Should land that is naturally too dry for crops be irrigated? What
are the benefits and drawbacks?
Deep dark topsoil,
lots of sun and plenty of rain. The Midwest has all the right resources
to grow plentiful crops. Not all regions are so lucky. Farmers in
the west and southwest have lots of sun, but little rainfall and
thin, mineral and salt-laden soil to deal with. They rely heavily
on chemical applications and irrigation to grow their crops. In
fact, agriculture accounts for more than 90% of the West and Southwest
regions' water use (80% in the rest of the nation), making less
water available for other users.
water is applied to cropland, not all of it is taken up by the crop
plants. Weeds look for water too, and some water runs off the field
into ditches, moving back into and
sources. That runoff can carry dissolved salts with it, as well
as the nutrients and pesticides that were applied to the fields.
The runoff can also pick up naturally occurring toxic minerals,
such as selenium and boron. At certain levels, these minerals can
harm aquatic wildlife and impair recreational waters.
If the runoff
carries dissolved solids into drinking water supplies, it can have
a wide variety of effects. Dissolved solids can increase the cost
of water treatment, or force plants to switch to alternative drinking
water sources. Those solids that make it through the water treatment
process can reduce the lifespans of water-using household appliances
by clogging up pipes with mineral deposits.
not only affects the drinking water; it also affects the irrigation
water. Increased levels in irrigation water can
reduce crop yields or damage soils so that some crops can no longer