How fast are yields increasing?

The so-called trend yield for corn edges up every year, but the past several years have brought more rapid increases from one year to the next. (At least when the yields are averaged out.) Has it been that same way with other crops? Soybeans, for example?

Grandpa was raising corn when the national average was less than 100 bushels per acre, but it seems the 2009 average of 165 took quite a jump upward. The trend yield for 2010 is about 158, and it hasn’t been all that long ago when the average yield was quite a bit less for corn. University of Illinois farm management specialist Gary Schnitkey analyzed yield trends for corn, beans, wheat, and alfalfa, and went as far back as 1960. The good news is that current yields are higher than they were in 1960. The news that causes you to scratch you head is the varying rates at which yields are increasing for those crops.

In his Farm Economics Facts and Opinions newsletter Schnitkey examined the yield trends for Illinois, but they are probably close to representative for much of the Cornbelt. He says growth rates vary tremendously from year to year, ranging from a high of 68% in 1989 (compared to the 1988 corn yield) to a low of -44% in 1988 (compared to the 1987 crop.) On the example of corn, Schnitkey says corn has a 1.9% annual growth rate from 1960 to 2009. Within the 1960’s when corn yields averaged 87 bushels per acre, a 1.9% growth rate equaled 1.7 bushels per year. In the latest decade, when the average yield was 162, the growth rate of 1.9% equaled a 3.1 bushel per year increase.

But that rate was not applicable to other crops. For the past 50 years, the yield growth rate for beans was 1.1%; for wheat was 1.5%, and for alfalfa it was 0.8%. When Schnitkey looked at recent decades, he found that from 1990 to 2009 corn yields increased 22% while bean yields increased 8%. Interestingly, the 1960’s were the decade that saw the greatest yield increases at 4.3% for corn, 2.7% for beans, 3.9% for wheat and 2.5% for alfalfa. The latest decade saw yield advances that were minimal compared to the 1960’s. While corn yields increased 2.3%, bean yields increased only 0.7%, wheat yields declined 0.7%, and alfalfa yields declined 0.5%.

Why would yields in recent years take a second place to yield increases of 50 years ago? Schnitkey suggests that declining growth rates may reflect a change in public priorities away from increased productivity to placing more research emphasis on environmental and other societal concerns. While private funded crop research is quite high tech, it takes a long time to obtain government approval of new technologies that increase yields. And he suggests the “fears” of adopting biotechnology have lead to even longer approval processes. Additionally, he says there is more emphasis on soil conservation, lower fertility rates, and other demands of society that do not result in higher crop yields.

Schnitkey believes that the higher rates of increase in corn yield, compared to beans, wheat and alfalfa, have resulted from the biotech advances in corn breeding, as well as farmer adoption of that technology. The 84% of IL corn acres planted to biotech corn hybrids in 2009 compares to zero acres of that type of corn in the 1990’s. He adds that increased productivity has provided many benefits, including lower food prices for the consumer and high growth rates will continue that trend.

Summary:

Over the past 50 years there have been increases in the yield of major crops, but not all at the same rate. Corn yields have advanced at a more rapid pace than beans, wheat, or alfalfa, but the rate of increase was even higher in the 1960’s than it was in the latest decade. Changes in priority away from productivity may have been the reason as research money was channeled elsewhere. Nevertheless, the yield advances have benefited the consumer with lower costs.

Stu Ellis