Thursday, September 4, 2014

Fertilizer Is Not a Dirty Word

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.

  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?
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.