Paul R. Ehrlich & Anne H. Ehrlich, The Population Explosion, 1990.

The Ecology of Agriculture

We've now considered the precarious food situation in the developing world, as well as the rising pressures on the world's fisheries. Before looking in more detail at the issue of global food security, let's consider where food comes from. In order to understand the world food situation, it is necessary to have a grasp of the principal features of agricultural ecosystems and their resources.

First, agricultural systems necessarily are and will remain spread out -- agriculture can't be concentrated in small areas. This characteristic traces to a fundamental circumstance: agriculture runs on photosynthesis, which in turn is driven by incoming solar energy. That energy arrives widely dispersed.1

Since humanity can do precious little about either the spread-out arrival of sunlight -- the most fundamental agricultural resource -- or the efficiency of photosynthesis, large areas must be farmed to feed a human population. Under extremely optimistic assumptions, a city of a million people would require almost 400 square miles of land in crops to "capture" enough sunlight to feed its citizens a basic, no-frills vegetarian diet. With realistic accounting for the fraction of the year that crops can be grown in most regions, the efficiency with which energy can be extracted from vegetable food, the pest losses and wastage between harvest and eating, the feeding of some crops to animals (and the pasture they require), and the need to produce some less calorie-rich crops to obtain variety and needed nutrients, that number could easily be multiplied five- or tenfold. The city therefore depends on thousands of square miles of farmland just to provide its food.


A second key point for understanding the food problem is that agricultural productivity is extremely sensitive to the weather. A myth has arisen that modern agricultural techniques and irrigation have somehow freed agriculture from dependence on suitable temperatures and rainfall. If anything, the opposite is true. Modern high-yielding strains of crops often respond with larger variations in yield to changes in weather than do traditional strains.

The importance of a stable and suitable climate for agriculture today was clearly demonstrated in the United States in 1988. The drought slashed the nations's grain harvest from its usual 300 million tons or so to less than 200 million tons -- even though the United States has as "modern" an agricultural system as there is.

The same source of energy that powers photosynthesis also creates the weather. The sun's energy drives the entire climatic system.2 Hot air rises; and air near the equator is heated more than air near the poles. Cold air also can hold less moisture (water vapor) than hot air; so, as rising air cools by expansion in the thinner upper atmosphere, its moisture is squeezed out, resulting in clouds (made of tiny droplets of water) and rain (bigger droplets). Each puffy cumulus cloud that hangs over a summer landscape marks the cooling top of a rising column of hot air.

These characteristics of air, combined with Earth's rotation and the complex pattern of the planet's surface (water versus land; flat land versus mountains; differences in the reflectivity of sunlight off various surfaces), create the behavior of the atmospheric system that we call "weather" and the long-term average weather called the "climate."

Climatologists can explain many major features of climate. A basic pattern is movement of warmed air poleward from the equator at high altitudes and of cooled air toward the equator from polar regions along the surface. This is not a simple loop, though. Hot air in equatorial regions spills out rain as it rises, cools, and then moves northward at high altitude, cooling further as it radiates away heat. The cooled dry air descends in subtropical latitudes, warming by compression as it falls and creating belts of desert north and south of the moist tropics. These desert regions include the Sahara, the American Southwest, the Atacama of South America, the deserts of southern Asia, southern Africa, and the center of Australia. Their climates are mostly too dry for productive agriculture, except where irrigation is practical.

Beyond the desert belts, strong prevailing westerly winds bring moisture from the oceans across the continents, providing rain and snow for the world's most productive agricultural regions. It is no accident that the majority of the world's people live (and most of the grain is produced) in the temperate zones, mainly in the north, where the bulk of the land also is located. Nearer the poles, weather is too cold and often too dry to support most crops. An exception is Europe, warmed and watered by the Gulf Stream.

Of course, there is a lot more detailed action in the system than this brief description indicates, and therein lies the rub. For instance, climatologists now believe that weather in North America is heavily influenced by the temperature of the water surface in the tropical Pacific. But a combination of too few accurate temperature readings and inadequate computer models prevents them from predicting the exact nature of that relationship.3

Perhaps the most worrisome aspect of the weather-agriculture relationship is that, as climatologists sometimes say, the climate runs on small differences between large numbers. Or, to put it another way, seemingly minor changes in such things as the relatively tiny amounts (less than one percent) of greenhouse gases in the atmosphere can have powerful influences on climate. In theory, small changes in weather patterns could sharply diminish the agricultural productivity of the U.S. Midwest. Similarly, alterations in atmospheric and oceanic circulation patterns could change the course of the Gulf Stream, producing an agricultural catastrophe in Europe as the climate there shifted toward that of subarctic Labrador, just across the Atlantic.

The threat to agriculture is severe even without a shift of climate into some dramatically new regime. Small changes in the average temperature, for example, might have little impact on agricultural production; but associated changes in extremes (such as blistering heat waves or out-of-season frosts) could wreak havoc. As the atmosphere warms from the greenhouse-gas buildup, variability in rainfall patterns might also increase, and extreme events (violent storms and severe droughts) might become more frequent.4 Finally, rising sea levels from the greenhouse warming will certainly not benefit farmers in coastal or low-lying areas, which often are among the most productive farmlands.


