Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 56
Technological Trajectories and the Human Environment. 1997.
Pp. 56-73. Washington, DC: National Academy Press.
How Much Land Can Ten Billion People
Spare for Nature?
PAUL E. WAGGONER
If people keep multiplying and farmers keep farming as they do now, farm-
ers will soon need to grow their crops on twice as large an area as what they use
todays Doubling the population without changing the way we farm would ex-
pand the cropland from its present tenth of the world's land to about a fifth. More
than any other factor, the success farmers have in feeding more people per hect-
are (ha) will govern what humanity is able to spare for Nature. I capitalize Nature
here and throughout to indicate a specific definition, namely, the features and
products of the earth itself, as contrasted with those of human civilization.
My essay presumes a population of ten billion people because that seems to
be the round number in sight. The billions may level off at ten, or they may grow
further (Lutz, 1994; see also Kates, this volume). In either case, we must contem
plate ten billion.
I presume also that humanity should spare lots of land for Nature. Propo-
nents of the sparing of land reason about portfolio, money, and ethics. They argue
that sparing land for Nature brings security by assuring a portfolio of biological
diversity. They assert that Nature saves our money through her free ecosystem
services (Norton, 1988~. At bottom, however, is the ethical argument that sur-
vives quibbling over the utility of genes in a jungle or whether a marsh purifies
water more cheaply than does a sewage plant. Although most religions empha-
size humanity, even Genesis declares, "Let the waters bring forth swarms of
living creatures, and let birds fly above the earth.... And God saw that it was
good." My title can presume, therefore, that humanity should spare land for
Nature without further justification (see Meyer-Abich, this volume).
The following example shows that expecting farmers to spare land is not a
56
OCR for page 57
HOW MUCH LAND CAN BE SPARED FOR NATURE?
70
in
~ 60
o
~0
o
._
-
40
30
20
10
1965 1970 1975 1980
-
57
I'm/
= Wheat Produced
(millions of tons)
.
~J
- ~17 ~ ~
~1 . . , 1 1
it'
~ Land Spared
32 44 ~0 57
_ ~_ _
Land Used
Year
1 985 1 990 1 995
FIGURE 1 The land Indian farmers spared by raising wheat yields. NOTE: The upper
line shows the area Indian farmers would have harvested at 1961-1966 yields to grow
what they produced. The lower line shows the area they actually harvested. The farmers
spared the difference. The numerals attached to the squares show the millions of tons of
wheat produced in six exemplary years. SOURCE: Extends a table compiled by Borlaug
(1987).
futile wish. From 1961 to 1966, Indian farmers on average grew 0.83 tons of
wheat per hectare on 13 million hectares of land. Then, applying the technology
of the Green Revolution, they raised production more than fivefold and used only
80 percent more land. Looking back from 1994 to 1961-1966 one can see that
Indian farmers spared 44 million ha, about the area of California, by growing
more per hectare (see Figure 11. "How much land can ten billion people spare for
Nature?" is a farmer's question; asking it is justified, and answering it is not
futile.
MAKING DO WITH PRESENT FARMING
The answer to what farmers can grow rests first on what they do grow today,
using 11 percent of the world's land, the 1.4 billion ha of cropland. We can
translate all agricultural production into food energy, or calories, and protein.
Actual national food supplies range from about 1,800 to 3,900 calories and 40 to
130 grams of protein. The US National Research Council recommends between
OCR for page 58
58
PAUL E. WAGGONER
1,900 and 3,000 calories and 50 to 60 grams of protein per day per person (FAO,
1992; National Research Council, 1989~. By dividing today's total calories and
protein into rations for ten billion people, we can relate present production to
future needs.
As evident in Figure 2, food crops, such as wheat and potatoes, would supply
about 1,800 calones; feed crops, such as maize and soybeans, would give another
1,000 calories to each of the ten billion people. Other agricultural products such
as tobacco and rubber are neither food nor feed but could be replaced by other
crops. This replacement of these other present products would provide little in the
form of calories and protein for ten billion people.
Animals appear twice in our accounting. Animal products, mainly meat and
eggs, provide a lot of protein and also add some calories. The calories and protein
for draft animals require some explanation: they represent consumption by the
animals. In 1910 the horses and mules on Amencan farms and in Amencan cities
consumed feed that was grown on an area 44 percent as large as that used to
cultivate products for domestic use; their replacement by tractors and trucks has
been blamed for the American grain surplus of the 1930s (lIassebrook and
Hegyes, 1989; US Department of Agnculture, 1962~. The present global popula-
tion of water buffaloes (139 million) and camels (20 million) will surprise a
Westerner, as will how much they consume.
1 IS00
C,°) 11200
A 1,OOO
800
600
400
200
1,S00 ~ If ~ Calories
1,400 _
_
1 ~1
~! ~ ~ ~
o
~0
~0
o
40 ~
Q
._
to
Q
10
Food Feed Other Arlimai Draft
Orop Orop Orop Product
O
FIGURE 2 World agricultural production of calories and protein and the consumption
of draft animals. NOTE: The calories or protein in each class are averages per day per
person for ten billion people.
OCR for page 59
HOW MUCH LAND CAN BE SPARED FOR NATURE?
