Sustainable Intensification of Rain-Fed Cereals In a Changing World.

Smallholder farmers cope with high variability, including rapidly changing market conditions, uncertain climate, and shifting government policies. There is urgent need for technologies that promote stability and system resilience – particularly for rain-fed agriculture. We reviewed the literature on field-based experimentation with intensification from sub-Saharan Africa, and derived the following principles for sustainable systems. Enhanced carbon and nitrogen fixation can be supported through crop diversification and targeted microdosing of inputs. Sustainable intensification (SI) technologies rely on extending plant growth and complementary combinations of species, along with judicious use of inorganic and organic inputs. In southern Africa, gains in yield stability were demonstrated at regional scales and over multiple years, from 10 to 45%, compared to intensification of monoculture crops. Gains in fertilizer efficiency with SI diversified systems were 30 to 100% higher. The benefits are less clear in terms of no-till and related technologies that reduce soil disturbance through herbicide reliance. There were reports of negative as well as positive performance in no-till. Longer term investment maybe required for no-till to meet biological and socioeconomic goals. Integrated combinations of biodiversification and reduced disturbance were understudied, and urgently require research and farmer innovation. Tradeoffs associated with SI occurred across the board, and were particularly noticeable in drier environments. Investment in resources and education were prerequisites for implementing the technologies. Further, many technologies required onerous labor investments. This highlights the need for returns on many fronts if technologies are to be attractive. A positive finding was that SI technologies were being adopted in some regions, and that they enhanced biological processes and efficient use of resources. Indeed, they offer a way forward, one that could promote agricultural resilience in the face of drought, floods and changing markets.