Because agriculture has to be a dispersed activity, while people are increasingly concentrated in cities (as is the manufacture of products needed by farmers), transport systems are vital components of agricultural systems. "Inputs" (fuel for farm machinery, seeds, fertilizers and pesticides) must be transported to farms, and farm products ("outputs") must be delivered to markets or to processing and storage centers and then sent onward to consumers. In the United States today, fewer than 2 percent of the population live on farms, and very few farmers grow all their own food. Indeed, food production more and more is regionally concentrated; nearly all of the lettuce and many other vegetables in the United States are grown in California and Florida (for East Coast markets) and shipped around the country, for instance. Virtually everyone in the nation depends on the smooth movement of trains and trucks to keep eating.

This dependency on the functioning of elaborate transport systems applies between as well as within modern nations. Along with grain and other foodstuffs, the inputs for agriculture are important elements in world trade, although many developing nations have become increasingly self-sufficient in producing their own fertilizers and seeds.

The inputs used in modern farming have been vital to the nearly threefold increase in global food production that has been achieved since World War II (while the population has more than doubled). They are the essence of the Green Revolution: the use of specially bred high-yield varieties of major crops, which require large applications of fertilizer and abundant water in order to produce their high yields (more grain per acre). Because high-yield crops usually are planted in extensive, genetically uniform tracts, they also require extra protection against pests; hence, the emphasis on pesticides.

Increases of yields on already cultivated land, rather than the development of new land for farming, have been responsible for four fifths of the rise in crop production in the last few decades.5 But humanity cannot rely on simply increasing inputs, especially fertilizers, to feed 95 million additional people every year indefinitely. First of all, fertilizers cost money. In much of the world, farmers now apply about all that is economically productive. In developing countries, this often means all they can afford or obtain, even though applying more might still be very helpful.

In much of the world, however, fertilizer applications have passed the point of diminishing returns. Fertilizers provide supplements of certain nutrients, mainly nitrogen, phosphorus, and potassium, to the soil. Yields of responsive crop varieties can be dramatically boosted by this enrichment, if sufficient water is supplied and other conditions are appropriate. But there are limits to how much of these nutrients crops can use. On the average worldwide in 1950, a ton of additional fertilizer used on grain crops produced 46 more tons of grain; in 1965, an additional ton of fertilizer produced only 23 more tons of grain; and by the early 1980s, the additional ton yielded only about 13 more tons of grain.6 Fertilizer applications by the 1980s were so high and so widely adopted that most of the potential gains had already been made. Nowhere is this more true than in the United States, where the technology was pioneered. The increase in yield earned by applying one more ton of fertilizer to a field in the U.S. corn belt has fallen from 15-20 tons of grain in 1970 to 5-10 tons today.

In short, the "magic" of fertilizer is running out. In much of the world outside the poorest developing nations, increased fertilizer applications have become uneconomic because the rise in crop yield is too small to pay for the cost of the fertilizer. It would be folly to expect a surge in food production in the future to match that achieved with fertilizer-sensitive crops between 1950 and 1975, when the Green Revolution was established in industrialized nations and transferred, with mixed results, to the developing world.

One can, of course, imagine rich countries supplying more aid to increase fertilizer use in developing countries where ample room remains for yield improvements before the crop's responses to fertilizer start to plateau. The brightest remaining opportunities to raise yields are in some of the hungriest nations; but in the tropics, the potential for raising yields this way is probably quite limited. A repeat of the Green Revolution successes achieved in India, China, Mexico, and East Asia may not be feasible in Central Africa or the Amazon basin (leaving aside whether it's desirable).7 Even if the Green Revolution should prove transferrable to the humid tropics, it's hard to see a way around the problem of diminishing returns from fertilizers. In drier areas, water may be a limiting factor, since to deliver their high yields heavily fertilized crops need plenty of it.

Along with the Green Revolution technologies, a major factor in the surge of food production since 1950 has been a massive increase in the acreage of land under irrigation. Much of this, of course, has been necessitated by the use of high-yield crop varieties. From 1950 to 1980, the amount of irrigated land expanded more than two and half times, but since then the expansion has definitely slowed, as the easy gains in production have been made and costs have risen. And, as aquifers have been drained and irrigated land has lost productivity from waterlogging and salt accumulations, land has been taken out of production. It is estimated that about a third of the world's irrigated cropland is losing productivity today because of these problems.8

It is seldom recognized that irrigation is usually a temporary game. Rainwater is essentially distilled water; it has been evaporated by the sun's heat and by the activity of green plants (in a process called "transpiration") and recondensed in the cool reaches of the atmosphere. It contains no significant amount of salts. Irrigation water, having run over or through Earth's surface after falling as rain, has had a chance to leach salts from the soil. When it is returned to the atmosphere from irrigated farm fields by evaporation and transpiration, the salts are left behind. Preventing their accumulation in most soils requires careful flushing. In the medium or long term, salvaging saline fields (when feasible at all) ordinarily costs more than farmers can pay -- some $265 per acre, according to a United Nations estimate in the late 1970s.9

Even in rich nations where modern irrigated agriculture is practiced, land is often gradually ruined by the process. California's highly productive Imperial Valley is threatened by sal-inization, and may end up growing just a few salt-tolerant crops. Parts of the San Joaquin Valley are not too far behind. Over 600 square miles were affected by high, brackish water tables by 1980, and it was estimated then that 13 percent of the valley, some 1700 square miles, will ultimately become unproductive unless expensive subsurface drainage systems are installed.10

In the Soviet Union, the ill-advised diversion of water for irrigation from rivers that fed the inland Aral Sea has led to a regional ecological disaster. The sea, once a productive fishery, has shrunk in area by a third; two thirds of its former volume is gone. Shoreline towns have been stranded far inland, and the fishery has been destroyed. Worse, the irrigated cropland has been turned into a salt desert, described by a Soviet scientist traveling 200 miles across it as "what appeared to be a snow-covered plain stretching to the horizon without a sign" of life."11 Salt, dust, and dried pesticide residues have been carried and deposited thousands of miles away by winds and rain, causing health problems for the population and affecting agriculture over vast areas. The regional climate also has become less benign as the sea has dried up.

