Is Salt In Mushroom Compost Harmful To Your Garden?

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In Brief: Is Salt In Mushroom Compost Harmful To Your Garden?

Adding salt to mushroom compost is a popular practice among hardeners but is this practice safe? How healthy is it to the soil? Adding salt to mushroom compost isn’t definitely not the best thing to do for your mushroom compost pile. But why not? Are there exceptions? We answer these questions below.

Mushroom composts are used by most gardeners to promote plant growth. However, there’s a common practice among people that use this compost type.

They tend to add a bit of salt, and there are times when they’re done with no caution. In this article, we will be looking at the outcome of such action and whether it’s beneficial to your garden.

But first, if you want to learn how to make a homemade mushroom compost, this video is your guide.


Should I Add Salt To Mushroom Compost?

Sources: Compost Turner

First off, mushrooms are grown with a high amount of sodium, but the most critical factor to consider is the requirement of the soil in your garden. Excess sodium hurts the soil and, in the long run, harms plant growth.

However, most gardeners tend to add extra salt to mushroom compost. It’s no surprise that newbies follow suit without really understanding what the soil needs.

A little analysis from Dr. Mike Fidanza, Associate Professor of Biology (Plant and Soil Sciences), The Pennsylvania, warns that gardeners shouldn’t use additional salts on their mushroom compost due to the high sodium content of the mushroom itself.

“With soils and composts, the salts of concern are those positively charged cations: potassium (K+), calcium (Ca2+), magnesium (Mg2+) and sodium (Na+).”

Several soil experts have carried out the salt experiment, and the conclusions are alike. In simple terms, excess salt in the soil skyrockets soil osmotic pressure, which goes a long way to affect water absorption.

Remember that mushroom compost isn’t the only high-sodium content that will be going into your garden.

Products such as fertilizers contain a decent amount of salt and provide just the right constituents the soil needs to thrive.

The summary is that adding salt to mushroom compost or another type of compost upsets soil balance.

It isn’t recommended for any form of agricultural activities, and this includes horticulture, gardening, or even crop production.

It’s evident that mushroom composts are widely overused and sometimes treated as a “second soil” due to their ease of blending.

It shouldn’t be used as a topsoil or an alternative to soil at all. If you ever need to use it, it should be in minute quantity, just like other composts.

The goal is for it to improve soil health and not take over it.

What Excess Salt Does To the Soil

Source: Grower Today

If you are adding salt to an already sodium-high mushroom compost, you need to consider the disadvantage of excess sodium in the soil. In plain terms, excess salt causes soil toxicity.

The aftermath of this is that it causes plant tissue to dry out due to the soil’s inability to retain moisture. This means the plants become starved, resulting in stunted growth.


Adding salt to mushroom compost isn’t quite the right thing to do. Not even a minute quantity of it is recommended. If you will be using mushroom compost, use it alone.

Adding salt upsets soil balance, thereby setting the plant tissues up for nutrient drought.