AGRICULTURAL PRODUCTION CAPACITY OF NORTH AMERICA'S SOIL RESOURCES Fred P. Miller School of Natural Resources, The Ohio State University, Columbus, Ohio, USA Keywords: Agriculture production, Global Food demands, Biotechnology, Genetics Contents 1. Retrospective – The Perils of Projecting into Unknown Futures 2. A World View – Ratcheting Up Demands on the Land 3. Can Global Cropland Yield More Food Sustainably? 4. North America’s Agricultural Production: Character and Nemesis 5. Capacity of North America’s Agricultural Productivity 6. What Production and Demand Scenarios Would Test the Limits of North America’s Agricultural Production Capacity? 7. Concluding Thoughts and Summary Related Chapters Bibliography 1. Retrospective – The Perils of Projecting into Unknown Futures To assess the capacity of agricultural productivity begs the foretelling of the future. As Arrow et al. (1995) noted, carrying capacities in nature are not fixed, static, or simple relations, but are contingent on technology, preferences, and the structure of production and consumption. Cohen (1997), too, cautions about predicting the future carrying capacity of the global biosphere since the ‘answer’ to this question must be probabilistic, conditional, and dynamic: probabilistic, because humans cannot perfectly predict the future; conditional, because the answer depends on choices yet to be made; and dynamic, because predictions and choices are susceptible to change. Agricultural production is driven and modified by a variety of forces and factors, including the character, capability, and care or stewardship of the natural resource base undergirding all agricultural production systems; climate and weather; product demand (economic); technology; political events and policies; demographics; and cultural customs (e.g., dietary preferences). Therefore, to speak of the capacity of manipulated ecosystems, one must be mindful of the potential impact of unforeseen technologies, events, and demand scenarios that will certainly alter projections of agricultural capacity based on the datum of the present. History is replete with bold prognostications of future outcomes that were well off the mark when such prophesies were later assessed against the reality of their targeted times. Cohen (1995a; 1995b; 1997) has done a comprehensive review of the literature on the many divergent projections of the earth’s capacity to support and sustain various population numbers. Projecting the capacity of agricultural production has seen its share of errant forecasts. The heralding of cataclysmic food and natural resources shortfalls has been sounded for centuries, from the Reverend Thomas Malthus (1798) to the more recent projections of Paul Ehrlich (1968; 1969) and Lester Brown (1995). Yet, despite the fact that about 15% of our global population is malnourished, global food production has more than kept pace with population growth. Between 1950 and 1997, the area planted to grain in the world expanded by 17% while total grain production rose by 190%, resulting in a 2.5 fold increase in grain productivity over this period. This rate of increased food production has more than kept pace with the global population growth rate. For the more than 800 million people suffering hunger and malnutrition, the problem is mostly one of deprived food access and poverty-induced inability to pay for available food exacerbated by political conflict, regional climatic aberrations, inadequate food distribution and storage capabilities, and mismanagement. Malthus made his projection in 1798 that humanity’s penchant for procreation would eventually outstrip his capability and capacity to feed himself. His forecast was made from a datum of a global population less than one-sixth the population in 2000. But just five years later in the second (and rarely read) edition of his famous 1798 essay on the principle of population, Malthus was more sanguine about humanity’s prospects for the future, stating that "we may confidently indulge the hope" for a better future. Malthus’ hope in the progress of humanity was mostly faith-based since he did not and could not foresee the globalization of markets and technological advances that allowed agricultural production to more than keep pace with population in most areas of the world (exceptions include parts of Africa, especially sub-Saharan Africa). Even Ehrlich’s previously pessimistic views of humanity’s future have mellowed, giving way to more hopeful scenarios (Ehrlich, 2000). This brief reflection on past attempts to predict the future carrying capacity of the earth should caution anyone attempting such an undertaking about the pitfalls of forecasting unforeseeable futures. It is against this backdrop that the capacity of North America’s agricultural production capacity will be discussed. 