I 8 Expedition 30(1):8-16 1988 Expedition, Vol. 30, No. 3 Putting Ancient Agriculture Back to Work Spanish chroniclers in the 16th fields had probably been aban- CLARK L. ERICKSON century described many aspects of doned before the arrival of the the indigenous agriculture, such as Spanish. Questions such as who he remains of an extensive terraces and irrigation canals, but constructed the fields, when were ancient agricultural system they did not mention raised fields. they built, what crops were cul- built and used by Andean This omission suggests that raised tivated, why the fields varied so peoples centuries ago are found throughout the vast high plain sur- rounding Lake Titicaca in the An- dean countries of Peru and Bolivia (Figs. 1, 2). Raised fields are large elevated planting platforms which provided drainage, improved soil conditions, and improved tempera- tures for crops, The remains of prehistoric raised fields, elaborate sunken gardens, and agricultural terraces cover tens of thousands of hectares in the region, and provide evidence of the impressive engi- neering abilities of the peoples who Lake Titicaca lived there in pre-Columbian times. Our recent investigations of raised field agriculture demonstrate not only the technological expertise of the past cultures, but also that these systems could be re-used today to make high altitude lands more productive. In a region such as the Andes, where conditions of soil and climate greatly limit agricul- tural potential, technological methods to augment productivity have been increasingly necessary to important archaeological site support the growing populations of Quechua and Aymara farmers who live there today. The reuse of raised fields may be an economical and ecologically sound alternative to agricultural development based on expensive imported technology. Until recently, very little was 1 known about the origins and evolu- Map showing distribution of raised field remains (based on Smith et al. 1968: tion of raised field technology in the fig. 1) and potential raised field sites within the Lake Titicaca basin of Lake Titicaca Basin. Observant southern Peru a Agriculture in the Lake Titicaca Basin” much in size and shape, and how raised field agriculture functioned needed to be answered. Between 1981 and 1986, I directed a small team of researchers inves- tigating prehistoric raised field agri- culture in the community of Huatta in the northern Lake Titicaca Basin of Peru. Huatta is located in the center of the largest block of raised field remains, estimated to cover 53,000 hectares. The project, com- bining archaeology and agronomy, addressed the important questions raised above, as well as those more relevant to modern agriculture, such as estimating the potential productivity of the raised fields and investigating their effects on the local agricultural environment. The investigation was based on archae- Lake Titicaca I ological survey and excavation of prehistoric raised fields and se- lected habitation sites, together with the construction and study of LEGEND experimental raised field plots (see box). To apply the results of this land above 3825 m. a s l. research, a small-scale development site project involving local Quechua farmers was begun in 1982 to put population center raised fields back into use. km raised field site 1 Raised Field 2 Agriculture and the Map showing locations mentioned in the text. Lake Titicaca caca in both Bolivia and Peru (Fig. more favorable environment for cul- Environment 1), have been badly eroded by a tivation, mild enough for special combination of wind, rain, flood- races of corn to be grown in shel- Raised fields are constructed by ing, and modern urbanization, but tered valleys and on the islands and excavating parallel canals and piling their remains can be seen clearly on peninsulas of the lake. The stored the earth between them to form the ground and in aerial photo- heat of the massive body of lake long, low mounds with flat or graphs. They were specifically water warms the areas around it, an convex surfaces. These raised plat- adapted to the particular environ- especially important effect at night forms increase soil fertility, im- ment, crops, and technology avail- when frosts are common. Farther prove drainage in low-lying areas, able to the indigenous farmers. from the lake, this warming effect and improve local micro-environ- Most of the land lies above 3800 m diminishes, but the entire region ments, primarily by decreasing (12,500 feet), and nights can be around the lake benefits from a frost risk. The canals between raised bitterly cold, despite warm sunny slightly higher than average annual fields provide vital moisture during days. The year is divided into rainfall. The major obstacle to lake- periods of short- and long-term distinct wet and dry seasons of side agriculture is that most of the drought. Water in the deep canals roughly six months each, but even surrounding land is either rocky