Over the last decade, Africa has been targeted by large-scale agricultural investments (LAIs) in the global rush for agricultural land and resources. This potential land use change has generated multifaceted and controversial political, environmental, economic, legal, and ethical issues. Despite this, in the case of Mozambique and Kenya, land use in the region remains dominated by small-scale farmers (SSFs) who are competing with LAIs for limited natural resources. In this study, the agronomic potential and environmental impacts of LAIs versus SSFs for two case studies in Kenya and Mozambique were investigated. The aim was to highlight major yield-limiting factors and environmental threats to better inform resource management and the sustainable integration of LAIs into the local landscape. Using data collected from interviews with LAIs and SSFs, a characterization of representative management practices and cropping systems was constructed. These “virtual farms” were analysed using a Life Cycle Assessment (LCA) approach to quantify potential off-site environmental impact indicators, namely: Eutrophication Potential (EP), Acidification Potential (AP), Global Warming Potential (GWP), the Water Footprint (WF), and Non-Renewable Energy (NRE) consumption. Furthermore, the APSIM model calibrated with local soil and weather data was used to quantify on-site soil degradation in the form of soil organic carbon (C) and total soil nitrogen (N) depletion and investigate yield gaps for each system.
Water scarcity was identified as the main limiting factor for SSF production in the Kenyan study region. The relatively high WF of LAIs and the collective WF of SSF irrigation pose a serious threat to already scarce blue water resources. A high demand for land was observed in the Mozambican study region. LAIs are contributing to land issues indirectly by displacing SSFs, thereby expanding cropland into areas previously under natural vegetation, and more directly through soil degradation.
The LAIs’ strategy of input intensification resulted in relatively high potential off-site impacts in both regions. In Kenya, this was offset by high yields, while in Mozambique the LAI yield gap remained high indicating low resource-use efficiency. Yield gaps for SSFs were high in both regions due to negligible input use in Mozambique and low resource-use efficiency in Kenya. Even though LAI systems are more productive than SSF systems,
their intensification strategies have been shown to be unsustainable if management practices are not improved. On the other hand, the low yields observed in SSF systems are agronomically unproductive and also environmentally unsustainable.
While acknowledging that there are a myriad of factors contributing to the adoption of sustainable crop production practices, management strategies should be revised if both systems are to co-exist sustainably for decades to come. It is recommended that policies should be implemented to capture the positive spill-over effects from the introduction and re-introduction of LAIs to the region, specifically by promoting sustainable technology and information transfers, credit and short-term loans, and by improving the supply chains of important agrochemicals.
Keywords: land grabbing, life cycle assessments, APSIM modelling, water footprint, virtual farm