Spraying with various types of agrochemical substances, including bi-ostimulants, is one of the basic agricultural treatments affecting the yield size and quality. The selected type of spraying nozzles can influ-ence biological effectiveness of the applied substances. A 2-year field study showed which of the investigated nozzles increase the effective-ness of foliar application of a free amino acid biostimulant. The type of nozzle used for the application of biostimulants was reported to signif-icantly influence the biometric properties and yield of soybean cultiva-tion. It was observed that spraying nozzles, which generate finer drop-lets positively influence positively the biometric properties of plants and seed yield of seed than injector nozzles, which produce coarser droplets. A significant reduction of the thousand seeds mass after ap-plying the biostimulant with standard flat fan nozzles is an exception. A 25.61% increase in soybean yield was reported after applying the bi-ostimulant with standard flat fan nozzles and a 11.35% increase – with injector nozzles.