Of course, where water is obtained by overdrawing aquifers, as in parts of the southern high plains of the United States that depend on the Ogallala, and in the desert Southwest, irrigated agriculture will be greatly reduced or will come to a halt as economically accessible groundwater is exhausted. Similar stories can be told for every non-antarctic continent (possibly excepting well-watered Europe). The problem of aquifer overdraft threatens grain production in arid and semi-arid regions around the world.


Agriculture is adversely affected by many forms of human-caused environmental damage. Climate change, deforestation, and widespread pollution obviously will seriously interfere with maintaining the crucial "genetic-library" service of natural ecosystems -- nature's inventory of species and genetic variants that are used in so many ways by humanity. That function is critical to the success of Green Revolution technology. Maintaining the genetic diversity of crop plants is essential so that geneticists can modify them to be productive under a variety of conditions. Genetic engineers can move genes from one organism to another, but they need the genetic raw materials found in existing plants and animals to do so.

As most of the productive land on Earth has been taken over for human use and more or less drastically altered in its biotic character, the remaining virgin forests, grasslands, and other natural areas throughout the world increasingly are islands in a vast sea of human disturbance. Those islands are the last reservoirs of genetic raw materials for use in agriculture and forestry to develop new crops or improve traditional ones.12

If the possibilities for substantial further increases in global yields on land already cultivated are limited, so are those for increasing the amount of cultivated land. Virtually all the reasonably arable land is being farmed. Indeed, much that shouldn't be cultivated has been, and it contributes greatly to statistics on land degradation from soil erosion and desertification.

As a consequence of humanity's massive takeover of Earth's productive land (noted in Chapter 2), people are already using or coopting or have destroyed nearly 40 percent of all the potential net primary production (NPP) on land.13 And, of course, most of that mammoth diversion of biotic energy is accounted for by agriculture and livestock production. All this must be viewed against the backdrop of a projected doubling of the human population by the middle of the next century.

Clearly, there are limits to further expansion, both through increasing yields on existing farmland and by opening up farmland in new areas. These limitations, indeed, are showing up in land-use assessments. Even by the optimistic estimates of "arable land" of the United Nations Food and Agriculture Organization (FAO), very little productive land exists in reserve in the Near East, North Africa, and Asia.14 FAO sees a lot of land waiting for the plow in sub-Saharan Africa and Latin America. But that assessment ignores the extremely poor, fragile soils of much of that land. More important, it ignores that much of it underlies tropical moist forests (especially in Brazil and Zaire). Those forests are among the most important elements of humanity's heritage, being critical both for the preservation of biotic diversity and to help slow climatic change, which threatens agriculture itself.

In the 1980s, more land went out of production (largely because of exhaustion, desertification, or failed irrigation) than was newly opened, and the world's cropland area shrank by some 7 percent.15 Perhaps a third of the cropland still in use is estimated to have lost productivity, although much of the loss has been masked by increased fertilizer applications. Sooner or later, though, the mask will slip, and that land will no longer produce a profitable crop.

Too much prime land is becoming marginal and then non-arable. Erosion is a big problem even in the United States, the "world's breadbasket." Around 1980, the United States was estimated to be losing nearly 4 billion tons of soil a year, enough to fill a freight train 600,000 miles long -- twenty-four times the circumference of Earth. About a third of America's cropland is affected, and drops in yield attributable to erosion have already been noted, including a 2 percent decline in grain production per acre in Illinois -- in the richest part of the grain belt -- between 1979 and 1984.16


A major source of confusion about the world food situation has been the complexity and inconsistency of United States agricultural policies. Subsidies have been turned on and off in response to the politics of the moment rather than the overall needs for the food-production system.17 In the early 1970s, the government was pumping huge amounts of money into maintenance and expansion of the irrigation system of California's Imperial Valley, while simultaneously paying other farmers to withhold their unirrigated land from production. Later, it paid the Imperial Valley farmers not to grow wheat, cotton, and other crops on the land it had paid to irrigate! Today western water is subsidized to the tune of about $1 billion to produce crops that, at least in some cases, other farmers are paid not to produce.18

American farm policy, unlike that of nations such as France and Switzerland, has encouraged the trend toward giant holdings and factory agriculture. This has sharply reduced the number of people who could make a living on the land. Every year between 1940 and 1960, a million Americans moved from farm to city, swelling the ranks of unskilled laborers and welfare recipients. In contrast, France and Switzerland avoided these social costs by adopting policies that kept small, relatively self-sufficient farms going, and accepting higher food prices. It has been argued that the savings in urban welfare and social costs more than compensated for the costs of subsidizing agriculture in this way.19

But there is an even bigger benefit to preserving family farms. Their owners are much more likely to conserve precious soil resources, to value the farm for its own sake, and try to pass it on to the next generation in superior condition. Large-scale farming, on the other hand, tends to focus on this year's bottom line" and sacrifice the farm's long-term productivity for short-term gain. The family farmer is very much aware that his soil is precious capital; the accountant for a large corporation that bought a farm as an investment is not.

