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AAREA Informe resumido

Project ID: 337128
Financiado con arreglo a: FP7-IDEAS-ERC
País: United Kingdom

Mid-Term Report Summary - AAREA (The Archaeology of Agricultural Resilience in Eastern Africa)

The Archaeology of Agricultural Resilience in Eastern Africa project (AAREA) aims to assess whether, and in so if what ways, archaeological data can contribute to assessments of the sustainability of agricultural strategies, and is doing so via two case-studies in East Africa: the abandoned terraced and irrigated landscape at Engaruka, Tanzania, occupied between the 14th and 18th centuries AD, and the currently farmed terraced and irrigated landscape in Konso, Ethiopia, thought on the basis of historical data to have its origins at least 500 years ago. If archaeological data is to contribute to modern questions of long-term sustainability it is necessary to demonstrate an ability to define how resource-use strategies develop, change and function through time, and to communicate these data and their strengths and weaknesses to audiences within governmental and non-governmental organisations that might seek to apply this information. To this end the project is employing a combination of stratigraphic excavation, soil chemistry and micromorphology, macro- and micro-archaeobotany, and Agent-based modelling, and is communicating results directly to key target audiences via the appointment of a full-time ‘development liaison’. Two seasons of fieldwork have been undertaken to date, the first at Engaruka in 2014, and the second in Konso in 2016.

The Engaruka research has demonstrated that a system formerly thought to have been irrigated due to a need to maximise available water did in fact have to deal with water levels capable of flooding large areas, and indeed inhabitants exploited these periodic inundations and the sediments entrained within them to create large sediment traps, the soils within which show micromorphological features most akin to paddy soils, and contain phytoliths (microscopic pieces of silica that form in the cells of some plants) confirming the cultivation of the African cereal sorghum, and strongly suggesting the cultivation of rice; the latter, if confirmed, being the earliest cultivation of rice in inland east Africa. Although the consumption (and hence assumed cultivation) of sorghum had been evidenced from excavations conducted in the 1960s, the recovery of the charred remains of sorghum, pearl millet, broomtail millet and various pulses from excavated cooking hearths by the current project greatly increases the range of crops known to have been exploited, and has a bearing on assessments of the sustainability of this agronomy since growing multiple crops potentially mitigates against crop pests, diseases and failures. Stratigraphic results demonstrating the sequence of field construction, and together with forthcoming results of Optically Stimulated Luminescence dating (OSL) and Infra-red Stimulated Luminescence dating (IRSL), inform the construction of hydrological and agent-based computer models which are exploring how this landscape developed, changed and functioned through time.

The results of soil and archaeobotanical sampling at Konso are forthcoming, but the stratigraphic results show that that in most locations all of the original topsoil and subsoil had been lost through soil erosion before the construction of the dry-stone agricultural terraces, with the soils contained within these terraces formed by later colluvium (i.e. material eroded downhill). This is an important finding because proponents of so-called ‘indigenous’ soil and water conservation techniques tend to assume that terraces are an effective means of preventing loss of fertile topsoils. As importantly, this lost topsoil and subsoil is almost certainly the source of the material captured in riverside sediment traps known locally as yela, which suggests a landscape development sequence where the earliest yela predate the earliest terraces: i.e. hillside erosion (presumably following the removal of vegetation and a period of cultivation of the hill slopes) led to widespread soil loss; these soils washed into the river, where the fine materials were carried downstream and were deliberately incorporated into fields by capturing these behind periodically heightened barrage walls; with these irrigable riverside sediment trap fields subsequently being protected from material eroding directly from adjacent hill slopes by the construction of terraces. This suggests that in the early phases at least, the yela were considered a far more important resource than the terraces; a hypothesis the project is attempting to assess via adapting a ‘natural capital’ approach, more common in assessments of modern economics, sustainability assessments, and eco-system services appraisals.

In both case-studies, therefore, the project has demonstrated that archaeological approaches can enhance studies of ‘indigenous knowledge’ by exploring how local technologies developed and functioned. Work to attempt to quantify the modern implications of these legacies and to explore whether these data are of use to modern development planners is ongoing.

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United Kingdom
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