ABSTRACT
Water is of crucial importance to agriculture. In many locations, precipitation is limited, and the input of moisture it provides must either be carefully stored in the soil and conserved (Chapter 6 of Agroecology: The Ecology of Sustainable Food Systems) or be supplemented through irrigation (Chapter 9 of Agroecology: The Ecology of Sustainable Food Systems). But water that can be used for irrigationeither from surface supplies or in the ground-is also limited in supply, and agriculture must compete with industry, cities, and water-dependent natural ecosystems for its share. Moreover, irrigation itself carries with it a number of potential problems, including salinization of the soil (Chapters 1 and 9 of Agroecology: The Ecology of Sustainable Food Systems). For all these reasons, sustainability depends on careful water management in agroecosystems. Agroecosystems are sustainable in terms of water usage if they use water efciently, minimize losses of soil moisture through evaporation, and are adapted to the regional climate and water supply (Chapter 9 of Agroecology: The Ecology of Sustainable Food Systems). Knowledge of soil moisture content and how it changes over time is a key basis for the design and management of such systems.
