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OCR for page 5915
Proc. Natl. Acad. Sci. USA
Vol. 96, pp. 5915-5920, May 1999
Colloquium Paper
This paper was presented at the National Academy of Sciences colloquium "Plants and Population: Is There Time?"
held December 5-6, 1998, at the Arnold and Mabel Beckman Center in Irvine, CA.
The growth of demand will limit output growth for food over the
next quarter century
D. GALE JOHNSON
Department of Economics, University of Chicago, 1126 East S9th Street, Chicago, IL 60637
ABSTRACT The rate of growth of world food demand
will be much slower for 1990-2010 than it was for the prior
three decades. The major factor determining the increase in
food demand is population growth. Income growth has a
much smaller effect. From 1960 to 1990, population growth
accounted for approximately three fourths of the growth in
demand or use of grain. For 1990-2010, it is anticipated that
population growth will account for nearly all of the increase
in world demand for grain. The rate of population growth
from 1990 to 2020 is projected to be at an annual rate of 1.3%
compared with 1.9% for 1960 to 1990 a decline of more
than 30%. World per capita use of grain will increase very
little perhaps by 4%. The increase in grain use is projected
to be 40% less than in 1960-1990. It is anticipated that real
grain prices will decline during the period, although not
nearly as much as the 40~o decline in the previous three
decades. Concern has been expressed concerning the dete-
rioration of the quality and productivity of the world's
farmland. A study for China and Indonesia indicates that
there has been no significant change in the productive
capacity of the land over the past 50 years. Contrary to
numerous claims, the depth of the topsoil has not changed,
indicating that erosion has had little or no impact.
The past half century has witnessed an unparalleled im-
provement in the per capita consumption of food in the
world. The improvement has occurred in both the developed
and, with the exception of sub-Saharan Africa, developing
regions. In the case of sub-Saharan Africa, the failure to
achieve a significant increase in per capita food supplies has
been due, not primarily to limitations of natural resources,
but to wholly inappropriate national policies that exploited
agriculture in the name of promoting economic development
as well as by ethnic and civil strife in several countries. A
World Bank study of the effects of governmental interven-
tion found for 1960-1984 that for three countries in sub-
Saharan Africa the returns received by farmers were reduced
by 51.6% (1~. This meant that farmers received less than half
what they would have received had their prices been at the
international price levels, with adjustment for local costs of
marketing and transportation. The study considered both
direct interventions, such as export taxes, and indirect ones,
such as overvalued currencies and industrial tariff protec-
tion. It was estimated that if farmers had received the
international market prices (i.e., the governmental interven-
tions were removed) that output would have increased by
57% (2~. This result assumed a period of adjustment of two
decades. The three countries were the Ivory Coast, Ghana,
and Zambia.
The prospectus for this conference noted that world grain
production doubled in the last three decades. The doubling
PNAS is available online at www.pnas.org.
of grain production in three decades was a remarkable
achievement, without parallel in the history of the world.
Such an important accomplishment would seem to merit at
least a mild amount of applause. But the next few sentences
of the prospectus seem to imply that the doubling has left the
world with a great array of problems that will be difficult, if
not impossible, to solve. Concern over the impact of popu-
lation and the spread of agriculture and other forms of
human settlements on the environment and the capacity of
the world to provide for a growing population is hardly new.
This statement is supported by the words of Quintus Septi-
mus Florens Tertullianus, written about A.D. 200: "Indeed
it is certain, it is clear to see, that the earth itself is more
cultivated and developed than in early times . . . The most
charming farms obliterate empty spaces, ploughed fields
vanquish forests, sandy places are planted with crops, stones
are fixed, swamps are drained, and there are great cities
where formerly hardly a hut ... everywhere there is a
dwelling, everywhere a multitude, everywhere a government,
everywhere there is life. The greatest evidence of the large
number of people: we are burdensome to the world, the
resources are scarcely adequate to us and our needs straiten
us and complaints are everywhere while already nature does
not sustain us. Truly, pestilence and hunger and war and
flood must be considered as a remedy for nations, like a
pruning back of the human race becoming excessive in
numbers." "translated from Latin by Bart K. Holland (3~.
