High crop
yields often come under scrutiny because of the need for fertilizers and the
perception of their potential environmental impacts. Newspaper articles,
letters, and advertisements from well-intended, but poorly informed, citizens
seem to perpetuate old myths and clichés about modern fertilization practices.
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The fact is, maintaining food production for
the growing world population requires the use of new technology and the
intensification of management to grow more food on the existing cropland...and
fertilizer is essential for accomplishing this.
Sometimes I
get tired of hearing about the negative fertilizer issues that are associated with
our abundant, affordable, and nutritious food supply...a truly amazing supply
of healthy food that is clearly unprecedented in the history of the world!
Misapplication and misuse of agricultural fertilizers have undoubtedly occurred
and their impact on the environment needs to be minimized. But to fairly judge
the use of fertilizers, the risks of their use should be compared with their
benefits for food production.
I have had
people tell me that raising yields with commercial fertilizer is somehow
immoral and dangerous for our soils... that strictly organic or specialty
products will meet the demand of global food production. You probably know
about the “stink test”... that is, when something smells fishy there is usually
a reason why! Many of these ideas and claims just don’t pass stink the test.
The time has
come for all of us dispel myths about fertilizers and nutrients, and to convey
a correct message to a world which is becoming increasingly urbanized and
removed from what agricultural production is all about... providing healthy food.
How
Does Fertilizer Contribute to the
Food Supply?
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| 2.5 tons: What a family eats in a year ~1970's |
A survey of
U.S. crop production estimated that average corn yields would decline by 40%
without N fertilizer. Even greater declines would occur if regular additions of
P and K were also halted. Numerous long-term studies have also demonstrated the
contributions of fertilizer to sustaining crop yields. For example, long-term
studies in Oklahoma show a 40% wheat yield decline would occur without regular
N and P additions. A long-term study in Missouri found that 57% of the grain
yield was attributable to fertilizer and lime additions. Similarly, long-term
trials from Kansas show that 60% of the corn yield was attributable to fertilizer
N and P.
Few people
appreciate that corn yields have continued to increase in the Corn Belt of the
U.S. without a similar increase in N fertilization. In fact, N use efficiency
has increased at least 35% in the past 25 years (where less N fertilizer is now
required to produce a bushel of grain). Remarkably, more corn is being
harvested without increasing N fertilizer application rates. Some of this
improvement has also come from modern genetics and improved agronomic
management.
