Abstract

The present study constitutes an initial effort to provide baseline information about the internal workings of the mucuna system. It includes a discussion of biological mechanisms which shape this system, especially with regard to nutrient cycling. Long-term trends in soil chemical and physical fertility are also analyzed. Chronosequences (also known as space-for-time substitution schemes) form the backbone of this long-term analysis: they were constructed by taking advantage of the diversity of adoption dates of the mucuna system among farmers. All field measurements were made at the level of small observation plots selected on uniform backslopes within farmers’ fields and subjected to a periodic agronomic monitoring throughout the maize growing season. After describing general characteristics of the mucuna system, an analysis of the various pools participating in nutrient cycling is conducted. Mucuna biomass accumulation and descomposition are then discussed, as well as the dynamics of mineral nitrogen in the soil profile, an analysis which in turn helps understand maize response to limited applications of nitrogen fertilizer. Although it appears that the mucuna system is too specific to the conditions prevailing in the North coast of Honduras to be extrapolated directly. After 12 years or more of continuous use of the mucuna rotation, a result which can undoubtedly be attributed to the high yearly organic additions and efficient nutrient cycling in this system.