2. A World View: Ratcheting Up Demands on the Land To suggest that feeding a UN FAO-projected 1.2 billion additional mouths in 2030 (Mann, 1997) will be without considerable effort is to miss the point. Not only will this expansion of humanity need to be fed, but increasing global affluence means many more people will be eating higher on the food chain. By 2020, one projection of global demand for rice, wheat, and maize sees an increase of 40%, or 1.3% per year (Mann, 1999). This double-barrel circumstance of more mouths compounded by increased affluence will require proportionately more grain production to feed both humans and the animals whose products they’ll demand. Furthermore, this demand scenario is occurring simultaneously with the slowing down of the Green Revolution as most grain and other crop yield increases have decelerated over the last three decades of the twentieth century. Global cereal grain yields have slipped from annual yield increases of 2.2% in 19671982 to 1.5-1.3% during the 1982-1994 period. If the Green Revolution is to be revived or a second Green Revolution is to occur again, squeezing out additional yield from crops and the land will be proportionately more difficult than the first Green Revolution. The low hanging "research fruit" has already been harvested. Exacerbating this situation is the fact that supplies of fresh water are becoming scarcer, soil quality is deteriorating across much cultivated land, and there is limited, problem-free uncultivated land left to exploit. Will humankind be able to feed itself adequately? The agricultural science consensus is that it can, but only if there is a global priority to fund the necessary research, see it applied, and distribute the produce equitably. Since food scarcity manifests itself locally, global food adequacy is meaningless without tailoring food access to local circumstances. 3. Can Global Cropland Yield More Food Sustainably? Daily et al. (1998) posit that there are two broad criteria by which one can judge humanity’s success in feeding itself: 1) the proportion of people whose access to basic nutritional requirements is secure, and 2) the extent to which global food production is sustainable. The land-soil resource base now committed to producing humanity’s food will bear the brunt of yielding even greater productivity in the future. It is not clear, according to Tilman (1998), which are greater—the successes of modern highintensity agriculture, which have been immense, or its short-comings. Laszlo (1994) argues that the wave of optimism engendered by recent gains in food production does not account for the fact that much of this gain is unsustainable. These unsustainable short-comings of high tech agriculture manifest themselves through such impacts as degraded and eroded land, release of greenhouse gases and loss of soil organic matter or carbon (SOC), soil salinization, contaminated groundwater, eutrophication of freshwater bodies and coastal waters, high energy and synthetic chemical inputs, heavy demands on scarce water resources, increased incidence of crop and livestock diseases, and loss of biodiversity. While many of these agricultural impacts are not clearly understood and are vigorously debated (e.g.: Pimentel et al., 1995; Crossen, 1995; Avery, 1997; Daily et al., 1998; Pimentel and Skidmore, 1999; Trimble, 1999; Trimble and Crosson, 2000a; Trimble and Crosson, 2000b; Nearing et al., 2000), the fact remains that if humanity is to manipulate nearly 1.5 billion hectares of global cropland to feed itself, it must strive to do so in a sustainable manner. About 38% of this global cropland base has been degraded to some extent by poor agricultural practices, thereby reducing to some degree the yield gains provided by technology. It is the consensus of most agronomists and allied agricultural scientists that global agriculture must accommodate high yielding production systems, albeit with more sustainable systems. Otherwise, continued agricultural expansion will consume lands and ecosystems now devoted to wildlife and a host of other land uses and ecosystem functions that would be forfeited. High technology agriculture, despite its exhaustion of resources and environmental impacts, has resulted in saving much land, habitats, and fragile ecosystems that would otherwise have been converted to cropland and pasture—a benefit that must be factored into any accounting of technology-based global food production. Ausubel (1996) points out that, despite societies’ chronic fears about the exhaustion of their potential to increase food supply, the reality is that the agricultural production frontier is still spacious, even without invoking the engineering of plants with molecular genetic techniques. There is still much agricultural production technology on the shelf that is yet to be implemented. In Iowa, the average corn-soybean grower has managed only half the yield of the Iowa master grower. Furthermore, the global situation is that the world grows only about 20%, per unit of land, of that grown by the top Iowa farmer (given Iowa’s ideal agricultural natural resource