Aboriginal Drained-Field Cultivation in the Americas

The three main types of land reclamation in aboriginal America were irrigation, terracing, and drainage. Of these, drainage techniques have received the least attention, probably because they are no longer important and because the remnants are not conspicuous. Nevertheless, drained-field cultivation was widespread and was practiced in varied environments, including high-land basins, tropical savannas, and temperate flood plains. Sites ranged from seasonally waterlogged or flooded areas to permanent lakes. Ridging, mounding, and ditching were emphasized, rather than diking. Tools were simple, crops varied, and fertilization was accomplished mainly by mulching. The presence of drainage agriculture probably indicates that populations exceeded the carrying capacity of the more easily cultivated land. When populations declined, following the conquest by Europeans, the drained fields were probably given up because of the large amount of labor required to cultivate them. Most of these lands are now used only for cattle, but could undoubtedly be reclaimed again for agriculture. However, the cost of such reclamation might be prohibitive where populations are sparse, transportation is poor, and distances to markets are long. The chinampas of Mexico are an exception, since there is a major urban market close at hand. The aboriginal cultures responsible for drainage ranged from the seminomadic Guato, to farm villages and chiefdoms, to the high civilizations. The ridged-field farmers of the savannas were capable people but certainly not comparable to the farmers of the efficient and sophisticated states of the Andes and Mexico. Most of the drained-field systems could have been constructed and managed through small-scale family and community cooperation, as in New Guinea, rather than through central political control. On the other hand, there does seem to be a frequent relationship between degree of agricultural intensification, population size, and complexity of social organization. Unfortunately, not much is known yet about the intensification process for drained-field cultivation or for other reclamation systems.