Sustainable agriculture could be defined in many ways, including the ability to meet indefinitely the demand for agricultural output at socially acceptable economic and environmental costs. By this definition, the U.S. agricultural sector appears to have performed well in the past with respect to economic cost criteria. But quantitative measures of environmental costs needed to complete this assessment are lacking. By examining past performance, we can imagine plausible scenarios for future performance and make tentative judgments about the continued acceptability of the economic and environmental costs of U.S. agricultural production. Of course, this acceptability may reflect, as it does today, the public's incomplete awareness of the relative size of different environmental costs.
Is U.S. agriculture sustainable? This question is generating increasing interest, as well as confusion. The confusion arises from the lack of a generally accepted definition of sustainable agriculture. Arguments about definitions are mostly a waste of time, because definitions are never right or wrong, only more or less useful. As a useful definition of sustainable agriculture, I propose the following: a sustainable agricultural system is one that indefinitely meets demands for agricultural output at socially acceptable economic and environmental costs.
Indefinitely is a necessary part of the definition because concern about sustainability reflects a sense that we have a moral obligation to manage our resources so as not to impair the welfare of future generations. Costs are part of the definition because they provide a measure of whether each generation meets its obligation to subsequent generations. If costs rise beyond socially acceptable limits, whatever those limits may be, the obligation is not met.
Two principal questions arise in making this definition of sustainable agriculture operational: What is the maximum acceptable level of economic and environmental costs of agriculture? Who are the judges of acceptability? These questions have no clear answers. Reaching a social consensus about whether the environmental costs of agriculture are consistent with sustainability is difficult. Environmental costs, unlike economic costs, are not registered in markets. Hence they are not priced, and we lack quantitative measures of them. An additional difficulty is that many people do not agree on the criteria for judging whether environmental and economic costs are, or are likely to be, acceptable into the indefinite future. The criteria might differ with respect to the acceptable level of costs, the relative importance of various costs, and the distribution of the costs within and across generations.
How are these disagreements about the significance of economic and environmental costs to be reconciled? Who decides what level of costs is consistent with a sustainable agricultural system? In the United States, the decision ultimately is made by the social, political, and economic institutions through which those with a stake in agricultural performance—which is practically everyone—negotiate their differences to form a consensus sufficient for decisions to be made. The outcomes often are ambiguous, in some ways even contradictory, and are always subject to review and change over time as information accumulates and values change. The lack of reliable information about environmental costs is a major contributor to the messiness of the decision-making process. Nevertheless, some tentative judgments about the sustainability of U.S. agriculture—as I have defined sustainability—can be made.
Below I make some judgments about the past economic and environmental costs of U.S. agriculture. I also summarize some findings from a 1992 RFF study for the U.S. Environmental Protection Agency (EPA), in which I explored three scenarios as a basis for making judgments about potential changes in the economic and environmental costs of U.S. agriculture between 1990 and 2010.
Economic costs—past performance
Between 1950 and the early 1990s, U.S. agriculture had impressive success in reducing the economic costs of production—as measured by declining real (inflation-adjusted) prices of farm commodities—despite an almost doubling in crop and animal production. The combination of lower prices and expanded output conveyed substantial economic benefits to consumers of U.S. farm output, both at home and abroad. The high natural fertility of much of the nation's agricultural land, greatly increased use of water for irrigation, and major advances in agricultural science and technology and in the managerial skills of farm people were the key elements in U.S. agriculture's strong economic performance.
It has been argued that the performance of U.S. agriculture since 1950 is not as good as it appears because the economic costs of erosion-induced losses of soil productivity are not reflected in prices of farm commodities. Concern about the effects of erosion on soil productivity goes back at least sixty years in the United States. Despite that concern and the billions of dollars spent since the 1930s to control erosion, it was not until 1977 that data collected by the Soil Conservation Service, an agency of the U.S. Department of Agriculture (USDA) permitted actual measurement of the effects.