The achievement of an ecologically and socially sound agricultural policy for the United States, the leading food ex-Porter, will be critical as the global population-food imbalance worsens. But such a policy won't be possible unless the nation's agricultural policies can be recaptured from their present dominance by agribusiness interests and made a concern of the public. Today, the system is so complex that almost no one in Congress understands it completely.

The Department of Agriculture is large, weak (compared to other executive-branch departments), and on occasion stunningly incompetent. The latter trait was displayed for all to see in the California Medfly disaster of the 1970s, in which the blame was largely and erroneously put on Governor Jerry Brown.20 If the United States is to be able to continue supplying large quantities of food for export in response to rising global need, it must get its agricultural house in order.

Recently, though, the U.S. Department of Agriculture's new Conservation Reserve Program slashed the national erosion rate by a third in just a couple of years -- one of the biggest conservation success stories of the century.21 The establishment of this program under the Food Security Act of 1985 was a big step toward an ecologically sounder agricultural policy. Over five years, the program is subsidizing farmers who will permanently set aside highly erodible marginal cropland, some 11 percent of the cropland base. These fragile lands are to be restored as grassland or woodland. Farmers also will be penalized for permitting too much erosion. The Soil Conservation Service estimated that the program had already reduced the U.S. annual soil loss by almost a half-billion tons by the second year.22

The initiative for the soil-conservation program came from Congress, however, and was not much favored by the agricultural interests that usually determine policies. Rather, it was enacted largely at the behest of environmental organizations such as the Sierra Club.

For the most part, the American agricultural system is flying blind, too much of it controlled by large agribusiness corporations that by their nature cannot be concerned about the long-term viability of the system. Exhaustion of soils in a half century or so simply is not a factor in their financial planning.23 Commodity prices are partly or largely in the hands of giant trading corporations that buy up grain from farmers and handle almost all grain exports. Their operations are so arcane that it seems impossible to determine who is buying the grain.24

In the context of today's changing world food picture, a major problem is that people can recall earlier American policies that seemed to convert surpluses to shortages and vice versa with ease. This created an impression that the productivity of American agriculture is now and forever boundless, and that proper policies will always be able to call forth all the food needed at home and abroad. But this may not always be so -- as the 1988 drought brought home.


In the 1980s, the United States was faced with competition on the world grain market from a new source: the European Common Market. Europe for generations had been a net grain importer; suddenly Western Europe was exporting and, using substantial subsidies for its farm sector, undercutting U.S. sales.

Most of the continent of Europe is blessed with a mild climate and evenly distributed, ample rainfall, all very beneficial for agriculture. Moreover, although the continent has been farmed for millennia, farming practices have mostly been sustainable. A long tradition of preserving soil and caring for the productivity of the land has resulted in little or no deterioration of farmlands and, in some cases, even improvement (proving that it is possible!). In addition, the continent's population is barely growing, on average; some countries have embarked on population shrinkage. So the increases in production achieved through modernization therefore were not consumed in the need to feed millions more people each year. Nevertheless, how carefully the modernization techniques have been applied in Europe is not entirely clear; if the centuries-old traditions of husbandry were abandoned as artificial fertilizers were embraced, the success might prove short-lived.

Of course, Western Europe's achievement has not extended to Eastern Europe, which, although potentially very Productive, has suffered from the same inefficient, overcentralized agricultural bureaucracies, as well as severe environmental problems, as have plagued the Soviet Union.

The result of the European Community's entry into the export market, however, has been a wrangle, with the United States trying to persuade the Europeans to reduce or eliminate their subsidies. The wrangle was silenced by the grain-production shortfall in 1988, but, if a new glut should build up, it may recur. And the even more tightly integrated economic union planned for 1992 may make the Europeans an even more formidable competitor.

If, as seems likely, food production continues to fall behind population growth in developing regions (and possibly for a time in the Soviet Union and its allies), the problems of competition may fade -- and the world may be grateful that another exporting region has turned up.

In an era in which global per-capita food supplies are likely not to rise very much, and may even decline for a substantial period, questions of distribution will become even more acute. Some rationalization and international regulation of the grain trade is clearly needed. When supplies are more than adequate, as they were during most of the 1980s, the unregulated, market-driven, system may function satisfactorily. But when the crunch comes, as it inevitably will (all that's needed is a second major drought before the grain stocks can be fully rebuilt), some better mechanism for allocating the supply (especially enlarged emergency stocks for the poor) than higher prices will be needed -- unless we are prepared to accept a multiplication of deaths from starvation in poor nations.25


Just what is the outlook for feeding the expanding populations of the developing nations? Even though agricultural conditions and prospects (as well as rates of population growth) vary enormously among nations and regions, some conclusions can nevertheless be drawn.

A few years ago, three international organizations collaborated in a systematic study of "population supporting capacities of lands," to determine the prospects for developing nations to increase their food production enough so they could feed their populations in the twenty-first century.26

The study concluded that the developing world (except East Asia, which was excluded from the study) could support twice its 1975 population, or 1.5 times the projected 2000 population, without significant modernization of agriculture. It also found that, with an intermediate level of modernization, four times the 1975 population could be supported. But these highly optimistic findings presumed an enormous unfettered trade in food between nations and regions -- and a carload of other unlikely or unrealistic assumptions.

Among those assumptions were: people would be fed only a subsistence diet with a minimum of animal products; no land would be used for feed crops or nonfood crops (such as cotton, jute, rubber, palm oil, tea, or coffee); all potentially arable land would be planted to food crops (including all that is now in forest or woodland); maximum advantage would be taken of irrigation opportunities; and crops would be ideally matched to soils and climates in order to produce the maximum number of food calories per acre. Under low-input conditions, significant soil loss and land degradation were expected and accounted for. Presumably, no agricultural products were to be exported to or imported from the developed nations.

