Research and small operational applications to study efficacy of pesticides applied by air or ground application equipment are frequently jeopardized by the use of poorly designed, ineffective mixing equipment. The result is the application of a badly mixed and frequently contaminated formulation. A trailer-mounted mixing-loading unit capable of handling suspensions, emulsions and solutions is described. The mixing tank is fitted with a paddle agitation and recirculation mixing system, can be readily cleaned, and has accurate metering of formulation. It is a self-contained system for power supply. An extra cleaning of the plumbing to prevent cross-contamination of the test batches of material.