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ARS Home » Southeast Area » Tifton, Georgia » Southeast Watershed Research » Research » Publications at this Location » Publication #227019
Title: Therman Infrared Imaging In Agriculture Using a Small Unmanned Aerial System

Author
item Sullivan, Dana
item BLAND, G - NASA GODDARD
item FULTON, J - AUBURN UNIV
item SHAW, J - AUBURN UNIV
item ENDALE, D - UGA
item LEE, R - UGA

Submitted to: International Geoscience and Remote Sensing Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2008
Publication Date: N/A
Citation: N/A

Interpretive Summary: Thermal infrared (TIR) emittance from agricultural fields shows great promise as a tool to evaluate crop productivity, monitor stress, predict yield and evaluate management alternatives. However, the utility of TIR imagery has been complicated by: 1) infrequent acquisitions, 2) coarse spatial resolution and 3) expense. An alternative to satellite and manned aircraft acquisitions is the use of small unmanned aerial systems (SUAS). Two ongoing studies utilizing a SUAS with TIR have been established in the Southeastern Coastal Plain (Georgia) and Tennessee Valley (Alabama) physiographic regions. At each site a SUAS was used to collect TIR imagery over an actively transpiring crop canopy as a measure of crop response to tillage, crop residue management and irrigation. Thermal infrared imagery was collected during peak crop water use periods over continuous cotton (Gossypium hirsutum L.) in the Tennessee Valley and a three-year corn (Zea Mays L.) rotation in the Coastal Plain. Results demonstrated that TIR imagery provided a more accurate and consistent measure of differences in crop response to management practice. However, preliminary results from the Coastal Plain site indicate that under severe stress and low canopy cover, thermal infrared estimates of crop response may be confounded by bare soil and/or crop residue exposure.

Technical Abstract: Thermal infrared (TIR) emittance from arable lands shows great promise as a tool to evaluate crop productivity, monitor stress, predict yield and evaluate management alternatives. However, the utility of TIR imagery has been complicated by: 1) infrequent acquisitions, 2) coarse spatial resolution and 3) expense. An alternative to satellite and manned aircraft acquisitions is the use of small unmanned aerial systems (SUAS). Two ongoing studies utilizing a SUAS with TIR have been established in the Southeastern Coastal Plain (Georgia) and Tennessee Valley (Alabama) physiographic regions. Studies were established to evaluate the integrated effects of tillage, cover crop management and irrigation on crop response. Crops consisted of continuous cotton (Gossypium hirsutum L.) in the Tennessee Valley and a three-year corn (Zea Mays L.) rotation in the Coastal Plain. At both sites, TIR (7 – 14 µm) imagery was acquired during peak crop water use periods at an approximate altitude of 90 m and spatial resolution of 0.5 m. Coincident with image acquisition, ground truth consisting of soil water content (0-5 and 0-25 cm), stomatal conductance and canopy cover were collected. Results from the Tennessee Valley location indicate that, compared to field measurements of stomatal conductance with within plot coefficients of variability ranging from 2%-75 %, variability in TIR emittance (< 40%) a more stable measure of crop response to current conditions. Using the SUAS, TIR emittance was more sensitive to irrigation and winter cover crop management compared to direct measures of stomatal conductance. Preliminary analyses from the Southeastern Coastal Plain site indicated TIR emittance also corresponded well with crop response to irrigation. However, in non-irrigated treatments where canopy closure was severely stunted, background crop residue and/or soil emittance inflated estimates of canopy temperatures, incorrectly suggesting lower transpiration rates in minimum tillage treatments.