of the time. (Read Tall Fescue Vs Kentucky Bluegrass)

This cow manure smell is the case with commercial manure. It’s usually mass-produced and not stored using the best methods. Instead, it can be stacked in large piles under plastic sheeting, which sucks oxygen from the mulch inside.

Furthermore, the majority of commercial mulch is packed in airtight sacks. When these processes are coupled, optimum conditions for anaerobic deterioration and the manure smell form.

It will produce acetic acid or hydrogen sulfide when it decomposes in these anaerobic conditions and leaves you with bad-smelling mulch.

That’s what causes sour mulch odor. Worse, the pH of mulch that decomposes in this way is acidic. The pH level can drop quickly from roughly 6.0 to around 2.0.

When mixed with toxins like acetic acid and methanol, acidic mulch can do more harm than good to your plants.

Mulch Decomposition

Rotten Odor from Mulch Decomposition

Decomposition is nearly always the cause of mulch that smells like manure. This is especially true if you use organic mulch.

Microbes such as bacteria and fungi are the main causes of mulch decomposition. However, the most harmful of the outcomes of manure decomposition is hydrogen sulfide gas.

It will smell bad like a rotten egg and is heavier than air. Your sense of smell becomes weary after a short time of breathing this gas, and you can stop smelling the foul odor.

Actinomyces are the most common suspects, and Anaerobic settings are ideal for these Actinobacteria. They produce humus, heat, water, and CO2 by decomposing organic matter.

It’s worth noting that Actinomyces is a crucial component in mulching.

They help a plant release nutrients that are good for them. But, to be honest, the odor of their decomposition isn’t all that overpowering. (Read Avocado Tree Leaves Turning Brown Guide)

Why Does My Mulch Smell So Bad?

If the bad smells come from black mulch or dyed wood mulches, the only option is to remove the mulch and replace it with a better-smelling organic mulch.

If your organic mulch smells bad, it may be overly wet, giving off a foul smell. Let it dry by spreading it out and exposing it to the air and sunlight.

The good news is that you have many options with natural mulches, and any of these can be the safest mulch for your garden. (Read Temporary Fix For Muddy Yard)

Pine Straw Mulch

Pine straw can be an excellent mulch because it is attractive and natural.

This is the mulch to use if you have a lot of pine trees in your neighborhood, as pine needles don’t easily wash or blow away.

Grass Cuttings

Besides avoiding weed growth, grass clippings provide nitrogen and potassium to the soil by preserving moisture.

It’s a fertilizer that’s added on top of the regular fertilizer. Some pests are also deterred by it. If you have a large lawn, you can accumulate grass mulch for free by bagging your clippings.

Mini Pine Bark Chips

This mulch has a dark tone that is ideal for landscaping, doesn’t wash away, and stays put. In addition, pine bark mini nuggets prevent the soil from drying out in warm weather.

The mulch is suited to potted plants as it stops soil splashing from watering; besides, it slowly decomposes and releases vital nutrients.

Cypress Mulch

Cypress Mulch

Although many gardeners don’t like to use cypress, mulch is organic and beneficial to plants as some trees are cut just to make mulch. The shredded wood of cypress trees, either bald cypress (Taxodium distichum) or pond cypress (Taxodium ponderosa), is used to make cypress mulch.

Is it necessary to remove old mulch is often asked when gardeners are new to using such additions. However, if your mulch is over a year old, it can be best to get rid of it. Such old sour mulch that is partially deteriorated can harm your plants due to root rotting.

Keep the organic matter to around 2 inches in your garden, as mulch can suffocate plants when there is too much.

At this stage, you may find mold in your mulch. This is because mold appears in mulch after it stands over time. The wetness of old mulch provides an ideal environment for fungi to thrive.

Mold can be harmful to your dogs in any form. Humans and flowers are particularly vulnerable to black mold. Remove mold with a trowel as soon as you find it in your mulch.

You can avoid mold if your mulch is just enough and not piled up over time.

How To Stop Mulch Smelling?

There isn’t much you can do with black rubber mulch. However, after a few days of mulch, the foul odor should dissipate on its own if out of direct sunshine and heat.

Aerating organic manure is recommended

Mulch in airtight bags is bad as you will have poor air circulation wherever you keep it. Instead, it is best to use burlap sacks or open bins such as you might use for your compost.

Examine the aeration of the mulch, and you can fluff up the materials to improve airflow in your mulch.

You can also disperse any unused mulch and cover it with a weed barrier or a tarp to help it dry out and stop the spread of bacteria.

A few rocks or earth staples over the fabric will keep it in place.

Puncture a few small holes in the bagged mulch, and keep it out of the rain in a dry but airy area.

Mulch will keep a typical smell rather than stinking ammonia or rotten compost if well ventilated, as the bacteria that break down the mulch can’t thrive.

You’ll find these are the best techniques to get rid of odors if your mulch smells; just spread it out in the open, and you can kill the harmful bacteria and remove pollutants like acetic acid and methanol. Just be sure to turn your mulch frequently.

Fluff Mulch to Get Rid of Smell

Mix and spread the mulch before fluffing it up. Cooking the sulfuric odor will enhance the aeration.

Remember that mulch that decomposes aerobically (with oxygen) has a pleasant odor.

Fluff up your mulch once a month. This is true if the mulch is rich in organic stuff.

Poke holes through the mulch for indoor plants as it improves soil aeration.

It would help if you didn’t use odorous mulch. If it has gone rotten, clean it up first. Toxic mulch causes many symptoms in your plant.

Why Does Mulch Smell Like Manure

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