In intensive or long-time agriculture systems, the soil ecological processes are negatively affected, resulting in a loss of regulatory mechanisms that provide stability to plant nutrient supply by microbial metabolism and must be substituted by synthetic fertilization face-off maintain crop production. The change in fertilization practices is a decision for peasants because it represents an economic risk if it is unfavorable, especially in crops that occupy a large area of land as oat crops in periurban agroecosystems of Mexico City. Therefore, this work aimed to evaluate oat crop yield and microbial activity after the change of fertilization regime in a periurban agroecosystem of Mexico City. For this, we substitute inorganic fertilizers with urea and organic amendments (cattle manure and vermicompost), so too, the fertilization suppression in a one-cycle crop field experiment on intensively managed and degraded volcanic soil, classified as Andic Anthrosol at a periurban agroecosystem. We can observe that the addition of cattle manure promotes the oat crop yield increase by 15 % than synthetic fertilization and improves the C use efficiency of the microbial community. In comparison, fertilization suppression decreases by 33 % the crop yield but promotes microbial use efficiency at the same level as cattle manure addition. These findings prove that the highly degraded soils lose resistance to changes in fertilization management. However, this can provide an opportunity to reestablish favorable microbial activity by adding organic amendments or after suppressing the unbalanced nutrient addition represented by synthetic fertilizers or C-poor substrates.