By Matt Reese
There has been much talk in recent years about the exploding world population. To feed all of these people, food production will have to increase dramatically and the world will be looking to the U.S. to shoulder much of the burden. In terms of corn production, experts think an ambitious, but maybe necessary goal is a national average yield of 300 bushels per acre by 2030.
“We know 300 bushels is an achievable yield, so maybe increasing the national yield to 300 bushels by 2030 is not so pie in the sky,” said Bob Nielson, Purdue Extension corn specialist. “To get 300 bushels, you need ears with 1,000-plus kernels — that is 18 rows by 60 kernels long. At only a modest 30,000 plants per acre and a modest 85,000 kernels per bushel, it equals 381 bushels per acre.”
Unfortunately, at the current rate of average gain in yield increases each year, the national average would only be at about 200 bushels per acre by 2030, far short of what the hungry world will be demanding.
“They started tracking corn yields in 1860 and the yields were flat for about 70 years. Then in the late 30s, yields starting increasing by .8 bushel per year with hybrids. Then with improved hybrids, mechanization, herbicides and fertilizer, yields started increasing around two bushels per acre per year after World War II,” Nielson said. “Some say the third quantum leap is upon us with biotechnology. I do not think that there is evidence of that yet since the introduction of Bt corn. So how do we increase yields?”
The potential is obviously there for 300-bushel yields, but the challenge is identifying and correcting the factors that are taking away yield.
“The secret to protecting yield is identifying what is holding you back,” Nielson said. “We have the answers if you can tell us what the problem is, but you also need to be careful to not use products for correcting problems you do not have. You have to pay attention to the yield influencing factors in your fields, both positive and negative. The four components of yield are plants per acre, ears per plant, kernels per ear and weight per kernel.”
To help growers optimize these factors in the fields, University of Illinois crop scientist Fred Below has compiled the “Seven Wonders of Corn Production.” Based on University of Illinois research, the Seven Wonders ranks the top seven factors that can positively impact corn yields and assigns an average bushel-per-acre value to each wonder that add up to an optimal 260 bushels per acre. Below set clear guidelines for a practice to qualify as a “Wonder” of corn production.
“Some practices are clearly important, but I don’t consider them as yield wonders because they are either one-time improvements like tile drainage, they protect rather than increase yield such as weed or pest control or they involve decisions that don’t need to be made every year — soil pH and nutrient levels. In my mind, good weed control, along with proper soil pH and adequate levels of phosphorus and potassium are prerequisites for crop production. They’re necessary to allow the seven wonders to express their positive impact on grain yield,” he said. “One nuance of the seven wonders is that they can interact with each other to either magnify or lessen a wonder’s impact on yield. As a rough rule, the higher the ranking of a particular wonder, the more control it can exert over the wonders below it. Understanding a wonder’s ranking, and its interaction with other wonders, gives farmers an opportunity to further increase grain yields through crop management.”
Below’s “Seven Wonders of Corn Production” are:
1. Weather: “Even with the other yield wonders optimized and constant, our research shows a 70-plus bushel variation in grain yield due to weather. Weather reacts strongly with other yield wonders, and all farmers realize weather can circumvent their best management plans,” Below said.
2. Nitrogen: “Because N fertilizer increases grain yield by an average of 70 bushels, and since most of the other yield wonders also can impact the availability or the use of N, nitrogen fertilizer management continues to receive considerable attention in the research world.”
3. Hybrid selection: “Hybrid selection is probably the most important decision farmers make. Most don’t realize the large difference in yield potential among elite commercial hybrids. Arrays of commercial hybrids, grown under conditions where the other wonders are presumed to be optimized, typically exhibit a 50-bushel range in grain yield,” Below said.
4. Crop rotation: This accounts for 25 bushels of corn production. “Previous crop clearly interacts with the first and second wonders. If sufficient N is available in a good growing year, the continuous-corn yield penalty can be reduced or eliminated,” he said.
5. Plant population: This has a 20-bushel yield influence. In terms of finding the ideal number of plants per acre in Ohio’s soils, Ohio State University Extension corn specialist Peter Thomison thinks growers should consider bumping up populations a bit in high yield situations to maximize potential.
“Plant populations have increased 14% in the last 10 years because hybrids can tolerate more stress,” he said. “Modern hybrids are bred to maximize yield in high populations and planting too low of a population is more likely to cause more yield loss than too high in low stress conditions.”
The stronger stalks and better disease and insect resistance of today’s hybrids make them more capable of being productive in tighter quarters. For low yielding soils or late planting situations, Thomison recommends plant populations of 23,000 to 24,000. In most situations, populations of 31,000 to 33,000 are more appropriate in Ohio fields. For the most productive soils, though, Thomison said populations could be pushed as high as 36,000 or 37,000 plants per acre.
6. Tillage (or lack of): Below said tillage can control a 15-bushel range in yields. “The degree and timing of tillage can make a big difference with the previous crop because most of the yield penalty associated with continuous corn is due to the residue. Similarly, the tillage system can have a big impact on plant population,” he said.
7. Chemicals. “This includes plant growth regulators and compounds that exert growth-regulator-like effects that lead to a positive change in growth or yield determination. Late-season leaf greening from certain foliar fungicides and new technologies that make the plant less sensitive to environmental stresses fit into this category. While the overall average is a positive 10 bushels, the success of these compounds depends highly on the other yield wonders, especially weather and hybrid,” Below said.
With such wonders at work in their fields, 300-bushel average yields may be in the realm of possibility moving forward, but farmers need to work out the details of corn production to gradually bump up yields. Careful management will be required to produce the necessary food for the world on less land and with fewer inputs in the coming decades.
“Instead of charging after 300 bushels, try for 15,” said Chad Lee, University of Kentucky Extension agronomist. “When you get that try for another 15 bushels. Eventually, you’ll get to 300.”