Agroecological management with intra- and interspecific diversification as an alternative to conventional soil nutrient management in family maize farming

In traditional polycultures such as milpas, soil degradation and the loss of agrodiversity, threaten rural food security. Although agroecological management using crop functional and genetic diversity could improve soil fertility and family nutrition, experimental evidence is scarce. We conducted a field experiment in which conventional agricultural management (CON) was compared to an agroecological alternative (AGR), with interspecific and intraspecific diversification factors. We hypothesized that: (1) the higher input of organic matter and the suspension of tillage in AGR plots would improve soil conditions, nutrient content and productivity in maize, and intra-root colonization by mycorrhizal fungi as compared to CON plots; and that (2) these conditions would further improve in AGR management with increased intra- and interspecific diversity, since a diverse plant community in the rhizosphere should enhance microbial activity. AGR increased pH, the soil availability of K, Ca and Mg, K in leaves, and mycorrhizal colonization. Within AGR, diversified treatments temporarily increased NO₃⁻ in the soil. The fixation of nitrogen by additional legumes could have produced this result. We conclude that AGR with interspecific diversification is a viable alternative to CON, since a variety of additional edible plants became available concomitantly with the improvement of mycorrhizal relationships and soil conditions.