Intercomparisons of Irrigation Scheduling Methods in Cotton Using Canopy Temperature.

In arid and semiarid regions where water resources for irrigation are being depleted, methods for more efficient irrigation scheduling are needed for commercial growers.  Canopy temperature (Tc) provides an easy to acquire indication of crop water deficit that has been used in irrigation scheduling systems, but interpretation of this measurement has proven difficult.  We compared the Stress Time method of irrigation scheduling with Stress Degree Hours on deficit irrigated cotton. To compare these two methods we developed coefficients for the Crop Water Stress Index (CWSI) appropriate for cotton grown our location here in West Texas.  Finally, we used the Cotton2k crop simulation model to simulate the amount of drought stress each day through the growing season for each deficit irrigation strategy. Each method for scheduling irrigation applied different amounts of water at different crop growth stages.