The impacts of global changes become more and more tangible, particularly on how we grow food, and governments, researchers, farmers, and other stakeholders are increasingly turning their attention to ClimateSmart Agriculture (CSA). With the rapidly changing climate, CSA builds on three dimensions: (1) intensifying productivity; (2) enhancing resilience; and (3) reducing greenhouse gas emissions.
The Global Alliance for Climate-Smart Agriculture (GACSA, ) was launched during the Climate Summit in September 2014 to engage leaders and advance climate action and ambition. GACSA is led by a team from FAO and CCAFS; to date more than 100 organizations have signed up with GACSA, including the African Union Commission (AU), the World Bank, the International Fund for Agricultural Development (IFAD), and Yara International. In July 2015, the Knowledge Action Group of GACSA released a series of practice briefs (http://www.fao.org/gacsa/resources/csa-practice-briefs/en/) that sought to provide operational information about the contributions of management practices to different indicators of CSA. Together with colleagues from the Natural Resource Management Unit and partners from the Alliance for a Green Revolution in Africa (AGRA) and the Institut des Siences Agronomique du Burundi (ISABU), we developed briefs on Integrated Soil Fertility Management (ISFM) and Coffee-Banana Intercropping (CBI). Each brief gives an overview of the practice, contributions of the practice to specific dimensions of CSA, and challenges to adoption, investment needs, metrics for evaluating impact, and case studies of implementation. The ISFM brief was a mini review of long-term trials and large dissemination programs in cereal-based systems comparing key indicators for the three CSA dimensions of practices. It illustrated that the combinations of mineral fertilizers with inputs of biomass residues or rotation of legumes result in a consistently greater crop productivity and value-to-cost ratio of inputs that improves food security and livelihood of farmers.
Several long-term studies have shown that ISFM practices reduce the variability in production between seasons implying that crops are more resilient to climate deviations. Cases were presented illustrating how input of organic residues or mixing of legumes can maintain a greater soil carbon stock, enhance fertilizer recovery by crops, and substitute for inorganic nitrogen inputs. The brief argued that ISFM practices may largely mitigate the greenhouse gas emissions compared to practices where only fertilizer is used or without inputs at all. Figure 1 gives the average grain productivity and seasonal variation in yield of maize cropping under different input practices across a 20-year trial at the research farm in Ibadan along with the total carbon content of soils at the start and end of the study period. This study presents some of the most comprehensive evidence about the contributions of ISFM to CSA. It showed that the grain yield of crops, resilience to drought, and the conservation of soil carbon in maize systems are all substantially greater when inorganic fertilizers and organic inputs are combined compared to other input practices.
The CBI brief, on the other hand, revisited studies on coffee-banana intercropping trials on fields of farmers and at research stations of IITA and its partners over the last 7 years. Research from Uganda, Rwanda, and Burundi was used to demonstrate that mixed coffee and banana planting benefit household incomes, improve resilience to climatic impacts, and sequester larger amounts of carbon than when growing either of these crops on their own. Figure 2 illustrates that practicing CBI can double annual revenues on land where coffee is grown without banana. Evidence showed that growing banana in newly established coffee farms reduces the farmers’ risk by offsetting cash flow constraints worth $10,000 during the first 4 years. It also described how the shading by banana reduces canopy temperatures in coffee by 2–3oC and prevents the distribution of pests and diseases. This makes the systems more resilient to climate change impacts and improves quality.
The CBI brief gave evidence that mulching of banana in intercropped systems leads to accumulation of carbon and nitrogen in the soil that may reduce greenhouse gas emissions. CBI is a traditional practice in areas with high population density due to diminishing farm size and soil degradation. It shows a great potential for adoption that could benefit 20-25 million farmers who depend on coffee and/or banana for their livelihood. It also emphasizes the need for change in the attitudes of value chain actors as well as decision support about the variety of banana, optimal planting densities, and proper timing and frequency of pruning to bring the CBI practice to scale.