This document discusses research on applying nitrogen late in the corn growing season. It provides data from studies in Ontario, Indiana, Illinois, and Eastern Ontario showing that late season nitrogen applications around tasseling (VT) generally do not significantly increase yields compared to earlier applications, but can provide benefits under certain conditions like wet weather. Fine-tuning late nitrogen with placement, products to reduce losses, soil testing, and precision agriculture is discussed. The conclusion is that applying nitrogen by the VT stage is best to reduce losses, and rate should be adjusted based on weather, soils and crop status.

1. Late Nitrogen Frenzy
Jason Van Maanen, Veritas
Scott Banks, OMAFRA
Greg Stewart, Maizex

2. Research in N
Uptake in Corn
• 37% of N needed after
tassel
• Modern hybrids use 37%
of N after tassel (30% in
older hybrids)
Source: Pioneer Crop Insights

3. Equipment options

4. High Yield Contest Winners
• Several (Francis Child,
David Hula, Randy
Dowdy) have spoken
across Ontario
• Promoted the concept
of feeding the crop late
(VT) to maximize yields.

5. Key Question?
• 1) Does a late season N application (V10 – VT)
provide an economic advantage over earlier
application strategies?
• Conditions:
• No Significant N Shortfall (not a Rescue N
Application)
• Total N Applied is Equivalent Across All
Comparisons

6. SW Ontario Data

7. Ontario Data – Impact of N Timing
Source: Ben Rosser
OMAFRA
Year / Location Planter Base
Broadcast
Planting
Timing
Sidedress
Timing
Late
Timing
Nitrogen Rates (lbs N/acre)
2014 Norfolk 27 50 100 100 100
Corn Yield (bu/ac) 220 219 220
2014 Lambton 3 30 150 150 150
Corn Yield (bu/ac) 169 163 173
2014 Huron 0 60 120 120 120
Corn Yield (bu/ac) 174 180 179
2014 Bornholm 19 70 50 50 50
Corn Yield (bu/ac) 132 152 160
2014 Elora 15 70 50 50 50
Corn Yield (bu/ac) 140 156 147
2015 Huron 40 100 100 100
Corn Yield (bu/ac) 207 205 210
Averages 174 179 182

8. Indiana Data

9. Timing of last N application
(50 pounds/acre) in Irrigated Corn
(mean of P1498 and P1360 at 2 populations in 2015)
180
185
190
195
200
205
210
215
220
225
230
235
V6 V10 V14 V18 V6 V10 V14 V18
30000 40000
Pop x N timing
R1 R1
Yields bu/acre
Source: T.J. Vyn

10. Becks Hybrids Data
High Clearance Sidedressing

11. Beck’s Hybrids
• 4 year average comparing
traditional sidedress to V10 High
Clearance Sidedress.
• + 3.06 bu/acre or $16.34/acre
• No adjusting for application costs

12. Illinois Data

13. 13
Treatment UR-15 MN-15 DK-15 Avg
PT UAN 150 injected 228 217 204 216
PT Urea/AT 150 broadcast 237 223 200 220
PT NH3 150 injected 219 213 201 211
*PT UAN/Instinct 150 broadcast 229 225 183 213
*PT UAN 100 inj + V9 UAN 50 drbl row 233 223 198 218
*PT UAN 100 inj + VT UAN 50 row mid 241 215 179 212
*PT UAN 100 inj + VT UAN 50 drbl in row 238 228 184 217
*New in 2015
Treatments added in 2015
VT applications performed well, but not clearly better than
some other treatments in a “high-loss” year
Source: E. Nafziger

14. Eastern Ontario Data

15. Y Drop Trial
Treatment Starter
N
Sidedress
N
Late
N
Total
N
Grower Rate 30 100 130
Grower Rate Split (2/3, 1/3) 30 60 40 130
Grower Rate Reduced (- 25 lbs) and Split 30 50 25 105
Grower Rate Increased ( + 50 lbs) 30 150 180
Grower Rate Increased and Split 30 100 50 180
Starter Only 30 30