59
What is the sum of all the categories? If we stopped feeding crops to animals,
became vegetarians, and replaced coffee beans with garbanzo beans, the crop-
lands would produce 2,900 consumable calories. What should the animal prod-
ucts add? Even efficient broiler chickens put only about a fifth of the calories they
eat into meat.2 Grazing animals eat more than feed crops, so agriculture, if not
cropland, must be credited with some part of the animal calories. Allowing for
some further release of calories by reduction in animal numbers but also a con-
tinuing role for draft animals, I add 200 calories to the 2,900 calories in crops,
bringing the total for ten billion people to 3,100 calories. I simply leave fish on
the table without counting its contribution.
The sum of 3,100 calories per day for a population of ten billion exceeds the
recommended daily allowances, and it exceeds the 2,920 calories that the Japa-
nese consume today. The same accounting provides an ample amount of protein
for ten billion people. This accounting of present farming makes the idea of
sustaining a population of ten billion while sparing land for Nature conceivable.
Although today's farming could sustain ten billion people, their wants are
surely more than just sustenance. Prophesying wants is chancy. Because animals
eat more calories in feed than they give in milk, meat, or eggs, future wants must
encompass original calories those for people plus their beasts. Forecasts of
consumption of original calories from rising income alone reach as high as 10,000,
but caloric restraint can limit the rise to only 4,400 per person per day (Parikh,
1992; Sanderson, 1988~.
Will people who are sticking to their accustomed meaty diets spoil this
picture of original calories and my implication that the 3,000 calories supplied by
today's agriculture might suffice? Large numbers of people do change what they
eat, as widespread rises in meat consumption in conjunction with riches in fact
illustrate. Nevertheless, annual American beef consumption peaked in 1976 at
close to 60 kilograms per person and has since fallen to about 45 kilograms. The
success of McDonald's restaurants, interestingly, has been attributed to potatoes
rather than to hamburger, and the consumption of potatoes has accordingly crept
up. Since 1910, fat in the American diet has increased 50 percent, but its rise
encompassed the opposing trends of much more fat from plants and much less
from animals (Kroc, 19771.3 In summary, by eating a more or less vegetarian diet
we can change dramatically the number of people that a plot of land can feed, and
over periods of decades large numbers do change diets.
LIMITS TO YIELDS OF FOOD
Suppose we do not simplify our diets and restrain our appetites. Might not
global shortages of the essentials needed for photosynthesis still fulfill the Malthu-
sian fears for ten billion or inhibit their ability to spare land for Nature?
At bottom, food comes from photosynthesis, supplied with carbon dioxide
(CO2) and water to combine into carbohydrates, energized by sunlight, and
OCR for page 60
60
PAUL E. WAGGONER
supplemented with fertilizer. Glut has driven fertilizer prices down. Global use
has been level since 1988 and in the United States since 1980. Globally, sunlight
and, increasingly, CO2 are also abundant. Because the same pores that admit CO2
into leaves let water out, an iron correlation attaches photosynthesis to water. But
globally the water on land far exceeds the amount needed to grow food for ten
billion people.4
Although cropland per capita expanded from the year 1700 to 1950, it has
since shrunk while per capita food production has risen (Richards, 1990; FAO,
1992. Having techniques that raise yield per hectare and having farmers use
these techniques are clearly preeminent in this historic reversal. About 1940,
World War II ignited the technological fuel that had been accumulating for a
generation in industrial nations, and then, under the banner of the Green Revolu-
tion of the 1960s, similar techniques raised yields worldwide. The rising trend,
illustrated in Figure 3 by wheat yields in three nations, is familiar.
But when will an upper limit end the trend? The supplies of sunlight and
water seem too large to cap yields until well past ten billion. Setting the limit by
fitting curves to the actual data in Figure 3 gives too much latitude to pessimism
or optimism. I chose, therefore, the real yield grown currently by a contest winner
as a prospective limit.
_
_ 0 France
U.~.
_
s
_
~ 4 _
ct
_ 1
2 ~"~''31~;.~6'~='
- ~#~-~
1 1 1
f) Hi_
1 800 1 840 1 880 1 920 1 960 2000
Year
FIGURE 3 The course of wheat yields in tons/hectare (t/ha) in Ireland, France, and the
United States.
OCR for page 61
HOW MUCH LAND CAN BE SPARED FOR NATURE?
25
~0
s 15
=5
a)
~ 1 0
._
.
Pasco, Washington ~ 1992
_
_ /
/Logistic rise
~ at 3.6°~Jyr
/ to 20.7 tJha
~ _ ~.
my_
1 _-
O 1 1 1 1 1
1940 1960 1980 2000 2020 2040 2060
Year
61
FIGURE 4 The logistic rise of the national average of US maize yields toward a maxi-
mum of 21 tons/hectare Steal.
Maize, with its efficient photosynthesis, is a productive crop. In 1992 the
annual National (US) Corn Growers' Association competition enrolled 2,470
entries from forty-four states (National Corn Growers' Association, 1993, 1994~.
