Agriculture & Water Consumption

Agricultural activities use a lot of the world's water resources for irrigation, to avoid years in which farmers would otherwise be able to produce little or not food. However, there are wasteful and non-wasteful methods of irrigating crops. Wasteful methods include overhead sprinklers, trench irrigation (canals carry water from a stream to the fields) and flood irrigation (in which fields are flooded with water).  They are considered wasteful because between 15-36% of the water never reaches the crops; it either evaporates or leaves the fields as runoff. Non-wasteful methods, such as drip irrigation, minimize evaporation and runoff by delivering small amounts of water directly to the soil.


Drip irrigation delivers water to the base of each plant so little is lost to evaporation and runoff. Photo courtesy of CK-12. 


If non-wasteful irrigation methods are available, why don't farmers use them? One is cost; drip irrigation is more expensive than trenches, flooding and sprinklers. Second, in the US, the government pays for much of the cost of water used for agriculture, so farmers do not directly feel the cost and therefore have little financial incentive to use a more efficient method. 


Source: Uses of Water. Retrieved from http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/r16/section/13.11/ on December 27, 2013.