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1 enough. This extra. water percolates below the rdot zone, and all too 2 often is either wasted, or worse, creates serious waterlogging or salin- 3 ity problems. This waste of both water and productive land must be pre- 4 vented if we are to intensify food production in present full-scale 5 irrigation projects. ~ ;, J,., 6 The use of closed conduits to distribute water within a field can 7 eliminate nonuniform infiltration caused by nonuniform soil properties 8 by transferring control from the soil to the irrigation system. This 9 occurs as the direct result of eliminating surface flow. If water is 10 applied uniformly to the soil from a closed-conduit system at a rate 11 less than the soil infiltrability, the infiltration rate ,Jill equal the 12 application rate, and every portion of the field can receive the same. 13 quantity regardless of soil nonuniformity. Because the closed-conduit .' 14 system effectively delivers'water to each plant, no minimum depth need 15 be applied to attain uniform distribution. As a consequence, water can 16 be applied in small enough quantities that the storage capacity of the 17 soil is not exceeded in any part of a field. In fact, if irrigations 18 are made frequently enough, the storage capacity of the soil is of such 19 little importance that one can farm extremely coarse-textured soils that 20 would otherwise be useless. Uniform, fre~uent irrigation made possible 21 with closed-conduit irrigation systems can, therefore, drastically 22 reduce the quantity of water lost by deep percolation, and can permit 23 this saved water to be used on marginal lands that otherwise could not . 24 be farmed. 25 Irrigating frequently can also optimize soil conditons for crop '26 growth (3). For one thing, it maintains the soil water content high. 27 The ri'ason for this lies in the fact that ,dth frequentVi..r~i~,*an,