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<br />~~:?"'~'. <br />:.:.;: <br /> <br />reduced their efficiency in 1991 compared to 1990. This could be due <br />to crop change (corn to alfalfa at site 43/44 and small grain to <br />alfalfa at site 46). Site 47 had an operator change. <br /> <br />~ In 1991 the va ria t ion i n e f f i c , en c i e s for i n d i v i .d u a I i r rig a t Ion s <br />lo': ranged from 22Y. to 82Y. for surface irrigation and from '35Y. to about <br />\':::\ 907. for sprinklers (Refer to Appendix D for more details on individual <br />41. irrigations). The sites with poor irrigation efficiencies generally <br />were i rr i gated sooner and longer than needed. Improper schedu I I n9 and <br />long set times caused excessive deep percolation on some of the sites. <br />Irrigation efficiencies ,can be improved at some sites ,with better <br />irrigation scheduling and adjusting set times or inflow rates. <br /> <br />d. Surge and Conventional Irrigation Comparison: <br /> <br />In five fields, surge and conventional sites were locat~d side by side <br />(separate acreages) for comparison. Dn these fields, 29 surge <br />irrigation events were monitored on about 47.3 acres; 29 conventional <br />irrigation events on 53.4 acres were also monlt'ored. Comparison 'of <br />surge and conventional irrigation in the same field with similar soils. <br />indicated that with the use of surge systems there could be savings in <br />water application; tailwate, and deep percolation could also be <br />reduced. <br /> <br />~~~~) A t a I I f 0 U reo m p a,.. i son sit e s, the red u c t ion- j n \.oJ ate rap p lie a t ion per <br />acre was direct lyre I ated to the number of hours of water app lied per <br />acre. With surge, the reduction in hours pe, ac,e of water appl ied <br />compared to conventional ir,igation varied from 2 to 20 hours. This <br />related to an average savings of 177. or 9 hours per acre of water <br />application with the use of su,ge systems (Table 5). This means a <br />red u c t I 0 ;, of about l5Y. i n 101 ate, a p p I i cat i on to the fie I d . W ate r <br />appl ication savings ranged f,om 3.0 to 19.3 ac,e inches pe, ac,e' with <br />an average sav i ngs of 9.2 ac,e ,nches per acre (Tab I e 5). However, <br />site 50 with a surge system had more applied to the field than the <br />conventional one (Table 5), This is an exception to the norm. <br /> <br />Comparison between surge and conventional irrigation also showed a <br />reduction in tai lwater amount with surge. Two surge sites (39,50) <br />had hi ghe, runoff than convent; ona I ones, however, on the average <br />the,e was a 3.8 acre inches pe, acre reducti on (Tab I e 5) for the <br />season, about 217. savings. <br /> <br />With reduced water application at su,ge sites, infiltrated depth also <br />decreased by an average of 5,4 inches per acre, about 12% savings <br />(Table 5). Reduction in infiltrated depth varied from 0.1 acre inches <br />per acre to 11.3 acre inches. The reduction In infi ltrated ,depth also <br />helped reduce deep percolation. Table 5 shows that deep percolation <br />reduction is directly proportional to infiltrated depth. <br /> <br />19 <br />