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<br />........, <br />....... <br />'~1 "-'. <br /> <br />~. <br />f.,. <br />~.';' <br />~ <br /> <br />(.;~!~;, <br /> <br />Most sites ~ere more than adequately irrigated. According to M&E <br />data, site number 18, 26 and 51 appear to be under irrigated. <br />Ho~ever, field moisture testing indicated adequate moisture during the <br />time M&E data indicat~d the field to be deficit. AI I these three. <br />sites have high water table and the operators krie~ the field did not <br />need to be i rr i gated very long. <br /> <br />Sites that have low deep percolation, about 15 to 207. of ETa, e.g. 16, <br />and 13 tend to be under-irrigated during the second through fourth <br />irrigation events (refer to individual irrigation data in Appendix D). <br />Surge sites such as 39 and 41 also tend to be under-irrigated. Some <br />sites with f~irly high Qveral I deep percolati6n for the season ~ere <br />under-irrigated at times. Site 33 with sprinkler had lo~ deep. <br />percolation and was under-irrigated most of the season. <br /> <br />g. Infiltration Estimates: <br /> <br />Figure 2 sho~s the application infiltration rates for the various <br />sites mon i tored in 1991. From these data, the app I i cat i.on <br />infiltration rate for the different soils monitored is provided in <br />Figure 3. The application infiltration rates have been extrapolated <br />from the individual site summary data provided in Appendix O. The <br />i nf i I trated depth ~as d i v i ded by the number of hours per set to <br />determine an appl ication inf'j 1 tration rate in inches per' hour. <br /> <br />In the above calculation, the wetted perimeter ~as not taken into <br />consideration and the data shown is based on 1007. ~etted acreage. In <br />the Grand Valley, it can be safely assumed that ~ith furro~ irrigation <br />the wetted.perimeter is actually less then 50/.. This means that the <br />application. infiftration rates provided in Figures 2 and 3 may be <br />dou~led f~r ~ites ~ith every row irrigation to get an esti~ate of <br />average soi I intake. rate (This is a conservative estimate based upon <br />having only half, 507., of the soil surface actually wetted and the <br />appl ication infi Itration rate based upon total, 1007., ~etted surface <br />area). Alternate ro~ irrigation is also fairly common in the Valley <br />and with this method the ~etted perimeter may be assumed to be about <br />257.. The app Ii cati on i nf i I trat i on rates prov i ded in Fi gure 2 may be <br />multipl ied by a factor of four when deal ing. ~jth alternate ro~ <br />irrigation in order to estimate soil intake rate. <br /> <br />Infiltration rate for the first irrigation is generally higher for <br />annual ro~ crops, but not necessari Iy so for perennial crops (Figure <br />2). The monitoring data indicates that for some soils such as Fruita <br />clay loam and Mesa clay loam, the infiltration rate may be higher than. <br />current estimates. Monitoring data from 1985 to 1989 also indicate <br />this to be true. <br /> <br />24 <br />