Systems and methods are disclosed to provide a plant nutrient by selecting a microbial solution with predetermined characteristics for agriculture use； iteratively and selectively breeding generations of microbes for microbial strain selection with predetermined microbial gene profiles to arrive at a predetermined microbial solution in a highly concentrated form of at least 1×107 cfu/ml (colony-forming units per milliliter), wherein multiple single microbial series are separately cultivated and followed with cross cultivation among the microbial series in a specific sequence； and mixing by-products produced by the crossly cultivated microbial series with humic acid and a filler.
