March 21, 2019
I recently learned that the area where I farm in Minnesota is the new state record holder for the most precipitation received in a calendar year. The location is Harmony, Minnesota, with an unofficial 2018 precipitation total of just over 60 inches. This total surpasses the previous Minnesota record by over 4 inches set in 2016 at Waseca, Minnesota, and the local annual total by 20 inches. According to the information provided in my Climate FieldView™ app, fields around Harmony, Minnesota, received approximately 35 inches of precipitation during the growing season (May–September). This is about 14 inches more than the 30-year average.
Precipitation and the intensity of the precipitation events have increased over the years, and I expect changes in precipitation patterns are likely to continue. Unfortunately, one of the most important inputs we apply to corn fields and often most influenced by precipitation is nitrogen. Nitrogen applied to fields, either through manure or artificial sources, is highly vulnerable to movement and potential loss through volatilization (NH3), denitrification (N2O), leaching (NO3) and runoff (Figures 1 and 2). Because of the increased loss risk, the need to look at alternative application/product technologies is necessary to help keep nitrogen where it was applied.
Figure 1. 2018 aerial image showing nitrogen deficiency occurring throughout a field because of rainfall amount.
Figure 2. Nitrogen deficiency showing up in lower corn leaves.
Application practices and mechanisms often used to help preserve the integrity of applied nitrogen include spring applications (vs. fall application), split applications which can occur at the time of greatest nitrogen uptake, bio-inhibitors (urease inhibitors, nitrification inhibitors) which help prevent volatilization and leaching losses, and polymer coatings which incorporate many of the previous-stated advantages into one technology.
Slow-release technology uses a polymer to coat urea granules. Once the polymer-coated urea granules are applied to a field, water moves through the polymer coating to dissolve urea, and eventually nitrogen diffuses out through the porous polymer membrane where it then encounters the soil complex and corn root systems. This technology helps prevent nitrogen losses through the volatilization, denitrification and leaching mechanisms, and helps to associate the release of the nitrogen when it is needed during the growing season. Yet, as with most good things, a couple challenges associated with polymer-coated nitrogen exist:
- cost (typically more expensive than other technologies)
- need for moisture to release the nitrogen from the polymer coating
With the need to increase nitrogen use efficiency and to help protect applied nitrogen from environmental losses, we need to look at alternative or new application or product mechanisms to help keep nitrogen where it is applied and help make it available when it is needed.
Sources:
The science inside ESN smart nitrogen. YouTube Video. https://www.smartnitrogen.com/
Ruark, M. 2012. Advantages and disadvantages of controlled-release fertilizers. University of Wisconsin. http://www.soils.wisc.edu/
Silva, G. 2011. Slow release nitrogen fertilizers. Michigan State University. https://www.canr.msu.edu/.
Additional Information:
Nitrogen Management Using Climate FieldView™. 2017. Demonstration Report. Channel.com. https://www.channel.com/agronomics/Documents/AgronomicContentPDF/Nitrogen%20Management%20Using%20Climate%20FieldView%E2%84%A2%20-%20HLC%20-%20CH.pdf
FieldView™ Nitrogen Management Recommendations. 2018. Demonstration Report. Channel.com. http://www.channel.com/agronomics/Documents/AgronomicContentPDF/FieldViewNitrogenManagementRec-Jan10-Channel-Corn.pdf
Web sources verified 1/23/19.