What is soil?
For millions of years plants have been growing and bearing fruit without the assistance of chemical inputs. This is credited to the functions of soil microorganisms continuing to supply nutrients to plants. Having productive life in the ground is what separates soil from dirt.
In soil, there are billions of different types of microorganisms, and each performs its own specific function. These ecosystems of organisms are the direct cause of nutrient availability by storing and releasing nutrients through processes called immobilization and mineralization.
Organisms and Their Functions
The microbial makeup of the soil is what selects for different plant growth. Naturally, different plants are going to require different organisms in different proportions. This is something referred to in the scientific community as 'Succession'

If and when there is a disturbance in the soil, as seen today in conventional farming with excessive tilling and chemical inputs, the microbial diversity and quantities are drastically reduced. When these levels become reduced, the soil, or dirt is more suitable to grow weeds than the intended crop.
Without Terraforma's technology, this process of succession can take thousands of years - which is why we intervene to help mother nature