Field Variability of Irrigated Cotton Foliage Temperatures

D. F. Wanjura and D. R. Upchurch


Accurate irrigation scheduling is needed to optimize the flexibility of center pivot irrigation systems for applying small irrigations in a timely manner. A method of irrigation scheduling that uses continuously measured canopy temperature can control sprinkler systems provided that the measured temperatures are representative of the field. Canopy temperatures were measured in a 160 acre field watered by a center pivot irrigation system. Temperatures were measured at multiple-fixed locations in three transects with handheld infrared thermometers to characterize the spatial variability of cotton canopy temperature. Averaged across days, 52 percent of the locations in all transects had canopy temperatures that equaled their daily transect averages. Canopy temperatures at 60 percent of all locations were within ± 1.0 C of the average temperature on every day of measurement, but on only 10 percent of the days were 95 percent of all locations within that range. Temperatures measured at multiple single locations or from larger areas are possibilities for estimating the field average within ±1.0 C.

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pp. 549 - 552
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998