The potential of wastes to improve nutrient levels in agricultural soils: A material flow analysis case study from Busia District, Uganda

Like many other countries in Sub-Saharan Africa (SSA), Uganda faces a remarkable soil nutrient deficit in farmland soils. In order to cope with this deficit, many authors suggest increasing the recycling of hitherto unused nutrient sources from human excrement and urban municipal solid waste (MSW). However, a quantification of the potential of these nutrient sources to overcome soil nutrient deficits in Uganda has not been carried out so far. This research paper presents a case study calculating the soil nutrient balance for nitrogen (N), phosphorus (P), and potassium (K), as well as the potential of hitherto unused human excrement and urban MSW to decrease soil nutrient deficits in agricultural land by applying the method of material flow analysis (MFA) in Busia District (Uganda). Results show a high soil nutrient deficit of agricultural soils in the district, with values of −33 kg N ha−1, −6 kg P ha−1, and −41 kg K ha−1. The potential to reduce these negative balances is negligible for hitherto unused urban MSW (1-3%), but higher for human excrement (17-60%). The low potential of urban MSW as well as the hygienic problems associated with human excrement (particularly feces) means that other measures such as soil conservation and mineral fertilizer application should not be ignored in the effort to increase agricultural productivity. This is not only valid for Busia District, but also for other regions in SSA.