Some of the assumptions in this study, if followed, would precipitate environmental disaster. First and foremost, consider the assumption that all remaining tropical rain forests should be cleared and that they could be successfully converted to productive agriculture -- an assumption that has been repeatedly proven wrong.27 The removal of seasonal forests and woodlands would be disastrous for rural populations dependent on them for fuelwood -- and would probably accelerate local cropland erosion and cause weather changes as well. The likely desertification that would result from such policies and the temporary nature of most irrigation projects appear to have been ignored. Finally, ruling out nonfood crops and assuming that "ideal" crops would be used everywhere (regardless of nutritional values other than calories, let alone differing traditions and tastes) are completely unrealistic.

Despite these incredibly optimistic assumptions, the study concluded that some developing nations and regions couldn't feed themselves after 2000 without unrestricted access to surplus food from elsewhere, even if their agricultural systems were fully modernized. Nineteen of the 117 nations studied would fall short, with 47 million more people than they could feed in 2000. With agriculture only partially modernized (intermediate levels of inputs -- fertilizers, pesticides, etc.), thirty-six countries would fall short, with an "excess population" of 136 million. With little modernization (low inputs), which, given the progress since 1975, is most likely for the majority of developing countries, sixty-five nations fail the test, being short of food for 441 million people.

If a carefully devised study of the agricultural-resource base of developing countries, using absurdly optimistic assumptions, shows an ominous food crunch facing the developing world as soon as 2000, what would a more realistic assessment reveal? What of the outlook beyond 2000, as populations continue growing and the modernization of agriculture has supposedly been accomplished? And what possible avenues remain for creating a brighter prospect?

Very few; most hungry countries are tropical, and growing more food in the tropics is not easy. The people doing this research appear to have fallen into an old trap -- the assumption that, because tropical rain forests are luxuriant and extremely productive biologically, crops that replaced them would be similarly productive. Except in cases of rich volcanic soil (as in Java) or regularly flooded areas (as in parts of the Amazon Valley), the soils beneath rain forests are generally thin and poor. The forest's nutrients are stored largely in the vegetation, not in the soil; so when a forest is cleared, a substantial portion of the nutrients go with it, and those remaining in the soil are quickly leached away by heavy tropical rains.28 Experience has shown that permanent agriculture in these areas is largely an illusion, but large numbers of people, including policymakers, still pin their hopes on it.

Even outside of tropical rainforest areas, agricultural development in the tropics has long been problematic, despite numerous attempts to transplant the all-too-successsful (in the medium term) technology of temperate regions. There are many reasons for this failure.29

The lack of a strongly defined winter (or dry season) to suppress pest populations is one important reason. Modern high-yield agriculture is based on planting in monocultures -- a single crop, composed of thousands of genetically similar individual plants, covering large areas of land. Such a system is an open invitation to pests. With heavy rainfall typical of the tropics, soil erosion is often high, and fertilizers and pesticides re quickly washed away. Consequently, in order for them to effective, large and frequent applications of both are seded, compounding the off-site pollution problems. Soil ex-osed to direct sunlight is often overheated and damaged, losing productivity. Small wonder attempts to farm this way have so often failed within a few years.

Another important reason for lagging food production in e tropics has been neglect until recently of indigenous crops r Green Revolution geneticists. Crop-improvement efforts have been concentrated on wheat, corn, and rice, which either db not grow well in many tropical areas, particularly in Africa, or are not part of local farming tradition and experience. Efforts are now under way to remedy this oversight by investigating and developing traditional tropical crops. But valuable time has been lost during which countless potential crops and wild relatives of existing crops have been unwittingly pushed to extinction in the rush to "develop."30 Meanwhile, agricultural ecosystems in many poor regions are being overstressed in the desperate attempt to feed people this year, grinding down their capacity to produce more food in the future.

Successful traditional agricultural systems could be models for a new tropical farming approach. Many unfortunately have been all but forgotten or were corrupted beyond recognition under colonial regimes, but a few scientists are trying to recover some of the lore. Some have collapsed as population pressures made them unsustainable or because environmental degradation undermined their productivity. Belatedly, some tropical agricultural-research stations and nongovernmental organizations are now beginning to work toward a more ecological approach to agricultural development.31

Success has been met in some experimental research in tie tropics, in which the structure of the original natural com-n|unity is imitated in agriculture -- for instance, tree crops with shade-loving shrubs or vegetables beneath them (so-called "forest farming").32 Another often successful approach is to plant two, three, or even more crops together in a field. In one project in southern Mexico, for instance, corn, beans, and squash were planted together. Since the crops matured at different rates, the ground was never left bare. The result was a sharply reduced need for pesticides and fertilizers (the beans are nitrogen fixers) and very little soil erosion. Surprisingly, the yields of each of the three were only slightly less than they would have been if planted alone and supported by massive costly inputs.33

These efforts are still too few and scattered. Since they are necessarily small in scale, they must be multiplied thousands of times over if they are to make a real dent in the tropical food situation. Part of the problem is communicating the experiences of different groups to others that might benefit from them. And the preference of international assistance agencies is still for large-scale projects -- despite the repeated failures and untoward environmental consequences -- simply because they are easier to administer and monitor.


