All fresh water is delivered by the soil. There are two critical junctures: when rain hits the ground—where it may infiltrate or run off carrying the soil with it; and in the soil itself—where it may evaporate from a bare surface, be taken up by roots, or drain to streams and groundwater. Both partitions are managed by farmers so every land-use decision is a water-use decision. Green water is held in the soil and used by plants—the more green water, the more primary production; and the best soils supply orders of magnitude more than the poorest. Practices that maximize the green water resource, such as conservation agriculture, arrest soil erosion, maximize soil water storage and groundwater recharge, and moderate floods. But water consumed in the fields where it falls is not available for use elsewhere.