Explore the critical role of soil in global food security and water management through this AGU Fall Meeting Langbein Lecture. Delve into the concept of "green water" and its significance in crop production, examining how soils function as both provisioning and regulatory hydrologic agents. Investigate the challenges posed by increasing global food demand and climate variability, and understand the need for a deeper quantitative understanding of soil functions in the water cycle. Learn about soil composition, including mineralogy, organic matter, and microbiome, and their impact on hydrology. Discover the importance of productive green water flow and its application in Millennium Villages. Gain insights into potential solutions for enhancing global food security through improved soil and water management practices.