In the Mexican tropics, farmers use mainly the traditional roza-tumba-quema, or slash, fell and burn (S-F-B) farming system. This system has been the subject of criticism because of the severe degradation it has caused. To reduce its environmental impact, in the Tulijá Valley in Mexico, farmers are using the maize (Zea mays L.)-mucuna (Mucuna deeringianum Bort.) agroecosystem. This article
... [Show full abstract] analyzes the effects of this agroecosystem on soil properties, weed dynamics and maize yield in traditional farming systems in the Tulijá Valley in Mexico, in the autumn-winter (November-April) seasonal cycle. A completely random design was set up with three replicates, in five-year periods to find out the effect of mucuna on the ecological production relationships and compare it with its not being used. As a result, it was observed that as the period of use of mucuna increased, nitrogen, phosphorous and potassium concentrations in the soil also increased, mainly in the surface layer of the soil (0-0.15 cm). There was a relative decrease in the number of species, of individuals and of families the longer mucuna was used. Grain yield was observed to be statistically lower in the system without rotation with mucuna (1.99±0.26 t ha -1) and highest in the system with mucuna for 15 years (5.72±0.51 t ha-1). In conclusion, the maize-mucuna agroecosystem increases and maintains agroecological sustainability of soils over time and favors production of maize. 2 INTRODUCTION In the Mexican tropics, the traditional roza-tumba-quema, or slash, fell and burn (S-F-B) farming system, also known as the milpa, itinerant or migratory agroecosystem (Brady, 1996) is used. The peasants cultivate small fields for two or three years and then, when the soil is worn out and crop productivity falls, they abandon it, allowing natural vegetation to grow and return its fertility, and then they can be planted gain after a fallow period. This cultivation system comprises the most important part of the Mexican agricultural production to date (Hernández, 1985; Brady 1996; Ochoa-Gaona and González-Espinosa, 2000; Ávila-Romero, 2007). The lower productivity of crops, especially maize, beans and squash, is attributed mainly to gradual decrease in soil fertility (Hernández et al., 1995) and to the rapid growth of the weed population, phytophage insects and diseases.