Whether or not the world is faced with rapid population
growth, we do know that the rate of world population growth
is now much lower than it was and that prospective rates of
population growth are expected to be much less than either
recent or current rates. From 1950 to 1990, the annual rate
of growth of world population was 1.88%; the annual rate of
growth peaked in 1965-1970 at 2.1%. Bos et al. (4) of the
World Bank projected that the annual rate of growth of
world population for 1995-2000 would be 1.43% and for
2000-2005, 1.24~o, and for 2020-2025, 0.85~o a decline of
60% from the peak rate. Is 1.43% or 1.24% annually a rapid
rate of population growth? What about the 1.04% projected
for 2015-2020? The rates are not holding constant. They are
projected to decline and decline substantially over the next
quarter century. At least to me, these are substantial declines
and do not represent a rapid growth rate unless any positive
rate of growth is so considered.
It is quite common to note with alarm that one or more
measures of world per capita production or consumption is
declining. Let me state categorically: in the world of the past
half century, changes in world per capita production or
consumption provide little or no useful information. It is
possible for world per capita production or consumption of
grain to remain constant or to actually decline a little, and
*To whom reprint requests should be addressed. e-mail: dgjohnson@
uchicago.edu.
5915
OCR for page 5916
5916 Colloquium Paper: Johnson
yet for every person in the world to be consuming more grain.
How can this be? The reason is that there are large differ-
ences in per capita food consumption by income levels, and
the population weights used to calculate the world per capita
averages over time are shifting weights the low-income
consumers with their lower per capita consumption of grain
have increased in relative importance in the world's popu-
lation. Although the example given is possible, it is only
hypothetical. But we do know that from 1979-1981 to
1990-1992 that world per capita grain production increased
only from 325 kilograms to 326 kilograms while per capita
production in developing countries increased by 7% (14
kilograms) and in developed countries by To (14 kilograms)
(51.!
Concern is expressed that world agricultural output will
not grow at as rapid a rate in the future as it did, say, between
1960 and 1990. It is argued that world grain production and
world food production as well have grown quite slowly during
the l990s and that world per capita grain production has
declined. World grain production has not kept pace with
world population growth since 1984. Is this a cause for
alarm? As I will argue, it is not.
The Rate of Output Growth Is Slowing. Let me state at the
outset that the future growth of world grain production and
of any other measure of world food supply will be signifi-
cantly slower than the annual rate of growth during 1960-
1990. This is nearly as certain as it is that the sun will rise
tomorrow morning. And it is not a cause for alarm or
concern and don't let any one tell you that it is. Or at least
don't believe them if they do.
The reason for the slower growth will be economic rather
than the limitations of the biological potential for increasing
yields or deterioration in the natural resources used in
producing food. Farmers of the world would face disaster if
future output grew at the same rate as in the past several
decades because if output grew exogenously at that rate,
there would be sharply declining real prices. Consequently,
output will not grow at the same rate as in the past. But let
me hasten to add that the supply of food will grow more
rapidly than will demand, real food prices will fall, and per
capita food consumption in developing countries will con-
tinue to grow at about the same rate as in the past two
decades.
It will be the growth of demand that will limit the growth
of agricultural output over the next quarter century. This is
no change from the experience of the last three or four
decades of the 20th century. The primary difference is that
both demand and output will grow at much slower rates than
in the recent past. While grain output increased by nearly
2.5~o annually from 1960 to l99O, it did so while the real
international prices of grain fell by about 40% (see Table 1~.
The growth of grain output would have been substantially
greater had real grain prices not declined by such a large
percentage. In other words, if demand had grown faster so
that real grain prices would not have declined, the growth of
supply would have been greater than it actually was. There
would have been incentives for farmers to produce more by
bringing more land under cultivation, increasing the appli-
cation of chemical inputs per unit of land cultivated, and
taking other measures to increase yields that would have
been profitable at substantially higher real output prices than
they actually received. There would also have been incentives
for both governments and the private sector to have invested
lThe same difficulty in interpreting an average applies among regions
in developing countries or even between rural and urban areas in a
given country. Whenever there are differences in consumption levels
that are correlated with changes in the rates of growth of population,
changes in per capita averages will transmit little information and
may, in fact, be misleading.
