Abstract

This study was carried out in two zones of the Brunca Region using a biological inoculants of the Rhizobium sp bacteria. The objective was to reduced the chemical fertilizer utilization. Four treatments were evaluated: Absolute control; Inoculants (0,7 kg/ha); Inoculants (0,7 kg/ha)+ Fertilizer 10-30-10 (63 kg/ha is) and Fertilizer10-30-10 (125 kg/ha) in property of farmer at a density of 30-32 kg seed/ha. A partial budget and an analysis of Dominance (CIMMYT, 1988) were used to carry out the economic analysis determining net profit and marginal rate of return. In the zone of Changuena, Buenos Aires the use of single inoculants presented the higher net profit and a rate of marginal return of 388%. For the zone of Pejibaye de Pérez Zeledón the use of single fertilizer obtained the higher net profit and a rate of marginal return of 621%, inoculants+ fertilizer 814% and single inoculants 173%. The use of biological inoculants was a practice economically profitable for the farmers