Abstract: A closed agri-chemical mixing and transferring system ideally adapted for mixing agri-chemical concentrate for subsequent use in agricultural spraying operations. The system comprises a plurality of independently operable subsystems for generating vacuum, intaking raw concentrate, and subsequently loading a sprayer device. The self-contained vacuum subsystem comprises a pump for generating partial vacuum, and means for selectively introducing partial vacuum to preselected ones of a plurality of chemical holding tanks. The mixing subsystem comprises a plurality of couplings adapted to be connected to external probes which may be attached to external chemical concentrate containers. Probe inlet switching valves in fluid flow communication with holding tanks direct partial vacuum to draw chemical concentrate through the probes into the holding tanks.