Proc. Natl. Acad. Sci. USA 96 (1999)
Table 1. Real export prices for wheat, maize, and rice in selected
years from 1910 to 1997
Year(s)
Wheat Maize
Rice
1910-1914
1925-1929
1930-1934
1935-1939
1945-1949
1950-1954
1955-1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
299.3
308.3
236.4
236.4
385.1
284.3
206.5
194.5
206.5
209.5
206.5
206.5
185.6
185.6
191.6
179.6
170.6
158.6
161.6
161.6
239.4
329.2
284.3
239.4
173.6
182.6
200.5
197.5
185.6
167.6
158.6
149.7
140.7
119.7
95.8
113.7
143.7
120.1
91.4
112.7
110.0
110.3
134.9
157.2
127.7
221.5
227.5
254.4
254.4
281.3
239.4
182.6
158.6
155.6
155.6
167.6
170.6
170.6
167.6
161.6
143.7
143.7
155.6
149.7
137.7
188.6
236.4
227.5
191.6
155.6
149.7
149.7
149.7
149.7
116.7
131.7
137.7
113.7
95.8
74.8
101.8
104.8
99.7
95.1
93.4
88.9
91.7
97.5
122.2
97.6
366.3*
484.6t
394.3
421.1
390.2
338.6
369.4
777.8
1,013.1
621.5
417.4
419.1
526.5
424.4
483.3
492.4
293.0
273.4
244.7
209.7
212.1
225.5
281.7
285.8
249.7
273.4
249.9
239.3
280.0
262.7
278.9
279.2
All prices are in 1982 dollars per ton deflated by the U.S. wholesale
price index. Wheat and maize prices are U.S. export prices, and rice
price is Thailand milled rice, 5% broken.
*1950.
tl955.
substantially more in agricultural research and thus have
increased output-enhancing innovations and contributed to
a higher rate of growth of agricultural output. But the fact
was that the growth rate of supply exceeded that of demand
for 1960-1990 and real farm prices fell, not by a little but by
a lot. The growth rate of demand is not the same as the
growth rate of consumption or use. The growth rate of
demand measures the shift in the demand function and it
would be the same as the growth rate of consumption only
if real prices remain unchanged. Put another way, the growth
rate of consumption is the result of the shift in the demand
function and the change in real prices. From 1960 to l99O,
the world's demand for food grew more slowly than did
supply. This is the reason that real international prices of
grain declined so very much in the three decades. Had
OCR for page 5917
Colloquium Paper: Johnson
demand increased at the same rate as supply, real food prices
would have remained constant.
As I shall show later, the growth of demand for grain (and
food generally) will be at a much lower rate than in the recent
past. To approximately match the growth of demand, the
growth of supply will be much lower than in the past.
Recent Trends in World Grain Production. It has been
noted that since 1990 or even earlier world per capita
grain production has been declining, and some believe that
this is a cause for concern. There are two good reasons why
this decline, which has occurred, should not be a matter of
significant concern to the populations of the developing
countries.
As noted earlier, changes in world per capita measures of
production or consumption need to be interpreted with
extreme caution; per capita grain production tells us almost
nothing about the adequacy of food supplies for particular
large segments of the world's population.!
As noted, world per capita production of grain was 325
kilograms in 1979-1981 and 326 kilograms in 1990-1992. If
per capita production had remained constant in both the
developing and developed regions between 1979-1981 and
1990-1992, world per capita production would have declined
from 325 kilograms to 312 kilograms a decline of 4%.
When there are divergent regional trends in population
growth, world average figures are not reliable measures of
what is happening to the production or consumption levels
in either the developing or developed countries.
The other reason is that the decline in per capita world
grain production that has occurred in the l990s needs careful
interpretation concerning its cause and its implications to
the large majority of the world's population the population
of the developing countries. The decline in the rate of growth
of world grain production in the l990s is due primarily to the
sharp decline in grain production in Central and Eastern
Europe (CEE) during the transition from planned econo-
mies to market economies. If grain production in that region
had been maintained at the 1985-1989 level rather than
declining by more than 100 million tons, the rate of growth
of world grain production from 1990 to 1996 would have
been at an annual rate of 1.8%, only a little below the rate of
2.1~ for the 1980s (74.
Did this decline in grain production in the CEEs adversely
affect consumption in the rest of the world? The net effect
of the transition process on both production and consump-
tion of grain in the CEEs was to increase grain supplies in the
rest of the world compared with what it would have been if
grain production, utilization, and trade had been maintained
at the 1985-1989 levels. This outcome occurred because the
consumption of grain in the CEEs decreased more than did
production. This was due mainly to two factors. First, the
consumption of livestock products was highly subsidized in
the U.S.S.R. as well as elsewhere in the region. Consumers
in the U.S.S.R. paid less than half of the cost of bringing meat
and milk to the grocery store. These subsidies were elimi-
nated after 1991, and the consumption of livestock products
was reduced substantially as a result. In addition, real per
capita incomes have fallen, reducing the demand for live
lThe per capita grain consumption in the developing countries has
increased at a somewhat higher rate than production because net
imports have increased at a faster rate than population. Whereas the
developing countries were net importers in both 1980 and 1990, the
percent increase in net imports was only moderately greater than the
percent increase in population. Net grain imports per capita in 1980
were 18 kilograms and in 1990, 21 kilograms. If net grain imports of
developing countries increase to 160 million to 210 million tons as
projected in the three studies referred to earlier per capita grain
imports would increase to 28-36 kilograms per capita by 2010 (6~. To
put this amount in perspective, imports would account for about
12-15% of grain use in the developing countries in 2010.