Whatever the technical problems of improving agricultural production and getting food to some 80 million more people in developing countries each year, they are not going to be solved without simultaneously dealing with the sociopolitical realities of Third World agriculture. These, of course, vary from region to region, but certain themes are nearly universal. One key difficulty is that national leaders live in cities, and national leaders have an aversion to being killed by mobs. That has generated an all-too-understandable tendency to give higher priority to placating urban masses than to taking care of the needs of rural people.

Nothing makes city folk more likely to get together and go politician-hunting en masse than food that is too scarce or too expensive. This is not just a rule in poor countries; Douglas MacArthur led U.S. troops using tanks and tear gas to drive five or six thousand hungry "bonus marchers" out of Washington in 1932.34 Today, Soviet and Polish leaders are very nervous about the attitudes of their people toward perpetual food shortages and rising prices, food shortages traceable in part to the traditional Marxist disdain for agriculture and country people. Anyway, leaders like to keep food plentiful and cheap and employment high in the cities, and they design their policies accordingly. Needless to say, this doesn't help the farmers, who need a fair return on their efforts if they are to grow food for sale.

After independence, governments in Africa were naturally responsive to the demands of powerful -- and multiplying -- urban groups. They were also committed to a substantial expansion of public services and a drive to develop an industrial sector.35 There was no place to look for the resources to accomplish the latter goals, except tax revenues from the agricultural sector.

The threat of insurrection has played an important role in shaping bad government policies toward agriculture in Africa. As one observer put it, in regard to West Africa:

The short-term preoccupation of West Africa's rulers is with the immediate danger of an unsatisfied urban mob. Long-term planning for the countryside is entirely incompatible with the siege mentality of politicians, soldiers, and bureaucrats who are literally counting the days before they lose their power (and lives) in the face of growing anger. . . . This anger means most in the major cities; it commands constant attention and the award of temporary palliatives, one after the other, all adding up to the relative impoverishment of farmers.36

The deepening problems of hunger in Africa are likely to have dramatic environmental consequences. There are already strong pressures toward population relocation, from the deser-tified lands bordering the Sahara to the "underpopulated" rain forests of the Congo, Zaire, Gabon, and the Ivory Coast.37 Should massive transborder migrations occur, one can expect the same kind of disasters as those now afflicting the rain forests of Brazil (also in no small degree due to ill-advised government agricultural policies).

Establishing effective programs of population control is obviously an essential step in addressing the problem of hunger in poor nations on any long-term basis, simply because of the long lag time before such programs can have a significant effect. But other steps obviously should be under way now as well. The most important is to initiate programs to bolster agricultural economies, especially programs that reach the poorest farmers.

Exactly what those latter programs should be will vary from place to place, and what they should be in detail is beyond the scope of our discussion. But among the priorities should be arrangements for making credit available to poor farmers and giving them access to adequate markets. With credit, the farmers can decide for themselves the best production strategies.


One can't leave a discussion about increasing global food production without considering the potential impact of biotechnology, especially genetic engineering.38 The first thing that must be understood is that biotechnology has already vastly increased the amount of food available to us. The high-yielding strains of wheat, corn, and rice that formed the basis of the Green Revolution are products of it. Those strains were engineered by plant evolutionary geneticists, primarily by artificial selection (directing evolution by choosing parents with desired characteristics generation after generation).

Of course, "genetic engineering" now ordinarily means using recombinant-DNA techniques to manipulate the genetic endowment of organisms, transplanting genes from one strain to another or from one species to another. There is no question that these techniques eventually may speed the directed evolution of strains of crops or domestic animals and produce combinations that would be practically impossible using classic methods. In theory, plants can be created more readily with these techniques to produce higher yields, grow with less water, tolerate saltier water, be more resistant to pests, or more conveniently cultivated, and so on. And speed may be of the essence for changing old crops and developing new ones on a planet facing unprecedentedly rapid environmental changes.

There are no agricultural "free lunches" even with genetic engineering, however. One often-discussed project is to transfer genes that permit nitrogen fixation from legumes (where they occur naturally) to grains (where they don't). The prospect of nitrogen-fixing grains, eliminating much of the need for nitrogen fertilizer, is attractive indeed. But the task appears difficult, and the result, if successful, uncertain.39 Grains are already more productive (in calories produced per acre) than legumes, and nitrogen fixation carries a cost, since energy that could go into edible parts is diverted into nitrogen fixing. Careful evaluation of trade-offs and extensive field testing will be required to determine whether future nitrogen-fixing grains can fulfill the dreams of some biotechnologists.

Overall, the potential of genetic engineering for improving crops is a long way from being realized, and the direction in which much biotechnological development is going does not hold very much promise for the agriculture of poor nations. For instance, much of the research is aimed at improving the interactions between crops and agricultural chemicals. But if strains are produced with seeds resistant to herbicides (one of today's goals, since it would allow chemical weed control in seeded fields), it won't be much help to peasant farmers in poor countries, who have little access to either specially developed seeds or herbicides.

Neither will the development of male sterility in new grains, which would bring the sort of vigor found in hybrid corn to other cereals.40 These innovations are best adapted to large-scale agriculture, where farmers can afford the expensive seed, since they can't produce their own in the field. But large-scale agriculture invites increased pest problems, especially in the tropics, problems that would be exacerbated by the genetic uniformity of hybrid crops.

