Depending on the heat treatment method of raw materials we recommend following substrate materials for growing oyster mushrooms.
- When using hydrothermal treatment
Sunflower husks are preferable: its preparation process less time-consuming and energy-saving. Nutritional value of husk is relatively high, nitrogen content is 0.6 and above, allowing to work without using nutrient supplements which can cause spoilage. In case of manual stuffing husk is easier to stuff into the spawn bag. If we compare it with straw, later must be grounded in a straw chopper.
If husk has insufficient nitrogen content you can add some chopped alfalfa hay, about 7 -5% max. Husk, as a rule, is not bought at once for the whole growing season, so a fresh batch of husk initially contains rather small amount of dust. At the same time straw catches a lot of soil dust from the field with high content of spores of various pathogens. Even a prolonged heat treatment of straw using hydrothermal method cannot prevent the spoilage. It is due to the fact that this method does not allow a large number of spores to germinate prior to heat treatment, and the temperature 72-75 degrees destroys only “hatched” spores and spores themselves are not destroyed.
Best used in such methods of raw materials treatment:
- Xerothermic treatment – where steam is used to destroy a great number pathogen spores, the rest of spores do not have enough time to hatch beacuse of short treatment and addition of lime.
- Pasteurization. In this method, long preparation of presoaked substrate enables most spores to hatch or hydrate and they are subsequently killed during the heat treatment in a tunnel. To improve the substrate quality and increase its nutritive value technologists arrange substrate blends. The straw is used as a basis for the substrate blend. The additives are: – hay and/or legumes straw (soybean, peas, sainfoin, lucerne) – to raise the nitrogen content up to 0.8-0.9 units; – husk and straw from various cereals species (with varying stem softness degree) – to improve substrate structure. When using xerothermic treatment and pasteurization in tunnel you can use multicomponent mixtures with husk and straw in varying percentages. For example, the husks can amount up to 70% with less hay added (as in husk, nitrogen content is greater than that in straw). It is also possible to use a mixture of husk and straw of various plants, for example, wheat – 20%, rye – 10% barley – 10%, husks – 55%, alfalfa hay – 5%. In order to determine which formulation works best in your environment, you need to experiment with different percentages when mixing your components. Also you need to keep record of compositions and then compare the productivity of various batches.