Proc. Natl. Acad. Sci. USA 96 (1999J 5917
stock products and, thus, the use of grain as feed. The net
effect has been that annual grain imports by the CEEs have
fallen by at least 30 million tons, compared with the late
1980s. Consequently, the rest of the world has been able to
increase its utilization of grain by 30 million tons as a result
of the changes that have occurred in the CEEs.§ Again let me
emphasize, one must exercise great care in interpreting
average changes for the world, such as declining average
yields or declining per capita production or consumption. It
behooves us to look behind the changes in the world averages
and determine what factors were involved before coming to
any conclusion concerning the interpretation of the change
in the average.
Growth of Demand. Demand growth for the next two
decades will be at a much lower rate than in the recent past.
The growth in the world's consumption of food is a function
of four variables population, real per capita income, the
relative price of food, and differential rates of population
growth among countries or regions with different levels of
real per capita incomes. Real incomes affect food demand
through the income elasticity of demand a 1% increase in
real per capita income increases per capita demand by much
less than 1% in the case of grain perhaps by about 0.10-
0.25%., As real incomes increase around the world, the
income elasticity of demand declines. Food prices at the farm
level have a minor effect on per capita food consumption
because the farm price represents only a part of the cost to
urban consumers, and the price elasticity of demand has
become quite low and will be lower in the future than it now
is. The primary factor affecting the growth in demand for
food is population growth.
There seems to be little recognition by those who express
concern about future food demand growth of how fast
fertility is declining in today's world and how much further
it will decline in the years ahead. Based on data for 1960-
1990, the growth of population accounted for approximately
three fourths of the growth in total grain consumption.
Increased real per capita incomes and declining grain prices
accounted for the remaining quarter of the increase in per
capita consumption. Of the 2.46% annual growth in total
grain consumption, population growth accounted for 1.9%
and per capita consumption growth for 0.55%.
What does the future hold? The projections of world
population growth by the United Nations and the World Bank
imply a sharp fall in prospective growth rates compared with
those for the last decades of this century. The projections that
I shall refer to are the medium projections, not the high or the
low.
Two recent projections of the world population for 2020
are 7.67 billion by the United Nations and 7.742 billion by the
World Bank. These represent percent increases relative to
1990 of 45.6 and 47.0 respectively. These compare with the
actual growth of world population of 77% from 1960 to
§It is not implied that the 30 million tons annually has gone to
importers; some part of it remained in the exporting countries. The
only point is that the decline in grain production in the former
U.S.S.R. has not imposed a reduction in grain utilization in the rest
of the world.
TThese are rough estimates of the income elasticity of demand, with
0.25 being for the developing countries. An annual growth of real per
capita income of 2% would result in annual increases in the per capita
consumption of grain of 0.5%. Because of the uncertainties concern-
ing developments in grain production and incomes in the former
Soviet Union it is much more difficult to estimate the income
elasticity of demand for grain in the developed countries. Pinstrup-
Andersen et al. (8) projected a very small increase in world per capita
demand for grain from 1993 to 2020 less than 2% for the entire
period, but with a significant increase in the per capita consumption
of grain in the developing countries.
OCR for page 5918
5918 Colloquium Paper: Johnson
1990.ll According to the World Bank estimates (4), the
growth rate of population is projected to decline by 38%,
from an annual rate of growth of 1.9% for 1960-1990 to 1.3%
for 1990-2020. In 1994, the three major international orga-
nizations with concerns for agriculture, the Food and Agri-
cultural Organization (FAO), the International Food Policy
Research Institute (IFPRI), and the World Bank (WB),
completed studies of the prospective food demand and
supply to 2010. There was remarkable unanimity of results,
both with respect to the growth of demand and to supply.
The consensus of the three studies was that for the two
decades ending in 2010, world per capita consumption of grain
would remain approximately constant, but would increase in
both developing and developed countries by small percentages
(9~. According to these studies, the world consumption of grain
is and will be moved almost entirely by population growth. At
the time the studies were being prepared, the projection of the
annual rate of world population growth for 1990-2010 was
1.5 To. Their consensus estimate was that world consumption of
grain would grow at approximately 1.5-1.7~o annually, which
was consistent with their conclusion that the weighted average
of world per capita consumption would increase very little.