base). This production ratio of producers has not changed much since 1960 (Ausubel, 1996). Economists and non-agriculturalists tend to be much more optimistic about future trends and the earth’s capacity to feed humanity sustainably. That’s because agronomists, plant breeders- geneticists, soil scientists and other agricultural scientists know the challenges involved in coaxing out a second Green Revolution over the next 20 to 30 years. Economists can project trends, but agronomists and plant breeders-geneticists must deliver the future food. Yes, global cropland can yield more food. And this food increase can be accomplished more sustainably, but not without providing the necessary incentives and policies for farmers to accomplish such an immense undertaking. Smil (2000) has provided a thorough review and assessment of our global food carrying capacity and how to sustain a global food future that eases the burden that modern agriculture puts on the biosphere. Also, Lackey (1998) has provided a blueprint on how global ecosystem management can be accomplished and made more sustainable. Technology without social science input will not get us there. 4. North America’s Agricultural Production: Character and Nemesis Table 1 provides a snapshot of North America’s agricultural enterprise and land resources in relation to its global counterpart. Clearly, North America’s endowment of natural resources coupled to state-of-the-art science and technology and an efficient food production-processingtransportation infrastructure sets it apart as a continental cornucopia. With Canada and the U.S. having relatively stable or slow-growing populations and Mexico rapidly ascending the ladder of developed nationhood, the agricultural land resource base of North America is more than adequate to meet any foreseeable food production needs of its projected populations. Table 1. Economic, population, and agricultural production parameters for North America and the World; 1995-1998. (Data from WRI, 2000 unless noted otherwise) Compared to the foraging and pastoral cultures that occupied North America centuries ago, that supported less than one person per square kilometer, modern agriculture now supports well over 1000 people per square kilometer of arable land. Thus, humans have been able to achieve a thousand-fold expansion of the land’s carrying capacity through applications of science and technology. However, as noted previously, the trade-offs for this achievement include massive transformations of natural ecosystems, increasing reliance on fossil fuels, alteration of mineral and biological cycles, and significant environmental impacts. The Achilles heal of North American agriculture has been soil erosion (both water and wind) and the attendant loss of soil organic carbon through tillage. While these soil-land resource impacts have been significant in the sense of soil loss and soil quality impairment, the overall reduction of North America’s food production capacity has been relatively minor. Despite the fact that soil erosion has declined in USA over the last half century, soil scientists fret that production technology has become the talisman of growers since the impact of the insidious eating away of soil quality by soil erosion/soil carbon loss is masked by continually increasing crop yields. While North America’s agricultural productivity has primarily served the needs of its continental population and economy, global trade and demands have increasingly played a role in shaping its productivity profile. Increasing demands from both North America and the world’s nations seem to be a foretelling of the future, thus begging the question, just what is the potential and capacity of this continent’s agricultural productivity? 5. Capacity of North America’s Agricultural Productivity 5.1. How Much Can Be Gained from Expanding the Agricultural Base? Estimates of potentially arable land for the world are in the neighborhood of 22 to 24% of the earth’s terrestrial ecosystems. Yet only about half of this 3+ billion hectares is currently used for cropland. While expanding the earth’s croplands is feasible, there are profound consequences. First, most of the better land and soils already have been committed to cropland. Expanding cropland will encounter less productive lands and soils with constraints such as slopes that are vulnerable to erosion; lands requiring drainage or irrigation; soils that are highly acid, alkaline, or nutrient deficient; and soils with shallow root zones. Second, expansion of cropland will require conversion of existing land uses and ecosystems (e.g., pasture, forest lands) with significant repercussions on the environment and wildlife habitat. And third, there will be social disruptions to such major conversions of land. Humans have already appropriated approximately 40% of the earth’s biological capacity to satisfy its needs and wants—an amount that suggests caution in further constraining the planets’ ecosystems capacity to sustain the earth’s life support system. Similar impacts of cropland expansion exist for North America. Nearly 22% of US land in its 48 contiguous states was used for cropland in 1997, amounting to 166 million ha (USDA, 2000b). A 1975 study of potential cropland for the US (Dideriksen et al., 1977) showed that an additional 45 million hectares of Capability classes I-III land had high to medium potential to be added to the 162 million hectares of cropland used in 1975. This potential cropland accounted for 42% of the total land in Capability Classes I-III that was not used for cropland in 1975. Using a similar guideline for the 1997 US National Resources Inventory (NRI) database, 40% of the noncropped Capability classes I-III land amounts to nearly 40 million hectares of potential US cropland that could be added to the nation’s 166 million hectares of cropland (13.2 million ha of which were set aside in the Conservation Reserve Program) in 1997 under a high demand scenario. This estimated potential cropland in the US was used for pasture (28.1 million ha), rangeland (25.5 million ha), and forestland (45.7 million ha) in 1997. Whatever demand scenario would drive such land conversions would have to be intense enough to overcome the opportunity costs of such conversion. Nevertheless, the point is that the US has much flexibility in bringing additional cropland into production if necessary. Canada has some, although limited, potential to add to its cropland base. Only about 5% of Canada’s vast terrain is suited for crop production (ca. 46 million ha). In 1991, Canada’s cropland totaled 33.5 million ha with another 7.9 million ha in summer fallow. An assessment of potential cropland using 1991 data for Canada’s Prairie Provinces (Manitoba, Saskatchewan, Alberta) indicated that 53 million ha or 28% of the land in these provinces could be used for producing annual crops compared to 35 million ha of land actually used for crops and summer fallow (MacDonald et al., 1995). Again, future demand scenarios would have to be strong enough to convert Canadian lands now devoted to other uses into cropland. In Canada, such conversions also would be pressing against the limitations of growing season adequacy for most crops. This brief assessment of North America’s potential to expand its cropland base shows that while such potential exists, most agricultural production increases driven by future demand scenarios will most likely be satisfied by production-yield increases on existing cropland, pastureland, and rangeland. 5.2. How Much More Production Can Be Coaxed from Existing Cropland? Despite the declining rates of crop yield increases over the last 30 years, the absolute production increases for most crops have approximated a straight line increase (Tweeten, 1998). Since increasing, although decelerating, rates are calculated from an ever-expanding denominator, one must not lose sight of the fact that since WWII, plant and animal breeders along with other production specialists have been able to continually coax ever more yield and production out of the genetic potential of most food-derived species. These food production increases have more than kept pace with global population growth. On average, food supplies were 24% higher per person in 1997 than in 1961, and real prices were 40% lower. Global population doubled from 3 to 6 billion people during this period. But because of poverty and food access-deprived people, approximately 790 million people in the developing world are still chronically undernourished, almost two-thirds of whom reside in Asia and the Pacific. Although various regions of the world have chronic food deficits and must rely on imports and food assistance, the global food capacity has never been tested in the sense of unleashing the full production capacity of those areas endowed with such capacity. This spare agricultural capacity lies chiefly in the developed world, especially North America and Europe. 6. What Production and Demand Scenarios Would Test the Limits of North America’s Agricultural Production Capacity? Since WWII, American farmers have been teased and admonished to produce at full throttle in response to forecasts of global needs and calls for feeding the world, only to see commodity prices plummet at the first sign of increased production. American farm policies, as well as its European counterparts, have been oriented to constraining production and subsidizing agricultural commodity prices for most of the latter half of the twentieth century. Even with these production constraints and low commodity prices, North American farmers in 1998 produced nearly half (48.1%) the world’s soybeans, over 40% of the world’s corn and 12% of the world’s wheat, and accounted for 57, 70, and 30% of the world’s exports of these three commodities, respectively. Indeed, North America’s agricultural production capacity is immense. But what future production factors might limit this capacity and what demand scenarios could test North America’s agricultural production capacity? 