Poor nations appear likely to face severe difficulties created by the successes of biotechnology. For instance, efforts are now under way to use the new techniques to produce natural vanilla flavor in the laboratory. Success is just around the c°rner; but it threatens the livelihood of some 70,000 farmers in Madagascar, the world's biggest producer of vanilla beans. Laboratory production of cocoa butter and thaumatin protein, a substance several thousand times sweeter than sugar, could put out of business more than 10 million cultivators of cacao and sugarcane in poor countries.41

The complexity of the food problem is highlighted by these difficulties, since one reason there are so many hungry people in developing countries is that governments have concentrated on supporting production of cash crops for export, rather than food for local markets. The cash crops earn foreign exchange, which helps the relatively well-off, especially in the cities, but gives little benefit to subsistence farmers in the countryside or to the urban poor.

Foreign-aid programs for developing countries often follow the same course. In the famine-stricken Sahel, for instance, almost 30 percent of the limited aid for agriculture and forestry went to cash crops, mostly cotton and peanuts. As a result, production of these crops for export often rose as overall food production dropped.42

Unless institutional arrangements are made to prevent it, biotechnology seems likely to bring agriculture in the industrial nations even more under the control of large corporations, with ecological and economic results that are difficult to predict. Unless the rich give high priority to helping the agricultural sectors of the economies of poor nations in ways that provide food for hungry people and direct biotechnology research to that purpose, its achievements won't do much to improve their lot.

And, even with the best of planning, the research, development, and deployment required to establish new crops or crop varieties are time-consuming processes. Just establishing a new variety of a familiar crop can call for overcoming a series of social, political, and economic problems before the new variety is integrated into a nation's food system. That process can take as much as ten years. The development and wide adoption of an entirely new crop, however productive and otherwise useful, may take several decades.

So biotechnology, whatever its long-term promise, is very unlikely to improve agriculture fast enough to help humanity through the next few critical decades. It is no immediate panacea for the food problem, and no justification for complacency about population growth.


As you can see, supplying people with food is a complex process, made all the more difficult by the explosive growth of the human population. As Lester Brown, president of Worldwatch Institute, recently noted, every year farmers have to grow food for 95 million more people, using some 26 billion tons less topsoil -- a loss about equal to the amount of topsoil that covers Australia's wheatlands.43 Furthermore, he has estimated that world grain production will be increased by only 0.9 percent per year in the future -- a horrifying prospect when one considers that the world population seems committed to a growth rate of closer to 2 percent per year for the next few decades.44 While certainly no long-term solution to the problem of hunger is possible without population control, clearly population control is no short-term solution. Barring some catastrophe, the momentum built into world population growth assures that decades will pass before large reductions in population size of rich nations will be seen, and almost a century before populations of today's poor nations can show substantial shrinkage.

While it is essential that population-control programs be rapidly expanded and their goals made much more ambitious, humanity faces a long period of coping with high levels of overpopulation without destroying Earth's life-support systems. The need to bring birthrates well below death rates, increase food production while preserving the environment, and distribute food to all who need it is the greatest challenge our species has ever faced.


1. The sun's energy arrives at an average rate of about 145 watts for each square yard of land surface. Only about half of that energy lies in the part of the solar spectrum that the plants can use, and they actually manage to use only about one percent of that on average. Suppose crops could bind solar energy at a rate of 2 watts per square yard over and above what they need to run their own life processes and that they could do it all year round (an extremely optimistic assumption). By comparison, about 120 watts of energy are needed to run the life processes of an average person. If a person could extract 5 percent of the energy available in the crop plants to support his or her life processes, then each square yard of crop field would yield about 0.1 watts (.05 X 2). One acre of cropland would thereby support 4 people, 2.5 acres would support roughly 10 individuals, and a square mile could feed 2600.

2. By far the best overall treatment of how the climate works and what it means, addressed to a lay audience, is S. H. Schneider and R. Londer, The Coevolution of Climate and Life (Sierra Club Books, San Francisco, 1984).

3. The degree of accuracy to which climate/weather ever will be predictable is still a matter of debate, depending in part on the role chaos may play in the system.

4. See S. Pimm, The Balance of Nature? (Univ. of Chicago Press, Chicago, 1990).

5. L. R. Brown et al., State of the World 1987 (Norton, New York, 1987).

6. L. R. Brown, "Reducing Hunger," in State of the World 1985 (Norton, New York, 1985), p. 32. See also E. C. Wolf, "Raising Agricultural Productivity," in L. R. Brown et al., State of the World 1987.

7. A. H. Ehrlich, "Development and Agriculture," in P. Ehrlich and J. Holdren, eds., The Cassandra Conference: Resources and the Human Environment (Texas A & M Press, College Station, 1988).

8. L. R. Brown et al., State of the World 1986 (Norton, New York, 1986).

9. "Economics and Financial Aspects of the Plan of Action to Combat Desertification," paper presented at UN Conference on Desertification, Nairobi, Kenya, Aug. 29-Sept. 7, 1977.

10. Council of Environmental Quality and Department of State, Global 2000 Report to the President (1980), vol. 2, p. 279.

11. Quoted in "Points of View," Surviving Together, Fall/Winter 1988. See also "Soviet Union Planned Paddy Fields for Aral Sea," New Scientist, May 20, 1989.

12. See P. Ehrlich and A. Ehrlich, Extinction: The Causes and Consequences of the Disappearance of Species (Random House, New York, 1981).

13. Vitousek et al., "Human Appropriation of the Products of Photosynthesis," BioScience, vol. 36, pp. 368-73 (1986).

14. M. S. Swaminathan, "Global Agriculture at the Crossroads," Earth '88: Changing Geographic Perspectives (National Geographic Society, Washington, D.C., 1988), pp. 316-29.

