ABSTRACT
All commentators now agree that food production worldwide will have to increase substantially in the coming years and decades (World Bank, 2008; IAASTD, 2009; Royal Society, 2009; Godfray et al., 2010). But there remain very different views about how this should best be achieved. Some still say agriculture will have to expand into new lands, but the competition for land from other human activities makes this an increasingly unlikely and costly solution, particularly if protecting biodiversity and the public goods provided by natural ecosystems are given higher priority (MEA, 2005). Others say food production growth must come through redoubled efforts to repeat the approaches of the Green Revolution; or that agricultural systems should embrace only biotechnology or become solely organic. What is clear is that more will need to be made of existing agricultural land. Agriculture will, in short, have to be intensified. Traditionally agricultural intensification has been defined in three different ways: increasing yields per hectare, increasing cropping intensity (i.e. two or more crops) per unit of land or other inputs (water), and changing land use from low-value crops or commodities to those that receive higher market prices.
