Jan 10, 2006 9:26 AM
By Blake Sanden, Irrigation, Agronomy Farm Advisor, UCCE, Kern County, Calif.
California water planners and the environmental community would like to meet increasing urban water demand by efficiency improvements in ag irrigation. A 75 percent to 80 percent irrigation efficiency has been considered good to excellent in the past. However, Kern water districts and growers have said for more than 20 years that they are operating at a higher efficiency due to increasing water costs and continued low commodity prices.
New innovations in microelectronics now provide cost-effective opportunities for growers to monitor soil moisture to document and, in some cases, improve the precision of irrigation to increase crop yield. Starting in the winter of 2001 Kern UCCE worked together with the local Resource Conservation District Irrigation Mobile lab to instrument grower’s fields with neutron probe access tubes, tensiometers, electrical resistance blocks (Watermarks) and a continuously recording data logger (Hanson AM400) with a visual display that does not require downloading to a computer.
Growers were faxed one page weekly irrigation scheduling recommendations also containing a seasonal summary of CIMIS ET estimates, soil moisture and applied water history to optimize crop performance and irrigation water use efficiency (WUE). Additional fields on the Westside of Kern County were added to this program in 2002 as part of a two-year CalFed Ag Water Use Efficiency project. Additional grower fields (from 8 to 18) have been instrumented every year since 2003 with a low-cost logger/sensor combination for a total of 138 fields covering 11,491 acres farmed by 27 different producers in 14 different crops, 11 soil textures and 9 different irrigation system types have been set up by the end of 2005.