To enroll, farmers had to enter a minimum of 4 ha of maize and keep accurate
production and harvest records. The winning, irrigated field in Pasco, Washing-
ton (46° north with a sunny climate) grew a full 21 tons (t) per hectare! There
were other yields above 18 t/ha (287 bushels per acre), proving that 21 t was not
a fluke. Providing still further proof that it was no fluke, the Pasco farmer came
back in abnormally cool, wet 1993 to grow 19.6 t/ha on his supervised area and
16.3 t on 575 ha. Twenty-one tons would feed eighty people 2,900 calories/day
for a year. At eighty people per hectare, 125 million ha, or less than a tenth of the
present cropland, could support a population of ten billion.
In Figure 4 a logistic curve rises with the actual average American maize
yields toward the limit of the winning 1992 yield. Pessimists will worry whether
national averages can approach the yield of the irrigated winner. They may rea-
son that yields far above the primitive ones mean more effort must go into
maintenance of the yields (Plucknett and Smith, 1986), and they may observe that
averages have recently fallen and are further below the trend than typically oc-
curred during 1940-1970. Optimists will trust that new techniques can raise the
limit above 21 t and that a relay team of maintenance research and application
will steady the annual averages. But surely all will agree that, since a farmer grew
a real yield of 21 t on 4 ha while the national average in an industrial nation lies
OCR for page 62
62
PAUL E. WAGGONER
near 7 t, scope remains for raising yields to feed people everywhere while sparing
land for Nature.
BUT IN THE END, WILL FARMERS SPARE LAND FOR NATURE?
Production does fluctuate, and people do panic. For example, in the early
1970s fallen production drove food prices up, and US soybean prices doubled.
Anxious academics and politicians launched world hunger studies. Then produc-
tion recovered, sinking prices and bankrupting farmers. Looking beyond fluctua-
tions-and grain prices in 1996 show we are suffering one right now-takes
steady nerves.
The logistic curve extending past improvements in yields toward 21 t/ha
could mislead humanity into thinking that an unseen hand lifts yields effortlessly.
In fact, vigorous research and enterprising farmers do the lifting. Remembering
the lag of decades between discoveries and their impact on world averages, one
asks whether any innovations are on the shelf that can raise yields soon. Heralded
for decades, some techniques from biotechnology now sit prominently poised for
application, and both scientists and practical people expect them to raise yields as
well as protect crops and lessen environmental harm (US Congress, Office of
Technology Assessment, 1992; Weiss and Brayman, 1992~.
Concrete, statistical evidence that techniques remain to be more fully used
appears in the comparison of best and average practices of maize farmers (Iowa
Crop Improvement Association, personal communication; see also various years
of the FAO Yearbook and the US Department of Agriculture's Agricultural Sta-
tistics). Figure 5 displays the trends since 1960 of maize yields grown by the
winners of the Iowa Master Corn Growers' Contest and also the trends of average
yields by Iowa and world farmers. In percentages, the annual gains by world and
Iowa averages do exceed the gain by Iowa Masters. Absolutely, however, the
Masters gained 0.14 t/ha annually, more than the Iowa average and twice the gain
of the world average. The winners of the Iowa Master Soybean Growers' Contest
also steadily stay ahead of the Iowa average soybean yields. The reality of win-
ners staying steadily ahead of averages confirms that new technology remains at
hand for American farmers. A survey of irrigated Pakistani farms shows a similar
gap between master and average yields. Ahmad's tabulation of yields of major
crops showed that progressive Pakistanis grow about three times the average
yields (Ahmad, 1987~. Technology remains on a nearby shelf for farmers every-
where.
Because widespread use lags behind discovery by decades, the inventory on
the shelf cannot be filled on need but must be replenished continually. The
expenditures by the Consultative Group on International Agricultural Research
provide an index of effort to refresh the inventory worldwide. Expenditures,
which are on the order of a quarter billion dollars, peaked in 1989 and in 1994
OCR for page 63
HOW MUCH LAND CAN BE SPARED FOR NATURE?
20
15
~10
N
._
Ct
~ =
1 _
1 ~
i
~ , _ _
O 1 1
1960 1965 1970
,,. ,`~,_-~ I
lowa Master
\1
lowa Average
World Average
63
1975 1980 1985 1990 1995
Year
FIGURE 5 The trends since 1960 of maize yields in tons/hectare (t/ha) grown by
the winners of the Iowa Master Corn Growers' Contest and also of average yields of
Iowa and world farmers. NOTE: The rising trend of per-year yields for Iowa Mas-
ters is 1.1 percent, or 0.14 t/ha; for Iowa, the average is 1.S percent, or 0.10 t/ha;
and for world maize growers, the average is 2.2 percent, or 0.06 t/ha.
were about 20 percent below the peak.5 So while the shelf currently holds tech-
nology, what it will hold in a few decades causes us to worry justifiably.
Technology left on the shelf butters no parsnips. Whether it will be em-
ployed depends on the profit the farmer foresees or the rules that discourage him.
In Transforming Traditional Agriculture, Schultz (1964) argues that even poor
farmers in poor places do profitable things. A book with the illuminating title of
The Bias Against Agriculture (Bautista and Valdes, 1993), however, tells how
societies have both discouraged and encouraged farmers' production. For ex-
ample, in Peru during 1969-1973 favors for industry and price controls on farm
products lowered the production of farm products. In Zaire during 1966-1982
price controls on food to depress real farm wages, as well as taxes on farm
exports to provide cheap credit for industry, were designed to encourage indus-
try; they cut the growth of food production in half and of export crops by even
more. None of these workings of an invisible hand would have surprised Adam
Smith.
