Nitrogen Year in Review

Nitrogen year in review
Scott Schwanke, Agronomy Manager, Plainview (507) 259-7611

If you are a producer of corn, you realize that how you manage nitrogen is one of the most important decisions you can make.  I am sure many of you have heard of the work Dr. Fred Below has done at the University of Illinois on the “Seven Wonders of the Corn Yield World”.  He lists nitrogen as the second most important factor influencing corn yield.  It is actually the number one factor in which we have some control.  The number one overall factor is weather, which we haven’t quite figured out how to control yet.  Since it is so important to corn yield, let’s take a look at what we learned about nitrogen in 2016.

Progressive Ag Center has been working with the Minnesota Department of Agriculture and their Nutrient Management Initiative (NMI).  This is a program that allows agronomists to work with growers in setting up trials to test different nutrient management practices.  The trials we had set up this year looked at whether or not we could see a response from split applying nitrogen verses putting it all up front.  We don’t have results yet from all of the trials that were done across the state, but we do have results from the trials we did out of Plainview.  We will get a summary from the Department of Ag at a later date.  From yield results we have so far, it appears as if it didn’t pay to split up nitrogen in 2016.  They all came back with virtually the same yield whether we split applied nitrogen or put it all up front.  Early data from the Winfield Answer Plots are pointing to similar results.

So why go through the expense and hassle of split applying nitrogen if we can’t get a response from doing so?  We need to remember that these trials are from just one year, 2016.  Since weather plays such a large role in how nitrogen acts in the soil, we need to look at the weather in 2016. It was actually a pretty good year for having nitrogen available for our corn crop.  It was a wet growing season, but we did not have the excessive rainfall in April, May and June that can leach our nitrogen away.  We did have excessive rains in July, August, and September, but we also had warm temperatures.  Those warm temperatures allowed our soils to mineralize a lot of nitrogen from organic matter.  It is estimated that soils can mineralize 10-30 pounds of nitrogen per acre for every percent of organic matter present in the soil.  With the warm temperatures we had late in the summer, we were probably on the high end of that range.  That means if you have a 3% organic matter soil, you could have up to 90 pounds of free nitrogen available to the corn crop later in the season.  These are some of the reasons we did not see responses to split applications in 2016.  We will continue to do more trials in future years and look at some of these treatments under different environmental conditions.

What did we learn in 2016 that we can apply to 2017?  The biggest thing is to look at the amount of rainfall we receive early in the growing season.  This will be a pretty good predictor of the response we will get to an in season application of nitrogen.  Other items to watch are some of the computer models, such as Climate Corp.’s nitrogen predictor.  These models continue to improve on nitrogen forecasting.  The work we did with nitrogen in 2016 reinforced what we already knew; that nitrogen rates and timing are moving targets that are heavily dependent on environmental conditions.  We will continue to work on learning more about this important nutrient.  If you would like to dig deeper into nitrogen, give your Progressive Ag Center agronomist a call. 

Last but not least I would like to wish everyone a very Merry Christmas!  I hope everyone has a chance to enjoy the holiday with friends and family.         

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