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<br />o <br />l.'? <br />(f")' <br />o <br /> <br />. -, <br />'-..) <br /> <br />. <br /> <br />. <br /> <br />-, <br /> <br />CONCLUSIONS <br /> <br />It is theorized that some deep percolation is required to keep <br />salinity levels from rising into the root zone. Irrigation systems <br />such as microsprays (sites 17 and 28) and sideroll sprinklers (sites <br />33, 35, and 36) are eas i er to measure and contro I the percentage of <br />deep percolation, because they have a relatively uniform application <br />rate. These systems could be used to determine the minimum percentage <br />of deep percolation required to keep salinity below the root zone. <br /> <br />Furrow irrigation to establ ish a crop from seed wi II undoubtedly <br />result in a high percentage of deep percolation until the crop is <br />established. Soils in the monitoring area have properties which cause <br />them to wet across slowly and properties which cause excessive surface <br />crusting. Soi I surfaces must be kept moist during establ ishment to <br />keep plants from crusting in. These soi I conditions wi II result in a <br />high percentage of deep percolation from furrow irrigation during <br />estab I I shment of crops. Th i s is ill ustrated in Tab I e 8, Part I of <br />this report. The greatest amount of deep percolation for annual crops <br />occurs during the first irrigation when seedlings are being <br />estab I i shed. <br /> <br />Cu I tura I pract ices may have as much to do with the annua I changes In <br />Eee readings as actual rise In salinity levels in the surface 6 <br />inches. <br /> <br />Increases in soi I sal inity levels wi II probably occur when the amount <br />of deep percolation is below the acceptable amount required to keep <br />sal inity levels below the root zone (Refer to Part I for more detal Is <br />on acceptable deep percolation). <br /> <br />26 <br />