Measuring the Sustainability of Intensified Maize-Legume Systems in Malawi

To paraphrase C.S. Lewis, without milestones, without signposts, we are on a gradual road, gentle in slope … possibly leading to Hell. There is widespread agreement that we need sustainable intensification (SI) metrics to measure our progress, to provide milestones along the way. Many indicators have been proposed; the vast majority of which encompass the ‘big picture’, measuring human well-being, ecosystem services and land use change. More elusive are practical SI metrics that can be used by local actors. We present a case study of such measures, assessing SI trajectories in maize. Maize is a principle staple crop around the globe, and nowhere more important than for smallholder communities in Sub Saharan Africa. A transdisciplinary action research program supported by Africa RISING in Malawi was conducted to assess – with farmers and other stakeholders – innovations in maize-legume systems. On-farm ‘mother and baby trial’ experiments are underway with over a 1000 farmers, with indepth characterization at 16 sites representing an environmental gradient from hot, dry semi-arid sites to mid-altitude mesic sub-humid sites. We measured at the plot level variability and quantity of grain, protein, resource efficiency (maize response to fertilizer and rainfall), vegetative cover, stocks of active soil C and nitrogen fixation inputs, as well as assessing implications for food security at the farm level through linked modeling. Assessment of profitability, farmer ranking and adaptations of technologies provided additional socio-economic metrics. Overall, maize systems that included ‘pulse plus’ legumes supported SI trajectories for poor and well-off households. Pulse plus systems scored high in terms of farmer acceptability, grain and protein production, enhanced C and N fixation, reduced variability of yield, and profitability. A key SI metric was the type of adaptations undertaken by farmers: in our case study 70% of farmer innovations involved planting new legume species, or combinations of legume varieties, inputs and improved maize.  Research findings were projected over space and time through modeling to assess tradeoffs and sustainability of trajectories. The farm-level SI metrics assessed here provide a minimum data set that agronomists, economists and policy makers can use, and a relevance check for sustainable intensification assessments at regional and global scales.