摘要：Who feeds the world? Two billion small-scale farmers who in addition to feeding themselves also produce surpluses for local markets — these are the food producers for a global population. Domestic markets along with the food consumed by the producers’ families constitute more than 70% of the world’s food consumption and are often overlooked in the food security debate. The importance of these producers to overall global food security is not in dispute, but can these farming systems continue to perform at current or improved levels, considering the influence of human-induced land and water degradation and associated effects on ecosystem services? Soil erosion, depletion of nutrients and soil organic matter, salinisation and surface and groundwater pollution are challenges that have confronted agricultural and urban communities for decades, and still do. Land degradation associated with inappropriate and unsustainable land use practices is estimated to affect 5–10 Mha annually; 34 Mha of global irrigated areas is affected by salinisation; it is estimated that 25% of global freshwater storage capacity will be lost in the next 25–50 years unless measures are taken to control sedimentation in reservoirs; approximately 2 Mt of waste is dumped into rivers, lakes and wetlands each day; and it is estimated that there are now 12,000 km3 of polluted water on the planet, a volume greater than the contents of the world’s ten biggest river basins. This litany of land and water degradation issues represents a diminished ability of ecosystems or landscapes to support functions and services required to sustain livelihoods. Small-scale farmers, the engine of global food supply, are the mainstay of most developing country rural economies and often occupy marginal and vulnerable lands. It makes sound economic sense to address this ‘slumbering giant’ of degradation through increased conservation investments in land and water resources within this sector. Whilst technologies, technology packages and management practices have been developed that demonstrate the practicalities of addressing these resource degradation issues, adoption at scale has been disappointing. Government institutions and development and research organisations are tasked with sustainably securing future food supplies. Their central challenge is to develop greater insights into constraints inhibiting adoption of productivity-enhancing and conserving interventions, and to identify the driving factors and relevant levers to address these constraints. Time may not be on our side in addressing land and water degradation, central to one of the nine thresholds that define ‘a safe operating space for humanity’.