A study that a colleague and I did at RFF used these and other data to examine the effects of soil erosion on the trends of yields (output per acre) of corn, soybeans, and wheat in some 600 counties in Illinois, Iowa, Kansas, and Nebraska between the early 1950s and the early 1980s. The study showed that erosion had no significant effect on the trend of wheat yields. The effect on yield trends for corn and soybeans was significant, but small: over the thirty-year period the average annual increase in corn yields—1.98 bushels—was 4 percent less than it would have been absent erosion. The average increase in soybean yields—0.44 bushels—was 1.5 percent less.
If farmers have not undertaken additional erosion control measures, it must be because the cost of doing so would exceed the returns from eliminating erosion-induced soil productivity losses.
These erosion effects must have tended to increase the economic costs of corn and soybean production in the region studied. It does not follow, however, that the costs of these crops would have been lower, and farm and national income higher, if farmers had taken additional measures to control erosion. Such measures would increase farm costs, and farmers are highly cost-conscious in managing their operations. If farmers did not undertake additional erosion control measures, it suggests that the cost of doing so would have exceeded the returns received from eliminating erosion-induced productivity losses.
This assertion assumes that farmers were aware of both the cost of erosion-induced productivity losses and the cost of erosion control measures. The assumption may be wrong, but I do not think so. Farmers have a strong incentive to protect the long-term value of land because land is their most important single asset. If erosion were a significant threat to the land's value, farmers would know it. Moreover, soil conservation districts, which provide advice and (through the USDA) financial support to farmers for the control of erosion, would have alerted farmers to the threat of soil erosion. Thus, farmers have had the tools they needed to control erosion in those circumstances where control would serve their economic interest. It follows that had farmers sought to eliminate all the effects of erosion on corn and soybean yields, their production costs would have been higher than they were. Accordingly, judgments about the performance of agriculture in meeting the economic cost criterion of sustainability would be less favorable than they are.
Economic costs—future performance
Whether U.S. agriculture will continue to have success in meeting the criterion of economic sustainability into the indefinite future is problematic, since future events are inherently uncertain. Despite this uncertainty, recent experience suggests plausible scenarios for changes in the economic costs of U.S. agriculture. In a 1992 study for EPA, I explored three such scenarios, which I called business as usual, competitive edge, and environmentally friendly. Under each scenario, I investigated the economic costs (as well as the environmental costs) in the period 1990–2010 of producing grains and soybeans, the crops that are the main users of land and other resources. Below I outline these scenarios and their implications for future cropland erosion and for the future adequacy of supplies of land and water for grain and soybean production
The business-as-usual scenario is based on continuation of 1980s trends in domestic and foreign demands for U.S. production of grains and soybeans. in prices of production inputs, and in technical and managerial improvements in grain and soybean production. The competitive edge scenario assumes that improvements in technology and management would proceed at a more rapid pace than under the business-as-usual scenario. These rapid advances would permit U.S. farmers to increase their penetration into foreign markets, resulting in more production than under the business-as-usual scenario. The environmentally friendly scenario assumes that dietary changes in the United States would result in less growth in domestic demand for grain and soybeans for animal feed and that foreign demand would slacken because of developing countries' continued success in producing these crops. As a result, grain and soybean production in 2010 would be only slightly greater than that in 1990.
None of the three scenarios would be likely to put enough pressure on U.S. agricultural capacity to increase the economic costs of grain and soybean production, unless the nation's agricultural research capabilities were greatly diminished. Although real public spending on agricultural research has increased little if at all over the last decade, private research outlays have continued to rise. Moreover, the increases in technological and managerial advances underlying the three scenarios are comparable to the relatively modest increases experienced over the last decade or so.
Supplies of land appear to be quite adequate to accommodate the production levels stipulated in the three scenarios, given the modest increases in crop yields expected from future technological and managerial advances. The United States now has over fifty million acres of cropland in reserve programs. The economic costs of returning this land to crop production would be low.