6.1. Divining Future Global Food Demands Future global food increases will be driven primarily by population growth in developing countries. Between 1995 and 2020, the world’s annual population increase will average about 73 million. Simultaneous with this population increase, per capita incomes are expected to increase in all developing regions. Developing countries will account for about 85% of the increase in global demand for cereals and meat when projected to 2020 with demand for meat expected to double between 1995 and 2020. To meet this demand, the world’s farmers will have to increase cereal production 40%. This global food demand scenario has potentially profound implications for North American agricultural productivity. While the developing world’s agricultural productivity is projected to produce about 60% of the world’s cereals and meat by 2020, there remains a food shortfall that will have to be accommodated by cereal imports by developing countries. In response to the strong demand for meat, demand for animal feed grains will double in developing regions. Maize will increase more than for other cereals and is projected to overtake demand for rice and wheat by 2020. Expansion of cultivated area is expected to contribute only about 20% of the global cereal production during this 1995-2020 period, thus, productivity increases from existing cropland will have to be relied upon to meet this projected food demand. North American agricultural productivity will be a major supplier of the projected cereal import demands of the developing world with USA expected to meet 60% of this cereal demand (Pinstrup-Andersen, et al., 1999). 6.2. Soil Quality, Can It Be Sustained? Soil with its diversity of microorganisms and their myriad biochemical functions acts as a major ecological engine that powers a variety of ecological processes, including the nitrogen cycle, carbon cycle, and other biogeochemical cycles and functions. These soil micro- and macroorganisms provide a dynamic soil biology that contributes to and sustains the soil’s organic matter matrix, which is critical to providing a good plant root growth medium and reservoir for nutrients, water, and O2-CO2 exchange, and water. Soil biology functions also sustain the soil’s structure or tilth, contributing to the soil’s infiltration and water-holding capacities which act to ameliorate the terrestrial components (e.g. infiltration, soil-water storage) of the hydrologic cycle. A half-century after Selman Wakesman received the Nobel Prize for his discovery and isolation of the soil microbe Streptomycin, and after much research by soil microbiologists-ecologists on the biodiversity and functioning of soil organism communities, many ecologists still are unaware that most of the biodiversity in terrestrial ecosystems occurs in the soil (Andre et al., 2001). Soil organic carbon and the diversity of soil biology are keystone parameters for monitoring soil quality and sustainability. The sustainable agricultural production capacity of North America’s (and the world’s) soils will be very much tied to how well the soil’s biological diversity and functions can be sustained under future soil management and soil ecosystem manipulation systems. Thus, it is imperative that soil erosion, tillage-induced soil carbon losses, soil compaction/hardening, and other types of soil degradation be curtailed through proper soil management. This is a tall order, given that much of today’s agricultural soil management is unsustainable (IFPPRI, 2000) and that future agricultural production systems will be extracting even greater yields and demands from soil resources. 6.3. The Impact of Genetics and Biotechnology on Carrying Capacity Can future food and plant material adequacy be delivered by biotechnology? Between 1950 and 1990, farmers around the world raised grain yields by an annual average of 2.1%, nearly tripling grain harvests during this 40-year period (Mann, 1997). It must be pointed out, however, that this 40 year, 2.1% annual yield increase is a decelerating average, i.e., the percentage yield increases in the latter portion of the period are half or less than the percentage increases in the early part of the period. These yield increases were driven primarily by three factors: 1) crop breeding, 2) chemical fertilizers, particularly nitrogen, and 3) irrigation. The cultural aspects of crop production (e.g., plant density-spacing, nutrient management, water management, tillage, pest suppressing control, etc.) have largely been played out for intensively managed agriculture in developed countries, although better efficiencies can and will be attained, thereby squeezing out some additional yield. For less intensively managed agriculture in developing countries, there is much potential for greater yields through adoption of existing technology that is as yet unavailable or