Field trials were conducted in the Al-Husein Society, a 64km stretch along the Cairo-Alexandria desert road in Giza Governorate, Egypt, during the 2021-2023 seasons. These experiments aimed to evaluate the impact of irrigation regimes (800, 1000, and 1200 cubic meters per feddan) and potassium foliar spraying (control, 0.5 and 1 gram per liter) on quinoa cultivars (Chipaya and Q5) grown in sandy soils. The results of these trials revealed significant differences among irrigation regimes, potassium foliar spraying, and quinoa cultivars for various plant traits, including branch count, spike length, spike count, thousand-grain weight, grain yield, harvest index, and protein content. Quinoa plants irrigated with 1200 cubic meters per feddan and treated with 1 gram per liter potassium foliar spray, or those irrigated with 1200 cubic meters per feddan using the Chipaya cultivar, consistently exhibited the most favorable outcomes for all studied traits in both seasons. While interactions between the studied factors were not significant for branch count, thousand-grain weight, and harvest index in either season, they were observed for spike length in the second season. Additionally, grain yield, spike count, and protein content were significantly influenced by the interactions between these factors in both seasons. Overall, the findings demonstrate that quinoa plants irrigated with 1200 cubic meters per feddan and treated with 1 gram per liter potassium foliar spray, particularly when the Chipaya cultivar is used, exhibit enhanced grain yield and quality traits in sandy soil conditions prevalent in Egypt