Abstract

In one of the most arid places on Earth, the Atacama Desert in northern Chile (18-21 degrees S), pre-Hispanic cultures developed different types of tillage and irrigation systems in the Guatacondo Ravine. Their agrarian production, based on a summer precipitation regime, enabled the formative villages of Ramaditas (2300-2600 years BP) and Guatacondo (2400-2800 years BP) to emerge, along with seasonal agriculture. Despite the insight gained into their agricultural technology, we know very little about how this type of soil management affected the soils' plant nutrient status. Thus, our main objective was to determine if the different tillage systems affected the soils' properties. We analyzed the soils and the pollen composition of different tillage systems and carried out direct radiocarbon dating (C-14) of sediments. The soils' chemical properties (total nitrogen, phosphorus, and organic carbon contents) indicate greater nutrient retention in the square bed system, associated with a higher silt content and the use of organic fertilizers. Pollen analyses show the presence of crop, weed, and riparian species. In conclusion, the analysis of ancient soils gives us valuable information about the innovations and changes implemented in ancient times in the Guatacondo Ravine.