nitrogen loss research joel ransom ndsu extension agronomist
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Nitrogen Loss Research
Joel Ransom
NDSU Extension Agronomist
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
1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 20140
100200300400500600700
Trends in the price of urea
Price
($/t
on)
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
Wet cycle increases likelihood of N losses
Nitrification
Principles to guide N loss reductions
• 4 R’s of nutrient stewardship– Right fertilizer source – Right rate– Right time– Right place
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
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
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
Rate of nitrification
0 3 60
10
20
30
40
50
60
70
80
90
100
AAUreaUANAN
Weeks after application
Perc
ent a
s ni
trat
e N
Source: Schwab and Murdock, U of K
• Goos, unpublished
Release rate of ESN compared to corn N uptake, Manitoba (Heard and Ginter, MAFRD).
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
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
Effect of additive yield of corn, Fargo and Prosper, 2011.
Fargo Propser80
85
90
95
100
105
110
115
120
125
130
UreaAgrotainSuperUInstinctNutrisphereYi
eld
(bu/
acre
)
Effect of nitrogen management practices on yield of corn in five environments, 2012.
60
70
80
90
100
110
120
130
140
150
Urea
Urea plus nitrapyrin
Poly coated urea
Urea @ planting & UAN 6 lf stage
Urea @ planting & UAN+DCD+NBPT 6 lf stage
Yiel
d (b
u/ac
re)
Effect of nitrogen management practices at lowest N rate on yield of corn in five environments, 2012.
60
70
80
90
100
110
120
130
140
150
Urea
Urea plus nitrapyrin
Poly coated urea
Urea @ planting & UAN 6 lf stage
Urea @ planting & UAN+DCD+NBPT 6 lf stage
Yiel
d (b
u/ac
re)
Effect of nitrogen management practices on yield of corn in five environments, 2013.
Fargo Fargo T Hitter. Barnes. Cass. Average80
100
120
140
160
180
200
Urea alone Urea plus nitrapyrin Poly coated urea
Urea @ planting & UAN 6 lf stage Urea @ planting & UAN+DCD+NBPT 6 lf stage
Yiel
d (b
u/ac
re)
Effect of nitrogen management practices at lowest N rate on yield, all locations, 2013.
60
70
80
90
100
110
120
130
140
150
Urea
Urea plus nitrapyrin
Poly coated urea
Urea @ planting & UAN 6 lf stage
Urea @ planting & UAN+DCD+NBPT 6 lf stage
Yiel
d (b
u/ac
re)
Effect of nitrogen management practices at lowest N rate on yield of corn in Casselton, 2013.
60
70
80
90
100
110
120
130
140
Urea
Urea plus nitrapyrin
Poly coated urea
Urea @ planting & UAN 6 lf stage
Urea @ planting & UAN+DCD+NBPT 6 lf stage
Yiel
d (b
u/ac
re)
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 ~$660-690/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)
Six Lf Milk
23.5
16
25
18.5
21.5
18.5
22
16.5
18.5 18
Effect of N practice on NH4+ average of all locations and years.
Urea Urea + Nitr Urea + ESN Split Split + DCD+
Kg p
er h
a
Ammonium Total0
5
10
15
20
25
30
35
40
45
50
Eff ect of N practice on ammonium and total N at 6 lf stage, Fargo tiled, 2013.
Urea Urea + Nitr Urea + ESN Split Split + DCD+
Kg/h
a
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
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