It allows plants to put out larger root systems easily. When there is lots of air in the soil, microorganisms flourish and speed mineral release. Good tilth allows delicate seedlings to get a good start. Unfortunately, using only chemicals for soil improvement results in a rapid loss of humus, the food source for soil microorganisms. These tiny creatures do more for soil than tons of chemicals ever could.
Nitrogen stimulates humus-consuming bacteria.
Adding chemical fertilizers to the soil causes bacteria to consume two or three times the amount of humus it would ordinarily. Once this has occurred, life level in the soil drops, new soil particles are not broken down as rapidly and the plants become dependent on chemicals. The nutrient level in the soil shoots up, but then drops off after a few rains or irrigations wash the soluble chemicals out of the soil. The fertilization process must be repeated every four to six weeks, which is not feasible with reclamation projects. With organic-based products, the release is slow enough that one application usually provides nutrients throughout the growing season and longer.