1. Nitrogen Loss Research
Joel Ransom
NDSU Extension Agronomist

2. Background
Nitrogen fertilizer third most costly input in corn production
Nitrogen losses can be significant (only ~1/3 of N applied is used by the crop)
Off site loses are environmental concerns

3. Why worry about N use efficiency?
N is biologically and chemically very active in the soil
Each N compound behaves differently in the soil affecting potential for loss
Nitrous oxide is a potent greenhouse gas (impacts climate change?)
Excess nitrate in surface waters causes eutrophication and anoxia

4. Wet cycle increases likelihood of N losses

5. Nitrification

6. Principles to guide N loss reductions
4 R’s of nutrient stewardship
Right fertilizer source
Right rate
Right time
Right place

7. Addressing sources of loss
Volatilization
Placement, urease inhibitors, polymer coated urea, soil moisture status (AA), application timing relative to rain (surface applications)
Leaching and denitrification
Delaying the conversions from ammonium to nitrate
Nitrification inhibitors
Soil temperature at time of application
Polymer coated urea or slow release
Banding vs. broadcasting
Applying nearer the time of greatest uptake
Slow release urea
Split applications

8. Urease inhibitors
NBPT is the most commonly available and widely tested (Agrotain, SuperU, etc.)
Volatilization of NH3 from urea anytime moisture, urea and urease are present in temperatures that range from 11ºF to 105ºF.
Urease inhibitors block the conversion of urea to ammonia for a period of one to two weeks allowing time for incorporation by rainfall or other means
UAN contains 50% urea

10. Nitrification inhibitors
Slow the conversion of NH4+ to NO3- by killing or reducing the activity of populations of Nitrosomonas and Nitrococcus bacteria.
Two most common commercial inhibitors are nitrapyrin and DCD

12. Rate of nitrification
Source: Schwab and Murdock, U of K

13. Goos, unpublished

15. Release rate of ESN compared to corn N uptake, Manitoba (Heard and Ginter, MAFRD).

16. Treatments included in recent research
Standard treatment – urea pre-plant incorporated
Instinct – new formulation of nitrapyrin that inhibits nitrification (ammonium to nitrate)
Polymer coated urea – (ESN) coated so that it will release gradually and when temperatures are warmer (30% of total N applied)
Split application – UAN applied at the 6 lf dribbled between rows
Split with UAN + Agrotain Plus – urease inhibitor plus nitrification inhibitor in powder form for ease of mixing with UAN

17. Experimental locations
2011 two locations
2012 and 2013 five locations
2012 dry but productive year, limited N loss in most environments
2013 excess moisture early, dry later in the season

18. Effect of additive yield of corn, Fargo and Prosper, 2011.

19. Effect of nitrogen management practices on yield of corn in five environments, 2012.

20. Effect of nitrogen management practices at lowest N rate on yield of corn in five environments, 2012.

21. Effect of nitrogen management practices on yield of corn in five environments, 2013.

22. Effect of nitrogen management practices at lowest N rate on yield, all locations, 2013.

23. Effect of nitrogen management practices at lowest N rate on yield of corn in Casselton, 2013.

24. Prices Urea $550/ton ($60 per 100 lbs/N)
ESN $675/ton ($73 per 100 lbs N = 22 lbs N)
28% UAN $360/ton ($64 per 100 lbs N)
SuperU ~$ /ton (~$190 over price of urea)
Instinct ~$11 per acre
Agrotain $56 per ton ($6 per 100 lb N)
Agrotain Plus $65 per ton ($11 per 100 lb N)

27. Conclusions
No compelling evidence that additives were profitable in any of the environments included
Split applications were both positive and negative depending on the environment
Protection of UAN with urease inhibitor in one environment in 2013
Additional research would be beneficial to sample additional environments
Rate of Instinct may need adjustment
Ratio of ESN may have been too low to pick up response