Irrigation Scheduling for Improved Water Use Efficiency at Crop Field Level.

In this study, we used a Bowen ratio technique to partition energy fluxes between maize transpiration and soil evaporation at crop field level. Results from this technique were compared to sap flow gauges and weighing lysimeter measurements. Also, the Bowen ratio technique measurements were taken during a six days wet (daily irrigation) and dry (irrigation was halted) periods. During the wet period, canopy and soil surface were fully evaporating water and no major energy exchanges between soil surface and canopy were observed. During the dry period, the canopy was absorbing sensible heat flux that was generated at soil surface. The later contributed up to 31% to latent heat flux from canopy. This study shows the importance of irrigation scheduling in reducing soil evaporation, increasing transpiration, and consequently improving water use efficiency at crop field level.