Extending the consensus projection of the three studies for
1990-2010 to the year 2020, I project that the production of
grain will increase by 17% in the developing countries in 2020
and by 9% in the developed countries. This would increase per
capita production to 250 kilograms in developing countries and
to 750 kilograms in the developed countries. In 2020, it is
projected that the developing countries will have 82.2% of the
world's population, up from 77~o in 1990. World per capita
production in 2020 would be 339 kilograms t(0.178 x 750) +
(0.822 x 250) = 3393.~* This is an increase of To from the
1990 world per capita production. In terms of annual growth,
the projected growth in world utilization of grain would be very
slightly more than 1.3% annually the projected rate of
growth of population plus a 4% increase in per capita use.
Enough Food to Eliminate Malnutrition? There are many
people in the world who are chronically undernourished. As of
1988-1990, 781 million were estimated to be chronically
undernourished. The indicated projection of demand assumes
that the number will decline to 637 million in 2010 and to about
575 million in 2020. The primary factor responsible for mal-
nutrition is low income levels rather than an inadequate supply
of food. Low levels of caloric intake are not the sole cause of
malnutrition and perhaps not even the major cause. Deficien
The medium projections may well be on the high side for years some
distance in the future. The reason is that in the two projections noted
in the text, the demographers who make the projections must decide
what to assume for the countries that now have fertility rates below
replacement level. They resolved this issue by assuming that fertility
will actually increase to the replacement level in the not too distant
future. For example, Germany is assumed to increase its fertility level
to 2.1 (actually 2.076) by 2035 compared with its recent level of 1.3 (4~.
China is thought to have a fertility rate of 1.9 in 1995-2000 and this
is projected to increase to 2.127 in 2025-2030. I report this aspect of
the two projections to make it clear that the projected levels of
population do not assume that countries that have fertility below
replacement levels will continue to follow the path of recent trends.
Quite the contrary, it is assumed that in these countries fertility will
increase over the next three decades or so and in some cases by
significant percentages. So far as I know, there is no foundation for
this assumption but some assumption had to be made to complete the
projections.
* *Per capita utilization of grain would differ somewhat from per capita
production because of projected imports of grain by the developing
countries. In 1990, developing countries imported 21.5 kilograms of
grain per capita and they are projected to import 28-36 kilograms
in 2010. If developing country imports continue to grow between
2010 and 2020 at approximately the same rate as from 1990 to 2010
then per capita consumption might be 285-290 kilograms. Given the
shift in population weights, the increase in world per capita utili-
zation would be a little less than Who.
Proc. Natl. Acad. Sci. USA 96 (1999J
cies in the availability of micronutrients such as vitamins A and
D, iron, iodine, and calcium, plus the heavy incidence of
dysentery in many low income areas of the world, contribute
to the problem.
The Food and Agricultural Organization (10) has estimated
that to increase the dietary energy supply to 2,300 kcal (1
kcal = 4.18 J) per day in 2010 of the countries that had a supply
of less than 1,850 kcal/day in 1990 would require 46 million tons
of grain. This assumes that grain supplies 60% of the energy
supply and would do so in 2010. The addition to the supply of
grain for the developing countries that in 1990 had per capita
daily energy supplies of less than 1,850 kcal/day would be 8.5%
of the projected supply in 2010, but only 2.4% of projected
world grain production. It would require a rather modest
increase in the price of grain (almost certainly no more than
10%) to achieve such an increase in world grain production.
But even if all of the increase in calories had to come from
grain, the required increase in grain would be about 75 million
tons, or less than 4% of current world grain production, and
approximately 2.5% of projected world production in 2020.
Recent Price Trends. Table 1 gives data on the real prices of
wheat, rice, and corn for the period since 1950. These are based
on U.S. export prices for wheat and corn and Thailand's export
prices for rice, and the deflator is the U.S. wholesale price
index. During the 1990s, the international prices of grain
have been nearly the lowest that they have been in the 20th
century. This is in spite of the temporary run-up in prices in the
mid-199Os. The price increases in 1995 and 1996 have now been
largely erased, and the real export prices in 1997 had almost
returned to the low levels of 1990-1994.
This year, China introduced a price support program to raise
the low market prices of grain that farmers were receiving.
