The soybean Yield Gap Analysis Project Phase II (SYGAP II) carries out on-farm research focuses on con-straints faced by farmers who want to adopt research findings to increase their soybean production. During the Project life (1989-1991). the study was undertaken through cooperation between the Ministry of Agriculture and Cooperatives and the CGPRT centre. On-farm trials were the viable parthway to solver farmers' problems and the meaningful dis-semination of the SYGAP team's experience to farmers' decision in the adoption of the package of technology (POT). The findings reported on the testing of POT were able to attain a better yield but at a higher cst per unit weight. There appear a considerate points to carry on an additional on-farm trials and demonstration plots. Then the national team decided to readjust the POT with a set of proper land preparation techniques and appropriate kind of fertilizer during the last two years of the Project and tho come up with a possible choices of cost reduction while maintaining the yield level. The out-comes showed satisfactory results for economic returns. The input package recommendation may include the application of planers, either inverted-T seeder of hand pull planter. and the change of fertilizer grade form 12-24-12 to 16-20-0 under the test condition in Chiangmai.