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(j ~, .. ;,i,.' o4:lo. l\) W 0) ..... . " . Annual expenditures to operate and maintain irrigation improvements are also given in Table 5. These costs which include labor are higher in all cases than the base conclitions because of the previously stated assumption that improvecl management would be a part of the program. Specifically, a farmer whose improvements ranged from simple head c1itch linings to complex pressurizecl systems would be expected to inclucle irrigation scheduling compo- nents et peak operating efficiency. If these assumptions are not valicl'or not included in the quality control program, many improvements would actually show nagstive 0 & M casts because of labor savings. The pressurizecl system shoulcl still heve acIc1ed 0 & M costs because of greater equipment complexity. The costs of pumping ancl aclding pressure to the irrigation water, above those for the bsse conclitions, are presentecl in Table 5. These costs have been delin....ted from the 0 & ~ c.osts to illustrate the consequences of chang- ing irrigation systems. Energy costs are increasing much faster than other ,irrigating costs. and, therefore, shoulcl be evaluatecl eareful1y in salecting on-farm salinity control measures.. The energy cost results shown in the last column of Table 5 shoulcl be understood since the impression may be given that converting to sprinkle and trickle irrigation systems al"Ways means more energy bills. This may not be true if an existing groundwater suppliecl surface irrigation system is highly . inefficient. For example., conversion to a sprinkler system may actually relluce energy costs since the increasecl efficiency.means less water pumpecl even though the pressure is higher. Ii The total annual costs associated with each alternative irrigation system improvement can be c1eterminecl by summing the average values. One can see that annual costs cover a wide range in the irrigstion industry. Simple head ditch linings are more than an orcler of magnitucle cheaper than most of the pressur- ized conversions. However, the improv~~ent in application efficiency is also a factor in the cost-effectiveness of the measure as a salinity control alter- native. Ueecl ditch linings would improve the irrigation efficiency by the amount of seepage prevented, whereas the remaining improvements also create increases clue to better water control ancl uniformity. ~ The values presentecl in Table 5 agree quite closely with the data pre- sented by Reed et al. (1977) for the same field sizes. Reecl et al. (1977) c1icl not inclulle annualized initial investment costs, but c1icl inclucle taxes, insur- ance, ancl depreciation. Development of the On-Farm Cost-Effective Analysis-- The cost-effectivenass function for the on-farm improvements meets the same general criteria as the other salinity control measures. Specifically, C j " ^ (mj ) (24) subject to: o .:::. mj .:::. mj (25) 59 '. 6' . ~