15. L. R. Brown et al., State of the World 1989 (Norton, New York, 1989).

16. Goldsmith and Hildyard, The Earth Report: The Essential Guide to Global Ecological Issues (Price Stern Sloan, New York, 1989), p. 142, based on U.S. Dept. of Agriculture statistics.

17. J. Sokoloff, The Politics of Food (Sierra Club Books, San Francisco, 1988).

18. S. Postel, Worldwatch Institute, personal communication.

19. Sokoloff, The Politics of Food, p. 36.

20. PRE observed the incompetence firsthand when he, along with several colleagues in entomology and biology, was called in to consult on the problem.

21. S. Postel, personal communication.

22. N. A. Berg, "Making the Most of the New Soil Conservation Initiatives," Journal of Soil and Water Conservation, January/February 1987.

23. Technically, the economic system is too much based on a high discount rate to allow such long-range factors to be considered. From the viewpoint of standard economics, the family farmer has "noneconomic" reasons for conserving soil. For example, he may wish to pass on to his children a farm fully as productive as (or more so than) the farm he inherited.

24. Sokoloff, The Politics of Food. See also F. M. Lappe and J. Collins, Food First (Houghton Mifflin, Boston, 1977).

25. International Institute for Applied Systems Analysis (IIASA), "Hunger amid Abundance," Options, no. 1-2 (1987).

26. UN Food and Agriculture Organization (FAO), the UN Fund for Population Activities (UNFPA), and IIASA in Austria, Potential Population Supporting Capacities of Lands in the Developing World, Technical Report of Project on Land Resources for the Future, FPA/INT/513, Rome, Italy, 1982. Using the year 1975 as a baseline, the researchers attempted to integrate detailed information on soils and potential yields of crops with population projections for the developing countries, and determine whether or not they could, at least potentially, be self-sufficient in food after 2000.

27. See, e.g., R. Repetto and M. Gillis, eds., Public Policies and the Misuse of Forest Resources (Cambridge Univ. Press, Cambridge, 1988).

28. See N. Myers, The Primary Source: Tropical Forests and Our Future (Norton, New York, 1984); and C. Caulfield, In the Rainforest (Alfred A. Knopf, New York, 1985).

29. A. H. Ehrlich, "Development and Agriculture," and references therein.

30. Ehrlich and Ehrlich, Extinction; and N. Myers, A Wealth of Wild Species: Storehouse for Human Welfare (Westview, Boulder, Colo., 1983).

31. Some successful efforts to establish sustainable agricultural-assistance programs are described in W. V. C. Reid, J. N. Barnes, and B. Black-welder, Bankrolling Successes: A Portfolio of Sustainable Development Projects (Environmental Policy Institute and National Wildlife Federation, Washington, D.C., 1988).

32. J. S. Douglas and R. A. de J. Hart, Forest Farming (Intermediate Technology Publications, London, 1984).

33. S. R. Gleissman, E. Garcia, and A. M. Amador, "The Ecological Basis for the Application of Traditional Agricultural Technology in the Management of Tropical Agro-ecosystems," Agro-ecosystems, vol. 7, pp. 173-85 (1980).

34. They were veterans demanding that Congress help them in their time of need by accelerating payment of a bonus due in 1945.

35. M. Lofchie, "The Decline of African Agriculture," in M. Glantz, Drought and Hunger in Africa: Denying Famine a Future (Cambridge Univ. Press, Cambridge, 1987), pp. 85-109. Here again the Marxist focus on factory workers rather than peasants often has played a role.

36. K. Hart, "The State of Agricultural Development," in The Political Economy of West African Agriculture (Cambridge Univ. Press, Cambridge, 1982), p. 10.

37. Independent Commission on International Humanitarian Issues, Famine: A Man-Made Disaster? (Vintage Books, New York, 1985).

38. Techniques of biotechnology are very diverse and include such things as cell culture (especially with cloning, which makes the culture genetically uniform), tissue culture, cell fusion, fermentation, artificial insemination, embryo transfer, artificial selection, genetic engineering, and so on.

39. For an excellent brief discussion of this issue and of genetic engineering of crops, see P. H. Raven, R. F. Evert, and S. E. Eichorn, Biology of Plants, 4th ed. (Worth, New York, 1986). This book is a gold mine of information on plants in general.

40. The ability to produce uniformly high-quality corn plants depends on making each generation in the field the product of crosses between two different inbred strains. In order for this to be done, seed must be produced without self-pollination of the corn plants. Originally, this was done by hand removal of the tassels (pollen-producing structures); now it is accomplished by using genetically determined male sterility. Self-pollination is eliminated, but the genetic composition of the strains is manipulated so that the sperm produced by the pollen of one can fertilize the ovules of the other, producing viable hybrid seed. Unfortunately, one side effect of this process is that the crops are genetically uniform and therefore may be very susceptible to pathogens and pests.

41. A. H. Jamal, "The Socioeconomic Impact of New Biotechnologies in the Third World," Development Dialogue, 1988, no. 1-2, pp. 5-8.

42. Independent Commission, Famine: A Man-Made Disaster?, p. 87.

43. Address to the Forum on Global Change of the National Academy of Sciences/Smithsonian Institution in Washington, D.C., May 3, 1989. See also "Reexamining the World Food Prospect," in State of the World 1989, p. 49.

44. Personal communication. The basis of the estimate will be published in the forthcoming State of the World, 1990 (Norton, New York, 1990).