So I recently listened to a great podcast from Sustainable World Radio where the host, Jill, interviewed John Kempf from Advancing Eco-Ag. In the interview John Kempf discusses how one of the fastest ways to build healthy soil is by growing healthy plants. When the plants are at optimum health root exudates will begin to occur, which will boost soil fertility and soil biology.
John Kempf also published a couple great works here in which he goes into detail about the concepts of optimum plant nutrition. According to his plant health pyramid there are four stages to optimum health and they occur in order similar to Maslow's hierarchy of needs for human psychological health. According to John Kempf the basis of plant health is successful photosynthesis. Then production of complete protiens. Then storage of surplus energy. Then the production of plant secondary metabolites. Through this process resilient plants will be grown, and the soil will be recharged.