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<br />. (,.] <br />C) <br />c') <br />c' <br />,.--, <br /> <br />',", <br />_..,I <br /> <br />these sites. Producers at sites 18 and 26 are of the opinion that <br />there is high water table in the fields being monitored and that <br />they do not need to irrigate as much. <br /> <br />The producer at site 16 is aware of water usage because of limited <br />water for his fields, thus, the site never gets over-irrigated and <br />deep percolation is low or non-existent. In 1991, deep percolation <br />was 5.9 inches per acre or only 15% of ETa. The desired deep <br />percolation was achieved with a 20 year old irrigation system <br />(concrete ditch with siphon tubes). The producer obtained good <br />alfalfa yield in 1991 and said that this was the best hay he has <br />produced in several years. <br /> <br />CUrrently, the monitoring water budget program does not have the <br />capacity to adjust for high water table. Additionally, there is no <br />equipment on hand that could give a quick reliable estimate of soil <br />moisture in the field to make needed adjustments to the computer <br />generated values. <br /> <br />The greatest deep percolation losses occurred at sites 37, 49, and <br />50 with over 30 inches per acre of deep percolation. site 50 has a <br />surge system and still had high deep percolation losses. <br /> <br />Comparison of sites 31 and 37 show that although they have similar <br />crop, soils and irrigation system the deep percolation losses for <br />site 31 was 24.3 inches and 36.4 inches for site 37. The <br />difference between the two sites can be attributed to slightly <br />better water management at site 31 compared to site 37. Site 37 <br />had almost 40 inches more water application than site 31, even <br />though site 31 had three more irrigations. <br /> <br />In contrast, the differences between sites 16 and 37 can be <br />attributed to differences in soil type and management practices. <br />Site 16 has Billings silty clay loam and site 37 has Hanksville <br />silty clay loam. The irrigation system and crops are similar but <br />there is a vast difference in deep percolation between the two <br />sites, 5.9 inches at site 16 and 36.4 inches at site 37. The data <br />to date indicate that Hanksville soil with shale layer at 20" to <br />40" depth is harder to manage in terms of irrigation scheduling and <br />water management. In this soil, water takes a long time to reach <br />the end of the furrow because of uneven water distribution. Water <br />tends to go underneath through surface cracks and flows over shale <br />layer and eventually to the Colorado River. Farmers keep <br />irrigating till all the furrows are wet to the end. <br /> <br />Nine of the monitored sites had deep percolation losses greater <br />than the average for 1991, 15.9 inches per acre. Sprinkler sites, <br /> <br />18 <br />