16. Locations Agri-Business
Agrodrain Systems Ltd. 360 Yield Center
Brugmans Farms Cropland Consulting Inc.,
Cedar Lodge Farms Dekalb,
Hilltone Farms Ltd. DuPont Pioneer
Jockbrae Farms Ltd. GPS Ontario
Kemp Farms Inc. OMAFRA
Nandale Farms Ltd. OSCIA
Panmure Farms Ltd. Ottawa-Carleton SCIA
Vanden Bosch Farms P.T. Sullivan Agro Inc.
Vernon Valley Farms Ltd. SGS Agri-Food Laboratories

17. Corn Yield Response to Late N Application
Y-Drop Project - 2015
Jockbrae Panmure
Total N Yield (bu/ac) Yield (bu/ac)
34 173 221.7
103 198 224.0
109 207 222.8
118 208 226.0
154 215 226.5
149 208 226.0
111.2 201.5 224.5
20 (19-22) (22-56)
14 (7-21) (21-46)
Summary of Plots Total N
No side dress 48
Grower Split with 75 % 84
Grower Rate 113
Grower Split with YD 117
125 % of grower rate with YD 141
125 % of grower rate 141
Average 107.3
Average PSNT-June 5( range) 39
Average PSNT-June 17( range) 34
Soil Texture
Previous Crop
Sandy Loam
Soybean
Silt loam to loam
Winter wheat
Summary by P.T. Sullivan Agro Inc.

18. Corn Yield Response to Late N Application
Y-Drop Project - 2015
Cooperator: Nandale Farms
Y-Drop: N Pre/Planting: 11 lbs/ac Previous Crop: Soybeans
Treatment
Planter
N
Broadcast
N
Y Drop
N
Total
N
Yield
(bu/ac) Net ($/ac)
O 11 0 11 131
Reduced 11 65 25 101 161 $56
Standard 11 115 126 167 $13
Std. Y Drop 11 75 40 126 167 -$3
N High 11 160 171 174 -$8
High Y Drop 11 110 50 171 172 -$17

19. Nandale Farms –Y Drop 2015

20. Corn Yield Response to Late N Application
Y-Drop Project - 2015
Cooperator: Nandale Farms Previous Crop: Soybeans
80
90
100
110
120
130
140
150 30
65
100
135
170
205
240
275
310
345
380
415
450
485
520
555
590
625
MERN(Nlbs/ac)
Distance Down Field (feet)
MERN ( N lbs/ac)
Yields Plots 9 = 11 lbs N and 10 = 171 lbs N

21. Summary of Results
• Evidence Does Not Suggest That Later is
Significantly, Consistently Better (Yield or
Economics)
• Appears to be Little Negative Impact of
Applying up to Tassel (VT)
• Late N Advantage Disappears after Tassel

22. Late N Advantages
• Reducing the Size of the Nitrate
Pool that is at Risk to Loss
• Rate Adjustment for Various
Conditions

23. Advantage - Reducing the
Nitrate Pool
• Leaching
• Lighter soil – Early N moving down
with moisture
• Denitrification
• Heavy soil – Gaseous losses of N in
saturated conditions

24. 0
10
20
30
40
50
60
70
25-Apr 9-May 23-May 6-Jun 20-Jun 4-Jul 18-Jul 1-Aug 15-Aug 29-Aug 12-Sep 26-Sep 10-Oct 24-Oct 7-Nov
NO3-N(ppm)
Year 2009
ESN138 Urea138 Control5
Nitrate Monitoring in Oxford
County Site, 2009

25. Advantage - N Rate Adjustment
•Preplant vs Sidedress vs Late
•Decisions are 30 Days “Smarter”
• Crop Yield Potential
• Rainfall x Soil Type
• Soil Nitrate Status
• Crop Health (Colour / NDVI)
•Making your N rate more precise

26. What to do after 9 inches of rain in June?
G. Stewart, Maizex Seeds

28. Nitrogen Management
Millbank Site
Hybrid Over the Tile Between the Tiles
No
Additional
N
Plus 50
lbs/acre N
No Additional
N
Plus 50 lbs/acre
N
MZ3515DBR 174 194 138 172
MZ3066DBR 185 205 126 191
MZ2810DBR 194 206 166 191
Average 184 202 143 184
Source: G. Stewart, Maizex Seeds

