Environmental Engineering Reference
In-Depth Information
Volume of water required to produce the following food:
Wheat: 1,000-2,000 liters (260-520 gallons) to produce one kilogram of wheat.
Other grain: 1,000-3,000 liters (260-780 gallons) of water to produce one
kilogram of grain.
Grain-fed beef: 13,000-15,000 liters (3,380-3,900 gallons) to produce one
kilogram of grain-fed beef.
FIGURE 1.2 How Much Does It Take?
Source : Food and Agriculture Organization of the United Nations (FAO).
report that closely follows water availability across the country.
(Check it out at http://drought.unl.edu/DM/monitor.html.)
Not all the water used by agriculture, however, disappears, adds
Rippey. A percentage used for irrigation is returned to the ground.
How much depends on the amount absorbed by the crops; the par-
ticular crop and its water needs; the type of soil (some soils, like
clay, are not as porous as others are); the weather (more evapo-
ration occurs in hot weather); and the climate—arid or not, for
example. “As we fi nd with everything to do with water, it's all more
complicated than a simple question and answer,” Rippey adds.
The Food and Agriculture Organization (FAO) of the United
Nations estimates that the average individual requires two to four
liters of drinking water a day (or slightly more than a half gallon
to more than a gallon). Compare that with the 2,000 to 5,000
liters (520 to 1,300 gallons) of water it takes to produce that same
person's daily food. 17 See Figure 1.2.
Though experts differ on the amount of water actually used to
grow a particular crop or raise certain livestock, there's no ques-
tion that it takes a lot. In fact, it takes so much that the amount
of irrigated, cultivated cropland acreage in the United States has
declined, in part due to dwindling groundwater supplies, according
to a report from the National Water Management Center, part of the
U.S. Department of Agriculture's Natural Resources Conservation
Service. 18 The report points to the following areas of concern:
￿
The High Plains of Texas lost 1.435 million acres of irrigated,
cultivated cropland over the period 1982-1997, according
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