The covering of the ground assumes an important role in the integrated handling of the harmful plants, allowing in some cases to minimize the use of herbicidas with reduction of doses (LEATHER STRAP; REZENDE, 2008). The productivity of the soy in the system of direct sowing (SSD) is affected by the convivncia with the harmful plants from 33 days after the emergency (DAE), what it consists of the previous period to the interference (FATHER); the control of the harmful plants must be carried through until the 66 DAE, that consists of the total period of prevention of the interference (PTPI). The interval between these two periods, that is, between 33 and 66 DAE is characterized as critical period of prevention of the interference (PCPI). For the system of conventional sowing (SSC), the FATHER is of 34 DAE, and the PTPI of 76 DAE, consequently, the PCPI is of the 34 to the 76 days after the emergency of the soy. The PCPI corresponds to the period where effectively the culture must be kept in the absence of the harmful plants (NEPOMUCENO et al., 2007). Although the culture systems are distinct, the previous period to the interference (FATHER) is similar, around the 30 days after emergency of the culture (DAE), with a total period of prevention of the interference (PTPI) ten days longer in the SSC, extending itself until about the 80 DAE, probably in result of lesser density and accumulation of dry substance of the harmful plants in the critical period of prevention of the interference (PCPI) (NEPOMUCENO et al., 2007). Matocompetio in the culture of the Cotton plant the cotton plant is one of the main plants domesticated for man and one of oldest, having registers of its use more than 4,000 years, being cultivated commercially in more than 65 countries; in Brazil it is cultivated in 15 states. .