THE INTEGRATED USE OF SIMULATION AND STOCHASTIC PROGRAMMING FOR WHOLE FARM PLANNING UNDER RISK*

Methods of whole-farm planning under risk are briefly reviewed, noting especially associated operational problems. A planning problem relating to spatial diversification of beef production in the Clarence region of N.S.W. is investigated using a model comprising both simulation and linear programming components. It is concluded that such composite models are valuable for the analysis of sequential stochastic decision processes not presently amenable to solution by stochastic programming alone.     

FOOD SECURITY IN KWAZULU: RESULTS OF A HOUSEHOLD-BASED PROGRAMMING MODEL

A mathematical programming model of rural KwaZulu, excluding three northern districts, was developed to simulate agricultural production in regions of high and low cropping potential. This model aggregates enterprise levels predicted for four representative households of which two are in the high-potential region and two in the low-potential region. Several economic scenarios are simulated with the model to predict, inter alia, responses to changes in cereal prices, input subsidies, changes in off-farm employment and a rental market for crop land. Long-run food supply response is estimated to be inelastic with respect to changes in product and input prices. Higher food prices harm the majority of rural households. Lower input prices have little impact on household welfare. Conversely, it is predicted that a rental market for arable land could have a large positive impact on crop production and would improve household welfare.     

DYNAMIC PROGRAMMING: A TOOL FOR FARM FIRM GROWTH RESEARCH

This paper is concerned with dynamic programming as a tool for studying the process of farm firm growth. Studies of growth are restricted by characteristics of the analytical tools used. Dynamic programming provides a method for including added realism in conceptual and analytical growth models. This paper illustrates the formulation of a firm growth problem in a dynamic programming framework and discusses advantages and disadvantages of such models. The type of results obtained from dynamic programming is contrasted with that normally obtained from dynamic linear programming formulations.     

GOAL PROGRAMMING AND MULTIPLE CRITERIA DECISION-MAKING IN FARM PLANNING: SOME EXTENSIONS

This paper is the sequel to a previous article by Romero and Rehman on the role of multiple criteria decision-making (MCDM) techniques, particularly goal programming (GP), in farm planning. This assessment of the potential usefulness of the MCDM paradigm is carried further and now covers the extensions to GP and other related methodologies such as multiobjective programming, compromise programming, multigoal programming and generalised GP. Later analysis is focused on methods of dealing with uncertainty and risk in farm planning models, by demonstrating how game theoretic principles and the MOTAD approach (along with its main variant, target MOTAD) can be incorporated within the MCDM framework.     

GOAL PROGRAMMING AND MULTIPLE CRITERIA DECISION-MAKING IN FARM PLANNING: AN EXPOSITORY ANALYSIS

Several paradigms can be used to analyse multiple-criteria decision-making problems. Of these goal programming is probably the most widely used one, at least in management science. Goal programming seems to offer considerable potential for application to multiple-criteria problems in farm planning. However, its applications in agricultural economics have been few and far between. Even these attempts seem to suffer from some serious misconceptions. In this paper an effort is made to explain the structure of a goal programming model by deriving it from the familiar paradigm of linear programming. This is done to put the potential usefulness of goal programming and its relationship to linear programming in perspective, and to encourage further applications to multiple-criteria decision-making in farm planning.     

A FARM GROWTH MODEL FOR POLICY ANALYSIS IN AN EXTENSIVE PASTORAL PRODUCTION SYSTEM

The development of a simulation model of an extensive pastoral farming system to assist analysts in their assessment of government policy measures is described. The model was designed to simulate, over a number of years, the physical and financial operation of a sheep and beef production system typically found in the North Island hill country of New Zealand. By manipulating model parameters and data related to prices, costs, taxation and credit, a range of policies can be represented and their effects simulated. The model is used to undertake an ex post analysis of the farm-level impact of the supplementary minimum price scheme in New Zealand and to project farm performance following the abolition of the scheme. Consideration is given to the use of the model to represent sheep and beef production systems elsewhere.     

A DYNAMIC PROGRAMMING MODEL OF EARLY POTATO HARVESTING

A vegetable producer often faces complex harvest decisions where yield increases through time and varies across crop area, price is determined in erratic seasonal markets, and harvest rate is constrained. In this paper, a simplified two-period potato harvest problem is developed to define a set of marginal conditions for an optimum. The model is then extended to the multi-period case and numerical solutions are generated for a representative farm in South Wales using dynamic programming. The model provides a general framework for analysing crop harvesting systems and prescribing marginal changes, such as adjustments in the harvest capacity, which improve profitability over myopic harvest patterns.     

ASSESSMENT OF THE OUTPUT OF A STOCHASTIC DECISION MODEL

The concept of stochastic dominance is described and its use is illustrated in relation to the evaluation of the output of a systems simulation model of lucerne haymaking in south-west Spain. Two alternative machinery systems are ranked for various lucerne areas using the criteria of stochastic dominance, and These results are compared with those obtained using mean-variance analysis.     

