A pumpkin fit for Linus. This behemoth weighed 2,819.3 pounds (1,278.8 kg), claiming a new world record on October 6, 2025, for twin brothers Ian and Stuart Paton at the 6th Wargrave Nursery Giant Vegetable Weigh-off in Reading, UK. How much further up can humans push the yield curve? Image: Mgiganteus1

An article in AgFunder News published on February 1, 2018, reported that a bag of corn had a yield potential of about 500 bushels per acre. In 2017, the US average corn grain yield hovered around 176 bushels per acre, 2 bushels above 2016, and far away from the AgFunder News report. Meanwhile, in 2015, David Hula of Charles City, Virginia, produced 532 bushels per acre; one year before, Randy Dowdy of Valdosta, Georgia, marked 504 bushels. This caught many experts off guard, prompting them to return to their research plots to figure out what they were doing wrong. Some even criticized the yield numbers as fake. In fact, the biophysical limit for corn grain yield was estimated by Matthijs Tollenaar in 1985 at ~1,320 bushels per acre, using optimized yet realistic values for quantum efficiency, grain-fill duration, harvest, and leaf-area index. At the time Tollenaar published his estimates, Herman Warsaw had just produced a (then) record-breaking 370 bushels per acre on his Illinois farm.

If you are unfamiliar with Herman Warsaw, I invite you to watch a three-part film about him, produced by the Office of Agricultural Communications at the University of Illinois in 1986. All told, the film is less than 30 minutes. And yes, it is dated, having the pedagogic look and intonation of flicks you may have been forced to watch in some long-ago high school class. But Herman Warsaw's challenge to question, study, and judge carefully the factors limiting production remains timeless. He was also an early adopter of conservation tillage, relying on non-inversion chisel plowing for residue management and soil building on his farm. Warsaw, Hula, and Dowdy all produced record-breaking yields without recourse to big data or drones and, in Warsaw's case, before the advent of precision management and GPS-guided technology. Herman Warsaw passed away in 1989, just prior to the twin revolutions in plant breeding and genetics. Since then, technology has advanced light-years. Yet, as recent US average corn grain yields admonish, the yield growth curve, though an increasing function, is a stubborn thing that is not easily borne aloft.

Precision soil mapping is one approach to improving crop yields. Herman Warsaw emphasized high soil-test levels of plant-essential nutrients, such as potassium and phosphorus. The film shows him manually pushing a steel probe into the soil, underscoring his commitment to sound nutrient management. The AgFunder News article also stresses soil testing, albeit using more modern automated systems. Yet there is one peculiar fact about the Hula and Dowdy production systems that differs from Herman Warsaw's: both rely heavily on fertigation for in-season nutrient management. In other words, Hula and Dowdy are bypassing their sandy, relatively nutrient-poor Coastal Plain soils by conducting tissue tests and feeding nutrients directly to the plants. I know this isn't music to soil scientists, but this approach overcomes many inherent physical and chemical factors in a rooting medium that, for all practical purposes, can't be changed or require long-term devotion to soil building to nudge up the metrics. It also calls into question the popular orthodoxy that "the answer lies in the soil".

Or does it?

There is nothing wrong with soil building, cover crops, organic matter, rotational or strip cropping, and related practices. Each may find a place within the production system, depending on the farm operator's goals. Crop failure and/or underperformance are crucial factors when devising a management plan. In the film, someone asks Herman Warsaw why he didn't plant all his corn at the highest population density to produce 370 bushels per acre everywhere. His reply was that the risk of crop failure and/or crop losses would be significant because not all his land is equally endowed, and the weather in any growing season was too uncertain. By varying plant populations and hybrids across his operation, corn yields would improve on average, he contended. The bottom line is that many factors must align perfectly even to reach 300 bushels per acre, let alone 500. This is why operators must continually calibrate their inputs and adapt agronomic practices year to year to remain productive and in business.

To use a musical analogy, farming is like conducting a hundred-piece symphony orchestra, in which each instrument must be perfectly balanced and tuned to achieve the desired effect. Every single off-note, errant staccato, or minor second, puts the whole movement out of sync in some small yet not inconsequential way. For example, in farming, ground conditions are often unsuitable for heavy equipment traffic during the critical period of plant development, when yield potential is being formed or 'sinks' are actively filling. This period also typically coincides with field operations such as side-dressing, cultivation, and pest control prior to plant canopy closure. After that, it's up to the gods, who may be crazy or not. It stands to reason that operators would like to harness the plant-soil-water realm for as long as possible to mitigate risk, watching gods be damned. This is where modern technology and human ingenuity merge. Operators are questioning time-honored orthodoxy and figuring out how to produce big corn, soybeans, pumpkins, you name it. We should not stand in the way because they challenge our cherished ideas or threaten our professional conceits. Aerial and over- and under-canopy programmable machine detection and delivery systems are evolving rapidly, driven by the unrelenting quest to reduce uncertainty, increase control, and maximize efficiency. This is how we will reach 500 bushels per acre and beyond. This is how we will continue to manage feeding the world's population even as living standards rise.

I don't want to downplay the importance of soil mineral nutrition and soil testing in general, but often this isn't what determines yield. Drainage, growing degree days (GDDs), vapor pressure deficit, evapotranspiration-water balance mismatch, plant nutrient uptake, and a host of other biophysical factors can downregulate yield regardless of mineral nutrient levels or their placement in the soil. Going back to the symphony analogy, these are the musical mishaps that, collectively, determine the shape of yields to come, and whether this year will be record-busting or simply a bust.

Each season promises a new beginning for the farmer, a clear ground upon which he or she will leave fresh tracks, so inscribing a record of their deeds. Here's hoping that your tracks lead to bathtub-size squash, 20-row ears of corn, triple-digit soybeans, and gluten-full wheat.

Further Diggings

Reetz, H.F. 2000. Producing high corn yields — Herman Warsaw's challenging legacy. Better Crops vol. 84. International Potash and Phosphate Institute. https://www.ipni.net/ppiweb/bcrops.nsf/$webindex/768E8C2C854019AE852568EF00543357/$file/00-1p20.pdf

Tollenaar, M. 1985. What is the current upper limit of corn productivity? Proceedings of the Conference on Physiology, Biochemistry and Chemistry Associated with Maximum Yield Corn. Foundation for Agronomic Research and Potash and Phosphate Institute. St. Louis, Missouri, 11-12 Nov. 1985. https://s10.lite.msu.edu/res/msu/botonl/b_online/library/maize/www.ag.iastate.edu/departments/agronomy/yield.html

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