Question

Which of the following statements about the effects of agricultural techniques on the environment is true?
a.
Fertilizer used for agriculture can enter bodies of water, causing eventual oxygen depletion.
b.
Pesticides and herbicides are potentially harmful to bodies of water only before they degrade.
c.
Agricultural practices have limited impact on the surrounding environment.
d.
Tillage is an important agricultural practice that has no known environmental impact.

Answer 1

a. Fertilizer runoff (nitrogen and phosphorus) can cause eutrophication — algal blooms whose decomposition depletes dissolved oxygen and creates hypoxic "dead zones."