In central Brazil, the tropical savannah ecosystem known as Cerrado, small scale farmers (around 20 ha) occupy marginal land scattered among large commercial farms on wide plateaux. Close to 90 % of the agricultural land farmed by large holders in the Cerrado is managed under direct seeding mulch based cropping systems (DMC). However, this system is almost not used by small scale farmers of the same region, even if their soils are often very susceptible to degradation (erosion, losses of soil organic matter), and they crucially need to stabilize their corn production in other to insure sustainability. Since 2005, Embrapa and Cirad tried to develop, in interaction with small farmers of Unaí region (Minas Gerais), new DMC systems adapted to their conditions and compatible with their own objectives. However, even if those systems increase soil fertility significantly, they also often deeply modify crop management as well as the use of resources available at farm level. Such systems have thus strong consequences on economical, environmental or social aspects of the system, (Scopel et al., 2005).