World agriculture towards 2030/2050: the 2012 revision - Fao

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PROOF COPY larger than their annual renewable water resources. Groundwater mining also occurs in certain parts of some other countries of the Near East and in South and East Asia, Central America and in the Caribbean; even if at the national level the water balance may still be positive. On average irrigation based on groundwater withdrawal accounts for some 38 percent of all irrigation at the world level (Siebert et al., 2010), with high proportions for groundwater based irrigation in (apart from the countries mentioned above) India (64 percent), Bangladesh (74 percent) and the Syrian Arab Republic (68 percent). Such high reliance on groundwater extraction which often causes rapid declining groundwater levels should be a cause for concern. In concluding this section on fresh water use in irrigation, for the developing countries as a whole, water use in irrigation currently represents a relatively small part of their renewable water resources. With the relatively small increase in irrigation water withdrawal expected between 2005/07 and 2050, this situation will not change much at the aggregate level. Locally and in some countries, however, there are already very severe water shortages, in particular in the Near East/North Africa region. 4.2.6 Crop yield growth As discussed in section 4.2.1, it is expected that growth in crop yields will continue to be (and even more so than in the past) the mainstay of crop production growth, accounting for nearly 80 percent of the latter (well over 70 percent in developing countries and for all of it in the developed countries). Although the marked deceleration in crop production growth foreseen for the future (Table 4.3) could point to a similar deceleration in growth of crop yields, such growth will continue to be needed. Questions often asked are: will yield increases continue to be possible and what is the potential for a continuation of such growth? There is a realization that the chances of a new Green Revolution or of one-off quantum jumps in yields, are now rather limited. Some even believe that for some major crops, yield ceilings have been, or are rapidly being, reached. At the same time, empirical evidence has shown that the cumulative gains in yields over time due to slower, evolutionary annual increments in yields, have, for all major crops, been far more important than quantum jumps in yields (for example see Byerlee, 1996). Such concerns are often based on the observed slowdown in yield growth for major crops, in particular cereals. Figure 4.10 shows the annual growth rates of cereal yields over sliding 25-year periods, which indeed confirm a gradual slowdown in such growth. The reasons for such slowdown however are more likely to be found in the observed slowdown in world cereal production than in certain resource constraints (including the genetic potential) becoming binding. As explained in Chapter 3, growth in cereal production, which at the global level equals demand for cereals, is decelerating in response to a slowing population growth and to an ever-increasing share of world population attaining medium to high levels of food intake. Figure 4.10 also shows that more recently growth in cereal yields even exceeded the growth in cereal production permitting a decline in the area allocated to cereals. 125
PROOF COPY Figure 4.10 Annual growth rates of world cereal production and yields (over preceding 25-year period; historical 1961 - 2007) 3.00 2.50 2.00 1.50 1.00 0.50 0.00 yield production harvested land -0.50 1985 1990 1995 2000 2005 2010 Harvested land and yields for major crops As mentioned before, the production projections for the 34 crops covered in this report are unfolded into and tested against what FAO experts think are plausible land-yield combinations by agro-ecological rainfed and irrigated environment, taking into account whatever knowledge is available. A major input into this evaluation are the estimates regarding the availability of land suitable for growing crops and of yields attainable in each country and each agro-ecological environment which originate in the Agro-Ecological Zones work (Fischer et al., 2011). In practice such estimates are introduced as constraints to land and yield expansion but they also act as a guide to what can be grown where. The resulting land and yield projections, although partly based on past performance, are not mere extrapolations of historical trends since they take into account present-day knowledge about changes expected in the future. Chapter 1 (Figures 1.9 - 1.14) has examples of what future yields would be if they had been derived as mere extrapolations of historical trends. The overall result for yields of all the crops covered in this study (aggregated with standard price weights) is, at the global level, a more than halving of the average annual rate of growth over the projection period as compared to the historical period: 0.8 percent p.a. during 2005/07 to 2050 against 1.7 percent p.a. during 1961-2007 (for the developing countries the annual growth rates for these periods are 2.1 and 0.9 percent respectively). This slowdown in the yield growth is a gradual process which has been under way for some time (for example for the last ten-year period 1997-07, the annual yield growth was 1.6 and 1.9 percent for the world and the group of developing countries respectively) and is expected to continue in the future. It reflects the deceleration in crop production growth explained earlier. Discussing yield growth at this level of aggregation however is not very helpful, but the overall slowdown is a pattern common to most crops covered in this study with only a few exceptions. The growth in soybean area and production (Table 4.12) has been remarkable mainly due to an explosive growth in Brazil and Argentina. Soybeans are expected to continue to be one of the most dynamic crops, albeit with its production increasing at a more 126
