The present invention provides an irrigation system that includes a control system for determining whether to apply an applicant to an agricultural field. In an implementation, the control system includes memory operable to store one or more modules and a processor coupled to the memory. The processor is operable to execute the one or more modules to cause the processor to receive one or more signals representing a microbe characteristic from a soil sensor. The processor is also operable to determine whether to apply an applicant (i.e., water having a concentration of a biological or a microbe therein) to a soil based upon the microbe characteristics and to initiate operation of the irrigation assembly to apply the applicant to the soil in response when the soil requires the applicant.