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<br />, ~ <br />, . <br /> <br />I'.::J <br />~ <br />-4' <br />::-... <br /> <br />~:,:.. <br /> <br />6. The 1990 data also show that on surface irrigated sites, <br />perennial crops contributed about 37% of the total deep <br />percolation and annual crops about 63%. Deep percolation for <br />perennial crops remained fairly uniform throughout the season. <br />Among annual crops, the deep percolation decreased drastically <br />from the first to the second irrigation event and then <br />gradually decreased through the rest of the irrigation season. <br /> <br />7. Several years of monitoring data from improved surface and <br />sprinkler irrigated sites indicate that the ,~verall average <br />deep percolation (surface+sprinkler) for the Grand Valley is <br />approximately 16 acre inches per acre. When surface and <br />sprinkler irrigated sites are considered separately, deep <br />percolation is about 18 inches and 10 acre inches <br />respectively. Deep percolation from surface sites could be <br />reduced by as much as 50% with use of surge irrigation <br />techniques. In 1990, comparison of surge with conventional <br />sites showed that surge could also reduce total water <br />appl ication and tai Iwater runoff by about 30::{. Additionally, <br />appl ication efficiency could be increased by 10% with surge. <br /> <br />8. Atmometer data indicates that with proper care and maintenance <br />it can be used as a tool for irrigation schedul ing which would <br />help improve IWM. The atmometer ET data comes within 10% of <br />the calculated reference ET values using Penman equation. <br /> <br />9. Producers need to be assisted in the proper management <br />and operation of the new improved irrigation system <br />immediately after it is installed. <br /> <br />10. Where improved irrigation systems have been installed, the <br />deep percolation losses can be reduced substantially by proper <br />management of i nd i v i dua I i rr i gat I on events. Reduc I ng set time <br />(number of hours per set) and waiting longer between <br />i rr i gat ions (i rr i gat i on schedu ling) wou I d reduce deep <br />percolation significantly, and also increase irrigation <br />efficiency. <br /> <br />11. Proper management of i nd i v i dua I i rr i gat i on events requ i res a <br />knowledge of improved water management techniques. This can <br />be accomp I i shed best when SCS fie I doff i ce p'arsonne I can <br />regularly work with individual irrigators on a one to one <br />basis during the irrigation season so that producers wi I I <br />apply water based on crop needs. The SCS wi II especially need <br />to target those farmers that manage a large number of aCres <br />with limited man-power, and part-time and week-end farmers. <br /> <br />12. Salt load reduction through IWM can only be achieved through <br />intensive technical assistance and education programs on IWM <br />techniques and crop economics tied to water appl ication. <br />Demonstration projects on irrigation schedul ing would be very <br />effective. <br /> <br />6 <br />