'Lost city' used 500 years of soil erosion to benefit crop farming

21 August 2017. Engaruka, Tanzania. Researchers at the University of York working on a 700-year old abandoned agricultural site in Tanzania have shown that soil erosion benefited farming practices for some 500 years.

The study, published in Quaternary Research, shows that historical practices of capturing soils that were eroded from the hillside could be valuable to modern day farming techniques.

Research demonstrated that sophisticated irrigation systems and terraces at the site of Engaruka were not built to prevent soil erosion, as originally thought, but were instead built to capture eroded sediments to feed the arid landscape below.

Engaruka first came under the spotlight in 1935 and was thought, at the time, to be a 'lost city' of up to 40,000 inhabitants. It has since been recognised as the remains of the largest abandoned system of irrigated agricultural fields and terraces in sub-Saharan Africa.

Covering 20km2, the site was mysteriously abandoned 200 years ago, which some experts believe was due to climate change or deforestation reducing the water supply to the fields.