Passage: Several individuals revolutionized the branch of permaculture. In 1929, Joseph Russell Smith added an antecedent term as the subtitle for Tree Crops: A Permanent Agriculture, a book which sums up his long experience experimenting with fruits and nuts as crops for human food and animal feed.  Smith saw the world as an inter-related whole and suggested mixed systems of trees and crops underneath. This book inspired many individuals intent on making agriculture more sustainable, such as Toyohiko Kagawa who pioneered forest farming in Japan in the 1930s.In Australian P. A. Yeomans' 1964 book Water for Every Farm, he supports the definition of permanent agriculture, as one that can be sustained indefinitely. Yeomans introduced both an observation-based approach to land use in Australia in the 1940s and the Keyline Design as a way of managing the supply and distribution of water in the 1950s.

Question: What was the Keyline Design used for in terms of agriculture in the 1950s?
managing the supply and distribution of water