Weeds as crops: The value of maize field weeds in the valley of Toluca, Mexico

Maize field weeds or agrestals are widely used in central Mexico as potherbs (quelites) and forage. This work presents quantitative data on these uses from the village of San Bartolo del Llano, Municipio de Ixtlahuaca, Valley of Toluca, an area with a relatively intensive, semicommercial agriculture. We interviewed 24 families of the village and 10 vendors at the market of Ixtlahuaca regularly during one rainy season (1995) on type and quantity of weed use. Also, the weed vegetation was surveyed and we interviewed 49 farmers on their farming practices and on costs. All of the 74 weed species found in maize fields were useful as forage, potherb, medicinal, or ornamental. Within the village, 11 species were eaten; an average family consumed 4.5 kg of wild potherbs per month during the rainy season. In Ixtlahuaca, 2150 kg of 10 species were sold, worth 3054 pesos (US $611). For quantity and gross economic value, forage was much more important. On the average, 1 ha of maize field produced a harvest of 1.5 t of green forage, worth about 25% of the gross value of the maize harvest, and 55% of its net value. The combination of maize with forage weeds for stabled animals constitutes an interesting integrated farming system. The weeds increase the useful biomass of the field, improve nutrition of the farmers, do not reduce the yield of the main crop, as the fields are kept weed free during the critical period, and provide erosion control, shade, and green manure.