The spread of Conservation Agriculture: justification, sustainability and uptake

Conservation Agriculture (CA) has been practised for three decades and has spread widely. We estimate that there are now some 106 million ha of arable and permanent crops grown without tillage in CA systems, corresponding to an annual rate of increase globally since 1990 of 5.3 million ha. Wherever CA has been adopted it appears to have had both agricultural and environmental benefits. Yet CA represents a fundamental change in production system thinking. It has counterintuitive and often unrecognized elements that promote soil health, productive capacity and ecosystem services. The practice of CA thus requires a deeper understanding of its ecological underpinnings in order to manage its various elements for sustainable intensification, where the aim is to optimize resource use and protect or enhance ecosystem processes in space and time over the long term. For these reasons CA is knowledge-intensive. CA constitutes principles and practices that can make a major contribution to sustainable production intensification. This, the first of two papers, presents the justification for CA as a system capable of building sustainability into agricultural production systems. It discusses some of CA's major achievable benefits, and presents an overview of the uptake of CA worldwide to 2009. The related paper elaborates the necessary conditions for the spread of CA.