Greening the African green revolution: Exploring agroecological transitions in East Africa
Nearly 80% of countries in sub-Saharan Africa (SSA) face problems of nitrogen (N) scarcity, which together with poverty causes food insecurity and malnutrition. Across sub-Saharan Africa (SSA), agricultural systems are rapidly changing in response to the African Green Revolution. Although fertilizer use is increasing, we have little understanding of the fate of nitrogen (N) fertilizer in these tropical croplands. Experimental maize plots were established in a randomized complete block design in western Kenya (high-clay soil) and mid-western Tanzania (low-clay soil). Plots were amended with 0, 50, 75, and 200 kg N/ha/yr as mineral fertilizer. We tracked N movement through soils, plants, water, and gas-exchange for two years, and present data on N balances that highlight the need for locally-specific agroecological transitions from subsistence to intensified agriculture.
We find N losses from high-clay soils to be nearly two orders of magnitude lower than low-clay soils with implications for both productivity and environmental quality. Fertilizer use efficiency was much higher in the high-clay compared to low-clay soils in the absence of organic inputs. Mulching with native leguminous species show great potential to improve moisture and nutrient retention in low-clay, low-fertility soils. Such practices hold great potential for supporting sustainable soil management, but require a coherent policy framework to support their wider adoption and long-term investment by farmers. Fortunately, a growing global demand for good quality, low-cost soils data has been moving forward, which inform national and international efforts that invest in agricultural intensification across SSA. Agroecological transitions can adapt to future demands for food and other ecosystem services. Future research efforts in SSA should focus on how to adapt land management practices to enhance soil ecosystem services, and improve system resilience.