Two field experiments were conducted at a special farm, in El Mansoura, Dakahlia Governorate, Egypt, during the two growing summer seasons of 2018 and 2019 to find out the influence of soil drench by potassium Humate (KH) and yeast extract  (YE) as foliar application alone or combined (KH+YE) under different rates of N and P fertilization on plant growth, yield, quality and protection against some pests of soybean plants (Glycine max L.), c.v. Giza 111. The treatments of NP fertilization rates were arranged in the main plots and the HK and YE were arranged in sub-plots in a split-plot design with three replicates. Results indicated that the application of soil drench  KH and YE spraying and (KH+YE) had a positive effect on growth parameters, photosynthetic pigments, seed yield and yield components of the soybean plants. The duel application (KH+EY) showed a significant augmentation in all studied parameters compared to the control under 50, 75 .and 100% of the recommended mineral fertilization does (RFD. The whitefly Bemisia tabaci Genn. represented the most pest attacking soybeans with a ratio around 56 % followed by Aphis cracivora Kock  (30%), While Tetranychus urticae Koch ranged (8-10%). respectively .But mealybug Phenococcus solani Ferrisia in % occurrences a ratio around (3-6%) during 2018 and 2019 seasons. In treatment were spray (combined of KH+YE ) decreased population of B. tabaci Genn. (9.75 nymphs /10 leaves). Therefore, this investigation revealed that the synergistic effect of HK (5 ml l^-1) and YE (4 g l^-1 ) in combination treatment with 75% NP is important for improving plant quality and this decreased insect infestation and the environmental pollution caused by repeated application of agricultural chemicals as mineral fertilizers and pesticides.