Weekly NDVI Relationships to Height, Nodes and Productivity Index for Low, Medium, and High Cotton Productivity Zones T. Sharp, G. Evans and A. Salvador Department of Agriculture Jackson State Community College Jackson, TN January 5-9, 2004 Beltwide Cotton Conference

Introduction  Researchers have been trying to identify crop management zones based mainly on the variability of the crop yield.  Airborne multispectral imaging of cotton can provide important spatial information. o Spatial variations in crop vigor can be observed in green, red and near infrared wavebands.  Multispectral images can be used to monitor the spatial and temporal changes in the growth of crops.

Ground-Based Imaging Systems New ground based imaging systems are being developed by various researchers. New ground based imaging systems are being developed by various researchers. Ground based imaging can possibly supplement airborne imaging systems in crop production applications. Ground based imaging can possibly supplement airborne imaging systems in crop production applications. GreenSeeker ® was developed by a research team at Oklahoma State University for use in crop production applications as a ground based imaging system. GreenSeeker ® was developed by a research team at Oklahoma State University for use in crop production applications as a ground based imaging system.

Objective: The objective of this study was to investigate (or ground-truth) the potential use of the “GreenSeeker ® ” “GreenSeeker ® ” sensor system for use in cotton production.

Materials and Methods The study site was established in 1998 and has been in continuous study since. The study site was established in 1998 and has been in continuous study since. Zones were established in 2000 using airborne multispectrial imagery and image analysis. Zones were established in 2000 using airborne multispectrial imagery and image analysis. Zones on this site are stable temporally and spatially. Sharp 2003 Beltwide Cotton Conference. Zones on this site are stable temporally and spatially. Sharp 2003 Beltwide Cotton Conference.

Karcher Farm Site Site established in 1998 Site established in 1998 First Imagery in 2000 First Imagery in 2000 Zone data for 2000, 2001, 2002, 2003 Zone data for 2000, 2001, 2002, 2003 Fayette County

Study Design Four farm replications established. Four farm replications established. One field of each pair has been in conventional (CV) management since One field of each pair has been in conventional (CV) management since VR CV Example of one of four farm replication sites

Image Based Control (or Check) Each year aircraft based imagery has been obtained Each year aircraft based imagery has been obtained Field based ground- truth sampling has been annually collected for zone confirmation since Field based ground- truth sampling has been annually collected for zone confirmation since 2000.

2003 GreenSeeker ® Data Trial Data Collected Data Collected GreenSeeker ® NDVI data was collected with a JD 6000 mounted 4-row imaging system GreenSeeker ® NDVI data was collected with a JD 6000 mounted 4-row imaging system GreenSeeker ® NDVI data was collected with a hand carried one row system GreenSeeker ® NDVI data was collected with a hand carried one row system Plant physical data was collected weekly from each low, medium and high zone Plant physical data was collected weekly from each low, medium and high zone

Field Study Design Four different farm site locations (4 Site Reps) Four different farm site locations (4 Site Reps) Each farm site classed into low (L) medium (M) and high (H) productivity zones. Each farm site classed into low (L) medium (M) and high (H) productivity zones. Within each zone Within each zone four different georeferenced point sample data collection locations (4 Point Sample Reps / zone) four different georeferenced point sample data collection locations (4 Point Sample Reps / zone) 16 Observation sites per zone. 16 Observation sites per zone.

Data Collected On a weekly basis the following data was collected. On a weekly basis the following data was collected. GreenSeeker ® NDVI GreenSeeker ® NDVI Cotton Height Cotton Height Total Nodes Total Nodes Elongation of the 4 th internode Elongation of the 4 th internode Standard COTMAN © data Standard COTMAN © data End of season End of season Total final plant maps Total final plant maps Aircraft platform multispectral imagery Aircraft platform multispectral imagery Crop Yield Crop Yield

Results: NDVI by Weekly Observation After June 30 th, the “L” zone always expressed a lower NDVI than the “M” and “H”. Dry Wet and Cool 10 Oz Pix 6 Oz Pix 16 Oz Pix

Height Elongation 4 th Internode NDVI Total Nodes Composite representations of weekly plant physical measurements. (HT / NDVI) + (Nodes / NDVI) Power Index

Low Zone Medium Zone High Zone Zone Characteristics Low zone Fewest Nodes Fewest Bolls per node Medium Zone Medium in Node Production Highest in first position bolls on nodes 6, 7, 8 and 9 High Zone Most total nodes Most nodes with bolls

Stability Comparison Geo-coded pixels comparing year 2001 Base Image to the 2002 and 2003 zone classed maps

Yield by Zone by Year for Conventional Management Zones are different. Zones are different. Zone productivity may not agree with zone yield. Zone productivity may not agree with zone yield. Zone yield is an expression of zone management success or failure. Zone yield is an expression of zone management success or failure

Conclusions GreenSeeker ® accurately represented the zones as identified by historical and same year aircraft image data. GreenSeeker ® accurately represented the zones as identified by historical and same year aircraft image data. Weekly GreenSeeker ® NDVI data agreed with weekly physical ground truth plant measurements Weekly GreenSeeker ® NDVI data agreed with weekly physical ground truth plant measurements

NDVI data and final cotton yield my not agree NDVI data and final cotton yield my not agree Productivity (Vigor) zones are accurately mapped through the use of imaging systems Productivity (Vigor) zones are accurately mapped through the use of imaging systems Conclusions: Acknowledgements: National Science Foundation National Cotton Council Cotton Incorporated N-Tech Industries Oklahoma State University SST Development Group (SST Toolbox) GPS Inc. (Johnny Williams)