Mycorrhizal fungi are relatively few in some soils and may be at a greater distance from newly formed plant roots. This can slow down the formation of mycorrhizal symbiosis and have a positive effect on plant growth. The sooner mycorrhiza is established, the better for the plant. In addition, in some soils, mycorrhizal fungi populations can be significantly negatively affected by previous agrotechnological practices (deep ploughing, use of fertilisers, pesticides, etc.), so the application of mycorrhizal fungi is necessary to revive the soil.