Maintaining yield growth is critical to climate change mitigation in the agricultural sector since the conversion of forestland to crop and livestock production is the single largest source of CO2 and overall GHG emissions from agriculture. If growing demands for agricultural goods are not to be met by expanding acreage, yields must rise, and post-harvest technology must improve to reduce loss and spoilage.
Continued yield growth is a necessary, but not sufficient, condition for higher agricultural output without land conversion. While higher yields imply that more food can be produced without land expansion, higher yields do not necessarily reduce pressures for land expansion (Mundlak, 1997; Larson, 1994). Some types of technologies may increase demand for land or displace labour, encouraging migration to frontier areas (De Janvry, 1988; Fearnside, 1987). Much research is needed to identify the conditions under which different types of yield-increasing technologies reduce or increase demands for land expansion.
The international system of agricultural research and technology transfer has been highly successful in raising global agricultural productivity, albeit unevenly across regions. Between the beginning of the 1960s to the end of the 1980s, global production of major cereals doubled (Table 11.5). About 92 per cent of this doubling can be attributed to yield increases with only 8 per cent coming from expansion of agricultural land. Yet, in some parts of the developing world, particularly Latin America and sub-Saharan Africa, agricultural land expansion remains an important source of agricultural growth (Table 11.5). In the 1980s, about 8 per cent of the world's tropical forests were cut down. Three-quarters of this occurred in Latin America and sub-Saharan Africa.
|Table 11.5 Contribution of increases in area and in yields to growth of cereals production in developing regions and high income countries between 1961 to 1963 and 1988 to 1990|
|Country Group||Percent Growth in Cereal Production Attributable to Increased Area||Percent Growth in Cereal Production Attributable to Increased Yield||30-year Growth Rate of Cereal Production(per cent)|
|High Income Countries||2||98||67|
|North Africa / Middle East||23||77||68|
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