There is little information on how improve onion dry yield and status of nutrients in plants and soil under water scarcity. To fill this gap, two field experiments were conducted during two consecutive winter seasons. Three treatments of irrigation levels were designed in the main plot (100% of crop evapotranspiration, 80% ETc and 60% ETc). Four bio-stimulants soil treatments were designed in the sub-plot: control, yeast extract (YE), potassium humate (KH) and YE+KH. Generally, bio-stimulants increased onion productivity significantly and decreased the negative impact of water shortage. During both seasons, YE followed by YE+KH recorded the highest bulb yield, water use efficiency and irrigation water use efficiency for bulb dry yield, dry matter content, NPK content, NPK uptakes, protein yield and soil water holding capacity. While KH followed by YE+KH or YE recorded the highest available soil NPK, EC and soluble ions values. The pH lowest values were recorded in soil treated with KH or KH+YE. Comparing the 80% ETc with YE treatment and the 100% ETc with YE treatment, it was found that the amount of reduction in dry onion yield amounted to only 3.18% as an average for the two seasons with saving 20% of irrigation water. However, onion dry production was greater with YE at 80% ETc than with untreated plants under 100% ETc irrigation level by 24.36% as average of two seasons. In conclusion, YE and or YE plus KH may be major factors in enhancing soil fertility and plant stress tolerance by insufficient irrigation water.