Urban Market Gardening Improves Soil Health: A Case Study in Burkina Faso

In sub-Saharan Africa, urban market gardening is characterized by the intensive use of chemical inputs, which could have adverse effects on soil health. This study therefore aimed to assess the impact of urban market gardening on soil health. Topsoil samples were collected from 69 plots at a market gardening site in Bobo-Dioulasso, Burkina Faso, with cultivation histories ranging from 0 to over 50 years. Twenty-six chemical, biological, and physical soil properties were analyzed. Principal component analysis was used to identify minimum data sets for the assessment of soil health. The selected variables were standardized and aggregated into two soil health indices on a scale from 0 to 100: an overall index based on all properties combined and an average index based on the mean of the biological, physical, and chemical components of soil health. Both indices revealed a clear improvement in soil health over time, with the overall index rising from an initial value of 0.35 to 0.64 after 60 years and the average index rising from 0.30 to 0.62. The average index, which enables the separate assessment of its three components, accounted for a greater share of the temporal variability (R² = 0.59) than the overall index (R² = 0.47). These findings highlight the positive impact of urban market gardening practices on soil health at the study site, which was attributed to the large additions of organic amendments.