Submitted to: Irrigation Association Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 2, 2002
Publication Date: October 26, 2002
Citation: THOMSON, S.J., FISHER, D.K., THOMAS, D.L. EXPERIENCES WITH THE UGA EASY EVAPORATION PAN FOR IRRIGATION OF COTTON GROWN IN MIDSOUTH CLAY SOILS. IRRIGATION ASSOCIATION CONFERENCE PROCEEDINGS. 2002. CD-ROM. Interpretive Summary: Simple but effective methods are needed to schedule irrigation on the farm. Soil moisture sensors, evaporation measuring devices, and models that predict crop water use do a good job predicting when to irrigate and how much water to apply, but they have found only limited use by farmers. The time involved reading and interpreting sensors and instruments in a labor-intensive farming operation has precluded their use in most cases. A unique evaporation pan whose readings can be seen from the edge of the field has good potential for farmer adoption. This device, first developed by researchers at the University of Georgia, consists of a washtub with a float connected to an adjustable rod that is hinged to allow it to swivel. The rod is connected to a pointer, which indicates crop water status against a back plate. The back plate has a black line that indicates when soil is saturated and a red line that signals when to irrigate. Preliminary tests of the pan for irrigation scheduling of cotton indicated that the pan could be used successfully for Midsouth clay soils with minor adjustments to the basic design.
Technical Abstract: A novel, yet simple, device was developed to provide farmers with a visible indication of evaporation, which can be related to crop water use. The UGA EASY evaporation pan consists of a washtub with a float connected to an adjustable rod that is hinged to allow it to swivel. The rod is connected to a pointer, which indicates crop water status between lines drawn on a back plate that can be seen from the road. A black line indicates field capacity and a red line signals to the observer when to irrigate. The rod can be adjusted back and forth according to soil/crop combination and period of the season. Preliminary experiences using the UGA EASY Pan irrigation scheduler for cotton grown in a Sharkey clay soil are presented. Data from soil moisture sensors placed at three depths provided additional indication (other than visual) of crop water stress and gave an idea of the zone of root activity. Results indicated that the EASY pan could be adapted to crops grown in Midsouth clay soils with minor adjustments to the basic design. Good correlation was observed between readings from the pan and soil water sensors.