Use of Surface Renewal Method for ET Estimation Under Saline Conditions.

In the western San Joaquin Valley (WSJV) soil salinity and poor drainage have been major constraints to agricultural production for decades.  Most recently severe reductions in irrigation water deliveries have increased the need for the utilization of saline water sources for irrigation.  A current practice is to grow salt tolerant row crops and forages on fields irrigated with saline-sodic drainage water (DW).   Although region-specific ETc estimates exist for most of the major crops in this area, ET estimates under saline irrigation are lacking, particularly for these less conventional, salt-adapted forages. This research is aimed at refining estimates of forage ETc utilizing micro-meteorological methods based on Surface Renewal (SR) technology.  Such ETc estimates will be useful for irrigation districts in calculating the volume of DW required for growing these forages under saline irrigation.  SR is a lower cost system which is beginning to be employed in this area and shows promise as a robust method better suited to the more patchy growth and heterogeneous canopies common to saline fields.