Various methods and systems are provided for monitoring and control of soil conditions. In one example, among others, a method includes obtaining one or more aqueous sample from at least one suction probe within a soil substrate and analyzing the one or more aqueous sample to determine a chemical composition of the soil substrate. Amounts of an additive may be determined to adjust the chemical composition of the soil substrate. In another example, a method includes installing at least one suction probe within a soil substrate; drawing a vacuum to induce hydraulic conduction of at least one aqueous solution from the soil substrate; extracting one or more aqueous sample; and analyzing the one or more aqueous sample to determine a chemical composition.