Disclosed is a method to achieve certain soil conditions. The method comprises: A composition of a fertilizer solution (FS) that has been supplied to a soil substrate including a root activity zone of a plant species is obtained by a computing device. A chemical composition within the root activity zone is obtained by the computing device. The chemical composition is determined by analysis of an aqueous sample obtained from a suction probe positioned within the root activity zone after the FS is supplied to the soil substrate. The nutrient utilization by the plant species based at least in part upon the FS composition and the chemical composition of the root activity zone is determined by the computing device. An amount of additive that is added to irrigation water to produce a subsequent FS that is supplied to the soil substrate is provided by the computing device.
