Shiitake Mushroom Winter Greenhouse Cultivation: Lower Costs, Higher Returns
As the saying goes, "Laba, Laba, freeze your chin off." In the rural areas of Northeast China, after the Start of Winter each year, the ground freezes over, and there is not much for people to do - in the Northeast dialect, this is when "winter hibernation" begins. But in Muniu Town, Xiuyan County, Liaoning Province, every household is bustling with activity, all busy growing shiitake mushrooms.
Because mycelium growth has strict temperature requirements, the mycelium-running stage needs a temperature of around 20ºC, while at the fruiting stage, a relatively large temperature difference is needed to stimulate the mycelium to knot and form mushroom buds. Therefore, in most places where shiitake mushrooms are grown, the mushroom logs are made and mycelium is run in summer, and the shiitake mushrooms are harvested in winter.
Generally speaking, winter mycelium running takes a relatively long time, about half a year. To start harvesting mushrooms at the end of April, the logs must be made in early November of the previous year. But Muniu Town is located in the Changbai Mountain area, which is the coldest time in Northeast China, with an average outdoor temperature of minus 20ºC, while mycelium growth requires a temperature of around 20ºC - a difference of 40 degrees. How can this unfavorable condition of low temperature and severe cold be overcome?
Jiang Baiqiu is the deputy secretary of the Party branch of Yilin Village, Muniu Town. He has a wealth of experience in mushroom cultivation and is the local technical leader in shiitake mushroom growing. Faced with the problem of mycelium running in the severe winter season, Jiang Baiqiu worked out a set of techniques that are both money-saving and highly efficient.
To reduce costs, the first thing Jiang Baiqiu thought of was to use abandoned greenhouses. Moreover, for a good sterilization effect, Jiang Baiqiu has strict requirements for the steaming time, which must reach 48 hours. After such a long period of high temperature, the mushroom logs just out of the steamer are very hot and must be cooled before inoculation, otherwise the spawn would be killed by the heat. In this way, the heat released during the cooling process can be used to warm the greenhouse, saving energy and reducing emissions at the same time.
With 4,000 logs coming out of the steamer each day and continuous steaming for 60 days, the total number of mushroom logs is 240,000. In terms of volume, that is nearly 80,000 cubic meters, equivalent to the capacity of 5 passenger train cars. The 240,000 hot mushroom logs huddled together are like small stoves, keeping the temperature inside the greenhouse at around 20ºC at all times.
The heat generated by mycelium growth is the second heat source Jiang Baiqiu uses in the mycelium-running process. It turns out that mycelium produces heat during growth and releases that heat through respiration. The longer the mycelium-running time, the more the mycelium grows, and the more heat is produced. In other words, for freshly inoculated logs, the mycelium relies on the residual heat given off by nearby logs to live; as it grows bit by bit, the mycelium produces more and more heat, and eventually meets its own growth needs with the heat it produces itself.
When the last batch of mushroom logs is moved into the greenhouse, the hot-air furnace has to be fired up. After burning for about a month, when the mycelium on the surface of the logs has grown to the size of a bowl mouth, the heating can be stopped, because by then the heat produced by the mycelium can sustain its own growth. The boiler, originally the main heat source for winter greenhouse production, becomes merely a supplement, greatly reducing the cost of growing shiitake mushrooms.