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<br />alternative cultural or management practice would be needed <br />~ to ensure stand establishment. <br />W <br />eo 4) Excess pre-irrigation, or the first irrigation, is the <br />~ biggest contributor to seasonal deep percolation losses. <br />This is directly related to high infiltration rate during <br />these irrigations, which subsequently decreases after the <br />first irrigation. <br /> <br />5) The 1992 data for surface irrigated monitored sites indicate <br />that, on the average, about 51% of the seasonal deep <br />percolation losses occurred during the first irrigation <br />event and about 57% by the end of the second irrigation. <br />The GV 1992 values are 30% and 45% respectively. <br /> <br />6) Deep percolation can be reduced by as much as 40 to 50% with <br />use of the surge technique. The GV 1992 value = 30 to 50%. <br />Using CSUCE data from 72 irrigation events, there was an <br />average savings of about 6.3 inches of deep percolation per <br />acre from the surge sites as compared with the conventional <br />sites. The GV 1992 value is 10.5. <br /> <br />f;~%" <br /> <br />7) Where improved irrigation systems have been installed, the <br />deep percolation losses can be reduced SUbstantially by <br />proper management of individual irrigation events. <br />Reducing set time (number of hours per set) and waiting <br />longer between irrigations (irrigation scheduling) would <br />reduce deep percolation significantly, and also increase <br />irrigation efficiency. <br /> <br />.),"r. <br /> <br />~. :" ".1 <br />."'i.". <br /> <br />1'...... <br /> <br />C) summary of water budgets <br />The results of the 1992 irrigation monitoring evaluations are <br />presented in individual site summaries located in Appendix A. <br />Table 2 summarizes the seasonal data, and represents ,the total <br />flows on and off, the field, total deep percolation and ET. ' <br />This information has been extracted from individual irrigation <br />summaries provided in Appendix A. <br /> <br />The precipitation and ETa data shown on Table 2 are measured <br />from planting date to harvest date. The amounts in these <br />columns vary for each site because of the length of record for <br />different crops. Some of the variations are due in part to the <br />different crops and climatic variations at each location. <br /> <br />Under individual summaries, the ETa and precipitation data are <br />shown on the tables as a value for each irrigation event. The <br />value shown is the calculated ET for that particular crop from <br />the time of a previous irrigation event; or for the first <br />irrigation event it is the ETa from the beginning of plant <br />growth to the date of the irrigation event. <br /> <br />. ::~~;-;. <br /> <br />14 <br />