Cassava Program Theory of Change
Building local resilience and addressing climate change challenges faced by smallholders growing cassava
(1) Diversified cassava for specific landscapes and uses
Cassava is grown in different environments, and the climatic differences between locations will become increasingly evident as the effects of ongoing climate change become more palpable. Cassava is grown for different purposes, with some traits more desirable for food and others for industrial uses. The Cassava Program is generating novel germplasm applying a product concept to its main deliverables, i.e. varieties carrying sets of prioritised, fit-for-purpose traits that include agronomic adaptation and quality attributes.
A driver for varietal diversification is to offer growers choices suited to their specific needs. One prioritisation criterium involves impact maximisation among target smallholder populations. For varietal uptake to occur, the current informal seed system needs to be understood and utilised as a conduit while at the same time developing local seed systems to manage pest and disease spread in ways that are culturally acceptable and easy to implement. Work has already commenced with the use of micropropagation poly-tunnels, proving that it is possible to establish local seed systems.
Cultural differences are evidenced for example by the dominance of one variety in SEA, while in LAC farmers grow a range of varieties, with some traditional varieties being handed down from generation to generation. This has to do with a longer tradition of growing cassava in LAC and predominantly for food, while cassava is very much an industrial crop in SEA. Ideally, SEA would require a greater genetic diversity for better agroclimatic adaptation and to better manage pests and diseases. In LAC, success in varietal diversification would be characterised by a shift to varieties better adapted to current climatic conditions and addressing emerging end-user requirements in an increasingly modern world.
Diversified used of cassava within farming systems incorporating other crops or livestock will help build local resilience. Research must focus on the integration of cassava in diverse farming systems, with agronomic practices that can support the transition from cassava to higher-value crops and increasing our understanding of the socioeconomic underpinning more diverse farming systems.
Achievement of this outcome will require activities in the following areas:
- Identification of opportunities and barriers for differentiation across the value chain.
- Increased understanding of cassava as a pathway to prosperity (at a regional level).
- Development of agronomic practices that support transition to or production in a broader farming system.
- Increased understanding of future regional needs, including climate change impacts.
- Increased understanding of regional emerging pest and disease pressures.
- Knowledge on changing end-user requirements and the ability to develop new end-uses.
- Identification opportunities for genetic solutions to meet end-user needs.
- Increasing the efficiency to identify purposeful genetic diversity.
- Conservation and characterisation of genetic diversity.
- Development of context-specific, climate-adapted varieties.
(2) Improving soil health on degraded lands
Cassava can be grown on marginal land and still yield a profitable crop with minimal input. This creates capacity for poor smallholders to gain a small return from minimal investment, which over time could turn into resources—such as capital—and capacity increase, leading to improved agronomic practices and fertiliser application. At the same time, cassava roots can serve to break up compacted soil and restore soil health on degraded land to create viable conditions for more valuable crops. This pathway has the potential for smallholders to gain an income while restoring land and use cassava to increase capital over time. This is rather speculative at this stage, given the small margins obtainable from such operation, and will need further research if identified as an avenue worth pursuing.
Cassava is often grown on mountainous marginal lands that are prone to soil erosion caused by rain, representing a significant threat to the sustainable use of such lands or their recovery from deforestation. Climate change will increase the number of storm events and the risk of soil erosion. Appropriate mitigation practices are required, with a transition to higher-value tree crop perennials providing longer-term sustainable opportunities.
Achievements in this outcome will require understanding of integrated farming systems and how cassava can be used in the transition to higher-value crops. This is an area for collaboration with other commodities offering longer-term and economically viable solutions for smallholders.
Achieving this outcome will require research in the following areas:
- Development of planting methods for quicker crop establishment on at risk soils
- Identification of traits required for restoration and soil health
- Development of integrated farming systems and practices for restoration
- Development of alternative local inputs, within local farming and processing systems
- Encouragement of value chains to supply and receive produce from new cassava growing areas (such as previously degraded lands in LAC)
- Varieties developed with faster establishment and growth.