An invisible hand also induces people and institutions to invent and apply
technology. The ratio of fertilizer to land prices induced about the same applica
OCR for page 64
64
PAUL E. WAGGONER
lions of fertilizer in countries as unlike as Japan and the United States. Passing
time changed the output per worker and per unit of land similarly in different
countries (Hayami and Ruttan, 1985~. By incentives and rules, nations will re-
plenish the technology on the shelf and lead farmers to use it or not, sparing land
for Nature or not.
Nations could choose Draconian rules against expanding cultivation and
favoring intensive farming to spare more land for Nature. But they must beware
the price of food. Mobs have taught the rulers of Rome, revolutionary France, and
modern states that costly bread incites riots. Thomas Malthus foresaw that no
sensible politician would do away with farm animals and require people to eat
only potatoes.
If one includes improved technology in an analysis, the desired outcome can
be envisioned without exploding prices. The outcome requires a per hectare
productivity rise of 2 percent annually; this target exceeds recent increases and
projected percentage rises for US crops but not the rise of global maize yield or of
US land productivity from 1950 to 1979. A reasonable analysis can produce an
annual decline of food prices of 0.5 percent, which matches the 1900-1984 fall of
world prices of the main agricultural products.6
DOES WATER CLOUD THE VISION?
Despite the abundance of water overall, its uneven distribution among re-
gions and its capricious variation among seasons plague farming. The brute ex-
pansion of irrigation grows harder. Nevertheless, opportunities to grow more
crops with the same amount of water kindle our hope. People usually see the last
oasis and pin their hopes on engineering lining, metering and timing, trickle,
surge, and drip (Poster, 1992~.
A peculiarity about evaporation creates a paradoxical but even greater op-
portunity: Bumper crops consume only a little more water than do sparse ones.
Doubling yield doubles water-use efficiency, as we see in Figure 6. Consider
irrigation with 450 mm of water. In a survey of Pakistani farms, increasing
fertilizer from 20 kg/ha to 100 kg/ha raised yield by 40 percent. Because no more
water was used, fertilizer also raised water-use efficiency by 40 percent. Ahmad
wrote, "Water cannot be considered to have become a real constraint to meeting
the world food supplies as long as there is the scope for manipulation of the
various underlying factors for. . . increasing . . . production" (Ahmad, 1987~.
Another paradoxical opportunity to make water go further is to supplement
rain. Water that supplements rain supplies the fast evapotranspiration that raises
water-use efficiency. For example, the water-use efficiency of sorghum in Texas
doubled when the water supply raised evapotranspiration from 250 mm to more
than 700 mm; water similarly raised the efficiency of maize in five US states
(Jensen, 1984) The simplest rationale for irrigation in humid places is that rain
provides some of the needed water for free.
OCR for page 65
HOW MUCH LAND CAN BE SPARED FOR NATURE?
2,0
1 8
1 ,6
-
~n
o
1 ~
, ,c
._
1 ,0
0 8
0,6
65
750 mm
- - - 450 m m
-·-SOOmm
-I'"
/
'~ d
.'
_1~
id
.~
0 20 40 60 80 1 00 1 20 1 40 1 60 1 80
Fertilizer (kilograms/hectare)
FIGURE 6 The complementarily of increasing irrigation and fertilizer. NOTE: The
three curves show different amounts of applied water, measured as precipitation in milli
meters (mm).
HOW MUCH WILL HIGH YIELDS TARNISH THE LAND?
If farmers increase their yields with techniques that harm the surroundings,
they will spare land, but the external effects may tarnish their victories.
Farmers do many things on each area of land they crop. In general, higher
yields require little more clearing, tilling, and cultivating than lower yields. Pro-
tecting a plot of lush foliage from insects or disease requires only a little more
pesticide than does sparse foliage. Keeping weeds from growing in deep shade
beneath a bumper crop may require less herbicide per field than keeping them
from growing in thin shade. The amount of water consumed is more or less the
same per area whether the crop is abundant or sparse, and growing higher yields
distills away only a little more water and leaves only a little more residue of salt
than lower yields.
Seed is planted per plot; choosing a higher yielding variety does not affect
the surroundings. If the improved variety resists pests, it lessens the external
effect of pesticides compared to a sprayed crop. If the pests in a crop had gone
uncontrolled and had decreased the yield, the new variety and its higher yield
OCR for page 66
66
PAUL E. WAGGONER
would be free, environmentally. By minimally changing the external effects of
things that farmers do per area, lifting yields will thus lower the effects per yield.
On the other hand, farmers use more of some things to raise the yield of their
crops. For example, farmers apply more fertilizer per plot to raise yields. Does
this leak more fertilizer into the surroundings per yield?
Consider again the complementarily of water and fertilizer (Figure 6~. A
given yield requires more fertilizer with 300 mm than 750 mm of irrigation.
Consider the yield of 1.4 t/ha. Even an infinite amount of fertilizer and great
fallout into the surroundings would not produce 1.4 tons on the field irrigated
with 300 mm of water. But 50 units of fertilizer would grow 1.4 tons on the field
irrigated with 450 mm of water. The hectare irrigated with 750 mm of water
would get the same 1.4 tons from only 30 units and would therefore have less
environmental fallout.
