By Marcy Nameth & Charles Walters
Ensuring that corn absorbs the right balance of nitrogen, phosphorus and potassium is crucial to increasing global yields, a Purdue and Kansas State University study finds.
A review of data from more than 150 studies from the United States and other regions showed that high yields were linked to production systems in which corn plants took up key nutrients at specific ratios — nitrogen and phosphorus at a ratio of 5-to-1 and nitrogen and potassium at a ratio of 1-to-1. These nutrient uptake ratios were associated with high yields regardless of the region where the corn was grown.
“The agricultural community has put a lot of emphasis on nitrogen as a means of increasing yields, but this study highlights the greater importance of nutrient balance,” said Tony Vyn, Purdue professor of agronomy. “We will not be able to continually boost global corn yields and achieve food security without providing adequate and balanced nutrients.” The paper was published online in the Agronomy Journal.
While U.S. corn producers have long relied on nitrogen fertilizers to improve yields, they should not overlook other nutrients such as potassium and phosphorus, Vyn said.
“Growers need to be as concerned about the amount of potassium available to their plants as they are about nitrogen,” he said. “Corn’s demand for nitrogen and potassium is similar. We need to focus on the nitrogen-potassium balance because that’s where we have the greatest deficiency in terms of application, especially in the eastern Corn Belt.”
Inputs vs. Efficiency
Agricultural historians still debate whether wheat or corn rate top historical billing. The land now known as Iraq is recognized as the birthplace of grain production. Ironically, Texas Plant & Soil Lab participated with the USDA and the 1st Cavalry Division in a wheat crop restoration project in Iraq that failed due to bureaucratic inefficiency. Wheat, in fact, was an international crop before there were nations, and the diligent work of plant breeding proceeded long before there were universities to teach the art. The art of feeding the soil to feed plants was well established in Homer’s time, but refinements of that art are still continuing to this day.
Corn is the one crop that exhibits production potential beyond the dreams of possibility. Twinning, even three ears per stalk, is evidently possible, even practical, albeit elusive.
High-density corn population can deliver more stover than ears per acre, but “How much of our resources should we be willing to spend to achieve the maximum grain and/or silage performance?” That question about production goals suggests more than one approach to other production programs. How many nutrients and how much water are we tying up in stalks before the factors of production run into that leaf, and the photons of energy process takes place? Energy must be stored in the grain — and more than one ear of grain on that stalk produces maximum economic yield (MEY). The whole picture always remains in question. The main source of energy is sunlight.
It hits that surface of the leaf and ignites all those miracles that go on within that leaf. “If we look at the physiology of that plant,” Agronomist Esper K. Chandler notes, “and plant growth hormones, activators . . . there are so many compounds, it dazzles the imagination. We have looked at three or four major hormones, but there are several dozen others we have not even looked at yet.”
This is not to say that independent investigators are not looking, but often hormone/enzyme-type products are being overlooked. Activators have arrived on-scene. Natural products can stimulate the overall functions of that plant physiology, but it all goes back to the sun’s photons of light reaching that leaf. In turn, the leaf has to have the proper moisture and flow of nutrients so that the photosynthate factory can function.
Chandler, co-author of Ask the Plant, admits that it puzzles him. “When I look at the Krebs cycle, compounds, sugars, starches, enzymes, as well as hormones — my head swims.” A head that swims often calls up memories of events occurring before the arrival of the present impasse. In Chandler’s case, it was a reminder that the farmer’s job is to work with Nature, not against her. The sheer complexity of Nature’s system knocks into a cocked hat the idea that our brand of research science has disposed of all the variables. We are nonetheless impelled to influence the demands and foibles of nature. And so the esoteric formulas of natural/organics beckon, even though the pursuit of economic yield stays on course, moving straight ahead.
The prep sheets that Chandler and his associates put out are not filled with doctrinaire imperatives divorced from bottom-line reality. Chandler cautions, “We can’t keep buying inputs for the fields without reference to what the stuff is doing to the bottom line. You see corn being grown in the Higher Plains where water is a finite resource. The Ogallala Aquifer is going down. In 10-15 years we’ll be searching for water. At the same time we have the sunlight units up there as well as growing conditions that enable those 300 and 400 bushels. Even so, there is a wasting away of resources with overpopulation of stalks, and overuse of water. In specific areas it may be good arithmetic — but poor economics.”
Unlike the government, Chandler never underwrites failures. His forté is called good practices. There are cross-currents. In the case of the High Plains and corn, the saving factor has become drip-irrigation, a system that becomes an inherent partner with the balanced nutrition that Chandler stresses, monitored by leaf and petiole analysis that proceeds almost as routinely as a dairyman taking a somatic cell count.
“Science-led and spoon-fed” might well serve as a Chandler slogan, along with “ask the plant.” “Spoon-fed” and “ask the plant” are more than wishful thinking. It takes discipline and a desire to bring the problem into compliance with his own objectives, which, more often than not, break traditional practices.
Chandler remembers the basics and he tags them with the term “efficiency.” Mass inputs do not constitute efficiency. Fence-row to fence-row farming does not square with maximum economic yields. Chandler never works out a crop equation without a full appreciation of the fixed costs and the variable expenses. Usually this means increasing yields with available inputs, in effect testing earlier yields, not with “get bigger,” but with “get smarter.” The real function is to bring the farm back to a natural state, one in which the natural nitrogen cycle works to the maximum possible, and one that serves up a natural carbon cycle as a working mechanism.