Effects of Late Nitrogen Application on Hard Spring Wheats

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Effects of Late Nitrogen Application on Hard
Spring Wheats
Russ Karow1, Ernie Marx1, Doug Engle2, Gary
Hareland3 and Jennifer Kling1
1Oregon State University 2USDA-ARS Washington
State University 3USDA-ARS North Dakota State
University
2
Background

• Wheat growers in the Pacific Northwest sometimes
  apply nitrogen at flowering to increase grain
  protein in an attempt to assure meeting minimum
  market protein levels
• Premiums are based on the assumption that higher
  protein equals improved end-use quality
• Some reports suggest that the increase in
  protein percent that may occur with late N
  applications is not always accompanied by a
  corresponding increase in baking performance

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Possible explanation for lack of improvement in
baking quality with increased protein content

• Late N application may increase nonprotein N or
  protein fractions that do not confer improved
  baking quality

4
Objectives

• Compare the effects of single vs. split nitrogen
  applications on wheat yield, protein, and loaf
  volume
• Determine if there are varietal differences in
  response to split nitrogen applications

5
Methods

• Location
• Hyslop Field Station, Corvallis, Oregon - 1998
  and 1999
• Varieties
• WPB936 hard red spring wheat
• Winsome hard white spring

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Methods

• Agronomic practices
• 30 PLS/ sq ft earliest possible spring seeding
• Harmony Extra and phenoxy at 3-lf
• Fungicide as needed for leaf rust control

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Methods

• Nitrogen treatments
• Early N single application at late-tillering
• Split N first application at late-tillering
  with 40 lbs N/acre applied as a foliar
  acid-neutralized urea solution at flowering
• Total N applied was the same for both Early and
  Split N treatments (40, 120, 160, 200, 240 lbs
  N/acre)

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Nitrogen application
9
Preboot
10
Near harvest
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Methods

• Baking quality
• Standard pup loafs at WWQL
• Experimental Design
• RCBD with four replications for grain yield and
  protein and two replications for loaf volume

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Analysis of Variance1998
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WPB936
Winsome
1000 kw (g)
Yield (bu/acre)
y 71.444 0.041x
WPB936
Winsome
y 66.15 0.0373x
120
160
200
240
120
160
200
240
Total N applied (lbs/acre)
Total N applied (lbs/acre)
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Regression of protein on total N applied 1998

Grain protein
Loaf volume (cc)
120
160
200
240
Total N applied
Total N applied (lbs/acre)
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Analysis of Variance1999
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Yield (bu/acre)
Yield (bu/acre)



Total N applied (lbs/acre)
Total N applied (lbs/acre)
17



1000 kw (g)
1000 kw (g)



Total N applied (lbs/acre)
Total N applied (lbs/acre)
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Protein
Protein





0
40
80
120
160
200
240
280
0
40
80
120
160
200
240
280
Total N applied (lbs/acre)
Total N applied (lbs/acre)
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Loaf volume (cc)
Loaf volume (cc)
0
40
80
120
160
200
240
280
0
40
80
120
160
200
240
280
Total N applied (lbs/acre)
Total N applied (lbs/acre)
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Conclusions

• Yield, protein content, and baking quality
  increased with total N applied in both years.
• In 1999, a split application of N reduced yields
  at lower N levels, but had no effect on yield at
  higher N levels.
• A split application of nitrogen increased protein
  content in a favorable year (1999), but not in
  1998 when the crop experienced other
  environmental stresses.
• A split application of N did not significantly
  increase loaf volume in either year.

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Conclusions

• The variety WPB936 was higher in protein content
  and had better baking quality than Winsome, but
  was lower yielding under all fertility regimes in
  both years. WPB936 had higher 1000 kernel weight
  than Winsome.
• Further studies are underway to investigate the
  effects of late N application on protein
  composition, to determine why there is no
  improvement in baking quality with increased
  protein content.

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