To provide a process for producing a plant/soil activation liquid in which injury by continuous cropping is avoided to improve the yield, taste, appearance or the like of harvest such as fruits, vegetables or grains and the growth of vegetable is promoted and which satisfies safety and profitability and a method of using the same.

A phytogenic fermentation material composed of an enzyme and an enzyme-producing useful microbe together with brown sugar produced from sugar cane is placed in a mineral ion water utilizing concentrated sulfuric acid, and symbiotic incubation thereof is carried out under aerobic conditions preferably at about 25°C. Foliar application and/or soil perfusion with the thus produced plant/soil activation liquid is carried out at the stage after saccharolysis but before initiation of putrefaction-fermentation, preferably at the stage of alcohol fermentation.