to out-compete antagonistic communities of microbes.
This is a balance between "good" and "bad" microbes.
Many microbial species (the good ones) kill or inhibit bacteria, fungi and nematodes (the bad ones)
that attack the root systems important for the exchange of valuable nutrients in the soil through competitive exclusion.
Good microorganisms improve the soil structure by producing glues, hyphae strands and tunnels for air and water.
Good microbes also eat a lot of toxic material that would otherwise make for poisonous soil,
but they do need healthy organic soil to consume with it.
An imbalance of soil microbes can result in parasitic infestations, root disease, breakdown of the soil structure and build-up of toxic compounds. When the soils are repeatedly treated with toxic chemicals, the balance between good and bad is disrupted and the soils can actually become toxic to plants.