How to make edible mushroom growing medium from biogas residue and biogas slurry?

Biogas residue is rich in nutrients, and the nutrients it contains are similar to those needed in edible mushroom growing medium, with few impurities, making it very suitable for the growth of edible mushrooms. Below is an introduction to the process of making a mushroom growing medium.

The carbon-to-nitrogen ratio of mushroom growing medium is required to be around 30:1. Usually, every 100 cubic meters of growing medium requires 5000 kg of biogas residue, 1500 kg of wheat straw or rice straw, 15 kg of cottonseed husk, 60 kg of gypsum and 25 kg of lime.

Making the growing medium requires piling the material first and then fermenting it. When piling, first cut the wheat straw into small pieces 30 cm long, soak them thoroughly with water, and spread them on the ground to a thickness of about 17 cm. Then, evenly spread biogas residue over the straw to a thickness of 30 cm. Following this method, continue to spread a second layer and a third layer on top of the first pile. When the third layer is finished, evenly splash biogas slurry over the pile until the pile is thoroughly soaked, and note down the amount of biogas slurry used. After that, spread the fourth, fifth, sixth and seventh layers in turn, splashing the same amount of biogas slurry on each layer, with the amount of biogas slurry used being about one third of the first amount, so that it is fully absorbed and soaked through with the biogas residue. Then pile the material for fermentation. After about 7 days of fermentation, when the temperature reaches 70°C, turn the material. After the first turning, pile and compost for another 5-6 days, and when the temperature in the middle of the pile reaches 70°C, carry out the second turning. At this point, dilute 40% formaldehyde water 40 times and use it to disinfect the pile. If the pile is dry at this time, an appropriate amount of biogas slurry may be added to moisten the pile, judged by whether it does not drip when lightly squeezed by hand. Continue composting for 3-4 days, then it can be moved into the seedbed for use as growing medium.