|Johnson, Karl - JOHNSON FARMS|
Submitted to: Workshop on Computer Applications in Water Management Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 23, 1995
Publication Date: N/A
Interpretive Summary: Irrigation scheduling can improve irrigation management decisions and reduce irrigation water use. A computer program called the SCS-Scheduler was used to schedule irrigations on a farm in the Texas High Plains in the Southern High Plains since 1991. The program helped the farmer make wise irrigation decisions and farm yields exceeded county average yields in excess of 25% and produced efficient use of water. Crop parameters needed for the model were determined from research measurements at Bushland, TX. The equation used in the SCS-Scheduler program to estimate maximum crop water use rates was compared with other widely used methods. The SCS- Scheduler program performed well in this evaluation, but obtaining data needed for input to the program remains somewhat difficult.
Technical Abstract: The SCS-Scheduler program has potential to improve water management but has not been evaluated widely in the Western U.S. The SCS-Scheduler program was evaluated on a farm in the Southern High Plains since 1991. The program provided useful information to the grower to schedule irrigations for winter wheat, corn, and sorghum. Field yields from scheduled fields were considerably above county-wide average irrigated yields and water use efficiency values indicated good irrigation management. Crop coefficients were determined for use in the SCS-Scheduler for wheat, corn, sorghum based on measured evapotranspiration at Bushland. The SCS-Scheduler PET (potential evapotranspiration) method was found comparable with the NP-PET values based on the Penman-Monteith equation but slightly higher than those estimated using Ref-ET based on ASCE Manual No. 70.