A well-established community of microorganisms in the soil promotes the plants we care about and makes it much more difficult for weeds to grow.
Weeds are usually pioneering plants. They appear in places of damaged soils. Such as a forest after a fire, a plowed field, around excavations or rubble. They are adapted to a poor food web and their biological goal is to produce and sow the maximum number of seeds as quickly as possible. It can be said that they testify to the initial stage of ecological succession.
Succession, in short, is a change in the composition of species over time. In our conditions, it runs from bare ground, through pioneering species (weeds), grasses, shrubs, to mature forest. Each of these stages also has a different composition of soil organisms. Correspondingly: from dominated by bacteria, to a balanced ratio of fungi to bacteria, to very dominated by fungi.
As farmers, it is our job to steer soil biology towards the desired stage of succession, depending on the specific crop. Thanks to treatments modifying the ratio of fungi to bacteria in the soil, we can make our plants have ideal conditions for development, and weeds will not want to grow.