China is not now a significant importer of grain, in spite of wild
and unsupported projections that it would be. China did import
significant amounts of grain nearly 20 million tons in 1995
but this was done in error; China had a bumper grain crop in
1995 as it did in 1996 and had no need for imports. China now
faces the problem of large stocks and low domestic prices of
grain. It exported an average of 5 million tons of grain in 1992,
1993, and 1994 (11), in contrast to its position as a net importer
of 13 million tons a decade earlier (1980-1983) (12~.
President Clinton visited China, and not long after return-
ing, he also announced that the price of wheat was too low. He
authorized the purchase by the U.S government of 80 million
bushels of wheat, which will be used for food aid and thus
(largely) removed from the domestic and world market. It is
estimated that this action will increase the market price of
wheat by 10 to 13 cents per bushel.
It is quite remarkable that politicians in the world's two
largest grain-producing countries should simultaneously decide
that so much grain had been produced that it was necessary to
take action to increase grain prices. True, a factor in the
current low prices of grain is the economic slowdown in several
Asian countries combined with a delayed output response by
farmers to the relatively high real prices of 1995 and 1996.
However, the current international market prices of grain are
not significantly below those that prevailed in 1990-1994.
Not all of the implications of the current low grain prices are
positive. The low prices do not encourage governments to take
tTI have used the U.S. wholesale price index rather than the World
Bank's index of the prices of manufactured products exported by the
industrial countries to the developing countries. Over time that index
increases much more than the U.S. wholesale price index and if it is
used as a deflator, the declines in the real prices of grains are much
greater than what is reflected in Table 1. For example, if the World
Bank's index is used, the real international price of corn declined by
48~o between 1950 and 1990. In Table 1, the decline is Who. The U.S.
wholesale price index has a much broader commodity coverage than
the World Bank index. The U.S. index includes oil and coal, for
example.
OCR for page 5919
Colloquium Paper: Johnson
the long-term view with respect to investment in agricultural
research or changing policies that adversely affect farm output.
It is possible that if these low prices continue for another year
or two, as they might well do, world grain production will stop
expanding and grain stocks will decline, resulting in another
price spike such as occurred in 1995 and 1996. This will not
presage a significant decline in the long run growth of grain
output, but price instability imposes costs on both farmers and
consumers.
Will Cropland Area Increase? It may be noted that in the
studies of future food supplies that I have used, there is an
implicit assumption that the area devoted to grain will increase
little, if at all, in the years ahead. True, there has been little
increase in recent years. In fact, the grain area harvested in
1996 was the same as in 1970 (7~. But why should there have
been an increase in harvested area? It was cheaper to find
substitutes for land than it was to increase the area of land
devoted to grain. With the rapid rate of decline of the real price
of grain, there was little incentive to pay the substantial cost of
increasing the cropland area even though there is widespread
agreement, even including the Club of Rome, that the amount
of arable land in the world could be increased by 50~o (13~. I
think it is unlikely that over the next two decades there will be
any significant increase in the cropland area, but there could
be if agricultural prices increased significantly. But higher real
prices for farm products are highly unlikely, so it is unlikely that
we will see the development of much new cropland. A failure
to increase cropland will be a signal that yield increases on
existing cropland have been sufficient to meet the slow growth
in demand that will occur.
Two Possible Threats to Future Food Supply. The increase
in irrigated area since 1950 has been an important factor in the
higher yields of grain and other agricultural products. It is
argued that it is unlikely that there will be a significant increase
in irrigated area in the near future and that it is possible that
the irrigated area could decline because of depletion of
existing supplies of stored water, of larger withdrawals from
aquifers than the rate of replacement, or of increased use of
limited water supplies by nonagricultural activities.
These outcomes cannot be ruled out. No country in the
world properly manages its water supply. Almost everywhere,
water is a common-property resource and no value is attached
to the water at the source, whether from an aquifer or from a
storage facility such as a lake or a reservoir (14~. At most,
farmers are charged for the cost of delivering the water to the
field. Several countries actually subsidize the delivery of water
to urban consumers and for irrigation. A large percentage of
the existing irrigated water is wasted, and there is a substantial
potential for saving water with little effect on output; the way
water is generally priced, the individual farmer has little
incentive to economize in its use. A common practice is to
provide a farmer with a particular volume of water at a fixed
price. The farmer gains nothing by using less than the fixed
volume of water. Or if water is being pumped from an aquifer,
there is seldom a limit to the amount of water that can be
withdrawn, and there is no charge for the value of the water in
the aquifer. Often, as is true in India, the electricity used to
pump the water is heavily subsidized: in the Punjab, the
electricity used in pumping water for irrigation is free. Until
governments recognize that water is a valuable resource and
price it properly, there is reason to be concerned that the
savings in irrigation water will not come soon enough to
prevent some irrigated areas from being abandoned because
they have exhausted their available supply of water or they
have been forced to give up their water for a higher value use.
