THREE LAYER COFFEE PLANTATION MODEL

Coffee is the most important international agrarian commodity. Latin Ameri¬can countries produces 65% of the total world 7200 millions of kilograms. Honduras produces 3% of the world-wide coffee in 236,462 ha (8% of total cropland). Coffee crop in Honduras is mainly under shade (between 95 and 98% of all the production of coffee) with yields from 700 to 800 kg/ha. Three layer coffee plantation model was built with Vensim® DSS version 5.6a, following system dynamic approach. Each layer corresponds with the leaf area distribution of shade tree, coffee tree and pasture. The model is divided in two levels, abiotic (climate and soil) and biotic (plant material), to study the relationship among all different subsystems by an explanation of material flow and information. Model calibration (shade tree, coffee tree and pasture) was made from literature. Full sun coffee plants simulated growth shows lower Leaf Area Indexes in relation with real growth data (9, 7 and 5.5 simulated vs 10, 8 and 5 observed for 10000, 5000 and 2500 coffee tree/ha). Simulated growth of coffee planta¬tion has exhaustion at seven years all, similarly than in field. The simulated produc¬tion pull down was higher on sunny plantation than on shade.