In view of the necessity to identify sustainable technologies for the cotton agribusiness, a need exists to establish new management strategies that can maximize inputs provided by microorganisms to soil, which will result in decreased use of fertilizers. This will ensure environmental balance and sustainability of this agro-ecosystem. The purpose of this paper is to quantify diazotrophic bacteria under different cultivation systems in association with cotton growing. The treatments used are as follows: T0 (indigenous vegetation), T1 (cotton each year on offset), T2 (cotton each year, half- direct seeding on Millet biomass), and S3 'a' and 'b' (a-cotton for direct seeding every two years and b-soybeans, followed by Sorgho associated with Bracchiaria), where samples of soils with depths ranging from 0 to 10 cm were collected. These samples were then forwarded to a lab for insulation of the bacteria in an NFb medium and quantification of diazotrophic bacteria through the Most-Probably-Number Method (MPN), based on whether a film in the semi-solid medium existed or not, according to McCrady's table. The outcome is not complete, and it refers to the first sampling. It was demonstrated that the choice of cultivation system has an influence on the density of endophytic diazotrophs