in the Maya areas was undoubtedly swiden agriculture, whereby fields were cleared, burned off, and planted with a variety of food crops, including maize, beans, squash, chilies, and such root crops as manioc ahd sweet potatoes. But whatever the crop, tropical soils become exhausted after several years of cultivation, and new fields must be cleared and planted while the old lie fallow. Swidden agriculture is nonetheless adaptable to a wide range of environments, from the highland valleys, and mountain sloes to the lowland jungle and scrub forest. For the modern Maya farmer, in fact, it remains the most commons method of cultivation, and it is still practiced from the highland of Guatemala to the lowland of the Yucatan.