1. Exploratory Research in Corn
and Wheat - Virginia

2. Previous Virginia Research
NDVI
Tiller Density
0.3
0.4
0.5
0.6
0.7
0.8
0.9
500
1000
1500
2000
0.1
0.2
Predicted Yield Index
Yield, Mg ha-1 1 2 3 4 5 6 7
0.001
0.002
0.003
0.004
0.005
0.006
0.007
Spring N rates for VA wheat production can be determined using spectral reflectance sensors and applied at a 4-ft2 resolution using commercial equipment

3. Standard VA Rotation (3 crops in 2 years)
No-till Corn
Conv.-till Wheat
No-till DC Soybean

4. Objectives
Refine current methods of determining variable topdress N rates and incorporate foliar P recommendations into fertilization algorithms for wheat using sensor-based technology
Develop a sensor-based N and P fertilization strategy for Virginia corn production
Evaluate the benefits of foliar P applications for wheat and corn production

5. ------- lb N / acre -------
Experimental Procedures - Obj. 1
6 site years (2 in each of 3 yr)
RCBD; 3 replications
TREATMENT STRUCTURE
Trt
GS 25 N
GS 30 N
Resolution
lb N / acre 1
NONE 2 30 60
FLAT RATE 3
120 4 5 6
NFOA
1 m 7
TILLER 8
TISSUE 13
NFOA3 14 15
NFOA3+PFOA2 16 9
NFOA2 10 11
NFOA2+PFOA1 12
Year 2
Year 3

6. Experimental Procedures - Obj. 2
12 site years (4 sites in each of 3 yr)
Irrigated and non-irrigated
Conventional and no till
RCBD; 3 replications
Preplant N (0 to 240 lb N/acre)
Starter N (0 to 70 lb N/acre)
Sidedress N (0 to 150 lb N/acre)
Plots will be fertilized and harvested using conventional plot equipment

7. Experimental Procedures - Obj. 2
Spectral measurements collected from canopy at V4, V6, V8, and V10
Chlorophyll and
tissue N and P
will be measured
at same growth stages
A PSNT will be conducted for each treatment prior to sidedress N applications at V6

8. Preliminary Results - Obj. 230 60 90
120
150
180
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
NDVI, V8
Yield, bu/acre
Dryland, No N
Irrigated, No N
Dryland, Added N
Irrigated, Added N

9. Foliar P Applications in Virginia
Determine from soil
test
Residual P can carry
over from starter
application to
previous crops
P can be banded with
wheat crop

10. PHOSPHORUS RESPONSE Foliar P Application
Foliar P No preplant P 90 lb P2O5
-- lb P2O5/acre bu/acre bu/acre --
Preplant P2O5 Tiller Density Grain Yield
-- lb/acre tillers/ft bu/acre --

11. Experimental Procedures - Obj. 3
12 site years (4 sites in each of 3 yr)
2 corn and 2 wheat
No till
Preplant P
STP
1/3 STP
2/3 STP
Foliar P rates
0, 4, 8, and 12 lb P2O5/acre for wheat (double for corn)
Applied at GS30 or V6

12. Expected Results
Virginia producers will have the knowledge required to implement existing variable-rate fertilizer technology into standard cash grain production systems
Grain yields will increase by applying nutrients at the resolution where variability exists
Nitrogen use efficiency will increase 30 to 50% while soil-applied P fertilizer will be reduced 50 to 100%