A method for producing an electrolyzed water biocidal composition for agricultural use is described. The method comprises: preparing an electrolyte solution comprising water and a mixture of at least four salts, in which the salts are selected from acidic, basic or neutral salts, and any combination thereof. The electrolyte solution is then introduced into an electrolytic cell comprising a plurality of boron-doped diamond (BDD, BDE) electrodes. A power supply is operated to apply a predetermined voltage to the solution to produce the electrolyzed water. The mixture of salts in the electrolyte are selected such that the electrolyzed water biocidal composition comprises a free accessible chlorine (FAC) concentration of the solution is in the range of 10 to 10000 ppm, and may have a dissolved ozone (03) concentration in the range of to 750 ppm.