For a given yield, optimum conditions for growth and high yield lessen the
fallout of such things as silt, pesticides, and fertilizer into the surroundings. If
factors that must be increased per plot to raise the yield are improved in step, their
improved coordination may diminish the fallout.7
STRAWS IN THE WIND
Having reviewed some of the elements of farming, we must look at how
global cropland and production are actually changing at the macro level. From
1975 to 1990 cropland expanded by only 3 percent, but from 1969-1970 to 1988-
1990 the supply of calories per capita rose by 11 percent (FAG, 1992~. Because
of the rising yields, farmers grow surpluses today, driving prices down.
To combat the bankruptcy of farmers, prices are supported, and farmers are
given incentives to idle their cropland. So far in the 1990s about a fifth of US
cropland has typically been idled by government programs.8 The geographers
Deborah and Frank Popper have made vivid the reversion of farms to range with
their phrase "The Buffalo Commons" (Matthews, 1992~. Looking forward, the
Dutch projected changes from the present farmland in nations of the European
Union to the year 2015 (Rabbinge et al., 1992~. Diverse scenarios built around
liberal trade, employment policies, and environmental regulation all shrank farm-
land by 40 percent or more. Straws in the wind hint that land can be spared.
A SCENARIO FOR SUCCESS
A tally of strategies to lessen deforestation is a good place to start the search
for a scenario about sparing land for Nature. A strategy of economic development
to attract settlers away from treasured forests takes too long. Encouraging migra-
tion to places other than the lands we wish to protect is usually insufficient to
deflect immigrants. In the minds and meeting rooms of environmentalists, desig-
nating Nature reserves may stop hungry people from clearing plots; but this is not
OCR for page 67
HOW MUCH LAND CAN BE SPARED FOR NATURE?
67
the case outdoors. And reserves for extractive but sustainable forestry support
few people. On the other hand, eliminating the need to abandon land that is
already cleared by maintaining or restoring productivity offers some hope. Ex-
periments for eight years on soil representing the Amazon basin grew undimin-
ished yields of about 7 t/ha; this productivity has continued over seventeen years
for forty crops (Sanchez et al., 1982, 1990; World Bank, 1992~.
Because numbers can impart a misleading aura of accuracy, I have written
more about directions than precise numbers. In the end, however, the question
"How much?" calls for numerical answers and familiar images of space such as
India or Amazonia. The plot for my quantitative scenario relates the area poten-
tially spared to: 19 A reference area, which I shall set at 2.8 billion ha of crop-
land. This is twice the size of the present cropland, six-tenths of the present
cropland plus permanent pasture, and a fifth of the land in the world. If farmers
use less than 2.8 billion ha as the population multiplies from about five to ten
billion, I assert that they spare land for Nature. 2J Diet, with a daily use of
calories from agricultural products varying from about 3,000 to 6,000 calories
per capita. 3, Yield, which can vary from 4 to nearly 80 million calories (Meal)
per ha.
Some examples of yields in tons (t) and corresponding Mcal/ha are: wheat
in an arid African nation, 1 t and 4 Mcal/ha; wheat in North America, 3 t and 12
Mcal/ha; wheat in Europe, 6 t and 24 Mcal/ha; wheat in Ireland or maize in the
United States, 9 t and 35 Mcal/ha; potatoes in Maine or Ireland, 30 t and 18 Mcal/
ha; and maize from the field of the national winner in Pasco, Washington, 20 t
and 78 Mcal/ha. The 12 quadrillion calories produced by agriculture plus con-
sumption by draft animals, which is shown in Figure 2, divided by the world's
1.4 billion ha of cropland produces an average of about 8.5 Mcal/ha or 2 t/ha.
To support ten billion people consuming 3,000 car/day, farmers averaging
the yield of wheat in arid Africa would spare none of the 2.8 billion ha of the
reference area (Figure 7~. If the ten billion consumed 6,OOO car/day, the yield of
4 Mcal/ha would spread over an additional 2.8 billion ha of other land. On the
other hand, an average yield of 16 Mcal/ha, one-third less than present European
wheat, would spare much of the land. Averaging 16 Mcal/ha, farmers would be
able to support ten billion people consuming 6,OOO car/day on the present crop-
land, sparing half of the reference area. If the ten billion consumed only 3,000
car/day, 16 Mcal/ha would spare for Nature about 600 million hectares of present
cropland, the area of the Amazon basin. Above 24 Mcal or 6 t per ha, farmers will
use little cropland, globally sparing an area of today's cropped hectares equal to
the land of India, even when people consume 6,000 car/day. If during the next
sixty to seventy years the world farmer reaches the average yield of today's US
corn grower, the ten billion will need only half of today's cropland while they eat
today's American calories.
OCR for page 68
68
PAUL E. WAGGONER
2.8
-
U,
s
4~
o
U)
0 1.4
._
-
o
0.0
\ 6,000
\Calones I Day
\ 3,000 \
\Calones J Day\
"India" Spared (0.35\
"Amazon" Spared (0.6)
Current
Cropland
Afri canNorthMai ne
WheatAm eri canPotatoes
Wheat
European
Wheat U.S. Corn\
o
2 4 6
Yield (ton grain equivalent per hectare)
8
FIGURE 7. The sparing for Nature of a reference area of 2.8 billion hectares of
cropland by farmers raising yields for ten billion people consuming 3,000 or 6,000
calories daily.
