Refining crop isotopic approaches to understanding past farming practice: gaining an archaeological insight into agricultural sustainability in West Africa

Background

Insights into farming practices are essential for understanding the economy of past agricultural societies; strategies for maximising crop productivity and generating agricultural surplus can reveal much about a society’s organisation and complexity.

Stable carbon and nitrogen isotope analysis of preserved crop remains provides a novel and direct method of detecting labour-intensive practices such as manuring and irrigation and thus determining how farming practice changed through time.

This project will focus on the Sahel region of West Africa, where over a decade of research at the Goethe University, Frankfurt has enabled detailed interpretation of archaeological remains spanning more than three thousand years.

Key Research Questions

What effect do farming practices have on crop isotope values in semi-arid West Africa?

The δ¹³C and δ¹⁵N values of crops growing in present-day fields in Senegal will reveal the effect of known farming practice on crop isotope values, providing the framework for interpreting isotope values of preserved crop remains from archaeological sites in the Sahel.

How did the intensity of farming practice in Burkina Faso change over 3000 years?

The δ¹³C and δ¹⁵N values of ancient crops from a series of well-investigated archaeological sites in Burkina Faso will provide insights into changing water and nutrient inputs as agricultural production increased from the Final Stone Age to the Late Iron Age. This work will be the first of its kind in Africa and will highlight the major potential of isotope analysis of charred plant remains in a new region of the world.

How can knowledge of past farming practice contribute to debates regarding present-day agricultural sustainability and resilience?

The archaeological results will provide a unique insight into the effect of truly long-term continuous cultivation on soil nitrogen cycling and water retention in the Sahel. This will inform the work of present-day agroecological projects and producers seeking to develop resilient agrosystems in this climatically vulnerable region.

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