Ph.D. - Agricultural and Resource Economics
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ItemPatterns of energy use, energy cost increases and their impacts on crop production on the Big Island of Hawaii : a linear programming approach( 1982)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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ItemAn aquacultural development decision support system (ADDSS)( 1995)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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ItemSpatial water allocation under conjunctive use( 1995)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.
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ItemThe evaluation of alternative decision models : a case of crop rotation in Northern Thailand( 1994)Economic evaluations of multi-location testing results at the Thailand Farming Systems Research Institute have not been sufficient in terms of whole-farm decision planning. If no risk is involved in farm decision planning, farmers should act as profit maximizers. since risk is inherent in agriculture, farmers should be concerned with risk when they make decisions on farm investments. Therefore, it is hypothesized that risk decision making models predict northern Thai rice farmers' behaviors better than profit maximization models. Two elements in the mean-variance (E-V) decision analysis are farmer's risk preferences and risk perceptions. A quadratic function is used to represent farmer's attitudes to risk. Farmer's risk perceptions concerning crop production are measured by farmer's expectations of yields and prices. The expected mean-variance (E-V) efficiency frontier for each farmer is derived by a quadratic programming algorithm. The E-V efficiency frontier together with the utility function are used to derive optimal farm plans. The Target MOTAD model, using a linear programming algorithm, is included as an alternative decision model, which involves safety-first considerations (i.e., cash cost and variable cost as a target income level). The results show that the expected utility maximization model predicts actual farmers' behavior more accurately than the expected profit maximization model. Moreover, the Target MOTAD model performs quite well and better than the expected profit maximization model in predicting actual farmers' behavior when the selected target income level portrays their risk preferences and goals, such as variable cost of farm investment. The results suggest the importance of risk in farm decision making. Investment decisions of farmers concerning the amount of land allocated to mungbean production preceding the rice crop in the yearly rotation are significantly affected by competition from alternative crops for limited farm resources, such as land, labor and cash capital. Therefore, formulation of programs or policies, such as the integration of a new crop into farmer's existing cropping systems, should take risk and interdependency among cropping enterprises into consideration.
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ItemEconomic development and income inequality : empirical evidence( 1993)Kuznets's inverted U-curve hypothesis regarding the relationship between economic development and income inequality has not been rigorously tested due to the unavailability and quality of data, problems with sample composition, and concept formulation. Likewise, the relationships between institutional factors and income inequality have been largely untested. This study has made an attempt to address these concerns by employing a more sophisticated approach and updated and more consistent data for a relatively long time span. In terms of methodological issues in testing the hypotheses, this study differs from previous studies mainly in the following ways: first, economic development is studied as a multiple-dimension concept and then measured by both real gross domestic product per capita and physical quality of life index; second, measurement errors of indicators for income inequality and economic development, resulting primarily from income concept variations among countries, are incorporated into the LISREL measurement model; third, a blend of time-series and cross-country approaches is employed. The research results strongly support the inverted U-curve hypothesis. This finding suggests that as economic development takes place, income inequality increases first and then decreases after it reaches a turning point. The assessment of the relationship does not explain what brings about this change. Since it is neither intuitively nor deductively obvious why economic development alone should promote income equality, the second part of this study introduces political, demographic and sociological factors for a fuller explanation of the relationships between economic development and income inequality. The study shows that population growth, economic growth, and primary education increase income inequality while health and secondary education tend to decrease it. However, it fails to find support for the hypotheses that freedom, political rights, and civil liberties are negatively associated with income inequality. It is concluded from all evidence that economic development is a necessary but not a sufficient condition for reduction of income inequality. Economic and non-economic measures have to complement each other to translate economic development into more equitable income distribution.
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ItemOptimal aquafarm structure and size : a case study of shrimp mariculture( 1993)Aquaculture is a relatively new industry particularly in the Pacific region. As with any new industry, not much research has been done on the optimal farm size, structure, minimum operation scale and operating strategies. For this paper, farm size refers to the land area used to culture sea animals, farm structure refers to the production phases carried out in a farm, minimum operation scale refers to the number of tanks or ponds necessary for economic profit and operating strategy refers to the make-or-buy decision on the intermediate products and stocking-harvesting scheduling. Almost all aquacultured animals go through four stages of growth in a life cycle after being hatched: nauplii, postlarval, juvenile and adult. The corresponding operation phases are maturation, hatchery, nursery and growout. An aquafarm may operate any combination of operation phases if markets exist for all stage animals. If no markets exist for intermediate-stage animals, an aquafarm whose target is to produce adult animals would have to operate all operation phases. This study attempts to determine optimal aquafarm size, structure and operating strategy using a nonlinear programming technique. The theoretical nonlinear programming models are developed by incorporating all operation phases under two assumed market conditions: (1) markets for all stage animals exist, this production system is referred to as the open system; (2) only markets for adult animals exist, and this production system is referred to as the closed system. To analyze the economies of size on shrimp production in Hawaii, hypothesized shrimp farms based on Hawaii's production experience are designed. Optimal farm size, structure and operating strategies are derived. Results indicate that, for Hawaii, hatchery operation is the most profitable operation, followed by maturation, nursery and growout in descending order based on profitability, for the open system. On-farm production of broodstocks from productive female spawners is economically preferable. Under the closed system, small farms are not economically feasible. Medium size farms in the closed system should adopt a biweekly stocking schedule while large farms should stock growout ponds weekly. With different assumptions on output prices, the minimum operation scales for each of the four production phases are also derived.
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