MODELING TAKE-UP OF RICE-FISH SYSTEMS WITH FUZZY LOGIC

摘要

Most current models analyzing technology adoption are based on a function that assumes farmers make decisions upon utility maximization but ignores cultural or social factors. The traditional production systems of the Mekong Delta were based on floating rice varieties and fish harvested both from rivers and rice fields. Since 1980 the presence of fish in the rice fields decreased and research developed the so-called concurrent rice-fish system to capture the advantages of the synergy. Whether this isa feasible option depends on the farmers' drives and motives for taking-up the technology. In 2000 we made an inventory among 60 farmers who adopted the rice-fish system in four districts to describe their resources and motivations. In 2006 we repeatedthis survey among 94 farmers including potential adopters, in order to evaluate the take-up potential of the rice-fish system in the Mekong Delta. Income/person and income/ha of the farm households with a rice-fish system were close to double, while their land area (2.5ha) was not significantly larger than those farms without a rice-fish system (1.95ha). Usually farmers integrating also pigs and fish had the smallest land area. The farmers' non-adoption of the rice-fish system was mainly due to low availability of capital and land, and to inappropriate location of the field in relation to the homestead, water availability, and agro-ecological conditions. To create space for more upland crops was an important argument for the construction of a rice-fishsystem. Modeling confirmed that under appropriate agro-ecological conditions the take-up of rice-fish systems can be stimulated by increasing know-how on fish and on system component integration. The sensitivity of the fuzzy logic simulation did not confirm the importance of land size and wealth ranking for the take-up.