TY - JOUR
T1 - Crop water stress index computation approaches and their sensitivity to soil water dynamics
AU - Katimbo, Abia
AU - Rudnick, Daran R.
AU - DeJonge, Kendall C.
AU - Lo, Tsz Him
AU - Qiao, Xin
AU - Franz, Trenton E.
AU - Nakabuye, Hope Njuki
AU - Duan, Jiaming
N1 - Funding Information:
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Daran Rudnick, Trenton Franz, Derek Heeren reports financial support was provided by National Institute of Food and Agriculture. Daran Rudnick, Trenton Franz, Derek Heeren, and Xin Qiao reports administrative support and equipment, drugs, or supplies were provided by Water for Food Daugherty Global Institute at the University of Nebraska. Daran Rudnick reports equipment, drugs, or supplies was provided by Nebraska State Climate Office. Daran Rudnick, Trenton Franz, Xin Qiao, and Derek Heeren reports a relationship with National Institute of Food and Agriculture that includes: funding grants.
Funding Information:
This study is based upon work that was jointly supported by the United States Department of Agriculture ’s National Institute of Food and Agriculture under award # 2019-67021-29312 , “A scalable real-time sensing and decision making system for field-level row-crop irrigation management”; Hatch Project # 1015698 ; the Daugherty Water for Food Global Institute; Nebraska Extension, and the University of Nebraska-Lincoln Institute of Agriculture and Natural Resources and Nebraska Extension, USA . We extend our sincere appreciation to our research lab manager, Turner Dorr, and summer helpers who participated in data collection as well as to the Nebraska State Climate Office for their Nebraska Mesonet weather data.
Publisher Copyright:
© 2022
PY - 2022/5/31
Y1 - 2022/5/31
N2 - There is a growing interest of using canopy temperature (Tc) based methods, including crop water stress index (CWSI), for irrigation management. However, different approaches exist to normalize Tc to microclimatic conditions, which can influence the accuracy and suitability of CWSI for irrigation scheduling. This study evaluated the performance of CWSI computation approaches and their sensitivity to changes in soil water depletion under different water stress levels. There were six different approaches – two empirical methods using developed lower baseline (i.e., CWSI-EB1, CWSI-EB2), two empirical methods using either artificial (CWSI-EA) or actual/natural (CWSI-EN) canopy reference surfaces, and two theoretical approaches which differ by how aerodynamic and canopy resistances are determined (CWSI-Th1, CWSI-Th2). Stationary infrared thermometers (IRTs) provided continuous Tc to calculate CWSI-EB, CWSI-Th, and CWSI-EN; whereas mobile IRTs and a thermal camera provided one-point-in-time Tc and temperatures of artificial canopy reference surfaces to calculate CWSI-EA. These measurements were all collected from full and deficit irrigated and rainfed maize plots in West Central Nebraska. Day-to-day variations within and across CWSI approaches were evident and their sensitivity to soil water depletion varied. Greater sensitivity and correlation strength to depletion (Dr,i) were observed with CWSI-Th and CWSI-EB under severe stress (i.e., Dr,i > 80%) at deeper soil depths of 1.8 and 2.1 m, producing r2 which ranged from 0.61 to 0.80 (slope: 0.03–0.05) and 0.69–0.79 (slope: 0.03–0.04), respectively. Observed differences in stress magnitudes among approaches and treatments, warrants a specific irrigation triggering threshold for each approach. Additionally, developing a robust index coupling both CWSI and soil water depletion is desirable to improve irrigation water management by accounting for both soil and plant water status.
AB - There is a growing interest of using canopy temperature (Tc) based methods, including crop water stress index (CWSI), for irrigation management. However, different approaches exist to normalize Tc to microclimatic conditions, which can influence the accuracy and suitability of CWSI for irrigation scheduling. This study evaluated the performance of CWSI computation approaches and their sensitivity to changes in soil water depletion under different water stress levels. There were six different approaches – two empirical methods using developed lower baseline (i.e., CWSI-EB1, CWSI-EB2), two empirical methods using either artificial (CWSI-EA) or actual/natural (CWSI-EN) canopy reference surfaces, and two theoretical approaches which differ by how aerodynamic and canopy resistances are determined (CWSI-Th1, CWSI-Th2). Stationary infrared thermometers (IRTs) provided continuous Tc to calculate CWSI-EB, CWSI-Th, and CWSI-EN; whereas mobile IRTs and a thermal camera provided one-point-in-time Tc and temperatures of artificial canopy reference surfaces to calculate CWSI-EA. These measurements were all collected from full and deficit irrigated and rainfed maize plots in West Central Nebraska. Day-to-day variations within and across CWSI approaches were evident and their sensitivity to soil water depletion varied. Greater sensitivity and correlation strength to depletion (Dr,i) were observed with CWSI-Th and CWSI-EB under severe stress (i.e., Dr,i > 80%) at deeper soil depths of 1.8 and 2.1 m, producing r2 which ranged from 0.61 to 0.80 (slope: 0.03–0.05) and 0.69–0.79 (slope: 0.03–0.04), respectively. Observed differences in stress magnitudes among approaches and treatments, warrants a specific irrigation triggering threshold for each approach. Additionally, developing a robust index coupling both CWSI and soil water depletion is desirable to improve irrigation water management by accounting for both soil and plant water status.
KW - Canopy reference surfaces
KW - Canopy temperature
KW - Infrared thermometers
KW - Irrigation scheduling
KW - Mobile sensing platform
KW - Soil water depletion
KW - West Central Nebraska
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U2 - 10.1016/j.agwat.2022.107575
DO - 10.1016/j.agwat.2022.107575
M3 - Article
AN - SCOPUS:85125719728
SN - 0378-3774
VL - 266
JO - Agricultural Water Management
JF - Agricultural Water Management
M1 - 107575
ER -