Canopy temperature bias from soil variability enhanced at high temperatures

Authors: DeJonge, Kendall; Zhang, Huihui; TAGHVAEIAN, SALEH - Oklahoma State University; Trout, Thomas

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/28/2019
Publication Date: 3/4/2020
Citation: DeJonge, K.C., Zhang, H., Taghvaeian, S., Trout, T.J. 2020. Canopy temperature bias from soil variability enhanced at high temperatures. Transactions of the ASABE. https://doi.org/10.13031/trans.13554.
DOI: https://doi.org/10.13031/trans.13554

Interpretive Summary: Maize canopy temperature was monitored on a continuous basis for two seasons in a limited irrigation maize experiments with 7 treatments and 4 replicates. Soil electroconductivity (EC) was measured and mapped to quantify variation in soil texture throughout the plots, and was correlated to soil field capacity. At lower temperatures indicating little or no stress, very little difference was observed between replicates within the same treatment. However, at higher temperatures soil texture (via EC) could bias canopy temperature up to 6 °C between replicates. Results demonstrate that canopy temperature under water stress has an increasing bias as stress is increased.

Technical Abstract: Maize canopy temperature was monitored on a continuous basis for two growing seasons in a limited irrigation maize experiment, with 7 separate irrigation treatments and 4 replicates of each treatment. Soil electroconductivity (EC) was measured and mapped to quantify variation in soil texture throughout the plots, and was correlated with average field capacity of the soil (R2 = 0.51). At lower canopy temperatures indicating little or no water stress, very little difference was observed between replicates within the same treatment. However, at higher temperatures soil texture had a greater influence on temperature with soils having lower EC (and therefore lower water holding capacity) showing more water stress. More specifically, at canopy temperatures above 29°C the influence of soil texture biased the temperature up to 2.0 °C over the EC range of 15 to 40 mS/m, and at canopy temperatures of 35 °C this bias can be nearly 6.0 °C between replicates. Similar results to continuous infrared thermometry were also found using nadir thermal images. Results indicate that placement of infrared thermometers should consider soil texture if the intent is to obtain a non-stressed or "least-stressed" baseline or reference.