Redesign of the traditional Mesoamerican agroecosystem based on participative ecological intensification: Evaluation of the soil and efficiency of the system

Mexico is one of the countries with the highest importation levels of basic foods worldwide; it is therefore highly desirable to adopt measures to guarantee local food autonomy. Agricultural production alternatives that present an appropriate relationship with the environment are required. The objective of this study was to generate, implement and evaluate different strategies of participative ecological intensification. These strategies were focused on improving soil quality and agricultural productivity based on the traditional Mesoamerican maize-based “milpa” agrosystem. Management agrosystems were determined and implemented in conjunction with producers in an experimental community plot over a period of two years (2012 and 2013). The alternative management practices included the use of organic amendments (solid and organic) and synthetic fertilizers. Changes in soil chemical characteristics and yields (maize, beans) were measured, as well as indices of economic efficiency, labor and fertilizer use. After 2 years, the organic management treatments showed a clear increase in soil pH (from 5.02 to 5.5–5.6), in contrast to the conventional treatment in which the soil acidified (pH 4.9) and presented reduced P availability. As a result of the higher soil acidity, yields were lower compared to the systems that used organic conditioners. Soil nitrate (NO₃) concentration in the year 2012 was greater in plots with chemical fertilizers and vermicompost than in the other treatments. However, in the former, there were higher losses of N through lixiviation that year (112.6 kg ha⁻¹) and in 2013 (212.2 kg ha⁻¹), which were related to the occurrence of high precipitation (972 mm in 2012 and 1231 mm in 2013). Yields of maize were greater in the conventional system but lower than the bean yield. In contrast, in 2013, a stormy year, the organic system (bokashi + lime) was the most resilient in terms of both maize and bean yields. The treatments of highest annual total cost in 2012 and 2013 were those that used liquid amendments, due to the increased number of working days required for fertilizer application. In contrast, the lowest cost treatments in 2012 were those with vermicompost and, in 2013, with bokashi and bokashi + lime. The conventional treatment presented the highest fertilization costs. Application of solid organic fertilizers allowed improvement of the milpa agroecosystem soil chemical characteristics in the mountain region of Guerrero. This system presented the most efficient use of resources and labor and proved to be more resilient against the impact of storms. Moreover, it produced higher bean and maize yields compared to the milpa with conventional inputs.