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<br />r--- <br />~ <br />M <br />f:;\ <br /> <br />. <br /> <br />. <br /> <br />".~-\ <br /> <br />deficit irrigation from the second to seventh irrigation, the plant <br />water needs were never met during these irrigations. The last 2 <br />irrigations had some excess deep percolation. <br /> <br />CONCLUS IONS <br /> <br />Based on the last 5 years of data, the following tentative conclusions <br />can be made at this time. <br /> <br />1. Poor irrigation efficiencies occurred at some sites <br />because the fields were irrigated too soon and too long. <br /> <br />2. AI I of the monitored surface irrigation systems are capable of <br />irrigating at 50% or greater efficiency with proper <br />management. <br /> <br />3. For surface irrigated monitored sites, on the average, 35% <br />of the seasonal deep percolation losses occurred by the end of <br />the first irrigation event and about 48% by the end of second <br />irrigation <Table 8). For annual crops (beans, small grain <br />and corn) 51% of deep percolation occurred by the end of the <br />first irrigation and about 64% by the completion of the second <br />irrigation <Table 8). <br /> <br />4. On surface irrigated sites, deep percolation for perennial <br />crops remain fairly uniform throughout the season. Among <br />annual crops, the deep percolation decreases drastically from <br />the first to the second irrigation event and then gradually <br />decreases through the rest of the irrigation season (Table 8). <br />Perenn i a I crops contr i bute about 31% of the tota I deep <br />percolation and annual crops about 69% <Table 8). <br /> <br />5. Excess pre-irrigation and or the first irrigation is the <br />biggest contributor to the seasonal deep percolation losses. <br />This is directly related to the high infiltration rate during <br />these irrigations, which subsequently decreases after the <br />first irrigation. This is supported by the "advance time" <br />data obtained from some of the monitored sites. When <br />infiltration is high, it takes longer for the water to reach <br />the end of the furrow. The "advance time" is less during <br />later irrigations because of the decrease In infiltration rate <br />due to seal ing of the surface. <br /> <br />6. Where improved i,-rigation systems have been installed, the <br />deep percolation losses can be reduced substantially bv proper <br />management of i nd i v i dua I i rr i gat i on events. <br /> <br />7. Proper management of individual irrigation events requires a <br />knowledge of improved water management techniques. This can <br /> <br />23 <br />