Symbiosis between Mushroom Cultivation and Vegetable Production

10 tonnes of spent mushroom substrates in Cham Shan Farm, ready to feed the soil!

Edible mushrooms need to be fed with a lot of nutrients to grow well. Common edible mushrooms like white button mushrooms and oyster mushrooms feed on dead organic matters. Unlike plants, they can only be grown in specially prepared nutrient-rich substrates, hay and straws mixed with manures and seed meals are most commonly seen.

After the substrates are properly prepared, mushroom hyphae will be placed in the substrates to grow. Hyphae are like roots, they absorb nutrients and transform them into the body of mushrooms. With each harvest of mushrooms, nutrients are taken away from the substrates, so after several harvests, the yield will drop. Mushroom farms will discard this spent substrate, and replace it with fresh substrates so they can sustain their yields.

L: What healthy mushroom substrates look like from a mushroom farm in WA. The white-gray mushroom threads (mycelium) are clearly visible in their grow bags. B: Close up: some remains of straws and white hyphae can be seen

These spent substrates that are constantly prepared and discarded are excellent resources for vegetable farms! Soil microbes are thrilled to feed on them, scavenging the remaining energy and nutrients, a crucial part of the life cycle in regenerative practices. With more active microbes in the soil, more nutrients are provided to plants and better soil structure can be built.

Restore farmers are big fans of spent mushroom substrates. Farmers find them amazing as mulch and apply them on vegetable rows with compost. Not only the substrates are a food source for microbes, they also reduce water evaporation and shade sunlight for the soil, providing a physical protection for the microbes beneath. Rapid microbe activities to cycle nutrients is key to good vegetable yield and health. Mushroom substrate has an optimal C:N ratio that drives fast microbes growth without the need to mix in other materials. That’s why farmers prefer the more expensive substrates over the freely available wood chips!

The substrates still contain abundant nutrients. The rapid growth of microbes will make the pile hot, just like composting. It is best to leave the substrates for some time so that it stabilizes and does not heat up when used near the crops (left). Loads and loads of spent substrates are produced from mushroom farms! All are valuable resources for vegetable farms (centre). Cherry tomatoes planted with mushroom substrates and compost as the foundation (right).