unaffordable. It appears that future increases in agricultural capacity will have to come primarily from genetic improvements of crops and animals, assuming significant expansion of cropland and irrigation are not feasible without major economic, environmental, and social costs and repercussions. The specter of increased world population (UN projections of 7+ billion by 2030, 9+ billion by 2050?), greater affluence resulting in demands to eat higher on the food chain, greater competition for arable land, and potentially greater demand for agricultural products as nonfood chemical feed-stocks suggest that plant breeders and agriculturalists will have to generate yet another Green Revolution. This demand surge will occur just as the first Green Revolution is petering out, as global grain yield increases have been decelerating (Mann, 1997). Can biotechnology birth another green revolution through such efforts as increasing the efficiency of plant photosynthesis or bioengineering leaf stomata to better adapt plants (and yield) to water-rich and water-deficit environments? While economists and futurists are confident these and other biotechnology initiatives will pay off and drive up crop yields again, agronomists are more pessimistic, viewing biotech as a long shot (Mann, 1999). Photosynthetic efficiency rarely approaches or exceeds 1%, i.e. converting incident solar energy to stored chemical energy (yield) in the plant. Tinkering with the photosynthetic process is a formidable task, given that this process has evolved over millions of years and is controlled by multigene mechanisms. Some plant scientists believe plant breeders already have pushed plants’ ability to capture solar energy and convert it to desired forms (e.g. more seed-fruit, less vegetative matter) about as high as it can go. And will biotechnology encourage the evasion of fundamental ecological reforms? As Paul Kennedy (1993) put it, "If crop species can be developed that thrive in salty soil or in hot, dry climates, will farmers ignore the sources of environmental damage and simply wait for scientists to engineer new seeds for new conditions?" Certainly, molecular genetics and plant and animal breeding will continue to ratchet up crop yields and animal production efficiencies. Clearly, the carrying capacity of the land will be increased. As to how much, only the future will reveal the outcome. 6.4. Water Availability - Scarcity Irrigated agriculture accounts for 17% (ca. 256 million hectares) of the world’s cropland but produces 35 to 40% of the world’s food (FAO, UN, 1999). In the US, only 11% of the nation’s cropland is irrigated but this land is disproportionately valuable, yielding 38% of the US total crop value. The irrigated Central Valley of California supplies about half the nation’s fruits and vegetables. Clearly, irrigated agriculture has been and is a major contributor to generating annual food stocks. Irrigation dramatically increases the land’s productivity and carrying capacity. Without irrigation, untold areas and ecosystems, from forests and wildlife habitats to wetlands and other fragile ecosystems would have been converted to cropland. Both land area/quality and water availability limit the expansion and potential of irrigated agriculture. Between 1970 and 1982, the global irrigated area grew at an annual average rate of 2%, but between 1982 and 1994, the annual expansion rate decreased to 1.3%. In USA, irrigated land doubled from 10 million hectares in 1950 to 21 million hectares in 1995. The Ogallala aquifer spanning eight states straddling the 100th meridian supplies water for one-fifth of the nation’s irrigated land. Mexico’s irrigated land in 1997 totaled 6.5 million hectares, accounting for about one quarter of its cropland. While irrigated agriculture produces much of the world’s and North America’s food bounty, it is not without problems, not the least of which is water depletion and scarcity. The irrigated area undergirded by the Ogallala aquifer fell nearly 20% from its 1978 peak of 5.2 million hectares to 4.2 million hectares in less than a decade with projections suggesting another 20% decrease by 2020 (Postel, 1999). California is over-abstracting groundwater at an annual rate of 1.6 billion cubic meters, equal to 15% of the state’s annual net groundwater use. On a global scale, more than one billion people live in severely water-stressed areas and the world’s farmers are collectively racking up an annual water deficit of at least 160 billion cubic meters—enough to produce half the US grain harvest. Such a deficit suggests that a tenth of the world’s current grain supply is underwritten by unsustainable water use (Postel, 1999). While it is beyond the scope of this chapter to comprehensively review the problems associated with irrigated agriculture, suffice it to say that about one in five hectares (ca. 48 million hectares) of the world’s irrigated land is damaged by salt. Because irrigated agriculture is