Populations & Nutrients

Trial Measures Correlation Between High Populations And Nutrients

 Julie Baniszewski, grad student working on a Master’s Degree, and Dr. Chad Lee,
 extension agronomist and professor, both at the University of Kentucky,
 discusses ultra high populations and nitrogen rates in corn. Lee works with corn, soybeans and wheat.          
 Photo by John LaRose

MidAmerica Farmer Grower

   Ultra high populations and nitrogen rates in corn was a topic of discussion recently by Julie Baniszewski, grad student working on a Master’s Degree, and Dr. Chad Lee, extension agronomist and professor, both at the University of Kentucky. Lee works with corn, soybeans and wheat.
   “There has been a lot of interest in irrigated corn in the state and historically corn production has gone from low populations to higher and higher populations,” Lee said. “We’ve gone from wide rows of about 40 inches down to 30 inches on most farms, and brought those down to more narrow rows over time, and so part of the project Julie is working on is how high populations can be pushed. Do those populations interact with nitrogen rates? Do we need to change the nitrogen rates to handle the high populations?”
   Baniszewski is focusing on the increased plant populations, considering 30,000 plants of corn per acre up to 60,000 plants of corn per acre. These are really high populations.
   “I’m also looking at four different nitrogen rates to see if those higher plant populations require more nitrogen per acre,” she said. “I have one year of data. I’m looking at those yields, I have three different locations in the state of Kentucky and I’m working this summer again too, at those same three locations, to see if the yields last year correspond to this year.
   “Last year all three of my locations varied as far as the highest yielding plant populations and the nitrogen rate required. I found that neither the lowest nitrogen rate, 175 pounds of nitrogen per acre, nor the highest rate, 325 pounds of nitrogen, resulted in the highest yield and the highest economic treatment. However, 225 to 275 pounds of nitrogen per acre and anywhere from 40,000 to 60,000 plants per acre had the highest yield and the highest return.”
   These studies were conducted under irrigation. The information received varies by site and what other inputs were used, such as potassium. One site resulted in some lodging, which may have docked some of the yields, so that’s very dependent on location. This year, the same three sites are being used to see if they correspond to last year’s results.
   “We’ve added more potassium this year to try to combat the deficiencies that were possible last year and then see if those same trends are visible,” Baniszewski said.
   Lee pointed out that, though there were some differences at each of the sites, some things that were common in all were that the populations in Baniszewski’s study were all above the current recommendations; and she noticed that at each site more nitrogen was not needed at the higher populations to maximize yield.
   “The best nitrogen rate at a site was pretty consistent across the populations,” Lee said. “However, we have a lot of producers right now that are looking at variable rate nitrogen and they are varying their populations also; they’re going from maybe 25,000 to 35,000 plants per acre and they’re adjusting their nitrogen rates as well. 
   “The one year of data suggests that we don’t need to do that. We need to focus on the ideal nitrogen rate and use that consistently across the populations in the field.”
   Baniszewski was testing 30,000 to 60,000 plants per acre, however most farmers are planting 25,000 to 35,000 plants per acre, so the test range is much, much broader than most farmers are using.
   Really high populations were tested because it was expected there would be all kinds of lodging, the plants would fall over, there would be low yields and poor pollination; all kinds of problems were expected to shake out because of the high populations, however, that was not the case.
   “These really high populations have given us decent yields, maybe not always the best, but still good yields,” Baniszewski said. “Overall, we have good standability except for the potassium problem at one site; that tells us that the genetic ability in these hybrids can support really high populations if we’re doing other things right to set up that kind of a scenario.
   “We have very few farmers at the moment that want to try this on any type of large scale, even on a small scale. About the highest we can get them to try is about 45,000 plants per acre right now in some test plots. We’d love to see them really push populations up and see whether or not that can be a component in helping us increase yields down the road.”
   “All of this wraps up in the term of the moment, sustainable intensification,” said Lee. “It’s the idea of maximizing yields on the land best suited for crop production. And on the land that’s not suited for crop production, keeping it out of crop production.
   “If we’re going to do that going forward we have to figure out how to increase yields and do it more efficiently. So all of this wraps up under that umbrella approach of trying to be more efficient with what we’ve got.
   “Also, we really appreciate our commodity boards for their funding; the Kentucky Corn Growers put the money forward for this project and they’ve helped us with equipment. They’ve helped fund Julie’s stipend to work at the university and they’ve helped us with some of the day-to-day operation; and farmers are helping us by hosting us on their farms, we appreciate that. Whenever we show up on a farm we add to the complexity of what they’re doing already and so the fact that they’re willing to host us and walk the fields with us and try to learn with us, we find that very, very valuable,” Lee said. ∆
   BETTY VALLE GEGG-NAEGER: Senior Staff Writer, MidAmerica Farmer Grower

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