Con el fin de evaluar el efecto del enriquecimiento con nutrientes (una sal de fosforo o un fertilizante comercial con N, P y K) como alternativa para mejorar la capacidad de degradacion de los microorganismos en una matriz solida, contaminada con los pesticidas organofosforados: clorpirifos, malation y metil paration, se realizaron experimentos de cultivo bajo condiciones controladas de oscuridad, temperatura y humedad por 30 dias. En todos los tratamientos hubo degradacion de los pesticidas; sin embargo, en el tratamiento con fosforo los tiempos para degradar el clorpirifos y el metil paration fueron mayores. La presencia de los pesticidas no genero efectos toxicos detectables sobre la microflora en ninguno de los tratamientos evaluados. La actividad biologica de las matrices no presento una relacion directa con la capacidad de degradacion. Abstract In order to evaluate the effect of inorganic nutrient addition (phosphorus or commercial fertilizer) over the microbial degradation capacity present in a solid matrix contaminated with chlorpyrifos, malathion and methyl parathion, microcosms assays were held under controlled conditions of light, moisture and temperature for 30 days. Results showed that even though three treatments microorganisms were able to degrade the three organophosphorus pesticides, microorganisms of phosphorus-enrichment treatment were less efficient to degrade Chlorpyrifos and Methyl Parathion than microorganisms of Fertilizer-enrichment treatment. It was not observed a direct relation between mineralization and microbial pesticides degradation capacity. The microbial activity was not affected by the presence of organophosphorus pesticides.