Environmental Engineering Reference
In-Depth Information
milk cow. Consequently, most U.S. establishments classifi ed as farms
produce very little, and most agricultural production occurs on a small
number of much larger operations called
factory farms.
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Nearly all farmers specialize in only one crop or animal, such as corn,
soybeans, wheat, chicken, cattle, or swine. The idyllic vista of a farm
that grows a variety of grains, vegetables, fruits, and a few chickens exists
only in our imaginations or in fi lms that romanticize farming as we
believe it existed one or two hundred years ago.
As little as we think about farmers, crops, and agriculture, we think
even less about the soil in which the crops grow or the food that the
farm animals eat. Perhaps this is a blessing. Who wants to consider the
facts that the topsoil is now half as thick as it was for the early settlers
and that the crops that grow in it have lost many of their nutrients, that
there are poisonous pesticide residues in the food on our table, or that
the farm animals we eat have been fed hormones and antibiotics for most
of their lives?
As unhealthy and unpleasant as these facts are, they should cause us
to ask questions such as these:
How did agricultural soil lose its nutrients? Does this affect the crops
that grow in them? Can the soil be restored to health?
Why do most farms grow only one type of crop?
Can we avoid eating pesticides three times a day?
Do the hormones and antibiotics the farm animals eat affect the health
of the humans who eat the animals?
In this chapter I look at these and other questions that affect our
environment and our health.
How Are Crops Nourished?
Agricultural soil is in a group with air and water as the most essential
commodity for human survival. And we are running out of it according
to a study by an earth scientist at the University of Washington.
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Six
inches of soil are needed for crop production, a thickness that takes many
hundreds or perhaps thousands of years to form, and human farming
activities are causing it to erode an average of 10 to 100 times faster
than this. Soil loss is not a problem in fl oodplain agriculture because
annual fl oods deposit new and nourishing soil each year, but most agri-
culture in the United States is in upland areas where lost soil is not
replaced.
