Hard Red Wheat - Foliar Nitrogen Applications

Foliar Nitrogen Applications to increase protein in Hard Red Wheat.  Conpilation of published research data.

Crop & Soils               Volume 43  Issue March-Apr 2010

• Urea penetrates leaf cuticle easily
• Timing application is critical – diurnal effect
• Water stress and time of day are critical
• pH needs to be between 4 and 6 for optimum uptake
• Addition of surfactant may be beneficial.

Minnesota Crop eNews. Late Season Applications of Nitrogen. March 6, 2006.

• Apply 5-7 days post anthesis
• Probability of crop response is 80%
• ½ to 1 percent protein increase with 30 lbs N/acre
• All varieties respond equally
• Nitrogen will become rate limiting for protein at lower rates, than for grain yield
• Foliar applied N resulted in largest increase in grain protein
• Foliar application of 30 lbs N/acre is most effective and should not significantly impact grain yield, test weight, kernel size, despite the visual effect of substantial leaf burning.

Post Anthesis N application studies North Dakota region and elsewhere.

Carrington 1988-1991 Dryland and Irrigated HRSW.

• Foliar N applied 7-10 days after flowering.
• Greatest protein increase was provided with 30#N per acre.
• Under irrigation, yield was depressed at N rates greater than 30 # N / acre.

RESULTS :                     Dryland Irrigated

Check              13.6%                 12.4%           Protein

30# N              14.7%                 14.2%           Protein

Check              27.4 bu               50.3 bu         Yield

30# N              27.6 bu               49.7 bu         Yield

• Under the right circumstances, as much as 1% protein increase from 30# N /ac.
• Care should be taken to prevent undue leaf burning by spraying during the cool of the day.

Increasing Wheat Protein. University of Idaho. 2000.

• Protein increased about 0.3% for each 20#N/Ac applied at heading regardless of planting date or variety.
• Late season moisture stress had little influence on protein response.
• Sulfur can be a limiting factor for both yield and for increasing protein with late late season N.
• Flag leaf total N content at heading or flowering have been the most closely related to grain protein.
• Flag leaf total N concentrations of 4.2% were associated with 14% protein HRS.
• Protein increase was greater for lower flag leaf total N.
• Flag leaf total N above 4.5% had little protein increases with 20 or 40#N/ac.
• Application of 40# N/ac was not adequate to achieve 14% protein  when flag leaf N was as low as 3%.
• Critical flag leaf N concentrations are higher when sampled before heading and lower when sampled after heading.
• Knowing the plant stage is critical for correct interpretation of plant samples.

Effect of Foliar Sulfur and Nitrogen Fertilization on Wheat Storage Proteins Composition and Dough Mixing Qualities. Cereal Chem. 81(6) 759-766.

• N and S supplies have a strong influence on the quality and quantity of wheat storage proteins and play an important role in the bread making process.
• Nitrogen and sulfur treatments increase the amount of 3 protein fractions.
• Urea N and S applied by foliar spray at anthesis stage influence quantity and composition of storage proteins as well as dough mixing qualities.
• Simultaneous application of foliar N+S increase molecular weight and compactness of the UPP fraction suggesting a synergistic effect.