Sub-regional linear programming models in land use analysis: a case study of the Neguev settlement, Costa Rica.

The paper deals with linear programming as a tool for land use analysis at the sub-regional level. A linear programming model of a case study area, the Neguev settlement in the Atlantic zone of Costa Rica, is presented. The matrix of the model includes five submatrices each encompassing a different farm type. The farm types are distinguished on the basis of land-labour ratios, considering farm size and three different soil types, and assuming a fixed availability of household labour. Land use activities are defined as a combination of a land unit (three soil types, with or without forest cover) and land type (cassava, logged forest, maize, palm heart, pasture with cattle, pineapple, plantain and tree plantain). These represent land use systems with fixed input-output coefficients. Two indicators for sustainability are taken into account: soil nutrient depletion and biocide use. These are built into the model via constraints, marking upper limits to the use of renewable resources and to the waste flow into the environment. The linear programming model forms part of the USTED (Uso Sostenible de Tierras En el Desarrollo) methodology for the analysis and planning of sustainable land use. Several land use scenarios are analysed to assess whether the income of all farms in the Neguev can increase through an improved, and sustainable, land use. First, a base scenario is calculated to serve as a reference for assessing the impact of policy measures. A striking feature of the base scenario is the large area with palm heart in comparison to the actual area. Sustainability-related policy measures studied are increasing biocide prices, and quantitative restrictions on biocide use and soil nutrient losses. Doubling the biocide price hardly affects its use, while a quantitative restriction on the use of biocides per ha of 50% in comparison to the base scenario use, reduces average incomes by less than 1%. A similar conclusion applies to soil nutrient depletion. Restricted to 'critical nutrient losses' per year over a ten year period, specified per land unit per farm type, average incomes are reduced by less than 3%. Other scenarios concern the impact of decreasing palm heart prices, as a consequence of increased supply, the influence of increasing wages and the role of the discount rate