The present invention relates to a composition, system and method for the promotion of soil health, and hence plants grown in the soil treated with the composition. The present invention may be used for the improvement of soils that are deficient in or depleted of nutrients, minerals, microorganisms or moisture (or any one or more of these), and are in need of "rehabilitation." However, the invention is equally suited to establishing and maintaining the health of any soil (and plant) ecosystem. The composition includes live nitrogen-fixing bacteria and fungi that form symbiotic relationship with plants to increase the bioavailability of nitrogen in the soil.