How can growing corn in Iowa using industrial agricultural practices contribute to the creation of a dead zone in the Gulf of Mexico? Refer to Figure 4.20.

Question

What will be an ideal response?

Answer 1

Iowa is in the Mississippi River Basin watershed.  Industrialized agriculture uses large amounts of synthetic fertilizers, particularly nitrogen fertilizer in the form of the water soluble nitrate.  When it rains, the excess nitrate is dissolved in the runoff and then transported to tributaries of the Mississippi. The abundance of fertilizer promotes the growth of algae and, when the algae dies, bacteria consumes it and uses up the dissolved oxygen in the water.  By the time the Mississippi River reaches the Gulf, all of the oxygen has been depleted and the bottom dwelling creatures die.