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<br />I, <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />1882 <br />relationships shown on Figures 3.5 and 3.6 depict the impact of <br />reduced crop evapotranspiration on yield. Crops harvested for <br /> <br />their vegetative parts, such as alfalfa, silage and hay crops, <br /> <br />generally have a linear yield relationship to water availability. <br />For example, if consumptive use is reduced 50 percent, crop growth <br />will be reduced to approximately 50 percent of its potentiaL A <br />different relationship exists for crops grown for their fruiting <br />parts (i.e. dry beans or grain corn). For these plants, water <br />shortages have different effects on yield depending on the time and <br />severity of the shortage. Water shortages usually have the most <br />severe impact during periods of germination, flowering, and <br />pollination. For these crops/ a general reduction of water to 50 <br />percent of that required may result in the loss of the entire crop, <br />particularly if water is limiced at one of the specific periods <br />mentioned above. However, if adequate water is supplied at the time <br />of flowering and pollination, respectable yields may be obtained. <br />The timing of water availability is often as important as the total <br />supplied. <br /> <br />The total amount of water which must be supplied to achieve optimum <br /> <br />crop growth must take into consideration the consumptive use <br />requirements of the chosen crops. In addition, (as discussed in <br /> <br /> <br />Chapter 4) the quality of the water supplied may require that an <br /> <br /> <br />additional amount will be needed to satisfy the leaching requirement <br /> <br /> <br />and prevent the build-up of salts in the irrigated soils. <br /> <br />3- 20 <br />