Seeds can be coated in naturally occurring soil microbes. When the seeds give rise to plantlings, the microbes cultivate the root tips and efficiently transfer nutrients to the plant. That can make fertiliser applications more efficient or less necessary and improve overall plant health. When applied to the root zone (especially at transplant, or just after emergence, the effects on yield, quality, soil and plant health is something that has to be experienced, since it is almost to wonderful to explain.