Irrigated areas may also be lost to salinization and waterlog-
ging, but at a cost these can be corrected.
Another common property resource that is important to the
world's food supply is that of ocean fisheries. Here the misuse
of the world's resource is similar to that for irrigation water.
Proc. Natl. Acad. Sci. USA 96 (1999) 5919
Outside the 200-mile limit, there is no significant effort to limit
the amount of fish taken access to the commons is not
limited. The amount now being taken exceeds current annual
growth, and the breeding stocks of several important fish
species are in serious danger of depletion. One important
reason for the depletion of ocean fisheries has been the
technological changes in the methods of catching fish that have
occurred in the past three or four decades. Another reason is
that many governments subsidize their fishing industry.
Water and ocean fishing are two areas where major prob-
lems affecting the world's food supply either exist or poten-
tially may do so. In both cases it takes action by governments
to find appropriate solutions. Although markets could be part
or all of the solution, markets for common-property resources
cannot exist without governments creating the necessary
framework by assigning property rights or by using markets to
privatize the rights. In one way or another, governments must
find ways of restricting access to common-property resources.
In the case of water, each government is largely in control of
its own destiny, although there are numerous examples of
where a common water source is shared among two or more
countries. In the case of ocean fisheries, agreement is required
among many governments if the world's fisheries are not to be
seriously depleted. If governments are either unable or un-
willing to find solutions for the common property problem that
falls entirely in their own jurisdiction, it may be unrealistic to
assume that they can find solutions for a common property
problem that requires agreement among scores of govern-
ments until the catch from ocean fisheries is substantially lower
than the current level and fish prices are much higher than they
are now. Unfortunately, fish farming has offset the loss of catch
from the oceans and thus permits governments to delay
seriously tackling the issue. I say it is unfortunate because there
is no feed cost to fish taken from the ocean; the only cost is
catching them. But most farm-raised fish require feed and in
significant amounts. By not solving the ocean fishing problem,
a source of food that directly competes with neither humans
nor domestic animals is lost.
Has the World's Cropland Been Seriously Degraded? It is
alleged that the quality of the world's land resource has been
degraded through erosion, loss of organic matter, and other
forms of loss of potential productive power. There are claims
that enormous quantities of topsoil are lost each year to water
and wind erosion. Does the world enter the next millennium
with soil that is badly degraded and of lower productive
capacity than it was when we entered the 20th century or in
1950 when the recent surge in agricultural productivity
started? There are many allegations that this is the case.
Such allegations emanate from the Worldwatch Institute
and the World Resources Institute, for example. Some aspects
of these claims were endorsed by the presidents of the Chinese
and the United States academies of sciences in a statement
issued in Beijing on January 16, 1997. They agreed that "The
need for improvement is urgent, since all resource indicators-
changes in the atmosphere, loss of topsoil, loss of forests, the
extinction of organisms have moved sharply and continu-
ously downward during the second half of the 20th century,
while both world population and levels of consumption con-
tinue to rise. Globally, these trends are not sustainable over the
long run." Among the impending disasters, I shall consider
only the loss of topsoil from agricultural lands.
ttErosion occurred long before man was a factor in affecting the
world's environment. And not all erosion has adverse effects on the
productivity of the land. An example is the southwestern part of the
state of my birth, Iowa. This part of Iowa has some of the deepest
topsoil in the world, and much of it was created by erosion; it was
transported by wind from Texas and Oklahoma. The soil is much
more productive where it now is than if the erosion had not occurred.
OCR for page 5920
5920 Colloquium Paper: Johnson
I agree with Peter H. Lindert (15, 16) of the University of
California at Davis that the claims that there have been serious
loss of topsoil from agricultural lands or other forms of
widespread deterioration of the productive capacity of farm
land are without foundation, i.e., not based on evidence of
change over time. Lindert (16) states the following: "Lacking
an actual quantitative history of soil conditions beyond exper-
imental plots, scholars have fixed on the useful but risky task
summarized by the title of this section.§§ The literature has
three main shortcomings: (1) using crude indicators that prove
little about human impacts on the soils, (2) using trends in
cultivated land area as clues about land quality, and (3) using
single-snapshot predictions as if they were time-series data.''1TlT
Lindert used long-run data from two large developing
countries, China and Indonesia, in an effort to measure
changes in the quality of the land resource. The data he used
were soil surveys, dating from the 1930s to the relatively recent
past, the 1980s in China and 1990 in Indonesia. This is not the
place to provide a detailed summary of his results, but his
following brief summary will provide a sharply different
perspective than those that are commonly given (16~.
