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Increasing irrigation water cost due to higher pump energy price and falling groundwater tables is a critical problem of the agricultural sector in Sulphur Springs Valley of Southeastern Arizona which is characterized as an arid region with low annual precipitation and high temperatures. Water saving irrigation techniques, side roll and center pivot sprinkler systems, are analyzed as alternatives of gravity irrigation. Natural gas, electricity, and diesel fuel are commonly available energy sources for pumping groundwater in the area. Four representative farm size groups, five crops, and five irrigation techniques are adopted for representative farm mixed integer programming models. The problem is treated as a complete switch from one energy source to another and twelve separate sets of computer data are developed for four farm sizes and three energy sources. Sensitivity analyses based on cotton lint price and natural gas cost variations are analyzed. The results are aggregated to determine the regional level impacts of energy source changes, cotton lint price declines, and natural gas price increases. The major conclusion of these analyses is that upland cotton is a dominant crop with wheat using residual land and water. July water and available land restrict the crop production. Increasing energy costs reduce the total annual water consumption through adopting the water saving sprinkler systems and/or crops. Under the initial conditions (cotton lint price is at $58.11/cwt and natural gas price is at $.1167 per therm) the farmers generate gross returns that cover their annual total cost. Decreasing price of cotton decreases the return above total cost and annual water consumption. Wheat production changes as a complement of upland cotton, but corn production varies as substitute because of irrigation water and land constraints and relative crop profitability.

Linear economic models were utilized to predict effects of various environmental control policies on individual firms. Four different linear models were specified and in some instances relatively minor changes in specification were made which resulted in additional sub-models. Models varied as to numbers and types of fixed factors, variable cost relationships, market products, and fixed factor requirements. Once each model or sub-model was described five or six policies were theoretically applied to that model. Policies used were: taxing market products, taxing variable factors, taxing a non-market externality (external diseconomy), a standard on the quality of the externality, subsidizing variable factors and subsidizing fixed factors. It was assumed that the non-market externality would be produced in a fixed ratio with market products. Furthermore, the assumption was made that alternative production techniques were available to the firm. The important aspect of the various techniques was that the proportion of the externality generated by a market product varied by production method. Consequently, strong emphasis in the analysis was placed on determining whether or not a given policy could induce the firm to switch to a lower externality generating production method. In addition to the strictly theoretical analysis a linear irrigated farm model was described. The farm model produced irrigation return flows which were considered to be creating stream pollution. From the theoretical analysis likely policies for controlling return flows were ascertained. Some of these policies were then applied to the farm model. Specifically, a water tax (variable factor tax) and a constraint on delivered water were administered to the farm model. Based on the theoretical analysis taxing market products did not appear to be a particularly desirable policy. For some models, the market product tax actually increased externality production. A tax on externality production (effluent tax) seemed to give the most consistent effects of all policies across all models. The externality tax either reduced or had no effect on externality production. The biggest shortcoming of the externality tax appeared to be administrative. Before the tax can be used the externality must be identifiable as to source. Consequently, a search was made for policies which generated results similar to the externality tax yet were not subject to the same administrative problem. It appeared that under specific conditions a variable factor tax, a tax on specialized fixed factors or a combination of a tax-subsidy scheme could be effective alternative policies. However, these latter policies, if improperly applied could result in increased externality production. Taxes as high as 65 cents per acre inch of water were applied to the farm model. Depending on assumed conditions the water tax resulted in reduced irrigation return flows. When labor was constrained tax levels needed to be higher to reduce return flows compared to the case where labor was not constrained. Placing a restraint on delivered water also reduced return flows. Again, when labor was constrained this policy was not as effective as when labor was unconstrained. The water tax policy reduced net returns to the farm model considerably more than the constraint on delivered water. The main difference in net revenues was attributable to the total water tax bill rather than reductions from other added costs and/or enterprise changes. / Graduation date: 1972

No description available.

The dynamics of salt accumulation in the soil over time is one of major important information input needed for decision-making in regard to irrigate with saline water. As all waters contain some dissolved salts, during the irrigation these salts tend to concentrate in the soil causing depressed plant growth. Saline irrigation water, low soil permeability, inadequate drainage conditions, low rainfall and poor irrigation management all contribute to the tendency of salt accumulation in the soil. The principal salt accumulation problem of economic importance arises when non-saline soils become saline as result of irrigation. The dynamics of salt accumulation in this study, is based on the model for tracing salt distribution in the soil affected by the quantity and quality of irrigation water, amount of nitrogen and initial soil salinity. To verify the model for tracing salt distribution in the soil and to statistically estimate a crop-production function and soil salinity relation, agronomic data were used from field experiment conducted at the University of Arizona, Maricopa Agricultural Center (MAC), during the 1985 growing season and that utilized cotton variety Delta Pine 61. From the point of view of the response functions and salt accumulation in the soil, many assumptions were made before formulating the models. Results show that (1) no conclusions could be drawn with respect to the model of salt accumulation in the soil, (2) in the case of yield production function and soil salinity relation, the water quantity coeffient had an absolute value greater than one, (3) water quality and nitrogen coefficients had an absolute value less than one, (4) initial soil salinity coefficient had negative value, (5) looking for the best combination amoung the variables inputs, the marginal rate of substitution was greater than the ratio of prices, (6) the time path for soil salinity converge to a steady state conditions, and (7) the profitability of cotton irrigated with drip system is sensitive to yield increases and increases in the price of cotton.

Call number: LD2668 .T4 1958 E29 / Master of Science

No description available.

The purposes of this thesis are to examine experimental results obtained with subsurface irrigation of maize in 1988, and to provide preliminary plans and an economic analysis for the subsurface irrigation of maize in Richelieu County, Quebec. A mean increase in maize yield of 3.7 % was observed in 1988 on experimental plots with subsurface irrigation at the Charbonneau farm. However, a review of results obtained at the same experimental site from 1982 to 1988 indicated that the mean increase in maize yield with subsurface irrigation was 29 %. / Plans for two possible water supply systems designed to provide 180 mm a year of irrigation water for the subsurface irrigation of 1,250 ha in Richelieu County were considered. An economic analysis indicates that subsurface irrigation using groundwater has the greatest net benefits with an internal rate of return of 22.92 % and benefit to cost ratios of 1.90, 1.72 and 1.56 for discount rates of 8 %, 10 % and 12 % respectively. However, much of the groundwater in this region is saline and its use for irrigation may need to be restricted. Subsurface Irrigation using surface water from the Yamaska River was also profitable with an internal rate of return of 17.31 % and benefit to cost ratios of 1.66, 1.46 and 1.30 for the same discount rates.

No description available.

A procedure that determines the economic feasibility of irrigation and determines the instantaneous pumping demand and seasonal water use of feasible irrigation systems was developed. A 54 year (1930-1983) precipitation record was used to determine the future probability of drought occurring in a specific location under a given set of conditions in Virginia. Econometric models developed by Taylor, et al. (1985) were used to conduct the economic analysis. Econometric models for various ranges for center pivot, traveling gun, big gun, and portable pipe irrigation systems were utilized in the procedure. The developed procedure was applied to the Pamunkey River area in Eastern Virginia. Projections on cumulative irrigated acreage, pumping capacity, and seasonal water use were produced. / M.S.