Expert Meeting on How to feed the World in 2050 Food and Agriculture Organization of the United Nations Economic and Social Development Department CAN TECHNOLOGY DELIVER ON THE YIELD CHALLENGE

This paper focuses on the yield prospects of wheat, rice and maize since these cereals dominate human diet, and since continued yield growth is considered the major route to meeting future global demand for food, feed and fuel. We define for a region farm yield (FY), attainable yield (AY, as reached with the best technology and prudent economics), and potential yield (PY, yield with the best varieties and agronomy and no manageable biotic or abiotic stresses). FY progress is a function of progress in PY and in closing the gap between PY and FY (we express this gap as a percent of FY). Globally wheat and rice annual yield increases (as a percent of current yield) are falling and are now just below 1 percent, while that for maize is 1.6 percent. For rice and wheat, the growth of yields in absolute terms (kg/ha/year) are also falling in developing countries. Global demand modelling to 2050 predicts large real price sensitivity to yield growth rates, with significant price increases if current rates cannot be increased. FY, PY and yield gaps are examined in more than 20 important “breadbasket” regions around the world. For wheat annual PY progress currently averages about 0.5 percent, and the yield gap 40 percent (range 25 to 50 percent), while for rice PY growth is also about 0.5 percent while the yield gap averages 75 percent (range 15 to 110 percent). Maize is distinctive with a current average PY growth of around 1 percent and a yield gap which ranges from around 30 percent (Iowa, some uncertainty with PY) to over 200 percent (sub-Saharan Africa). A yield gap of 25 percent or less probably implies that FY is approaching attainable yields, AY. Yield gaps tend to be larger in developing countries, and seem to be closing only slowly except in the case of maize in Iowa and major cereals in Egypt. Prospects for yield gap closing are discussed. A multitude of constraints can reduce FY, ranging from infrastructural and institutional ones bearing upon farm gate costs and prices and farmer skills and attitudes, to diverse technical constraints. The resolution of the latter in turn depends largely on agronomic and breeding interventions (e.g., better resistance to biotic stresses), though these must be resolved in concert with the other constraints if they are to have significant impact in resource-poor farmers’ fields. Yield gap closing must be a priority for maize in sub-Saharan Africa. Prospects for PY increase are discussed. PY gain is increasingly related to greater biomass production, implying greater efficiency of utilization of solar radiation. Recent progress appears to have raised this efficiency, while the theoretical limit still appears to leave scope for further increase. In addition PY in water-limited situations (PYw) will depend on further harvest index increase. In rice and wheat heterosis offers prospects for yield gain. We remain skeptical of the medium-term prospects of genetic modification (GM) for yield per se, especially PY, but recognize that existing GM crops often deliver higher yields because of gap closing benefits (such as reduced pest losses). New molecular tools for selection show promise for increasing breeding efficiency, but the marginal cost of yield gains is likely to rise. Strong private investment in breeding, as seen with maize, could play a bigger global role, accompanied by facilitating policies. We recognize in addition the importance of input efficiency and total factor productivity (TFP) for determining real prices, while prices of non-renewables (energy for traction and N fertilizer; phosphorus) are a relevant concern. TFP in agriculture continues to grow, and many examples confirm the general synergy 1 R.A. Fischer, CSIRO Plant Industry, PO Box 1600, Canberra City, ACT 2600, Australia ([email protected]); D Byerlee, 3938 Georgetown Ct NW, Washington DC, United States of America ([email protected]); G.O. Edmeades, 43 Hemans Street, Cambridge, New Zealand ([email protected]). This paper was produced for the FAO Expert Meeting on How to Feed the World in 2050 (Rome, 24-26 June 2009). The views expressed in this information product are those of the author(s) and do not necessarily reflect the views of the Food and Agriculture Organization of the United Nations. 2 FAO Expert Meeting on How to Feed the World in 2050 24-26 June 2009 amongst modern input technologies that achieve not only greater yield but also greater resource use efficiency (e.g. N, P, water, fuel, labour). There are also large gaps in input use efficiency that offer much scope for improved crop and resource management to deliver more with less. Investments in research and development, farmers’ information and skills, and good policy drive this process, and will determine future success or failure.