Learning from huge yielding crops

Record-setting soybean yield shows that there’s room to grow

Reading Time: 3 minutes

Many farmers find the crazy-high yield records of producers who grow for competition exasperating.

They shake their heads and say there’s no way those bushels of corn and soybeans are profitable, or particularly environmentally sustainable.

Why it matters: Even if the averages never reach record levels, those yields show that it is physiologically possible with current crop genetics. In other words, existing genetics aren’t yet tapped to their maximum.

Related Articles

University of Arkansas professor Larry Purcell says farmers can still learn from those who are willing to push the limits. He has spent time looking at the growing methods of Kip Cullers, the Missouri farmer known for his extraordinary and award-winning soybean yields.

Purcell said at the Southwest Ag Conference that there has been significant increases in yield in the U.S. since 1965, with gains of 27 bushels per acre to 50 bushels per acre. That’s an annual growth rate of about half a bushel per year.

However, the yield records have jumped at a quicker rate at about 1.7 bushels higher per acre per year. The “yield gap” has increased over the years, meaning the top yielders are increasing soy production quicker than average farmers.

Cullers produced 155 bushels per acre back in 2006, and peaked at 167 bushels per acre in 2010, setting another world record. He’s been producing about 100 bushels per acre in his competition plots since then, which is double the average yield across North America.

Randy Dowdy, a Georgia farmer smashed his own soybean record of just over 170 bushels per acre in 2019 with a yield of 190 bushels per acre.

Yield champions do more of everything right, says Purcell. They put on maximum fertilization. They irrigate. They plant precisely. They use herbicides and fungicides.

The yield contest winners always use irrigation, especially when the crop might be under stress, he says. But there are also things that are not in a farmer’s control, such as soil type and weather.

Purcell said there are some other areas that set Cullers apart. He observed and conducted research at his farm before trying to replicate Cullers’ production methods in research plots.

Protecting the seed and seedling stages from any setback is critical, he says.

Cullers applies large volumes of poultry manure to his fields. Soil testing was one area where he wouldn’t give Purcell access – likely because the levels were so high.

Purcell says that water is a must. It takes about 25 inches of water to produce 100 bushels of soybeans. The soybeans at the very top of the high yielders need almost double that and that’s just what the plant needs, not including soil evaporation.

Optimizing seeding rate is another area where Cullers excels. The keys to optimizing seed numbers include getting as much crop growth between first flower and beginning of seed fill. The longer that period takes, the more seeds in pods.

Increasing crop growth during this period means capturing the most amount of solar radiation possible. That means that the canopy has to be the greatest during the period of the year when the solar radiation is most intense, which is at the summer solstice. Cullers’ radiation efficiency levels are almost double normal, says Purcell.

Ways to capture more solar radiation include:

  • Early planting;
  • Seed treatment – keeps seeds germinating healthy;
  • Narrow rows – to promote quicker canopy closure for more plant leaves to capture light;
  • Avoiding crop stress, especially during this period;
  • Variety selection – Flowering closest to late June as is possible for the area where the crop is grown. It’s easier to get that in Missouri than in Ontario;
  • Starter nitrogen fertilizer – can help plant growth before nitrogen fixation starts, especially in soils with little nitrogen mineralization.

Another area where Cullers excelled is in optimizing seed weight. This is determined by genetics, but also by doing anything that can lengthen the seed-filling period. This can include soil fertility, tracking nutrient removal and supplementing when needed, soil moisture and protecting the crop from foliar disease and insects during seed fill.

One more area for which Cullers is known is a herbicide application to stress the crop at certain times. Soybeans will grow more vigorously after such an application and can increase crop canopy.

What about costs of all those applications? Purcell has been quoted as saying that it would take $18 per bushel soybeans to pay for Cullers’ growing methods.

About the author


John Greig

John Greig has spent his career in agriculture journalism and communications. He lives on a farm near Ailsa Craig, Ontario. Contact John at [email protected] or follow him on Twitter @jgreig



Stories from our other publications