"The broadest outlines of the interaction of soil and agri-
culture are now somewhat clearer for two developing coun-
tries. We have some idea which dimensions of soil quality have
improved and which have not. Soil organic matter and nitrogen
appear to have declined on cultivated lands in both China and
Indonesia. Total phosphorous and potassium have generally
risen. Alkalinity and acidity have fluctuated, with no over
overall worsening. The topsoil layer has not gotten thinner.
"Some of the mixed trends revealed here have more effects
on yields than others. China's patterns show that the decline in
soil organic matter and nitrogen makes little difference, pre-
sumably because fertilizers can substitute for the soil endow-
ment. More relevant are the pH and total potassium, for which
the trends are better."
Based on comparisons of soil surveys over a period of 50
years, Lindert (16) reaches the remarkable conclusion for
China and Indonesia: "The topsoil layer has not gotten thin-
ner." This conclusion is wholly inconsistent with the state-
ments from the presidents of the two academies of science and
from most other commentators on the subject.
This is not to deny that erosion exists in China, after all, the
Yellow River didn't get its name by accident. But to note that
there are obvious signs of erosion does not tell us from whence
it came or why it occurred. The data assembled by Lindert
indicates that it has not come to any considerable extent from
farmland. I find it hard to believe that farmers are as careless
with a resource that is very important to them as is implied by
much of the opinion expressed concerning the alleged enor-
mous loss of topsoil. I have long held that farmers are at least
as smart as the rest of us and I believe that they know how to
act in their own interest. It is not in the interest of farmers to
§§The title of the section was "Judging Soil Quality Trends Without
Measuring Them?"
tLindert (14) adds the following: "Most importantly, the proffered
data on soil quality trends are neither data nor trends. Rather they
are experts' predictions from a single snapshot, derived by combin-
ing data on slope, climate, and land use with what happens to such
soils under experimental conditions. Sometimes it is refined into
"expert opinion," as in the GLASOD map, but it is still not based
on any observation before the mid-1980s.
That it is not a real history does matter, since the complexity of
human soil interventions over a large countryside can defy simula-
tion on experimental plots. Farm populations react to the soil itself
with complex mixtures of crop rotations, amendments, fertilizer
application, investments in water control, and sometimes neglect and
mismanagement. To know the soil impact of recent human inter-
ventions, we need data on actual practice over long time spans and
large areas."
Proc. Natl. Acad. Sci. USA 96 (1999)
prevent all erosion because there are likely to be costs involved.
But in the range where the benefits and costs of preventing
erosion are approximately equal or the benefits exceed the
costs, it seems reasonable to assume that farmers are acting in
their own interest, at least until there is solid evidence to the
contrary. Lindert's analysis of historical data for two important
countries indicate that there may not be evidence to the
contrary. Soil surveys do exist in other countries. It is perhaps
time that more use is made of this neglected source of
information about the state of the world's land resource and
less reliance is placed on information that lacks a time dimen-
s~on.
Concluding Comments. The people of the world are better
fed than ever before. And more people will have more
adequate nutrition 20 years from now if the governments of the
world carry out their responsibilities with the same care and
intelligence as farmers display in their production activities.
In my opinion, an important danger to the future of the
adequacy of the world's food supply are low international
prices, given the responses governments of both developed and
developing countries are likely to make. In the face of current
low international prices for grain, will governments maintain
their investment in agricultural research? The declining real
support for agricultural research in the past decade or so has
been to some degree a response to low prices. If there are to
be continuing improvements in the adequacy of food supplies
in developing countries, the support of agricultural research
must not be reduced and probably should be increased.
A second danger is that there are still developing countries
that are following policies that discriminate against agriculture
and farm people. As long as these policies persist, the growth
of food production will lag and people will unnecessarily suffer
from malnutrition. A large percentage of the malnourished
people in the developing countries live in rural areas and
depend on agriculture for all or most of their incomes. For
these people there is a close link between farm prices, food
output growth, incomes, and their nutritional status.
Financial assistance from the William ImMasche Foundation is
gratefully acknowledged. I alone am responsible for the content of the
paper.
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Representative terms from entire chapter:
population growth
