Irrigation

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.

When irrigation 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 surface and groundwater 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.

The contamination not only affects the drinking water; it also affects the irrigation water. Increased salinity levels in irrigation water can reduce crop yields or damage soils so that some crops can no longer be grown