SURPRISES, BAD AND GOOD
Orderly people instinctively turn to experts for projections that will protect
them from surprises. Unfortunately, a century of scientific bloopers by heavy-
weights beginning with Lord Kelvin disabuses their instinct.9 Looking ahead to
what ten billion people might be able to save for Nature, I could be daunted by the
experts' historic lack of foresight. I could play it safe by conceiving a list of
surprises and writing that "all these might happen." Alas, the forecaster who
plays it safe by ending all predictions with "but it may snow" is worthless.
Beyond listing surprises that could happen, I must suggest which of them are
likely to occur and admit that good as well as bad surprises may be in store. From
this list of conceivable surprises, I choose four likely ones: fewer than ten billion
people, climate change, new pests, and new breakthroughs.
Because growing income and social security have been credited with the
slowing of population growth, I look at the speedy economic growth of China and
other Asian nations and wonder whether it might check the multiplication of their
great populations. The Black Death of the fourteenth century left Europe too
small for its clothes, and in 1918 the influenza pandemic left twenty million dead
in just a few months. Thus, a surprise like wealth or a pandemic could slow
OCR for page 69
HOW MUCH LAND CAN BE SPARED FOR NATURE?
69
population growth. Then, more land would be spared for Nature in the twenty-
first century as it was in the fourteenth.
Heralded for more than a decade, climate change may not come as a surprise.
But just as some unexpected happening is not necessarily a surprise while its
specific quality is, so it is with climate change. During a debate about supersonic
airplanes, cooling associated with their emissions was projected to have a dire
impact. Then, lengthening observations of rising CO2 levels brought projections
of warming and drying, with more projections of dire impacts. When the Ameri-
can breadbasket turned dry in 1988, the warmer, drier climate seemed at hand.
But during 1993, floods in the American heartland discounted predictions made
only five years earlier. Computer simulations, of course, had disagreed all along
about whether rising CO2 would make North America drier or wetter. I place
climate change among the surprises.
If cropland in temperate climates becomes hot or dry, yields will fall, and
land may be taken from Nature to be used for crops. On the other hand, if
cropland that is too cold warms and that which is too dry moistens, yields will
rise, saving other land for Nature. Conflicting and changing projections and
experience mean we are wise to diversify our portfolios in anticipation of the
surprises (CAST, 1992~.
Weekly forecasts of pest infestation and the weather affecting them underpin
modern pest management. The record shows, however, that pests are shifty, and
they may cause disastrous outbreaks and epidemics. New, surprising fungi caused
both the Irish potato famine of the 1840s and the Southern corn leaf blight of
1970. "History warns that new pests will appear but provides no data for a model
that tells where and when newcomers will appear or what they will be like. The
required warning system of sharp, exploring eyes in the field is old-fashioned but
remains our most effective approach" (National Research Council, 1976~. Sur-
prising pests could lessen the sparing of cropland for Nature.
Scientific breakthroughs, or their failure to appear, could also violate our
plans and expectations. In Figure 4 yields rise at a declining rate toward a ceiling
that is set by crops that are already grown. This projection assumes that societies
will continue to encourage, scientists will continue to discover, and farmers will
continue to venture toward that ceiling. Disorder from Dushanbe and Sri Lanka to
Kigali and Sarajevo to Port-au-Prince and Monrovia renders hopeless encourage-
ment by some nations. A decrease in money implies a decline in agricultural
research. So, a surprise could arrest the trend that is shown in Figure 4.
Yet I would like to point out that some surprises are happy ones. It is opti-
mistic but still rational to hope that some breakthroughs will become practice
before the population reaches the ten billion mark, surprising me as rising yields
after 1900 would have surprised Malthus and even a writer at the turn of the
century. The distance between average yields and the actual (not theoretical) 20
tons of grain on the hectares in Pasco, Washington, provides room for a surprise.
The surprise of leaps in productivity and new forms of food production would
OCR for page 70
70
PAUL E. WAGGONER
likely dislocate farming and displace farmers as changes have rapidly and cruelly
done since 1940. But it would spare land for Nature.
IN THE END
If people keep eating and multiplying and farmers keep tilling and harvesting
as they do today, the imperative of food will take another tenth of the land away
from Nature. So farmers work at the hub of sparing land for Nature.
By eating different species of crops and a more or less vegetarian diet people
can change the number that a plot can feed. And large numbers of people do
change their diets. The calories and protein available from present cropland could
provide a vegetarian diet to ten billion people. A diet requiring food and feed
totaling 6,000 calories daily for ten billion people, however, would overwhelm
the capability of present agriculture on present cropland.
The global totals of sun, CO2, fertilizer, and even water could produce far
more food than what ten billion people need. Encouraged by incentives, farmers
combine natural resources with new technology to raise more crop on each plot,
keeping food prices down despite the rising population. Differences in yields
among nations and between average and best performance continue to show that
yields can be raised much more.
