Home Discussion Forum Nutrient Management Nitrogen in wet springs

This topic contains 5 replies, has 3 voices, and was last updated by Profile photo of Jerome Lensing Jerome Lensing 2 years, 4 months ago.

  • Author
    Posts
  • #887
    Profile photo of Fabian Fernandez
    Fabian Fernandez
    Participant

    How can we manage nitrogen more effectively with the very wet springs we are experiencing?

  • #909
    Profile photo of Jerome Lensing
    Jerome Lensing
    Participant

    Wet springs always bring challenges to nitrogen management. If you applied your N as AA, AS, urea last fall after soil temperatures in the top 6″ where below 50 degrees Fahrenheit, N loss should be minimal since there was very little conversion of the ammonium to nitrate-N which is leachable. Depending on the amount of nitrate-N that was in any manure applications, the nitrate-N may have been leached deeper in the soil profile due to fall precipitation after application.

    One also needs to consider how the manure was applied last fall and this spring. The following link provides excellent information on Manure Management: http://www.extension.umn.edu/agriculture/manure-management-and-air-quality/manure-management-basics/manure-management-in-minnesota/doc/manure-management-in-minnesota.pdf

    If you are considering the need for side dressing N on fields with fall nitrogen applications, this link provides information on this topic: http://blog-crop-news.extension.umn.edu/2015/06/nitrogen-management-considerations-for.html

    Where spring applications need to made, the number on consideration is the soil conditions. To many times I have heard I need to get my fertilizer applied before planting. Remember that if the soil is too wet to work it is also too wet to make fertilizer applications, especially since application equipment size has increased – a good rule of thumb to consider – when axle weights are over 5 tons, the risk of compaction goes up. Here is a good link that discusses soil compaction: http://www.extension.umn.edu/Agriculture/soils/tillage/soil-compaction/

    Determining your N application rates this spring, remember to consider all sources of N that will be applied depending on what fertilizers are applied. N in your phosphorus fertilizer, ammonium sulfate, starter fertilizer, manure applications and previous crop credits. Here is the link to corn fertilizer suggestions in MN: http://www.extension.umn.edu/agriculture/nutrient-management/nutrient-lime-guidelines/fertilizer-recommendations-for-agronomic-crops-in-minnesota/corn/

    One may want to consider utilizing the soil Nitrogen test where applicable; following link provides information for use of the soil nitrogen test: http://www.extension.umn.edu/agriculture/nutrient-management/nitrogen/soil-nitrogen-test-option-for-n-recommendations/

    Bottom line – for maximizing your corn yields in 2017, wait till soils are ready to work for all practices you will be doing to plant your crop! Patience will pay huge dividends!

  • #911
    Profile photo of Fabian Fernandez
    Fabian Fernandez
    Participant

    Jerome, you listed many great resources in your comment! In general we don’t lose much N in the fall and winter if the N application in the fall was done correctly (once temperatures are below 50 deg. F and not in sandy soils or regions where the potential for loss is high due of large precipitation amounts or high drainage potential). In general where fall N is an allowed practice, the spring is the time that determines how much N there will be from a fall application. The two most important factors to keep in mind are how much of the applied N is in nitrate form in the spring and how much precipitation you are getting.  The more nitrate present the greater the potential for loss if the spring is wet. Nitrate can be lost by leaching if water is draining out or by denitrification (off to the atmosphere) if the soil is saturated with water.

  • #912

    What recommendations do you have to help farmers understand how much fall applied N (manure or commercial) is in the nitrate form in the spring?

  • #913
    Profile photo of Fabian Fernandez
    Fabian Fernandez
    Participant

    I wish there was an easy answer, but there isn’t because the amount of nitrification is dictated by the interaction of several factors. The best way to know how much of the applied N is nitrate is to take soil samples and do the analysis. At the very least I would suggest a 0-12 inch sample, better if you can also take a 12-24 inch sample. I would suggest collecting samples within a 10-foot radius to make a composite for lab analysis. If you banded the fertilizer the best way to collect the soil is to sample perpendicular to the direction of the band and take four cores in a straight line every 7 inches and composite the cores into one sample. For each sample I would repeat this 3-4 times so the composite sample is made from 12-16 cores. This works well if you can’t tell where the fertilizer band is. If you know where the band is, then you can use the same approach and take one core from the fertilizer band and three away from the fertilizer band to composite into one sample, repeating it three to four times (as I mentioned before). If N was broadcast, it is not as important to think about where to take the cores. Doing this approach I have seen anywhere from 20 to 90% of the applied N as nitrate, which highlights the point I made at the beginning: the amount present as nitrate is highly site specific. Finally, I would like to remind you that what you measure in the field now doesn’t mean it will be lost if it is nitrate. It simply tells you that if it gets very wet the more nitrate you have, the more chance for loss.

  • #921
    Profile photo of Jerome Lensing
    Jerome Lensing
    Participant

    Jeff Coulter, U of MN Agronomist posted an excellent article that provides excellent tips for good corn planting, which also are good practices for applying nitrogen in the spring of the year. Here is the link: http://blog-crop-news.extension.umn.edu/2017/04/key-factors-for-successful-corn-planting.html

You must be logged in to reply to this topic.