1. PRECISION SIDEDRESS UAN APPLICATION FOR CORN PRODUCTION
O k l a h o m a S t a t e U n i v e r s i t y
Kefyalew Girma
Oklahoma State University

2. O k l a h o m a S t a t e U n i v e r s i t y
Introduction
O k l a h o m a S t a t e U n i v e r s i t y
Nitrogen Leak

3. O k l a h o m a S t a t e U n i v e r s i t y
Introduction
O k l a h o m a S t a t e U n i v e r s i t y
Coulter UAN application in corn (Ames, IA). UAN surface application is made within the center of the row, 15 inches away from the base of each stalk.
The common use of UAN for sidedress N application in corn is to
apply this liquid fertilizer in the middle of rows using either
dribble surface bands, or rolling coulter injection.

4. O k l a h o m a S t a t e U n i v e r s i t y
Introduction
O k l a h o m a S t a t e U n i v e r s i t y
Excavated corn plants showing no overlapping of nodal root systems when corn plants were more than 10” apart, at silking growth stage

5. O k l a h o m a S t a t e U n i v e r s i t y
Objective
to compare three sidedress N placement methods on corn grain yield/where
Evaluate sidedress N rates
O k l a h o m a S t a t e U n i v e r s i t y
Sense by plant and treat based on yield potential

6. O k l a h o m a S t a t e U n i v e r s i t y
Treatment structure of precision sidedress UAN experiment,
Haskell and Lake Carl Blackwell,
Trt
Pre
Side d.
Placement method 1 40 20
Directed stream application at the base of each plant (1) 2
Directed stream application at the base of a row (2) 3
Dribble surface bands applied in the middle of two rows (3) 4 5 6 7 80 8 9 10
160 11 12 13 NA 14
Broadcast 15
200
O k l a h o m a S t a t e U n i v e r s i t y

7. O k l a h o m a S t a t e U n i v e r s i t y
By-row
By-plant
O k l a h o m a S t a t e U n i v e r s i t y
Between rows

8. Directed Stream Applicator
O k l a h o m a S t a t e U n i v e r s i t y
Directed stream application of UAN in corn applied at
the base of stalk of the plant

9. Design and Field LayoutW E N S
Location: Haskell-2005
III II
O k l a h o m a S t a t e U n i v e r s i t y I
Plot size 10’ x 20’ with 5’ alley
By plant N rate was determined as:
Calculate UAN/row
Divide the above by number of plants/row

10. O k l a h o m a S t a t e U n i v e r s i t y
Between row and within row by plant corn grain weight variability at Haskell (Hask) and Lake Carl Blackwell (LC), OK, 2005.
Row
Mean dry grain weight, lb/plant
Percent of no. of plants with yield > mean
Range, lb/plant
Standard deviation
lb/plant
Hask LC
Haskl 1
0.20
0.38 50 53
0.31
0.35
0.09 2
0.19 47
0.34
Pro ns
O k l a h o m a S t a t e U n i v e r s i t y

11. O k l a h o m a S t a t e U n i v e r s i t y
Between row and within row by plant corn grain weight variability at Haskell (Hask) and Lake Carl Blackwell (LC), OK, 2006.
Row
Mean dry grain weight, lb/plant
Percent of no. of plants with yield > mean
Range, lb/plant
Standard deviation
lb/plant
Hask LC
Haskl 1
0.21
0.20 45 41
0.41
0.53
0.12
0.11 2
0.19 46 40
0.43
0.55
0.13
Pro ns
O k l a h o m a S t a t e U n i v e r s i t y

12. Martin et al. (2005) Agron. J. 97:1603-1611
Regardless of yield level, plant-to-plant variability in corn grain yield can be expected and averaged more than 2765 kg ha-1 (44 bu/ac) over 46 sites (Ohio, Iowa, Nebraska, Virginia, Mexico, Argentina)

13. O k l a h o m a S t a t e U n i v e r s i t y
Effect of UAN sidedress placement method on corn grain yield
O k l a h o m a S t a t e U n i v e r s i t y

14. Effect of sidedress N rates on corn grain yield
O k l a h o m a S t a t e U n i v e r s i t y

15. O k l a h o m a S t a t e U n i v e r s i t y
Summary
Within row variability in grain yield was very high
By plant sidedress application of N according to individual plant yield potential would result in improved efficiency and reduced cost to producers
The gain in yields from the three methods ranged from 7 to 25% more than the broadcast treatment in three location-years
O k l a h o m a S t a t e U n i v e r s i t y

16. O k l a h o m a S t a t e U n i v e r s i t y
Summary
Under normal growing conditions, N should be sidedressed by plant at a rate of lb/A to maintain yield level and decrease loss in fertilizer N concurrent with within row plant to plant variability
Results are not conclusive as the corn growing season was extremely dry/hot
The experiment will be continued for 1 more year
O k l a h o m a S t a t e U n i v e r s i t y

17. O k l a h o m a S t a t e U n i v e r s i t y
Summary
Additional measurements such as ears per plant, 100-seed weight, ear size, plant spacing, and grain N concentration
O k l a h o m a S t a t e U n i v e r s i t y

18. O k l a h o m a S t a t e U n i v e r s i t y
THANK YOU!
O k l a h o m a S t a t e U n i v e r s i t y