29. 4 Key Factors in Late N Decisions
Factor Millbank Site
Yield Potential High - 37,000 PPA.
May / June Rainfall High - 9 inches in June
Soil Nitrate Values Relatively low
Plant Colour / NDVI Fading between tiles
G. Stewart, Maizex Seeds

30. Late Nitrogen Fine Tuning
Placement
Urea vs UAN:Agrotain Yes or No
Nitrate Soil Tests
Precision Ag Approaches

31. Fine Tuning - Placement

32. Fine Tuning – Products and
Protection
N Rate per Acre (lb N)
Product 50 65
Urea $38.00 $47.00
Urea + Agrotain $42.50 $52.00
UAN $44.00 $53.00
UAN + Agrotain $47.50 $58.00
ESN $51.00 $64.00
• Cost of material and application
J. Van Maanen, Veritas

33. The Cost of Loss
N Rate per Acre (lb N)
Product 50 65
Urea $38.00 $47.00
Urea + Agrotain $42.50 $52.00
UAN $44.00 $53.00
UAN + Agrotain $47.50 $58.00
ESN $51.00 $64.00
• Cost of material and application
J. Van Maanen, Veritas

34. The Cost of Loss
N Rate per Acre (lb N)
Product 50 65
Urea $38.00 $47.00
Urea + Agrotain $42.50 $52.00
UAN $44.00 $53.00
UAN + Agrotain $47.50 $58.00
ESN $51.00 $64.00
• Cost of material and application
J. Van Maanen, Veritas

35. Fine Tuning - Agrotain with UAN
Applications?
Factors to Consider:
Is the soil damp at the surface?
Is there significant residue on the soil
surface?
Is the weather forecast dry?
Is the canopy fully developed - windspeed?

36. Fine Tuning - Soil N Testing
(Late)
• What do Soil N Tests Mean once
Crop N Uptake is Significant? i.e.
V10 +
• Perhaps Nothing.

37. 38
0
50
100
150
200
250
300
350
4/6 4/26 5/16 6/5 6/25 7/15 8/4
SoilNintop2ft.,lb/acre
Sampling date
Sangamon County 2015
None 100 AA Fa 200 AA Fa
100 Fa+50+50 200 AA Spr 50 pl+150 SD
Yield
None 145
Fall NH3 270
Fa100+Pl50+SD50 269
Spr NH3 264
Pl50+SD150 277
Source: E. Nafziger

38. Fine Tuning - Precision Ag
Approaches
• Do Precision Ag sensors (i.e. GreenSeeker)
give you more meaningful information
later in the season?
• Crop canopy at V6 versus V12; NDVI signal.

39. Fine Tuning - Precision Ag
Approaches
• Crop canopy at V12 gives superior NDVI signal compared
to V3
Source: Veritas

40. Timing? Can You be Too Late?
• What is the risk associated with July
25th Nitrogen?
• Risk is real, if the soil is dry and no
rain occurs for three weeks, it is less
likely that you can get the N to the
crop.

41. Conclusions
• Evidence Does Not Suggest That Later is
Significantly, Consistently Better (Yield and
Economics)
• More Economic Advantage Can Be Realized if Late
N Applications are Rate Adjusted for the
Conditions that Exist. Defining those conditions?!
• N Loss Risks are Lowered by Reducing the Size of
the Nitrate Pool
• Urea is Much More likely to Benefit from Agrotain
than UAN (monitor conditions)

42. Conclusions
• Late (July) Soil N Test Not a Good Indicator of
Late N Requirements
• Late N Needs to be In To Plant by VT, watch
timing and conditions (i.e. too dry)

43. Thank you.
Contact Information:
Jason van Maanen
jason.vanmaanen@myveritas.ca
Greg Stewart
greg@maizex.com
Scott Banks
scott.banks@ontario.ca

47. Maizex Agronomy Data, 2015
Site Base N Late N Yield
Campbellford 150 203
Plus 50 - June 23 202
Plus 50 - July 16 210
Granton 150 235
Plus 50 - July 22 236
Erin 180 194
Plus 50 - June 18 196
Plus 50 - July15 192
Millbank 160 164
Plus 50 - July 5 193
Langton 160 187
Plus 50 - June 19 211
Plus 50 - July 11 207
Kingston 135 222
Plus 50 - July 16 230
Plus 100 - July 16 249
Source: G. Stewart, Maizex Seeds