Ph.D. - Agricultural and Resource Economics

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    Patterns of energy use, energy cost increases and their impacts on crop production on the Big Island of Hawaii : a linear programming approach
    ( 1982) Koffi-Tessio, Egnonto N.
    In recent years, drastic changes have occurred in input prices, output prices and in the institutional structure within which agricultural producers operate. These changes are largely the upshot of sharp increases in energy prices that are directly or indirectly translated into higher production costs for the farmers. The main objective of this study is to examine the interrelationship between the energy sector and the production of three agricultural crops (sugar, macadamia nut and coffee) by small growers on the Big Island of Hawaii. Specifically, it attempts: (a) to explore the patterns of energy use in agriculture; (b) to determine the relative efficiency of fuel use by farm size among the three agricultural crops; and (c) to investigate the impacts of higher energy costs on farmers' net revenues under three output price and three energy cost scenarios. To meet these objectives, a linear programming model was developed. The objective function was to maximize net revenues subject to resource availability, production, marketing and non negativity constraints. The application of the model to sugar, macadamia nuts and coffee yielded the following results. With respect; to sugar, indirect energy (fertilizer and herbicide) use appears to be an increasing function of farm size. Direct energy (gasoline, diesel and electricity) does not lead to a specific conclusion. In the case of macadamia nuts, both direct and indirect energy use, with the exception of gasoline and electricity, appears to be a decreasing function of farm size. With respect to coffee, the results indicate that direct energy use is a decreasing function of farm size. However, the relationship between fertilizer use and farm size is not conclusive. Findings also reveal that sugar, with only 10% of energy cost, appears to be more vulnerable to higher energy costs than macadamia nuts and coffee with 16% and 18% of energy cost, respectively. In addition, higher energy costs tend to have differential impacts depending upon the output price. Some of the major conclusions emerging from this study are: (a) higher energy costs have not significantly impacted on farmers' net revenues, but do have a differential impact depending on the resource endowments of each crop grower; (b) low output prices tend to reinforce the impacts of higher energy costs, whereas high prices tend to negate them; (c) farmers are faced with many constraints that do not permit factor substitution. In terms of policy formulation, it was observed that policy makers seem to be overly concerned with the problems facing growers at the macro level, without taking into account the constraints that growers face at the micro level. These micro factors play a dominant role in the context of resource allocation. They must, therefore, be incorporated into a comprehensive energy and agricultural policy at the county and state level.
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    An aquacultural development decision support system (ADDSS)
    ( 1995) El-Gayar, Omar F.
    Nowadays, aquaculture development is considered as a viable source for providing high quality cheap protein, particularly for developing countries where protein shortage already exists. Complexities in such development planning can be difficult without the aid of modern decision-making technologies such as decision support systems (DSS). DSS are already in wide use in the business and manufacturing sectors. However, their use in agriculture is limited and their use in aquaculture is almost nonexistent, The objective of this work is to design and implement a decision support system that would systematically aid the decision maker or the planner in making choices regarding the development planning of the aquaculture industry for a given region. Moreover, due to the lack of multiple criteria decision making (MCDM) models for regional planning for aquaculture development, it is also the objective of this work to develop such models. The system is composed of three main components: a model base containing all relevant models which are essentially multiple objective in nature, a data base containing all relevant data, and a dialog component providing a user interface to the other two primary components of the system. The MCDM model representing the core of the modeling component seeks the optimal allocation of resources and activity levels that would strike an acceptable balance among the various developmental goals under consideration subject to resource constraints, market constraints, and pollution constraints. To accommodate different decision situations. three different MCDM solution techniques are implemented, namely, multiple objective programming (MOP), compromise programming (CP), and weighted goal programming (WOP). The system allows the planner to specify the model by selecting the developmental goals, the decision variables (activities), and the constraints to be considered in the model. The system, which generates a user-specified model based on the data stored in the database, would answer questions such as, what species to grow? what technology to use? how much to grow of each species and/or technology? The recommended policy is generated in both text and graphics formats for ease of reference. Finally, the applicability of the prototype system is demonstrated through applying it to a case study from Egypt.
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    Spatial water allocation under conjunctive use
    ( 1995) Umetsu, Chieko
    This dissertation studies the optimal allocation for conjunctive use of surface and groundwater. The optimal model defines economic principles which determine the spatial allocation of surface and groundwater, the level of conveyance expenditure, the level of on-farm investment in water conservation, and shadow prices of surface and groundwater. The static spatial model identifies the economic principles which govern water allocation for conjunctive use of surface and groundwater. Two models, seepage in the canal and seepage in the canal and on the field are considered. The optimal water allocation is examined with fixed on-farm investment in water conservation and with different canal loss rates. The static base model is extended to incorporate endogenous on-farm investment in water conservation and to consider the effect of the seepage rate on choice of technology, conveyance expenditure, water allocation and land rents. Analytical results are obtained for endogenous crop choice when land quality is homogeneous and shadow price of water is spatially increasing. The study compares the effects of heterogeneous land quality, changes in output price, pumping cost, uniform price for groundwater, and uniform prices for water such as the marginal cost of water generation at the source. The spatial dynamic model of conjunctive water use defines conditions which govern the intertemporal and spatial optimal allocation of water. Five important results are as follows: (i) When seepage is small, the conjunctive use model does not make a significant difference, and the surface water model is a good approximation of the conjunctive use model. (ii) Additional seepage from the field generates a positive externality to water consumers and the resulting optimal shadow price of water is less than the shadow price of the utility. (iii) An output price increase, heterogeneous land quality, and a fixed price for water generate huge aggregate land rents. (iv) Spatial inequity of land rents is worsened by heterogeneous land quality. (v) Temporal allocation of water resources is governed by the Hotelling rule variant similar to the optimal allocation rule for exhaustible resources.