SUPPLY RESPONSE WITH STOCHASTIC TECHNOLOGY AND PRICES IN AUSTRALIA'S RURAL EXPORT INDUSTRIES

Risky output prices and production characterise Australian agriculture. Exports are vitally important, sometimes relying heavily on a particular market. In this study a model is developed to include explicitly both output price and technological risks as well as multiple output relationships. It is used to show that changes in US beef import policy generating a 10 per cent beef price fall could reduce Australian beef supply by 3.5 per cent and grazing industry net revenue by 8.4 per cent, despite some switching from beef production to other enterprises.     

A QUADRATIC PROGRAMMING INTERREGIONAL TRADE MODEL: AN APPLICATION AND A PERSPECTIVE*

This paper presents a theoretical activity-type model of U.S. interregional trade for the agricultural sector as an extension of the broad non-linear programming formulation of Samuelson [4] and the quadratic programming reformulation of Takayama and Judge [5]. A shorter model is applied to the problem of examination of the short-run competitive strength of Wisconsin, particularly in beef and pork (interregional) trade. The conclusions for Wisconsin suggest competitive price disadvantages in beef and beef feeding but with belter prospects for expansion for a pork sector At a time of growing interest in the probable impact of expanded and freer Canada-US. trade, this type of programming model is suggested as a significant approach to problems of Canada-U.S. trade. In addition, in an apparently emerging era of regulated marketing and production control, the employing of such a model for interregional market share analysis appears a major possible policy avenue Ce papier présenle un modèle théorique “Type-activiie” du commerce interregional aux Etats-Unis, pour le secteur agricuhurel, en guise ?extension du propos de vaste programmation non-lineaire, tel que formule par Samuelson [4], ainsi que celui de Takayama el Judge [5], qui proposent une réformulation de programmation quadraiique. Un plus petit modèle est appliqué au probleme ?examinalion de la force immédiate et compétitive de Wisconsin, tout particulièrement dans le commerce (interrégional) du boeuf et du pore. Les conclusions tirées pour Wisconsin suggèrenl un prix com-pétitif qui désavantagerait le boeuf el ?alimentaiion du boeuf, mais qui favoriserait ?expansion du secieur du pore A un temps oú?on se préoccupe de ?impact tout probable dûà un commerce plus libre et plus étendu entre le Canada el les Etals-Unis, ce genre de modéle de programmation est suggéré comme étant une approche significative aux problèmes de commerce Canada-Eiats-Unis. En plus, en celle époque qui semble mettre de plus en plus ?emphase sur le marché ajuslé et le comrôle de production, les possibililés ?employer un lei modéle pour ?analyse de la part du marché interrégional nous apparait comme étanl une possibilité majeure en fait de ligne de conduiie.     

AGRICULTURAL DEVELOPMENT IN ITALY:NATIONAL PROBLEMS IN A COMMUNITY FRAMEWORK

During the last twenty years Italian agriculture has undergone a process of fast growth but slow development: in spite of a sustained increase of gross agricultural production, intrasectoral and intersectoral income disparities become wider and the agricultural trade balance shows a mounting deficit. Both the CAP and national policy bear some responsibility in engendering these kind of trends. Community market and price policy has accorded to Mediterranean products levels of protection and support lower than those enjoyed by continental commodities, and its structural policy has been unable to provide satisfactory answers to those problems that show high regional specificities. National policy has unduly neglected critical areas such as agricultural research and extension, as well as those public actions needed to improve market structures and performance.     

A STOCHASTIC MODEL FOR THE OPTIMAL REPLACEMENT OF RUBBER TREES

Recognizing the lack of realism in optimal replacement analyses that assume constant prices and yield patterns over time, a stochastic model appropriate to rubber production is developed. Data drawn from Peninsular Malaysia are used to implement the model. The results suggest that efforts should be directed towards establishing bench mark maximum annuities as guides to more economic replanting decisions rather than emphasizing earlier replanting per se. The significance of price stabilization policies also becomes evident.     

CONTROLLING STRAW BURNING: FARM MANAGEMENT MODELLING OF THE POLICY OPTIONS USING LINEAR PROGRAMMING

Autumn-sown cereals place pressure on post-harvest operations, particularly straw disposal. Burning is often a private solution but imposes external costs on others. Policy options to control burning include an outright ban, standard regulations, pollution taxes and transferable discharge rights. The effects of such options on farm income are assessed for an East of England cereals farm using a Linear Programming model. Results are sensitive to assumed straw yields, the market price of straw, and incorporation costs. Transferable discharge rights offer a flexible and efficient instrument to regulate straw burning at a non-zero level.