Agriculture Reference
In-Depth Information
chemical fertilizers, as researchers sought varieties that would
consume N, P, and K in greater quantities.
Although the impacts of chemical fertilizer are almost
miraculous, it is their cost—not their direct impact on yields—
that is so astounding. Crop yields can be just as high using
organic fertilizers like compost and manure, but the availabil-
ity of organic manure is constrained by animal populations,
our willingness to eat food fertilized with human manure, our
eagerness to use products that can be composted (like potato
chip bags made out of corn), and the high cost of transporting
and applying manure and compost. Industrial processes of
making chemical fertilizers have been around for more than
a century, but technologies have improved considerably. The
price of nitrogen fertilizer, for example, has fallen 90 percent
since 1900.
Is Chemical Fertilizer Enough to Ensure Soil Fertility Forever?
No, for several reasons. First, chemical fertilizers are created
using nonrenewable resources, and it is not known if they
are economical using renewable sources. Nitrogen depends
on natural gas, and phosphorus and potassium are mined.
However, almost everything that takes place on a farm is
based on nonrenewable resources, including the tractor
driven by an organic farmer. Even many Amish farmers oper-
ate gasoline-powered generators. Second, plants require more
than N, P, and K, and eventually the soil will be depleted of
its micronutrients, like boron and copper. Third, these chemi-
cal fertilizers alter the soil's pH, which may prevent the plant
from being able to consume the nutrients. Fourth, some people
have an alternative take on the definition of soil fertility, and
may deem a field infertile whenever it lacks high amounts of
organic matter, even if that field provides high yields (but this
view is rarely held by agricultural scientists).
Micronutrient depletion is of particular interest because
it raises the question of how long chemical fertilizers can