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WORLD AGRICULTURE TOWARDS 2030/2050
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Acknowledgements PROOF COPY This pa
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Boxes PROOF COPY Box 1.1 Measuring
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PROOF COPY Figure A.2.1.6 India: fo
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PROOF COPY producing countries rema
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PROOF COPY may fall from 2.3 billio
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PROOF COPY Minimum Dietary Energy R
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PROOF COPY Concerning the main prod
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PROOF COPY vegetable oil imports fo
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PROOF COPY constraints can be signi
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PROOF COPY Figure 1.8 Irrigated are
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PROOF COPY Figure 1.9 World cereals
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PROOF COPY for both food and non-fo
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PROOF COPY 2050, reaching a peak of
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PROOF COPY 436 million in the over
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PROOF COPY CHAPTER 2 PROSPECTS FOR
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PROOF COPY Figure 2.1 kcal/person/d
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PROOF COPY The FAO estimates of und
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PROOF COPY by people. In particular
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PROOF COPY production potential. Th
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PROOF COPY Table: Growth in Populat
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PROOF COPY (Figure2.6), at 7.4 bill
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PROOF COPY Table 2.4 GDP assumption
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PROOF COPY Modest reductions in the
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PROOF COPY Such optimism notwithsta
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PROOF COPY in North Africa have hig
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PROOF COPY (which in our data appea
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PROOF COPY The other major commodit
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PROOF COPY Table 2.6 Changes in the
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PROOF COPY • Despite this slow pa
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PROOF COPY undernourishment and the
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PROOF COPY commodities and waste. F
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PROOF COPY Where does this leave us
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PROOF COPY Figure A.2.1.6 shows the
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PROOF COPY cereals for ethanol 41 .
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PROOF COPY consumption was heavily
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PROOF COPY Figure 3.2 Net agricultu
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PROOF COPY It is noted, however, th
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PROOF COPY Figure 3.4 Per capita fo
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PROOF COPY 2005/07. 45 Not all of t
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Page 87 and 88: PROOF COPY countries in per capita
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Page 91 and 92: PROOF COPY Figure 3.8 World feed us
Page 93 and 94: PROOF COPY The production of biodie
Page 95 and 96: PROOF COPY the exports of the two m
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Page 105 and 106: PROOF COPY Climate change In evalua
Page 107 and 108: PROOF COPY Table 4.1 Increases in p
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Page 111 and 112: PROOF COPY cropping intensities (6
Page 113 and 114: PROOF COPY No data exist on total h
Page 115 and 116: PROOF COPY Box 4.2 Agro-ecological
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Page 121 and 122: PROOF COPY place in sub-Saharan Afr
Page 123 and 124: PROOF COPY The bulk of arable land
Page 125 and 126: PROOF COPY Figure 4.7 Area equipped
Page 127 and 128: PROOF COPY The developed countries
Page 129 and 130: PROOF COPY 4.2.5 Irrigation water r
Page 131: PROOF COPY harvested irrigated area
Page 135 and 136: PROOF COPY million ha at an average
Page 137 and 138: PROOF COPY producers 81 are about h
Page 139 and 140: PROOF COPY the often unfavourable a
Page 141 and 142: PROOF COPY Table 4.15 Fertilizer co
Page 143 and 144: PROOF COPY under way for some time,
Page 145 and 146: PROOF COPY Livestock production is
Page 147 and 148: Argentina Bolivia (Plurinational St
Page 149 and 150: Wheat Rice Maize Barley Millet Sorg
Page 151 and 152: PROOF COPY and yields by irrigated
Page 153 and 154: PROOF COPY References Alexandratos,
Page 155 and 156: PROOF COPY FAO (1996), Food, Agricu
Page 157 and 158: PROOF COPY Ma, Hengyun, Jikun Huang
Page 159 and 160: PROOF COPY van der Mensbrugghe, D.,
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