The Effect of Adding Boron Fertilizer to UAN Foliar Applications on Flag Leaf Burn and Grain Parameters of Three Varieties of Spring Wheat at Brookings SD in 1996 (project no. 22196).

A. Bly, H.J. Woodard, and D. Winther

Introduction:

Foliar applications of nitrogen are known to produce leaf burn on wheat.  The effect of N rate and environmental conditions on N burn rates are difficult to predict.  The use of a substance along with foliar applications of N to reduce burn might be beneficial.  The objectives of this experiment were to evaluated the effect that additions of a boron fertilizer with UAN foliar applications might have on reducing burn in three varieties of hard red spring wheat (HRSW).

Materials and Methods:

An experiment site was chosen on the Sexauer farm near Brookings SD.  A composite soil sample was taken from the site to determine nutrient requirements for a 50 bu/a yield goal.  The site was shallow tilled twice with a chisel plow fitted with sweep shovels on April 30, 1996.  Seeds from three HRSW varieties (Krona, Russ, and Sharp) were planted at 1.2 million pure live seeds/a on 5' X 35' plots with a 7" spacing double disk drill on May 14, 1996.  Ammonium Nitrate (34-0-0) was broadcast spread at 86.2 lbs N/a on May 21, 1996.  Phosphorus as 0-46-0 was applied with the seed at 25 lbs P2O5/a.  Hoelon (2.66 pts/a), Buctril (1 pt/a), and MCP Ester (1.25 oz/a) was applied for grass and broadleaf weed control on June 20, 1996.  Post-anthesis N and Boron (B) fertilizer treatment combinations were foliar applied on July, 17 1996 with a 5' conventional boom sprayer protected with a spray hood to prevent wind drift.  The N rates were 0, 25, and 50 lbs N/a applied as concentrated UAN (28-0-0).  The B rates were 0, 0.25, and 0.50 lbs/a applied as Solubor (20.5% B) provided by U.S. Borax.  One of the B rates was applied with each N rate.  The proper amount of dry Solubor was added directly into the UAN solution and mixed before applying the treatments.  Solubor was added to water and applied at the correct rate for the B treatments without N.  Table 1 shows the details associated with the application operation.  The application rates were metered by a Raven computer controlled distribution system (model SCS 440).    Visual ratings of flag leaf burn were recorded on July 23, 1996. Grain was harvested with a small plot combine on August 27, 1996.  Grain samples were used to measure grain test weight, protein, and yield.  Grain protein was determined with near infra-red spectroscopy.  Variety and treatment means were statistically compared using SAS.

Results and Discussion:

The ANOVA indicated that variety significantly influenced flag leaf burn, grain test weight, yield and protein (Table 2).  Rate of foliar N significantly influenced flag leaf burn, grain test weight and protein but not yield.  Foliar applied boron or any interaction with boron did not significantly influence any of the dependent variables.  The variety and foliar N rate significantly influenced flag leaf burn but not any of the other dependent variables.   Variety differences of the dependent variables are expected due to genetic variation.   Foliar applied N and increasing rate significantly increased flag leaf burn, decreased grain test weight and increased grain protein.   Grain yield reductions occurred with increasing N rate, but could not be measured statistically.  The Krona variety exhibited less flag leaf burn than Russ or Sharp varieties.  Increases in flag leaf burn occurred as foliar N rate increased for all varieties.

Conclusions:


 
 Table 1. Operational parameters for the foliar application of B with UAN on hard red winter and hard red spring wheat at Aurora SD in 1995.
Nutrient Applied Foliar 
Spray Rate of Required Water
Spray Rate of Required UAN (28-0-0)†
Application Rate Required Solubor (20.5% B)‡
Spray Nozzle Number
Spray Pressure
Spray Amount
Tractor Speed
N
B
 
 
 
 
 
 
  
--lb./acre-- --lb./acre-- gal./a  gal./a g/gal.    psi. gal./min./nozzle mph
25 0   (§1) 0 8.33  0  8001 16-28 0.0625 3
50 0   (§2) 0 16.67 0 8001 25-28 0.0850 2
0 0.25 (1) 8.33 0 67.04 8001 16-18 0.0625 3
0 0.50 (2) 16.67 0 67.04 8001 25-28 0.0850 2
50 0.25 (*1)  0 16.67 33.50 8001 16-18 0.0625 3
25 0.25 (*2) 0 8.33 67.04 8001 16-18 0.0625 3
50 0.50 (**1) 0 16.67 67.04 8001 25-28 0.0850 2
25 0.50 (**2) 0 8.33 133.53 8001 25-28 0.0850 2
 
