Fertilizing and topdressing during edible mushroom care and management should follow the principle of "two suitables and two musts".

In the late fruiting stage during the care and management of edible mushrooms, in order to enhance the follow-up fruiting capacity, mushroom growers often carry out topdressing by adding nutrient solution. Only by following the principle of "two suitables and two musts" can the expected goal be achieved.

1. The addition method should be suitable. There are usually 3 methods for adding nutrient solution: spraying, soaking and hole irrigation. The time for spraying nutrient solution is suitable when fruiting bodies appear in large numbers. When spraying, note that the nozzle should not point directly at the fruiting bodies, and also note the "four no-spray" rules: do not spray on small young mushroom buds, so as to avoid swelling them to death; do not spray on places where mushrooms have just been picked or where mushroom residues remain, so as to avoid causing bacterial diseases; do not spray when air humidity is too high; do not spray when pests and diseases are severe inside the mushroom shed (room). The soaking method is mainly used for bag-cultivated edible mushrooms. After harvesting 1-2 flushes of mushrooms, if the cultivation bags are in a state of severe water shortage, they can be placed in a prepared nutrient solution to soak until they recover to close to their original weight.

When using the soaking method to add nutrient solution, generally the mushroom bags are placed into a nutrient solution pool and pressed down with heavy objects, and the soaking time must not be too long. If the mushroom bags have lost too much water, they can be soaked in several batches. The hole irrigation method is mainly used on mushroom beds, and this method can be used when the mushroom bed produces many mushrooms and water and nutrients are consumed excessively. The specific method is: punch holes in the mushroom bed at a hole spacing of 10 cm, flood-irrigate the mushroom bed with the prepared nutrient solution, and cover with soil after adding the nutrient solution.

2. The added concentration should be appropriate. When the nutrient solution concentration is too high, not only is it difficult for the mycelium to absorb it, but it will also hinder and even damage the growth of the mycelium; when the concentration is too low, the goal of high yield cannot be achieved. The concentration of the added nutrient solution should be determined according to the water content of the culture material: if the water content of the culture material is relatively high, the concentration of the nutrient solution should be increased, the amount of water used should be reduced, and ventilation should be increased after addition; conversely, the concentration of the nutrient solution should be reduced and the amount of water used should be increased.

3. The nutrients in the nutrient solution should be comprehensive. Several nutrient solutions should often be used alternately, so that the nutrients required for the growth of fruiting bodies will be both comprehensive and reasonable. If hormones are used to stimulate the growth of edible mushrooms, they should be applied after supplementing the nutrient solution.

4. Pay attention to changes in the environment. When the temperature reaches above 20°C, it is difficult for the mycelium to form high-quality fruiting bodies, and except for high-temperature-type edible mushroom varieties, nutrient solution may not be added. If the culture material has already been contaminated by miscellaneous bacteria, the miscellaneous bacteria must first be removed before adding nutrient solution. In order to prevent contamination by miscellaneous bacteria, a certain amount of bacteriostatic agent can also be added while adding the nutrient solution, so as to prevent the breeding and spread of miscellaneous bacteria.