For each ton of production, growing more food per plot lessens the fallout of
such things as silt and pesticides into the surroundings. If factors such as water
and fertilizer are improved in step, fallout may be diminished. Although the
uneven distribution of water among regions and its capricious variation among
seasons plague farming, opportunities to raise more crops with the same volume
of water kindle our hopes for the spread of high yields.
Rising yields have shrunk European and American cropland for decades, and
governments pay farmers to keep fields idle. Globally, cropland has been roughly
level since the middle of the twentieth century. If average fields in the world sixty
or seventy years hence, when we are likely to number ten billion, yield as much
food as today's potato fields in Ireland, wheat fields in France, or corn fields in
Iowa, large portions of the land currently in crops can revert to Nature. This will
not happen by itself, nor will it happen if today's scarcity of grain transfixes us.
Countering humanity's multiplying population and wealth to spare habitat for
Nature requires never-ending research, encouraging incentives, and smart farmers.
NOTES
1. This article briefly answers the question in the title. An ample answer with full citation of its
foundation has been published as Task Force Report No. 121, by the Council for Agricultural Sci-
ence and Technology (see CAST, 1994). Fallout into the environment is more fully examined in
Waggoner (in press).
2. Calculated at 2.6 times the weight of feed, containing 4,000 car/kg, to produce 1 times the
weight of meat, containing 2,200 car/kg. Feed per meat from US Department of Agriculture (1992).
OCR for page 71
SPARED FOR NATURE? 71 HOW MUCH LAND CAN B.
s of the US Department of Agriculture's Agricultural Statistics. The
nnual diet from 1909 to 1970.
usion. . . is that 1,000 billion people could live from the earth if photo-
r!" (deWit, 1967). Fallen fertilizer prices are reported, e.g., in Freeport-
thesizing 1 to 6 grams of biomass consumes a thousand grams of water.
poration from land matches photosynthesis to feed 400 billion. For
Gets for 1972-1994 furnished by Ralph Cummings Jr., US AID, and
he US consumer price index. See also Abelson (1995).
see Binswanger et al. (1985). The analysis, which W. D. Nordhaus
Vaggoner (1994).
he principle of a factor only raising yield when other factors are not
igins of plant physiology and agronomy. Recently, it has been related
if intensive farming, as in deWit (1992).
ltural Policy Research Institute (FAPRI) tabulated the area planted to
United States and the area idled by two programs identified by the
1 CRP. The idled areas have been, or are projected to be, steady from
jects them to decline after 1997 (FAPRI, 1992).
aws the feet of clay: The Experts Speak: The Definitive Compendium
on (serf and Navasky, 1984). When the US president appointed distin-
aers to report on technology that would matter to the nation during
antibiotics, radar, space exploration, and jet-engine aircraft. "In fact, if
he exciting things that happened over the next several decades, they
" (Townes, 1991).
REFERENCES
rational agriculture. Science 268:11.
, a constraint to world food supplies. Pp. 23-27 in Water and Water
applies, W. R. Jordan, ed. College Station, Tex.: Texas A&M Univer
s, eds. 1993. The Bias Against Agriculture. San Francisco: Contem
llak, M.-C. Yang, and A. Bowers. 1985. Estimation of Aggregate
Agricultural Research Unit Report 48. Washington, D.C.: World
~ institutions work a scientist's viewpoint. Pp. 387-395 in Water and
food Supplies, W. R. Jordan, ed. College Station, Tex.: A&M Univer
ural Science and Technology). 1992. Preparing US Agriculture for
. Report 119. Ames, Iowa: CAST.
ural Science and Technology). 1994. Task Force Report No. 121.
~84. The Experts Speak: The Definitive Compendium of Authoritative
fork: Pantheon.
~thesis: Its relationship to overpopulation. Pp. 315-320 in Harvesting
F. A. Greer, and T. J. Army, eds. New York: Academic Press.
~ use in agriculture. Agricultural Systems 40:125-151.
organization). 1992. FAO Yearbook 1991. Vol. 45. Rome: FAO.
-e Policy Research Institute). 1992. P. 83 in 1992 US Agricultural
.-92. Ames, Iowa, and Columbia, Mo.: FAPRI.
3. See also various yeas
book for 1972 tabulates the a
4. "The staggering cone
synthesis is the limiting facto
McMoRan (1993). Photosyn
At this ratio, the global eve
details see Waggoner (1994)
5. Expenditures and but
adjusted to 1983 dollars by tl
6. For past food prices
devised, is reported fully in
7. The annunciation of
limiting coincides with the of
to the environmental effects ~
8. The Food and Agricl:
fifteen principal crops in the
acronyms ARP/PLD/0-92 an
1989 to 1997, but FAPRI prc
9. The title of a book sh
of Authoritative Misinformat,
guished scientists and engin,
coming decades, they missed
you were to ask what were
missed all of them, every one
Abelson, P. H. 1995. Intern
Ahmad, M. 1987. Water a'
Policy in World Food S
sity Press.
Bautista, R. M., and A. Veldt
porary Studies Press.
Binswanger, H. P., Y. Mung
Agricultural Response.
Bank.
Borlaug, N. E. 1987. Makin
Water Policy in World
sity Press.
CAST (Council for Agricult'
Global Climate Change
CAST (Council for Agricult
Ames, Iowa: CAST.
