How You can Get More (Money) Out of Your Substrate!

While the title seems clickbaity, it’s actually not. Bare with me, and I will tell you why your substrate really can boost your income. Let’s go right into it.

When it comes to money, the secret is to know how you can get more out of what you already have. This doesn’t mean that you have to squeeze everything out of it, which means you want to become as efficient as possible.

Instead, it means that you should think carefully if what you call waste is really waste. Are you still with me?

Mushroom Production Cycle

To understand this concept, let’s take a look at figure 1. This figure describes in simple steps the whole mushroom production cycle from preparation until disposal. But it doesn’t stop there. If you look closely, you see a list of five fields that representing new income opportunities for you.

Figure 1: Mushroom production cycle form preparation of mushroom substrate to disposal

Figure 1: Mushroom production cycle from preparation of mushroom substrate to disposal[1]

But before we can examine some of them, we have to talk a little bit about some obstacles when it comes to spent mushroom substrate (SMS), especially if you’re living in a western society as I do. In one of the research papers, the author (Phan 2012) listed the following four obstacles.

  • Unsupervised spent mushroom substrate management
  • Plastic mushroom bags
  • Incineration
  • Shortage of land and landfill sites

Unsupervised Spent Mushroom Substrate Management

The first point (unsupervised SMS management) describes the issues of uncontrolled and unsustainable disposal practices. To overcome this issue, the author recommends licensing. What this will look like I will explain by using Germany as an example. I try not to go too deep into the rabbit hole. 

If you want to use spent mushroom substrate as a fertilizer for farmers in Germany, you have to know that spent mushroom substrate falls under the BioAbfallverordnung (biological waste ordinance).

Under this regulation, you as the provider, have to make sure 1) that the SMS was sterilized before bringing it onto the market, 2) that the amount of toxic element like Pd, Cd, Cr, … is below the threshold, and 3) that you keep track of to whom you gave your substrate.

Besides that, you have to make sure that the amount of nitrogen is below 170 kg per hectare.

But that’s not all. You have to keep all the records for at least 10 years, and besides all this regulation you are only allowed to bring a maximum of 20 tons of dry mass of biological waste or mixtures per hectare over three years in the fields.

If you think that’s typical Germany. Let me tell you this. You can get rid of many things I just told you by getting a certificate (RAL-Siegel). That’s Germany.

But if you think it is only, we Germans you are wrong. The table 1 below gives you an overview of controls and regulations concerning spent mushroom compost disposal in five Western countries.

Table 1: Summary of controls and regulations concerning spent mushroom compost (SMC) disposal in the United States, the Netherlands, the United Kingdom, Canada and Ireland

Table 1: Summary of controls and regulations concerning spent mushroom compost (SMC) disposal in the United States, the Netherlands, the United Kingdom, Canada and Ireland[2]

Growing mushrooms in plastic bags

Let’s move on to the next point – plastic bags.

If you’re growing your mushrooms in plastic bags, then you will be confronted with this issue. This issue isn’t that small. Think about it. To produce 1,000 lbs of fresh mushrooms every month, you will need 1,000 plastic bags each and every month assuming one bag is producing one pound of fresh mushrooms. And that is only you. But there are plenty of other small mushroom farmers out there.

To reduce the amount of plastic you should think about using, for example, a plastic bottle that can be reused or switching to fixed shelves as they use in the button mushroom industry.

Incineration of spent mushroom substrate

The third issue is incineration, primarily practiced in underdeveloped countries. Besides the fact that you are producing a lot of CO2 and harmful particulate matter (PM10), you are literally burning money.

If you do this, you not only harm the environment, you are hurting yourself at least twice – by accidentally inhaling the harmful particles and by not earning more money through using the spent mushroom substrate properly.

Shortage of land and landfill sites

The last point addresses the shortage of land and landfill sites. As mentioned in my Germany example, the amount of biological waste which you can spread over land is limited. Which is also limited is the number of landfill sites. Because each place is competing with construction and production businesses.

Now that we have talked about these obstacles let’s concentrate on the opportunities which we are provided with.

To understand the opportunities better, we have to look at the composition of spent mushroom substrate more in detail (table 2 and table 3).