practiced predominantly in arid and semi-arid regions, salt remains one of the gravest threats to irrigated agriculture and food security. Continued water depletion driven by growing urban and industrial needs, coupled with irrigated agriculture’s demands, has led to research on gaining irrigation efficiencies through such technologies as low pressure targeted applications, drip systems, and utilization of urban wastewaters. Other competing interests for water include restoration of fish populations, protecting endangered species, and protecting ecological functions of rivers and wetlands. Certainly, water scarcity and the need to use it efficiently loom large as potential future modifiers of agricultural productivity and the carrying capacity of land. 6.5. Global Change: Impacts on North America’s Agricultural Capacity While human-induced global changes are not a welcome experiment, its repercussions will influence the North American continent’s agricultural productivity. There are both potential benefits and negative consequences to agriculture of a warming earth. The potential impacts of global change on agriculture and its soil resource base are numerous. And they are uncertain. These impacts include shifting crop ecosystems, the "fertilizing effect" of higher CO2 levels on plants, expanded growing season, increased variability in weather patterns, more or less precipitation over various regions, coastal (agricultural land) flooding due to higher sea level and vulnerability to storm surges, and increased pest pressure and invasive species, to name just a few. The huge pool of sequestered carbon in the permafrost and cold regions of North America present a formidable potential to accelerate global warming as these areas release portions of their carbon under warming conditions. Frozen Arctic soils store a seventh of the earth’s carbon pool (Schiermeier, 2001). While the global change models are far from being certified ‘accurate,’ the future agricultural capacity of North America and the world will be affected by this phenomenon. Scientists envision the negative impacts of global warming will fall disproportionately on the poor. 6.6. Resource Competition for Non-Food Plant-Animal Products How much land and agricultural production resources will be diverted from food production to producing plant- and animal-derived chemical feed-stocks for non-food demands and industries? While such demands are relatively small at this time, the exploration of biodiversity for pharmaceuticals and precursors (e.g., enzymes) for various biochemical processes coupled with the potential for bioengineered plants and animals to generate specific compounds will certainly increase. Materials science has made great strides in developing composite materials that substitute for heavier metals. How much of our future autos, airplanes, and other durable goods will be fabricated from agriculturally derived biomass? And will the efficiencies of converting biomass to fuels reach the point of unsubsidized competition with fossil fuels? While the answers to these questions are unknown at this time, the potential impact on agriculture’s production capacity could loom large in the future. 6.7. The Impact of Urbanization-Development on Agricultural Productivity Globally, more than 471 million hectares are urbanized and built up, equaling about 4% of land area. In USA, developed land (i.e., land permanently removed from the rural land base such as urban land and committed to transportation systems), in 1997, totaled just under 40 million hectares or about 4% of the nation’s total land area—an addition of more than 10 million hectares since 1982. Over this 15-year period, the average annual rate of land development in USA amounted to 667 000 hectares. Of the 10 million hectares of land developed between 1982 and 1997, 2.88 million hectares (28%) were taken from cropland, based on the 1997 cropland total. The other 72% of developed land was taken mostly from pasture (1.7 million hectares), rangeland (1.3 million hectares), and forest (4.2 million hectares). The conversion of US cropland to developed land during the 1982-1997 period represents an average conversion rate of 191 700 hectares per year or 0.126% per year for a total of 1.8% of the nation’s cropland (using the 1997 cropland total) over this 15-year period. Is this rate of cropland conversion to developed land a threat to the nation’s agricultural capacity? Hardly, since annual crop yields more than make up for this small annual cropland withdrawal. Nevertheless, such conversions do have an impact, however small, on the nation’s agricultural capacity. Such impacts are felt more strongly at the local and regional levels. Compounding the development phenomenon is the fact that the rate at which land is converted far exceeds population growth—a reflection of larger amounts of land converted to urbandeveloped uses on a per capita basis. During the period 1945 to 1992, the population of