Irrigation dates back to roughly 6000 BC, when the waters of the Nile and Tigris-Euphrates were first diverted to feed farmers’ fields. Today, agriculture consumes 70 percent of the world’s freshwater resources, and irrigation is essential for 40 percent of the world’s food production. Because pumping and distributing water requires large quantities of energy, irrigation is a source of carbon emissions.
Irrigation technologies have evolved to help farmers use water more precisely and efficiently. Both drip and sprinkler methods make water application more exact, delivering as precisely as possible the amount crops need to thrive. With 70 to 90 percent application efficiency, they reduce overall water and energy consumption.
The benefits of drip and sprinkler irrigation are numerous: crop yields improve, costs drop, and soil erosion declines. Lower humidity curtails pests. Surface and groundwater resources are better protected, and conflicts among various stakeholders for water resources may ease. However, both systems require infrastructure and upkeep, which can be expensive, sometimes prohibitively so.
Other practices and technologies can also be effective. Irrigation scheduling and deficit irrigation are two methods of variable application. Sensors can monitor soil moisture and control irrigation systems automatically. Rainwater and runoff can also be captured and put to use.
6000 BC… Egyptians and Mesopotamians: Stewart, B. A., and Terry A. Howell. Encyclopedia of Water Science. New York: Marcel Dekker, 2003.
agriculture and irrigation consume…freshwater: World Water Assessment Programme. The United Nations World Water Development Report 4: Managing Water under Uncertainty and Risk. Paris: United Nations Educational, Scientific, and Cultural Organization, 2012.
irrigation is essential for…food production: World Water Assessment Programme, Managing Water.
[water] application efficiency: Phocaides, Andreas. Handbook on Pressurized Irrigation Techniques. Rome: Food and Agriculture Organization of the United Nations, 2007; Sauer, T., P. Havlík, U. A. Schneider, E. Schmid, G. Kindermann, and M. Obersteiner. “Agriculture and Resource Availability in a Changing World: The role of Irrigation.” Water Resources Research, 46 (2010).
farmland under drip…irrigation: Starke, Linda, Erik Assadourian, and Tom Prugh. State of the World 2013: Is Sustainability Still Possible? Washington, D.C.: Island Press, 2013.
4 percent of…irrigated land: Starke et al, State.
Asia [has] significant opportunity: Aquastat. “Irrigation and Drainage.” Food and Agriculture Organization of the United Nations. http://www.fao.org/nr/water/aquastat/irrigationdrainage/index.stm#reg.