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<br />Since slack exists only in lettuce production, both total
<br />production and amount of land used decrease to
<br />accommodate the requirements of the remaining
<br />crops. Hence, hoth production and land decrease
<br />throughout the 900 to 1400 mg/I TDS range (see
<br />sub-Appendix G for more information).
<br />
<br />Table 3-68 presents a list of the shadow prices
<br />generated by the model for each land clsss. Without
<br />exception, all classes show a trend of decreasing value
<br />over the range in question. Production restrictions
<br />placed on the model require at least a certain amount
<br />of production for the crops in question. In this
<br />particular situation, assumed conditions of availahle
<br />resources are such that the model produces every crop
<br />at the lower production level except lettuce which is
<br />slack. Attainment of higher levels are constrained by
<br />lack of sufficient land area. Therefore, given the fact
<br />that lettuce production contains the only available
<br />flexibility, demand for the various classes of land has
<br />peaked and is decreasing from the initial computer
<br />run. With limited flexibility as prescribed by the area
<br />conditions, land values decrease as net returns per
<br />acre decrease causing the above mentioned trend. In
<br />previQus areas, at least one or tnore crops were
<br />produced at upper production limits. Inflexibility in
<br />the model comes from the lack of alternatives to shift
<br />acreages and production levels among several differ-
<br />ent crops. In all cases, however, shadow prices are
<br />only relative values and should be viewed in that
<br />manner.
<br />
<br />Totsl available water for agricultural purposes is
<br />considered to be 400,500 ac ft. The model water
<br />demands cannot exceed this figure. Model results
<br />indicate that water availability is not a constraining
<br />factor as considerable capacity exists betweeen
<br />amount demanded and amount available.
<br />
<br />Information relating to total amount of water
<br />used, acre feet per acre applied, and the ratio of water
<br />used to net profit is presented in Table 3-69. Total
<br />amount used varies slightly as an increase is noted at
<br />1200, 1800, and 1400 mg/l TDS. However, the total
<br />magnitude of change.is only 191 ac ft. Still, a trend is
<br />developing where amount of water used increases as
<br />salinity rises. In this case, alfalfa does not dominate or
<br />offset the demands of the other crops and the ratio of
<br />water used to net profit decreases at an increasing
<br />rate as expected. Anticipated trends also exist for
<br />data presented in Table 3.70. Stated more specifically,
<br />
<br />Table 8.69. Ratio of amount of water used to /and
<br /> and profit all by level of TDS, Gil4 area.
<br />TDS Acre Feet Ratio of Net
<br />Acre Feet Dollar Return
<br />(mg/!) Per Acre Per Acre Foot
<br />900 162,263 5.143 44.83
<br />1000 162,263 5.143 44.81
<br />1100 162,263 5.143 44.78
<br />1200 162,278 5.144 44.75
<br />1300 162,470 5.150 44.26
<br />1400 162,454 5.149 43.89
<br />Table 8-70. Total and per acre net profit by TDS
<br /> levet Gil4 area.
<br />TDS Profit Per Acre
<br />(mg/!) (Dollars) (Dollars)
<br />900 7,274,676 230.58
<br />1000 7,270,947 230.47
<br />1100 7,266,752 230.33
<br />1200 7,262,480 230.20
<br />1300 7,190,687 227.92
<br />1400 7,130,585 226.02
<br />
<br />net profit declines as salinity increases and net profit
<br />per acre also decreases. The total net profit figures for
<br />each level of TDS are plotted in Figure 3.15.
<br />
<br />Differences between each respective level of TDS
<br />and the succeeding level are derived and accumulated.
<br />Table 3-71 is constructed using these data. Fitting an
<br />expouentlal function to these data points resulted in
<br />an R2 of 0.95. Predicted values calculated from this
<br />function are also included in the table. With respect to
<br />the derived function of the order Y = beDIX, b =
<br />.194497, e = 2.718281828, m = 0.009689, and x = any
<br />level of TDS. Both the observed data points and the
<br />predicted values are plotted in Figure 3-16. Estima-
<br />tion of primary monetary damages for the TOS range
<br />considered in this report will be calculated from this
<br />type of function.
<br />
<br />Summarizing some of the general indicators of
<br />damage losses for the Gila area, total damages were
<br />found to be $144,091, annual per acre damges to be
<br />$4.57, annual damages per mg/I to be $288.18, and
<br />annual damages per mg/I per acre to be $0.00913 (see
<br />
<br />.1
<br />
<br />,
<br />
<br />Table 8.68. Shadow price. of /and by class and level of TDS, Gil4 area.
<br /> 900 1000 1100 1200 1300 1400
<br /> mg!l mg!l mg!l mg!1 mg!l mg!l
<br /> (Dollars) (Dollars) (Dollars) (Dollars) (Dollars) (Dollars)
<br />Landi 541.3 541.3 541.3 541.3 515.3 493.7
<br />Land 2 541.3 540.4 539.9 539.7 513.7 484.8
<br />Land 3 541.3 539.5 538.6 538.3 499.1 460.8
<br />Double Crop 1 541.3 541.3 541.3 541.3 515.3 493.7
<br />Double Crop 2 541.3 540.4 539.9 539.7 513.7 484.8
<br />Double Crop 3 470.0 461.2 430.0 399.5 341.9 306.4
<br />
<br />170
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