Challenges to sensor- based N-Management for Cotton E.M. Barnes 1, T. Sharp 2, J. Wilkerson 3, Randy Taylor 2, Stacy Worley 3 1 Cotton Incorporated, Cary NC 2 Oklahoma State University, Okmulgee & Stillwater 3 University of Tennessee, Knoxville

Acknowledgements Tom Clarke, Glenn Fitzgerald, P. Pinter  USDA, ARS, Arid Land Research Center  Maricopa, AZ Pete Waller, University of Arizona  Paul Colaizzi, USDA, ARS – Lubbock, TX  Julio Haberland – Chile  Mike Kostrzewski - Arizona

Outline Cotton 101 Why cotton interest in sensors is high The challenges of Cotton One proposed solution

Cotton 101

Data from USDA, NASS The Cotton Belt

Cotton & Nitrogen Perennial plant managed as an annual  Indeterminate flowering pattern ~50 lbs-N per lint bale (1 bale = 480 lbs) Over-application of N:  Energy partition to vegetative vs. reproductive development  Large plants prevent efficient harvest  Growth regulators applied to control vegetative development

Why interest in sensors now? Cost of N Producers receiving In-Time images  And now Deere imagery through Jimmy Sanders On-farm tests done in Alabama to use GreenSeeker TM to apply growth regulator (PIX) Cotton researchers joining in

Lowest Biomass 7 Highest Biomass gpa 6.0 gpa 7.0 gpa 8.0 gpa 4.5 gpa, 24 fl. oz Prep, 1.5 dry oz Dropp 8.0 gpa, fl. oz Prep, 2.67 dry oz Dropp 8.0 gpa Location: Arkansas Delta Crop: Cotton Field Size: Acres Imagery Acquired: September 7, 2004 VR Defoliation Applied: September 14, 2004 Notes: This prescription was applied using a hydraulic aerial VR system. The consultant was able to achieve a one-time defoliation on this field, for $15.94/A in chemical. Variable Rate Defoliation

Variable Rate Nitrogen Top-Dressing Lowest Biomass 7 Highest Biomass 5 0 lbs./A 100 lbs./A 0 lbs./A 100 lbs./A Location: Arkansas Delta Crop: Cotton Field Size: A’s Imagery Acquired: July 5, 2004 VR Fertilizer Applied: July 13, 2004 Notes: This prescription was applied using a variable rate equipped high clearance spreader. Unity [16% nitrogen (N)] was applied midseason, to supplement areas in the field which had become N deficient. Classes 1 and 2 were beyond salvaging with the additional N, while classes 6 and 7 required no additional N.

Challenges

Wind blows & Index Changes + Heliotropic; + New Growth

Sample data set 1999 Growing season AGIIS sensor (calibration panel every minute) Water and Nitrogen treatments

1999 CCCI (relative to WN) Last N Application Squares Green BollOpen Boll

Yield = -m*NDVI + C ?

Possible solution?

Combining Data Use NDVI / Greenseeker as a “biomass” sensor Historic yield maps.

Concept

Application

Theoretical Example

Combined

Conclusions Cotton can be tricky to manage Efforts to apply sensors for N management are increasing rapidly Hope to learn from work here most efficient methods to develop cotton N management strategies

AgIIS (Agricultural Irrigation Imaging System) Bands (nm): Green (555), Red (670), Edge (720), NIR (790) IRT

Field during 1999 Cotton Season October 1, 1999 AgIIS

CCCI CCCI = (C-B)/(A-B) B C A

1999 RVI (relative to WN) Last N Application Squares Green BollOpen Boll