Want to do away with expensive inorganic fertilizers? Think about a 1000 year old Baobab tree! How does it get so big, or the missive Maroela tree in the National Park? There is not much around the base of the tree as all the baboons, Impala and elephants hang about eating the fruits and leaves. Sometimes it is very dry with little rain. So compost does not play a big role. Then it must be something deeper that feed the tree. It is all about the microbes, mainly bacteria deeper than the topsoil. It is cooler there. Hair roots die and regenerate with the change of seasons. Microbes turn the dead roots into organic nutrients (Humus). When the rain comes the tree absorb it again and grow new shoots, flowers and fruits without applications of inorganic fertilizers. The difference with row crops is instead of 364 days that the tree have, the row crop have only 3 to 4 months to complete the growing cycle. SBM speed up the cycle to suit the crop by adding high populations of microbes in the beginning of the growing cycle. This convert the organic material (dead roots) into organic nutrients (Humus), not compost which is mineralized organic material. Soils with low carbon content needs more organic materials incorporated to fulfill in the needs of the crop. No less than 5 groups of bacteria are needed to fulfill in the crops nutritional needs.