How to Make Mushroom Substrate With Manure

With mushroom substrate, you can grow nutritious and tasty mushrooms.

If you love mushrooms, consider growing your own delicious and nutritious varieties. Your first step is to make some mushroom compost or substrate, which is a mix of manures, wheat straw and other additives. Because your mushrooms will grow in this substrate, good quality ingredients will add flavor and nutrients to your 'shrooms. If you're not planning on going into mushroom farming, but simply wish to grow tasty food, a simple mix of ingredients will do fine. Start with the following formula, which will shrink down during the composting process. Your mushroom substrate will require aeration and water, which you'll add during the process.

Things You'll Need

• 10 pounds horse manure
• 2 cups chicken manure
• 1 bale wheat straw
• ½ cup blood meal
• 2 pounds cottonseed meal or molasses
• ¼ cup super phosphate
• 1 pound potash
• 1-3 pounds gypsum
• 8 oz. bag compost activators
• Mushroom spores
• Compost bin that turns
• 1 large plastic tub
• Long-stemmed thermometer
• PH tester

Instructions

1. Obtain all ingredients. Most are available at garden stores, but you'll need to contact a horse stable and someone with chickens for the manure.

2. Soak the bale of wheat straw for three days. Put the bale in a big plastic tub and add enough water to thoroughly soak it.

3. Mix up the remaining ingredients, except the gypsum, in a pile on the ground and add the straw, mixing it well. Check the moistness of the mix. The mushroom substrate should feel like a wrung-out sponge, neither completely dry nor gushing water. If it's too wet, let it sit for a day and check again. When it's ready, put the mix in the compost bin.

4. Check the temperature of the compost in three to seven days. It should be about 150 to 180 degrees Fahrenheit.

5. Check the temperature again after six days; it should be lower. This means the compost needs air, so turn the bin and aerate it well.

6. Take a close look at the compost. You should see a bright, white fungus near the center of the bin. These fungi are called actinomycetes; they're a sign that the compost is working.

7. Allow the compost to sit for a week. Check the temperature again; it should be in the 150- to 180-degree range.

8. Add the gypsum to the mix and water the compost. Aim for the same degree of moistness as in step 3. Turn the bin again to aerate.

9. Let it sit for five days before you water the compost and turn the bin again.

10. Turn the compost again after four to five days. Use the pH monitor; the pH level should be close to 7.0 to 7.5. If it is not, allow the compost to rest two more days and test it again. Repeat if necessary until the pH is right. The final substrate will be dark brown with white speckles from the fungi.

11. Pasteurize the compost by putting a small amount into an old turkey roaster and put on the lid. Put it in the oven for four hours at 140 degrees Fahrenheit. Let it cool, keeping the lid on. Take off the lid when you're ready to put your mushroom culture or spores in it. Place the mushroom substrate in a dark plastic bin and add your spores.

Tips & Warnings

• At a point in the process, your substrate will smell of ammonia due to the breakdown of the wheat straw. Don't worry; in another week, that smell will be gone.

• Dedicate an old turkey roaster to mushroom pasteurizing. If you don't have one, try looking in secondhand stores.

References

• What Be That; Mushroom Compost; Make Your Own Mushroom Compost
• Food from the Garden; Mushroom Compost is the Key to Growing Mushrooms; 2009

Resources

• Penn State University Extension; Basic Procedures for Agaricus Mushroom Growing; 2003