Variable upper and lower crop water stress index baselines for corn and soybean

• Published in: Irrigation science Vol. 25; no. 1; pp. 21 - 32
• Main Authors: Payero, J. O., Irmak, S.
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01-10-2006
• Subjects: Agricultural production; Air temperature; Canopies; Corn; Crop science; Crops; Growing season; Irrigation; Irrigation scheduling; Moisture content; Relative humidity; Soil water; Solar radiation; Soybeans; Temperature; Thermometers; Vapor pressure; Vegetables; Water balance; Water stress; Wind speed; USA, Nebraska
• ISSN: 0342-7188; 1432-1319
• DOI: 10.1007/s00271-006-0031-2

Upper and lower crop water stress index (CWSI) baselines adaptable to different environments and times of day are needed to facilitate irrigation scheduling with infrared thermometers. The objective of this study was to develop dynamic upper and lower CWSI baselines for corn and soybean. Ten-minute averages of canopy temperatures from corn and soybean plots at four levels of soil water depletion were measured at North Platte, Nebraska, during the 2004 growing season. Other variables such as solar radiation (R ^sub s^), air temperature (T ^sub a^), relative humidity (RH), wind speed (u), and plant canopy height (h) were also measured. Daily soil water depletions from the research plots were estimated using a soil water balance approach with a computer model that used soil, crop, weather, and irrigation data as input. Using this information, empirical equations to estimate the upper and lower CWSI baselines were developed for both crops. The lower baselines for both crops were functions of h, vapor pressure deficit (VPD), R ^sub s^, and u. The upper baselines did not depend on VPD, but were a function of R ^sub s^ and u for soybean, and R ^sub s^, h, and u for corn. By taking into account all the variables that significantly affected the baselines, it should be possible to apply them at different locations and times of day. The new baselines developed in this study should facilitate the application of the CWSI method as a practical tool for irrigation scheduling of corn and soybean.[PUBLICATION ABSTRACT]