Cerf, C., and V. Navasky. 1c
Misinformation. New
deWit, C. T. 1967. Photosy
the Sun, A. San Pietro,
deWit, C. T. 1992. Resourc
FAO (Food and Agriculture
FAPRI (Food and Agricultu
Outlook. Staff Report
OCR for page 72
72
PAULE. WAGGONER
Freeport-McMoRan. 1993. 1992 Annual Report. New Orleans: Freeport-McMoRan.
Hassebrook, C., and G. Hegyes. 1989. Choices for the Heartland. Walthill, Nebr.: Center for Rural
Affairs.
Hayami, Y., and V. W. Ruttan. 1985. Agricultural Development. Baltimore: Johns Hopkins
University Press.
Jensen, M. E. 1984. Water resource technology and management. Pp. 142-166 in Future Agricul-
tural Technology and Resource Conservation, B. C. Barton, J. A. Maetzold, B. R. Holding, and
E. O. Heady, eds. Ames, Iowa: Iowa State University Press.
Kroc, R. 1977. Grinding It Out: The Making of McDonald's. Chicago: Henry Regnery.
Lutz, W. 1994. The Future Population of the Earth: What Can We Assume Today? London:
Earthscan.
Matthews, A. 1992. Where the Buffalo Roam. New York: Grove Weidenfeld.
National Corn Growers' Association. 1993 and 1994. Tabulations of the Contestants in the 1992
and 1993 Maize Yield Contest. St. Louis: National Corn Growers' Association.
National Research Council. 1976. P. 128 in Pest Management in Climate and Food. Washington,
D.C.: National Academy of Sciences.
National Research Council, Subcommittee on the Tenth Edition of the RDAs. 1989. Pp. 33 and 285
in Recommended Dietary Allowances. Tenth Revised Edition. Washington, D.C.: National
Academy Press.
Norton, B. 1988. Commodity, amenity, and morality: The limits of quantification in valuing
biodiversity. Pp. 200-205 in Biodiversity, E. O. Wilson, ed. Washington, D.C.: National
Academy Press.
Parikh, K. S. 1992. Agricultural and food system scenarios for the 21st century. In Agriculture,
Environment and Health: Toward Sustaining Development in the 21st Century, V. W. Ruttan,
ed. Minneapolis: University of Minnesota Press.
Plucknett, D. L., and N. J. H. Smith. 1986. Sustaining agricultural yields: As productivity rises,
maintenance research is needed to uphold the gains. BioScience 36:40-45.
Postel, S. 1992. Last Oasis. New York: W. W. Norton.
Rabbinge, R., et al. 1992. Ground for Choices. Reports to the Government. Vol. 42. The Hague:
Netherlands Science Council for Government Policy.
Richards, J. F. 1990. Land transformation. In The Earth as Transformed by Human Action, B. L.
Turner et al., eds. Cambridge, England: Cambridge University Press.
Sanchez, P., D. E. Bandy, J. H. Villachica, and J. J. Nicholaides. 1982. Amazon Basin soils:
Management for continuous crop production. Science 216:821-827.
Sanchez, P., C. A. Palm, and T. J. Smyth. 1990. Approaches to mitigate tropical deforestation by
sustainable soil management practices. In Soils on a Warmer Earth, H. W. Scharpenseel, M.
Schomarker, and A. Ayoub, eds. Developments in Soil Science 20:213.
Sanderson, F. H. 1988. The agro-food Moliere: A macroeconomic study on the evolution of the
demand structure and induced changes in the destination of agricultural outputs. In The Agro-
Technological System Towards 2000, G. Antonelli and A. Quadrio-Curzio, eds. North Ho1-
land: Elsevier Science Publishers.
Schultz, T. W. 1964. Transforming Traditional Agriculture. New Haven, Conn.: Yale University
Press.
Townes, C. H. 1991. P. 17 in Cosmos Club Bulletin, October. Washington, D.C.: Cosmos Club.
US Congress, Office of Technology Assessment. 1992. Pp. 133-138 in A New Technological Era
for American Agriculture. OTA-F-474. Washington, D.C.: Office of: Technology Assess
ment.
US Department of Agriculture. 1962. Agricultural Statistics. Washington, D.C.: US Government
Printing Office.
US Department of Agriculture. 1992. Agricultural Statistics. Washington, D.C.: US Government
Printing Office.
OCR for page 73
HOW MUCH LAND CAN BE SPARED FOR NATURE?
73
Waggoner, P. E. 1994. How Much Land Can Ten Billion People Spare for Nature? Task Force
Report, No. 121. Ames, Iowa: Council for Agricultural Science and Technology.
Waggoner, P. E. In press. How much more land can American farmers spare? In RCA III Sympo-
sium on Crop and Livestock Technologies: Proceedings, B. C. English, R. L. White, and L.
H. Chuang, eds. Washington, D.C.: National Resource Conservation Service, US Department
of Agriculture.
Weiss, C., and S. E. Brayman. 1992. Assessment of biotechnology: The 'gene' revolution. Pp. 1-
7 in Biotechnology and Development: Expanding the Capacity to Produce Food. New York:
United Nations.
World Bank. 1992. Development and the environment: World development indicators. World
Development Report 1992. Oxford, England: Oxford University Press.
Representative terms from entire chapter:
billion people
