Mushroom Soil vs Compost – 5 Main Differences


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If you are looking to improve the soil in your garden, you are probably comparing some of the top soil improvers that are available, and wondering what the best options are.

You may have come across mushroom soil, and be looking for a comparison between this and compost so you can weigh up which is a better choice for your garden.

The biggest differences between mushroom soil and regular compost include the price, the nutrient value, the salt content, the pH values, and the nitrogen content. You can get different advantages from using compost vs mushroom soil, so we are going to compare the two.

Mushroom Soil vs Compost - 5 Main Differences
Differences between mushroom soil & compost

Difference 1 – Price

One of the biggest factors, whenever you are choosing a soil improver, is going to be the price, especially if you are covering a large area.

You might choose to swallow a high cost if you are just doing a small part of the garden, but if you are doing a big space, you need to look at the cost.

Mushroom soil tends to be a very cheap option.

It is effectively a waste product in many cases (assuming you are buying spent mushroom soil), and even when it hasn’t been used, it is rarely expensive.

Compost, by comparison, will be a lot more expensive.

You should expect to pay considerably more for compost, because it has been created specifically for its purpose.

While it does depend on waste products (garden waste and food waste), it is valuable and has been specifically created for improving your garden.

It is very unlikely that you will find compost that costs less than mushroom soil, so bear this in mind when comparing the two projects.

Your Call: If price is very important, mushroom soil may win the comparison.

Difference 2 – Nutrients

Of course, just because mushroom soil is better in terms of price does not mean it is better in terms of quality. Indeed, the reverse is often true.

It’s important to remember that there is a lot of variation between products, so you might find some really high-quality mushroom soil and some really low-quality regular compost.

As a rule of thumb, however, compost is usually more valuable in terms of its nutrients. It is made of very varied ingredients, so it has plenty to offer to the plants.

Mushroom soil, by contrast, has often had many of its nutrients depleted and is not made with many in the first place.

It uses manure, gypsum, lime, straw, and things like corn cobs, rather than a whole range of other things to enrich it. There is also a lot of chalk in it, which makes it very heavily alkaline.

If you want to give your plants a real nutrient boost, you should go for compost on the whole. Most kinds of compost are richer and more valuable, and they will help your plants to grow.

What To Expect: On the whole, mushroom soil does not offer much in the way of nutrients, and won’t really boost the plants.

Difference 3 – Salt Content

One of the very important things to assess when you are weighing up the pros and cons of mushroom soil vs compost is the salt content.

Many low-quality mushroom soils are extremely high in salt, and you need to be careful about how much mushroom soil you use on your plants.

You can reduce the amount of salt to a degree by washing the soil very thoroughly and allowing the water to drain away, taking most of the salt with it.

However, this is not a very reliable method and you may find that it’s better to buy a low salt mushroom soil, or to use regular compost.

If you are using mushroom compost, make sure that you don’t use it in large amounts, and don’t use it on plants that are sensitive to salt, such as azaleas.

Best Strategy: You can use a mixture of mushroom soil and compost to fertilize your plants. This is often a happy medium, because it allows you to take advantage of the reduced cost of the mushroom soil, and ensures you don’t end up with high quantities of salt in your garden.

Difference 4 – Alkalinity

Mushroom soil contains a large quantity of chalk.

If you buy mushroom soil, you will probably be able to see pieces of chalk inside the soil, and this makes the overall pH value very high.

Alkalinity in soil
Chalk in soil

Compost is usually mildly alkaline, but not nearly as alkaline as mushroom soil.

It tends to be between six and eight, so it can sometimes be acidic, especially if acidic ingredients have been included when making the compost.

Generally, compost that has just been made is more acidic, and it becomes more alkaline as time passes.

Which will offer greater benefits depends on what you are growing. Some plants need acidic soil, while others prefer alkaline.

It’s a good idea to check what pH value your plants prefer and use greater quantities of mushroom soil or compost accordingly.

Tools To Use: You should couple this with using a soil testing kit to measure the pH of your existing soil. This will help you decide whether you should use a greater quantity of mushroom soil or regular compost.

Difference 5 – Nitrogen Content

Mushroom soil tends to be quite low in terms of its nitrogen content, particularly if it is spent soil.

In general, the spent soil is cheaper to buy, but you may need to use a nitrogen rich fertilizer to make it balanced – which obviously does increase the cost.

Most plants require quite a lot of nitrogen, and if you only give them mushroom soil, they will struggle to grow.

Have You Noticed: Plants that are deprived of nitrogen will end up with pale green or even yellow leaves and won’t be able to produce enough chlorophyll to sustain healthy growth.


Overall, mushroom soil is not as valuable to your garden as compost, and you will find your plants don’t grow as well in it.

However, mushroom soil is much cheaper, so you may want to mix some into your compost so you get the maximum benefit of both.

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