Persevering with Great Abandon: An Archaeobotanical Investigation of Resilience and Sustainability in Eastern African Irrigated Terrace Agriculture

The site of Engaruka in northern Tanzania has been the focus of decades of archaeological research regarding the development of terraced field systems in East Africa. Engaruka is a vast agricultural landscape, occupied from the 14th century and abandoned in 18th century. The abandonment of such a large and intensively cultivated area has been interpreted by some policy makers as a response to a failure of the agronomy, as has been argued elsewhere. This PhD research represents the archaeobotanical component of the AAREA (Archaeology of Agricultural Resilience in East Africa) Project, which was focused on establishing the efficacy of applying archaeological results that are in a dynamic state of development to policy decisions regarding agricultural resilience and sustainability. This study focuses on the identification of crops in cultivation at Engaruka during its occupation based on the analysis of archaeobotanical residues (e.g. charred plant remains), as well as historic and ethnographic observations of cultivation throughout the region. The results confirm the presence of sorghum and other millets as well as several pulses, disproving the argument that ancient Engarukans were practicing sorghum monoculture. These data have been queried to address questions about the presence and preservation of millets and pulses and non-crop taxa in both expected and unlikely contexts, providing information on a range of issues including cultivation strategy and practice, specifically relating to harvesting techniques, the role of wild and weedy taxa, and differential use of space. Discussion is based upon detailed investigations of plant cultivation, collection/harvest, and exploitation through quantification of charred plant macrofossils, gathered weeds/wild taxa, and interview data relating to farming practices, thus highlighting the strengths of a multi-disciplinary approach for understanding resilience, sustainability, and, more generally, what it means to subsist in a challenging and dynamic agricultural landscape.