the US nearly doubled. However, the amount of land urbanized nearly quadrupled. In cities such as Chicago, Los Angeles, and Seattle, population growth during the 1970 to 1990 period grew 4, 45, and 38%, while the urban land areas grew 46, 300, and 87%, respectively. A more sinister developmental impact to agriculture, and one that is difficult to quantify, is the fragmentation of the rural landscape by small developments, businesses, and individual homes. This rural fragmentation conflicts with the coming trends in modern agriculture, namely, the consolidation and industrialization of agriculture. As Meyer (1993) noted, the central theme in the history of American agriculture has been the interplay between agrarian traditions and the inexorable drive toward modernization and industrialization of agriculture. To obtain the scales necessary to gain maximum efficiencies, agriculture requires large, contiguous land tracts. In the more densely populated agricultural regions of the US, this conflict between local non-farm and small farm residents vs. expanding farms has resulted in an anti-big agriculture movement. This conflict pits those who value a rural lifestyle and see farming as a near-birthright against those who view agriculture as a business enterprise. For most of America’s political jurisdictions, the unwillingness to control and plan rural land use will most likely have telling impacts on the efficiency and productivity of the nation’s agriculture, probably more so than the actual withdrawal of cropland and agricultural land for development. 7. Concluding Thoughts and Summary North America’s agricultural capacity is large, well beyond the foreseeable needs of its current and projected population. The physical and natural capacity of North America’s original endowment of arable and agricultural land (e.g. pasture and rangeland in addition to cropland) has been compromised to some extent by soil-land degradation, excessive water withdrawals and water scarcity-competition, and conversion of agricultural lands to development, reservoir sites, and other uses. Future demands on North America’s agricultural productivity will come primarily from export demand and heretofore unforeseen new uses/demands for non-food products. The greatest challenge facing agriculture in the twenty-first century is the double-barrel necessity to increase productivity per unit of land and to simultaneously attain ecological and environmental sustainability as the earth’s ecosystems are manipulated to obtain this productivity. Much, if not most, of the world’s current agricultural production, including North America’s agricultural production systems, is not ecologically or environmentally sustainable. The planet’s increasing human population coupled with its appetite and enhanced capability (affluence) for eating higher on the food chain will push the limits of many of the world’s agricultural ecosystems, perhaps even North America’s agricultural capacity. Humankind simply cannot continue to expand its agricultural land at the rate of 12.6 million hectares per year, the average rate between 1966 and 1996 (IPRI, 2000), infringing on ever-more fragile ecosystems. Therefore, future food production will have to rely predominately on existing cropland. Despite the potential for environmental leakages and impacts, yield-enhancing agricultural technologies are the most promising avenue to sustainable agricultural production, reducing the pressure on these fragile ecosystems. As Pinstrup-Andersen (1994) noted, poverty is a major driver of environmental degradation, thus, poverty eradication can be justified, besides its humanitarian argument, also on environmental grounds. Can the world adequately feed its growing population over the next half century? With an optimistic outlook, yes, it can. But such optimism must be couched in the reservation that only if the global community gives this challenge priority and the necessary means (e.g. research investment, infrastructure investment, open trade policies, etc.) can it be achieved. Evans (1998) reminded us that, although the limits to world food production set by the more pessimistic early estimators have been overtaken by innovations, we should not lose sight of the fact that the surge in cereal yields over the last third of the twentieth century, which still has some room to continue, has come from what may prove to have been a unique conjunction of agronomic and plant breeding advances which may not be repeated. Agriculture can easily get lost in the heady world of global and national GDP numbers and number of farmers because agriculture represents such a small fraction of the developed world’s GDP and farmers account for only a few percent of many nations’ population. But the vast majority of the world’s human-impacted terrestrial ecosystems are managed (for better or for worse) and manipulated by this small fraction of humanity. 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