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<br />In 1995, about half the sites monitored had deep percolation losses <br />~ greater than the 15% of ETa. This is considerably better than in the <br />1'-) past where only. one-third of the farmers stayed be~ow the 15% level. <br />00 NRCS has establ~shed a target of 15% deep percolat~on. <br />Co <br /> <br />Deep percolation decreases of 7.1 inches per acre in 1995 compared to <br />1994 could be related to dry spring weather in 1994. The below normal <br />precipitation in 1994 caused farmers to irrigate more frequently in <br />order to keep up with the drought conditions <br /> <br />Application Efficiency: Application efficiency is calculated as inflow <br />minus outflow minus the deep percolation divided by inflow, expressed as <br />a percentage. As a result, when there is under-irrigation, the <br />calculated application efficiency values will be very high and may not <br />necessarily be an indication of good irrigation. The seasonal <br />application for all sites is provided in Table 3. The table shows <br />average application efficiency to be 44% for surface irrigation sites. <br /> <br />The overall seasonal irrigation application efficiency was 45% in <br />1991,1992,1994; 48% in 1993, and 32% in 1995. This is considerably <br />better than 1985, which had an efficiency of 30%. A comparison of <br />irrigation monitoring data from 1985 to 1989 shows that during this <br />period irrigation efficiency increased progressively from year to year, <br />resulting in less water application, reduced runoff, and less deep <br />percolation (Table 3). Ten years of monitoring data indicate the <br />average application efficiency to be about 44% (Table 3). <br /> <br />In 1995 the variation in efficiencies for individual irrigations ranged <br />from 10.1% to 84.8% for surface irrigation. The sites with poor <br />irrigation efficiencies generally were irrigated sooner and longer than <br />needed. Improper scheduling and long set times caused excessive deep <br />percolation on some of the sites. Irrigation efficiencies can be <br />improved at some sites with better irrigation scheduling and adjustment <br />of set times or inflow rates. Landowners received site summaries of the <br />irrigation season and recommendations for improvement. <br /> <br />surqe and Conventional Irriqation Comparison: <br /> <br />A three year study of a comparison between surge and conventional <br />irrigation was conducted by Colorado Cooperative Extension. This report <br />is available from cooperative Extension. <br /> <br />Trends <br /> <br />summary of Hydrosalinity Monitoring and Evaluation in the Grand Valley <br />CRSCP in Colorado <br /> <br />Issue: <br /> <br />NRCS has conducted hydrosalinity monitoring in the Grand Valley Project <br />of the Colorado River Salinity Control Program for eleven years, at a <br />cost of approximately $705,000 including staff and equipment. The data <br />collected adequately represents the effect of the salinity control <br />program on irrigated fields. Funding has steadily and significantly <br />declined from early project years, creating staffing pressures to meet <br />both monitoring/evaluation and obligations with participants. <br />Managerial, programmatic, and technical aspects of the project must be <br />considered and kept in balance in order to satisfy all of the <br />stakeholders of the project. <br /> <br />11 <br />