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Towards an applied archaeology of east African agricultural systems

Funded by the AHRB with fieldwork supported by the British Institute in Eastern Africa and UCL, the project forms part the BIEA’s ‘History, Subsistence and Environmental Change During the Holocene’ research programme, and aims to explore the history of east African intensive agriculture and the ways in which perceptions of African agricultural history are employed in debates regarding developmental interventions. The project thus focuses on a group of communities that appear to have maintained relatively high population densities for extended periods through the use of soil and water conservation techniques; attributes which make them both archaeologically visible and attractive to development planners as potential paradigms for locally managed and environmentally sustainable resource exploitation. Recently referred to as ‘east African islands of intensive agriculture’, these historically and culturally distinct areas include the extensive terraced and irrigated landscapes in the southern Ethiopian highlands, as well as those in the Kerio Valley in Kenya and on the slopes of the mountains to the north of the Pangani river in Tanzania. However, although the majority of these agronomies appear to have their origins in the Late African Iron Age their early histories remain obscure, whilst historical and genealogical information relating to the more recent past attests to substantial political, economic and operational changes within these systems during the nineteenth and twentieth centuries. It is clearly misleading, therefore, to claim that local resource exploitation strategies are either unsustainable or environmentally appropriate in the absence of historical data regarding the longevity of practices, or where there is insufficient information concerning changes to environmental conditions through time.

Excavated irrigation furrows looking east towards the Rift Escarpment
Excavated irrigation furrows looking east towards the Rift Escarpment
Photo: Daryl Stump

With a view to examining whether archaeological enquiries could provide the information necessary to qualify these debates, the current project carried out three seasons of fieldwork at Engaruka, Tanzania. Comprising some 2000ha of stone-bounded fields overlooked by a series of terraced settlements, the site has been recognised since the early 1960s as the remains of a Late Iron Age, primarily arable, economy, whilst subsequent surveys undertaken by J.E.G. Sutton have demonstrated that the vast majority of the former cultivation area was served by a complex system of irrigation channels. Radiocarbon determinations commissioned by Hamo Sassoon, Peter Robertshaw and Ari Siiriäinen place the earliest occupation of the site in the early fifteenth or perhaps late fourteenth century AD, and suggest that the settlements and associated fields were employed for between three and four centuries. This makes the site a comparatively rare and early example of an east African irrigated agronomy, and indeed it is the largest known site of this type to have been deserted prior to European contact. The site thus offers opportunities to examine cultivation areas that have not been substantially disturbed by later exploitation.

Irrigation channel and furrow off-take looking east
Irrigation channel and furrow off-take looking east
Photos: Nick Black

Following a pilot study which aimed to examine the soil chemistry of the field areas with a view to assessing the veracity of the hypothesis that the site was abandoned due to falling soil fertility, the current project examined the stratigraphic development of agricultural terraces, irrigation channels and associated structures, whilst the habitation areas were investigated by excavations and surveys carried out as part of the University of Helsinki’s ‘Cultural Ecology of the East African Savannah Environment’ project. The combined results of these investigations demonstrate that the field and irrigation system at Engaruka supported a relatively high population density; that this system developed gradually with irrigation features as integral elements of the agronomy rather than later additions; and that although there is some evidence of soil depletion within the field areas, this would not seem to be of a level that would have produced a Malthusian collapse. In short, these results suggest that the site does not yet deserve its reputation as an example of environmental mismanagement and, moreover, demonstrate that relatively simple archaeological techniques have the potential to precisely model the development and expansion of African agricultural systems, and can do so over a longer period than the methods available to other disciplines. However, it is equally clear that archaeological studies alone cannot provide details of non-structural aspects of agricultural communities such as cropping and fallowing strategies, or of potentially significant cosmological conceptions such as local perceptions of the ‘environment’ or ‘climate’. Similarly, they will struggle to see and understand relatively rapid changes in resource exploitation strategies, as defined for other east African agricultural communities through the detailed examination of written and oral sources. This research concludes, therefore, that there is a real need for a truly interdisciplinary approach to this area of study, but that such an approach should include an archaeological component.

References:

Barker, G. and D. Gilbertson (eds.) 2000. The Archaeology of Drylands: living at the Margin. London: Routledge.

Sutton, J.E.G. (ed.) 1989. ‘History of African Agricultural technology and field systems’ Azania 24

Widgren, M. and J.E.G. Sutton (eds.). 2004. Islands of Intensive Agriculture in Eastern Africa. Oxford: James Currey.

 


© 2007 Editor, Sada Mire, and the individual authors of these African Heritage and Archaeology webpages

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