Microemulsion compositions include a blend of lecithin and a co-surfactant, and an acidifier. The compositions may further include salts of the acidifier, such as lactic acid or sodium lactate. The microemulsion may be used to produce a multi-functional agricultural adjuvant that is able to deliver an active ingredient such as a pesticide control, pH improvement, wetting, and penetration of an agricultural chemical, control droplet size, function at extreme pH or salt concentration and/or other provide another functional benefit.