might have been used to cultivate this situation may vary greatly from steep slope or flat, waterlogged aquatic plants and fish, as well as year to year, producing an unpre- lake plain which may be seasonally attract lake birds that were an dictable, high-risk agricultural en- inundated. Both areas have rela- integral part of the prehistoric diet. vironment. Frosts are most common tively poor soils and are classified as The raised fields of the Lake Titi- during the dry season, and at the areas of limited agricultural poten- caca region are diverse in form and beginning and end of the growing tial in government studies. Today, in size, but generally range from 4- (wet) season, but may occur locally large rural populations are located 10 m wide, 10 to 100 m long, and are at any time without warning, in areas that have better drainage, 1 m tall. especially in low-lying depressions favorable temperatures, and good The prehistoric raised fields, at the bases of hills. soils, combined with access to the covering some 82,000 hectares of The land immediately adjacent lacustrine resources of Lake Titi- low-lying land around Lake Titi- to Lake Titicaca has a somewhat caca. 10 The rich and varied biotic re- alpacas and exploitation of lacus- historic field svstems. The field sources of the region would have trine resources, provided a sound surfaces were’ originally much made it an excellent location for subsistence base for the civilizations higher, with deep canals between prehistoric experimentation with that developed in the Lake Titicaca them, which have now become domestication of plants and dif- Basin. filled with sediment. In some ferent cultivation techniques. Once The indigenous Andean agricul- trenches, several distinct phases of local peoples learned to protect tural tool inventory appears limited construction, use, reconstruction, fields from inundation, the pampa in technological complexity, but is and re-use of the fields can be (the grass-covered low-lying lake more than adequate for the needs of delineated (Fig. 4). Some early plain) would have been a relatively the Andean farmer. Traditional fields were narrow ridges of 5 m good area for crop production. In tools include the Andean footplow, wavelength (distance from canal fact, botanical and archaeological hoe, and clod breaker which are still center to canal center) which at a research indicate that the potato, the basic tools today, although the later time were expanded to larger quinua and cañihua (two seed crops stone and wooden blades have been fields of 10 m wavelength. From rich in vegetable protein), and replaced by metal blades (see Fig. each stratum of the trench profile, many other important Andean 10). The footplow, a remarkable samples were obtained for pollen crops were probably first domes- implement which is excellent for and soil laboratory analyses. The ticated in the Lake Titicaca region turning over blocks of tough pampa data obtained from these analyses (see also K. Chavez, this issue). sod for construction of lazy beds for provide interesting insights into Selection of special traits has pro- tubers and for plowing stony prehistoric agriculture. duced crop varieties that can with- ground on steep hillslopes, played a Soil analysis indicates that the stand harsh environmental condi- major role in the development of canal sediment, composed pri- tions, such as high altitude, intense raised field agriculture. marily of organic matter, is rich in solar radiation, low nocturnal tem- nutrients, much more so than the peratures, and crop pests. The The Archaeology of average pampa soil. In addition, nocturnal cold was put to use by the soil alkalinity, a major constraint on prehistoric inhabitants in an elab- Raised Field agriculture in the lake edge soil, is orate freeze-drying technique Agriculture markedly lower in the canal sedi- which enabled vast amounts of agri- ments. These rich sediments were cultural surplus to be preserved and Our trenches excavated through periodically removed from the stored indefinitely. This Andean the prehistoric raised fields showed canals and added to the raised fields crop complex and its accompanying that those seen today in the pampa to improve the crop soils. Pollen preservation technology, combined (Fig. 3) are only the badly eroded samples from these excavations with the herding of llamas and remains of fully functioning pre- have been analyzed by Dr. Fred Wiseman of the Massachusetts Insti- 3 tute of Technology. He finds that A panorama of ancient raised field remains of the Viscachani Pampa pollen grains of quinua and potato belonging to the residents of Collana Segunda, Huatta, Peru, shows only a are present in many soil samples small portion of the 82,000 hectares of ancient raised fields in the Lake from the raised fields, indicating Titicaca Basin. The lighter surfaces are water-filled canals and the darker that these may have been the crops surfaces are raised fields or drier pampa.