Table 2: Physical characteristics of fresh and aged spent mushroom compost (SMC)

Table 2: Physical characteristics of fresh and aged spent mushroom compost (SMC)[3]

By looking at table 3, we can already understand the advantages of using spent mushroom substrate (or compost).  

Table 3: Effect of pilot-scale solid-state fermentation on the contents of spent compost medium

Table 3: Effect of pilot-scale solid-state fermentation on the contents of spent compost medium[4]

But it doesn’t stop there. Ahlawat lists a whole table with different characteristics of spent mushroom substrate, which you can find below (table 4). The combination of all these characteristics makes the spent mushroom substrate valuable for many industries.

Table 4: Characteristics of spent mushroom substrate (SMS) reported in different studies

Table 4: Characteristics of spent mushroom substrate (SMS) reported in different studies[5]

And if you’re still following me, I hope that you’re starting to think differently about your spent mushroom substrate. And maybe you already have dollar signs in your eyes. For which I won’t blame you.

Let’s see how we (actually you) can bring the money home. Here are some of the ideas.

  • Sell your SMS as mulch for ornamental flower and vegetable crops.
  • Sell your SMS as an animal feedstock as a highly nutritious fodder and bedding for poultry and animals.
  • Sell your SMS as organic fertilizer to homeowners.
  • Sell your SMS as a soil conditioner in enhancing the physical and chemical properties of the soil.
  • Sell your SMS as a decontaminant for contaminated drainage and land.

Let’s start with the last point first, because this is not that obvious how that can work. When it comes to contamination, we usually think of using chemicals for removing them.

But there is an alternative to them, called bioremediation. One of the earlier persons who introduce this idea to use mushrooms for bioremediation was Chiu[6]. Since then, many studies have shown the capability of fungi in this field.

The general idea behind this is the fact, as you already know that mushrooms need in order to grow carbon. And while many contaminations consist of carbon, it makes total sense to use them as a vehicle to break them down.

If you want to learn more about that, I found this book Mycoremediation by Singh.

The next point on our list is to use SMS as a soil conditioner. A soil conditioner improves the physical structure and chemical composition of the soil. If SMS is added to the ground, it does exactly that.

It improves, for example, the water holding capacity, which is in some regions a huge topic. Because of the mineral content of SMS (see table 4) it enriches the soil and supports; therefore, the grows of the plants (figure 2).

Because of what we just learned, it would make sense that you start selling your SMS as a fertilizer or mulch too, for example, homeowners. In a study published in 2015 researcher found that adding spent mushroom substrate to plants increase the protein content, chlorophyll content, and carotenoid content. But see for yourself (figure 2).

Figure 2: Effect of spent mushroom substrate on the growth of Capsicum annuum L. (A: control, B: fresh spent mushroom substrate, C: spent mushroom oyster mushroom substrate leachate, D: spent weathered oyster mushroom substrate, E: fresh button mushroom compost, F: spent button mushroom compost leachate, G: spent weathered button mushroom compost, H: combined treatment of spent oyster mushroom and button mushroom substrate[

Figure 2: Effect of spent mushroom substrate on the growth of Capsicum annuum L. (A: control, B: fresh spent mushroom substrate, C: spent mushroom oyster mushroom substrate leachate, D: spent weathered oyster mushroom substrate, E: fresh button mushroom compost, F: spent button mushroom compost leachate, G: spent weathered button mushroom compost, H: combined treatment of spent oyster mushroom and button mushroom substrate[7]

Because of its high protein content and minerals, many people start to investigate spent mushroom substrate as a replacement for example of wheat bran for feeding animals.

This was done in a 2014 published article. The researchers looked at the performance of broilers, which were feed with different SMS levels. They found that in the starter and finisher phase, the broilers feed intake increased, so did the weighed.

As you can see from these examples spent, mushroom substrate has the potential to increase your income. All you have to do is to inform yourself about regulations in your state before bringing spent mushroom substrate onto the market.


[1] Phan (2012)

[2] Siobhán 2007

[3] Adopted from Siobhán (2007)

[4] Adopted from Ahlawat (2007)

[5] Ahlawat (2007)

[6] According to my knowledge

[7] Roy (2015)

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