On the horizon: Best nutrient management 

Everyone knows that Goldilocks didn’t want her porridge too hot or too cold but just right. Likewise, Minnesota soybeans prefer soil pH levels that are just right – not too acidic, not too alkaline. It all boils down to nutrient management. 

This year, the Minnesota Soybean Research & Promotion Council (MSR&PC) is investing soybean checkoff dollars to determine the best nutrient management for profitable soybean production. 

“We are getting in front of the ball,” MSR&PC Director of Research David Kee said. “We’re investing Minnesota soybean checkoff dollars to stay ahead of the problems that are on the horizon for growers.” 

The project is multi-faceted with various objectives, including evaluating the impact of liming on yield of soybeans and crops grown in rotation with soybeans over a five-year period. 

“A lot of the research I’ve done in the past that was funded by MSR&PC was looking at the rotational aspects of soybeans and how fertility should be managed,” said University of Minnesota Researcher Dan Kaiser, the principal investigator on the study. “The lime aspect is a new piece that I haven’t looked at yet. When we look at soil pH adjustments, soybeans should be one of the crops that is most benefited.” 

While Minnesota soybean growers can’t replace soil until they find the pH that is just right for their needs, they can make crucial soil management decisions that will get their soil where they want it to be. 

“The target pH for soybeans is 6.0, so typically there isn’t a great benefit for lime applications until you start getting to a pH of less than 6.0,” Kaiser said. “Some might opt for pushing closer to 7.0 but we know that once you get beyond pH 6.0, you don’t see much of an economic benefit when it comes to corn and soybeans.” 

All soil is not created equal, and some areas of Minnesota don’t have acidic soil that would benefit from lime application. 

“If you get into western and northwestern Minnesota, where they already have high pH, there is already free lime in the soil,” Kaiser said. “Traditionally, the greatest economic benefit has been central to eastern Minnesota where the subsoils are more acidic. You’re not going to see a lot of lime application for pH correction in Crookston compared to Rochester.” 

Talk to any farmer and they’ll point out the economic implication of lime application. Kaiser suspects that liming is a long-term investment, which he plans to investigate through this checkoff-supported project. 

“The studies that I have right now are longer-term trials to not just look at the year after application,” Kaiser said. “Last year we didn’t see that much of a benefit in the initial year, and I think a lot of growers who apply lime would agree. Because you may not see benefits right away, it’s important to have forethought and look at it long-term.” 

Other objectives of the research project include: 

  • Determine whether pell-lime can be banded or broadcast at low rates with and without sulfur to enhance soybean yield grown in rotation with corn. 
  • Quantify the impacts of sulfur source and placement prior to corn on the proceeding soybean crop. 
  • Determine whether in-furrow N-P-K starter can increase soybean yield in medium-high testing soils. 

MSR&PC can’t foresee everything that is going to be thrown at Minnesota soybean growers, but it can look to the horizon and do it’s best to stay ahead of the game. Anticipating soil nutrient management needs and investing in research to find answers for growers is yet another way the Council is making wise checkoff investments.   

“Soil pH is always changing,” Kee said. “Over time with multiple applications of nitrogen, the pH has dropped and become more acidic. That’s why soybean checkoff investments in this research are critical. We need to refine our knowledge base of soil pH management, including issues with acidic soil.” 

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