Since 1983, long-term field experiments have been carried out at the University of Debrecen's Látókép Experiment Site, where our research was also carried out. In the years 2021–2022, we examined the efficiency of biological foliar fertilisers under precision drip irrigation. Maize stands were treated at the 7–8-leaf stage with foliar sprays of Natur Plasma T biostimulant, Natur Active complex foliar fertiliser, and Zinc and Sulphur Mono additives. The applied foliar fertiliser treatments resulted in yield gains in both years. The use of these microbiological preparations allows rapid and efficient nutrient incorporation during the vegetative and generative cycles. During the growing season, important parameters of maize hybrids (SPAD, NDVI) were measured at critical phenophases (12-leaf stage, silking, physiological maturity). The obtained results showed that the incorporation of foliar fertilisers and biostimulants into agrotechnology improved the strength of maize stands and resulted in additional yield gains over and above the base fertilisation.