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Version: 2.0
(October 6, 2006)

Six Strategies for Conserving Water

10/22/2006






Agriculture accounts for 70% of all water used each year. Over the past 70 years, water use has grown six-fold, primarily due to an increase in population and unsustainable water use practices. California is an excellent example of this relationship. As of 2004, California uses 43 million acre-feet per year of water - that's more than one acre-foot for each of 30 million residents. One acre-foot of water is enough to meet the industrial and municipal needs of four people for a year. However, because of California's intensely agrarian economy and semi-arid climate, it's need for water is enormous and ultimately too excessive to be ecologically feasible.



Irrigation accounts for at least half of water used in U.S. agriculture, leading to such wide-scale problems as salinization, a rising water table, groundwater pollution, and the depletion of natural aquifers. Irrigation's role in agriculture is pivotal, but it's environmental impact is momentous. The United Nations Population Fund reports that "Worldwide, 54 per cent of the annual freshwater is being used. If consumption per person remains steady, by 2025 we could be using 70 per cent of the total because of population growth alone. If per capita consumption reached the level of more developed countries we could be using 90 per cent of the available water by 2025." Although these figures represent more than just agricultural water use, they do indicate the present and future relationship between population, food, and water.



There are many water conservation strategies:



1. Plant ground cover in fields during the interim between harvesting and planting. This slows water run-off, improves soil moisture and fertility, and minimizes water evaporation. Mulching achieves similar effects.



2. Break large expanses of fields into sections lined with trees and shrubs, thereby creating windbreaks. Windbreaks slow the force of rain and wind, thereby reducing erosion and evaporation. Trees and shrubs also help water penetrate the soil.



3. Grow plants appropriate to your area. For example, to grow a water-intensive crop like cotton in an arid region like Arizona is highly inefficient. Even though Arizona receives only 12.7 inches of rainfall each year and the average topsoil depth is a inch, Arizona grows enough cotton to make 1 pair of jeans for every person in the U.S.A. every year. Consequently, this requires obscene amounts of water.




4. In hilly areas, instead of planting on a slope as-is, terracing the fields will improve water absorption and maintain water quality by inhibiting runoff.



5. Irrigate appropriately. Drip irrigation is more efficient by delivering water directly to the plant out of the sun, thereby decreasing evaporation. Water wheels and sprinklers are much less efficient. Also calculating the needs of individual crops in conjunction with the outputs of irrigation systems and the absorptive capacities of soils will greatly reduce wasted water.



6. Make sure the soil has enough drainage. Excess water gathering on the surface of the soil will lead to salinization and water-logging. Again, calculate and monitor the water needs of crops and the absorption rates of soil.