Exploratory Research in Corn and Wheat - Virginia

Previous Virginia ResearchN

DVI

Tiller Density

0

0.30.40.50.60.70.80.9

0 500 1000 1500 2000

0.10.2

Predicted Yield Index

Yiel

d, M

g ha

-1

0

1

2

3

4

5

6

7

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007

Spring N rates for VA wheat production can be Spring N rates for VA wheat production can be determined using spectral reflectance sensors and determined using spectral reflectance sensors and applied at a 4-ftapplied at a 4-ft22 resolution using commercial resolution using commercial equipmentequipment

Standard VA Rotation(3 crops in 2 years)

No-till Corn

Conv.-till Wheat No-till DC Soybean

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

Experimental Procedures - Obj. 1

TREATMENT STRUCTURE

Trt GS 25 N GS 30 N Resolution

------- lb N / acre -------

1 0 0 NONE2 30 60 FLAT RATE3 0 120 FLAT RATE4 60 60 FLAT RATE5 120 0 FLAT RATE6 0 NFOA 1 m2

7 TILLER NFOA 1 m2

8 TILLER TISSUE FLAT RATE

13 0 NFOA3 1 m2

14 TILLER NFOA3 1 m2

15 0 NFOA3+PFOA2 1 m2

16 TILLER NFOA3+PFOA2 1 m2

9 0 NFOA2 1 m2

10 TILLER NFOA2 1 m2

11 0 NFOA2+PFOA1 1 m2

12 TILLER NFOA2+PFOA1 1 m2

Year 2

Year 3

6 site years (2 in each of 3 yr) RCBD; 3 replications

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

Experimental Procedures - Obj. 2 Spectral measurements

collected from canopy at V4, V6, V8, and V10

Chlorophyll and tissue N and Pwill be measuredat same growth stages

A PSNT will be conducted for each treatment prior to sidedress N applications at V6

Preliminary Results - Obj. 2

0

30

60

90

120

150

180

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

NDVI, V8

Yiel

d, b

u/ac

re

Dryland, No NIrrigated, No NDryland, Added NIrrigated, Added N

Determine from soiltest

Residual P can carryover from starterapplication toprevious crops

P can be banded withwheat crop

Foliar P Applications in Virginia

Preplant P2O5 Tiller Density Grain Yield

-- lb/acre -- -- tillers/ft2 -- -- bu/acre --0 50 8330 70 8560 80 9690 95 93

120 95 95

PHOSPHORUS RESPONSE

Foliar P ApplicationFoliar P No preplant P 90 lb P2O5

-- lb P2O5/acre -- -- bu/acre -- -- bu/acre --0 77 904 84 908 84 9312 87 98

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

Experimental Procedures - Obj. 3

12 site years (4 sites in each of 3 yr) 2 corn and 2 wheat No till

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%