§     Solutions for §1 and §2 were pure UAN (†).  The application rate/a was adjusted to attain the required rate of N/a.
     Solution 1 containing B fertilizer was formulated in water.  After application, the rate/a of 1 was doubled to attain the 2 rate of B/a.
*     Solution *1 containing N and B fertilizer was formulated.  After the application, the required rate of UAN (†)/a decreased by 50%,  and Solubor (‡) was added to the same solution to produce solution *2.
**     Solution **1 containing N and B fertilizer was formulated from solution *2 by changing the rate of UAN (†)/a.   After the application,  the required rate of UAN (†)/a decreased by 50%, and Solubor (‡) was added to the same solution to produce solution **2.
 

 
Table 2. ANOVA analysis of whole project.  Classes = variety, N, B, and rep
 
 
Dependant Variables 
Pr > F
              
  burn top sieve middle sv bottom sv test wt ker yield prot
classes: flaglf% % % % lb/bu g/250 bu/a %
variety(V) 0.0011 0.0003 0.002 0.0001 0.0001 0.0732 0.0001 0.0317
N rate (N) 0.0001 0.0023 0.0017 0.0167 0.0154 0.1261 0.083 0.0004
B rate (B) 0.9744 0.8564 0.8532 0.8733 0.974 0.9642 0.7111 0.4679
V * N 0.0015 0.3206 0.408 0.6819 0.6794 0.6333 0.9735 0.1671
V * B 0.4523 0.9645 0.6201 0.9752 0.9344 0.6061 0.473 0.9458
N * B 0.0805 0.6004 0.2519 0.4423 0.7856 0.8758 0.4238 0.2116
V * N * B 0.6198 0.8513 0.987 0.9274 0.6361 0.8657 0.9374 0.8812
                 
Whole project means:                
  burn top sieve middle sv bottom sv test wt ker yield prot
variety flaglf% % % % lb/bu g/250 bu/a %
Krona 18.9 56.1 39.8 3.5 55.9 7 37.2 14
Russ 31.4 65.1 33.2 1.7 57.9 7.4 44.6 14.2
Sharp 33.5 56.9 40.6 2.4 60.7 7.3 41.9 14.5
LSD.05 5.3 2.6 3.1 0.2 0.5 0.3 1 0.3
                 
N trt                
0 13.2 62.7 35 2.3 58.6 7.4 42.4 13.8
25 22.2 59.9 36.9 2.5 58.3 7.3 41.5 14.1
50 48.3 55.5 41.7 2.8 57.7 7 39.7 14.8
LSD .05 3.4 2.8 2.5 0.3 0.5 NS 2.4 0.3
                 
B trt                
0 28.1 59.2 38.3 2.6 58.2 7.2 41.1 14.3
0.25 27.5 59 37.8 2.5 58.2 7.2 40.9 14.2
0.5 28.2 59.8 37.6 2.5 58.2 7.2 41.6 14.2
LSD.05 NS NS NS NS NS NS NS NS
                 
                 
N * B                
0 0 15.8 61.3 36.3 2.4 58.5 7.4 41.4 14
0 .25 12.1 63.3 34.4 2.3 58.8 7.5 43.1 13.8
0 .50 11.7 63.4 34.4 2.2 58.5 7.4 42.7 13.6
25 0 20.4 60 37.5 2.4 58.3 7.3 41.3 14.1
25 .25 21.7 60.4 35.2 2.3 58.3 7.3 41.3 13.9
25 .50 24.6 59.3 38.1 2.6 58.2 7.2 41.9 14.3
50 0 47.9 56.2 40.9 2.9 57.8 7 40.7 14.9
50 .25 48.8 53.4 43.8 2.9 57.4 6.9 38.2 14.9
50 .50 48.3 56.9 40.4 2.7 57.9 7.1 40.1 14.7
  NS NS NS NS NS NS NS NS
 
Last Updated on 5/28/98
By Howard J. Woodard
Email: woodardh@mg.sdstate.edu

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