Producing 100 Bushel/Acre Soybeans – What Does It Take?
DR. DENNIS B. EGLI
LEXINGTON, KENTUCKY
Producer reports of 100-bushel soybean yields are getting more common, especially among yield contest winners. These reports raise the question – what does it take to produce 100-bushel yields? What can a producer do to reach this yield levell?
One suggestion is to just have patience. Soybean yields have been increasing steadily since the 1930’s and it seems reasonable to expect them to continue increasing in the future unless climate change puts the kibosh on yield growth.
In 1982 I wrote an article for the ‘Soybean News’ entitled ‘Why don’t 50-bushel beans make 70?” . In 1982 the average state yield in Kentucky was 31.5 bushels/acre; it was 55 bushels /acre in 2023, a 75% increase. Seventy-bushel yields that I fantasized about in 1982 are now common. In fact, average state yields in some states are approaching 70-bushels/acre (Illinois reached 65-bushels/acre in 2021).
Fifty-bushel yields were bragging yields in 1982, but no one brags about them today. Yield growth, a result of better varieties and improved management practices, continuously pushes yields higher, so eventually 100-bushel yields will be common. Just have patience and you will eventually see 100-bushel yields on your farm.
If you are not a patient type, you could speed up progress in Kentucky by moving to Union County. Union County has the highest soybean yields of any county in Kentucky. The average yield in Union County (2003 – 2022) was 52.6 bushels/acre, nearly 3.0 bushels above the next highest county (Davies) and a whopping 15 bushels above the two lowest yielding counties (Marshall and McCrackin). So, 100-bushel yields will probably be common in Union County before they appear regularly in other counties. Union County’s advantage is largely a result of better soils that store more water than most soils in other counties.
Water is especially important when shooting for exceptionally high yields. Water stored in the soil reservoir serves as a buffer between the intermittent rainfall and the continuous, unrelating use by the crop. The larger the reservoir, the longer the crop can grow unstressed without rain. A large reservoir also reduces year-to-year variation in yield, which in Marshall and McCracken counties was roughly twice that of Union County when measured by the coefficient of variation (CV = 26 and 14%, respectively).
What other options are available if you lack patience and do not want to move to Union County? Since it is unlikely that you can get 100-bushel yields if the crop experiences water stress, you may want to invest in an irrigation system. It is possible, but not likely, that the rainfall in any given year will be adequate and perfectly distributed so that the soybean crop is never stressed. Irrigation can fill in the rainfall gaps and minimize water stress. If irrigation is not possible, you can always polish up your rain dance and hope for the best.
Once water is taken care of, the rest is just a matter of doing a good job applying the best management practices that we normally use to produce soybean. As usual, the best management practices start with selecting a good high-yielding variety with a strong package of disease resistance, followed by planting early, getting an adequate stand and controlling weeds, diseases and insects. Planting on fertile soil with the appropriate pH and adequate levels of P and K is essential. One thing that, in my opinion, is very clear – there are no unique management tricks, no silver bullets, that will produce 100-bushel soybean yields.
We all know that applying the best management practices to a crop with plenty of water will not necessarily produce 100-bushel yields. Why not? That is a good question without, in my opinion, a good answer. We could blame it on temperature and solar radiation levels, the uncontrollable aspects of the environment, but that is not very satisfying or useful. The bottom line is - no one knows for sure how to reliably produce 100-bushel soybean yields year after year.
Another important question is – does it make any sense to strive for 100 bushels yields? We must not forget that, in the final analysis, the bottom line is more important than super-high yield. Spending money on additional inputs to chase the high yield rabbit may not be a profitable strategy.
One-hundred-bushel soybean yields will be more common as time passes and improvement in varieties and management practices continue to drive yields upward. In other words, it is just a matter of time unless or when climate change puts the brakes on yield growth. Chasing record high yield may not be the best road to riches. Realism is probably the best approach for managing soybean yields as stated by writer W.A. Ward (1921 – 1994) – “the pessimist complains about the wind, the optimist expects it to change, and the realist adjusts the sails”. ∆
DR. DENNIS B. EGLI: University of Kentucky