Chasing The Silver Bullet – An Exercise In Futility?

DR. DENNIS B. EGLI

LEXINGTON, KENTUCKY

This is the time of the year when contest winning corn and soybean yields are announced. Some of the winners set records for the highest yield ever – yields that can be as much as 3 or 4 times the average U.S. yield. Yields that high bring to mind the silver bullet syndrome – what single management practice was responsible for that extraordinary yield? The unspoken idea behind the silver bullet syndrome is - if we can identify a silver bullet, we can increase everyone’s yield. 

The production of yield by a crop community (a field of corn or soybean) is complex, starting with all the cycles, reactions and processes responsible for plant growth. The system requires a supply of raw materials (mineral nutrients, water and carbon dioxide), solar radiation to provide the energy to run the system, and the appropriate temperatures. Yield then is the integration of this system over the 100 to 120 or more days the crop takes to reach maturity. Identifying one aspect of this system, a silver bullet, which can be manipulated to dramatically increase yield is not easy.

Historical yield growth of corn and soybean was a result of genetic improvement (better varieties or hybrids) and improvement in crop management. Genetics removed negative plant characteristics (e.g., tendency to shatter and lodge, disease susceptibility) and improved the plant’s inherent productivity. Management improved the crop’s environment by controlling weeds, fertilizing, irrigating to avoid drought stress, manipulating planting date, row spacing, plant population, and controlling disease and insect infestations. These activities remove negative aspects from the crop’s environment, pushing it closer to the perfect environment that will maximize yield. However, the closer the crop is to the perfect environment, the less room there is for improvement.  

 These improvements resulted in a steady increase in corn and soybean yields in the US, (1.9 and 0.5 bu/acre/year, respectively, based on trend lines from 1980 to 2023). These steady improvements don’t provide much support for a role for a silver bullet – a single change that drastically increased yield.

We have a good idea of what it takes to produce high yields. High yield starts with the latest variety (hybrid) that has high-yield potential, good agronomic characteristics, and broad-spectrum disease and nematode resistance (when needed). Growing this variety (hybrid) in a fertile soil with high water holding capacity using recommended management practices (planting dates, populations, row spacings. fertility levels, good weed, disease and insect control) provides the foundation for high yields. Unfortunately, weather conditions and the water supply have the final say and they cannot be manipulated, unless irrigation is available. These management practices have evolved over many years and are the result of detailed field experimentation; testing and verifying individual practices in many environments.

It is worth noting that there are probably greater opportunities to improve efficiency of these systems (principally as a result of new technologies – precision agriculture,  see and spray systems, drones, remote sensing etc.) than to increase yield. Efficiency doesn’t necessarily increase yield, but it can improve the all-important bottom line. 

Chasing the silver bullet can distract producers from the use of tried-and-true best management practices known to provide high-yield potential. It can lead to excess and unnecessary fertilizer or pesticide applications that not only reduce profits but can contribute to pollution that may ultimately lead to unwanted governmental regulation. Overuse of pesticides may encourage development of resistance that reduces their effectiveness.

In my opinion, the search for a silver bullet that will lead to much higher yield is futile. Actually, it is worse than futile if it distracts producers from applying best management practices. If a silver bullet is found, it will be more likely to come from careful, detailed laboratory and field research than from haphazard trial and error efforts in farmer’s fields. Producers will be better off focusing on applying well-understood best management practices as efficiently as possible to improve their bottom line and keep their banker happy. In these matters, it is a good idea to remember the words of Hippocrates (Greek physician, 460 – 375 BC) “There are, in fact, two things, science and opinion; the former begets knowledge, the latter ignorance”.         

Adapted from Egli, D.B. 2021. Applied Crop Physiology: Understanding the Fundamentals of Grain Crop Management. CABI.   156 pp. n∆

DR. DENNIS B. EGLI: University of Kentucky