Sediment carried in runoff from farmer's fields can damage the quality of surface water. Farmers have little incentive to control sediment damage costs because these costs are borne mostly by nonfarmers
When returned to crop production, much of the land now in reserve would be subject to higher erosion than land presently in production. However, studies done in the early 1980s by me at RFF, by soil scientists at the University of Minnesota, and by soil scientists and economists at the USDA show that if cropland erosion were to continue at early 1980s rates for 100 years, crop yields at the end of the period would be only 3–10 percent less than they would be in the absence of erosion. Such small productivity losses could not significantly affect the future economic costs of production.
Future supplies of water for irrigation are likely to be more constraining than supplies of land. Studies done at RFF and elsewhere indicate that present rates of groundwater use in the High Plains of Texas, Oklahoma, Kansas, and parts of Nebraska will exhaust the economic life of that resource within a few decades. Indeed, that outcome is already evident in the Texas Panhandle and other parts of the southern High Plains.
Rising urban demands for water and for maintenance of instream flows to protect aquatic habitats are also likely to constrain future supplies of irrigation water (see "Environmental Values and Water Use" on p. 19). The result would be an increase in the economic costs of irrigation in the arid and semiarid west, where most irrigated crop production now occurs. Studies show, however, that significant opportunities for expanded irrigation exist east of the Great Plains. These opportunities, plus the availability of land in that region for additional rainfed production, suggest that the increasing scarcity of water for irrigation in the west will not significantly affect the future economic costs of production in the nation as a whole.
Environmental costs—past performance
In discussions of the sustainability of U.S. agriculture, environmental costs (or the damage done to the environment) excite more concern than economic costs. I deal with three of these costs: losses of plant and animal habitat, damage to groundwater quality from the use of pesticides and nitrogen fertilizer, and damage to surface water quality from sediment carried in runoff from farmers' fields.
Losses of habitat
Wildlife habitat (quite) probably suffered from the decline over the past fifty years in the amount of U.S. land in grassland pasture and range and the conversion of much of this land to cropland. The quality of habitat is positively related to vegetative diversity, and grassland pasture and range generally are vegetatively more diverse than cropland.
Wildlife habitat probably also suffered from changes in cropping practices and farm size. Until the 1950s, the typical U.S. crop farm raised animals. It also rotated a cash crop, such as corn or soybeans, with a soil-nutrient-restoring leguminous crop, such as alfalfa. But in the 1950s, crop farms began to shift away from this system toward one featuring only a single cash crop, such as corn, or a rotation of two cash crops, such as corn and soybeans. This shift in farming systems reduced the vegetative diversity on the land, with adverse effects on wildlife habitat. The shift in farming systems was accompanied by increasing farm size and the removal of fences and hedgerows. The removal of hedgerows and the vegetation around fences eliminated excellent wildlife habitat.
The drainage of wetlands to plant crops also has had unfavorable effects on wildlife habitat, especially for migratory waterfowl. At present, the nation has 90–100 million acres of wetlands, roughly 15 million acres less than in the mid-1950s. More than 85 percent of the wetland losses since the 1950s have resulted from the conversion of wetlands to agricultural uses, mostly crop production.
It would seem clear that increases in agricultural production and changes in agricultural technology have degraded wildlife habitat in the United States over the last fifty years. Yet studies done at RFF and elsewhere show that, with the important exception of waterfowl, populations of most species of wild animals in the country increased, or at least did not decrease, in number during this period. Populations of waterfowl seem to have stabilized since the late 1960s. The apparent anomaly of degrading farmland habitat and of generally increasing or stable numbers of wildlife may be explained in two ways. One is that the productivity of the remaining wildlife habitat on farms may have been increased by federal and state government programs designed for that purpose. The other is that wildlife habitat on nonfarm rural land probably has improved over the last forty or fifty years. For example, land in wildlife refuges under the jurisdiction of the U.S. Fish and Wildlife Service increased from a little more than nine million acres in 1950 to forty-three million acres in 1975. Moreover, since the 1940s, land in forests in the country has increased slowly but steadily, especially in the northeast. Among the various kinds of land cover, forests provide the best wildlife habitat.
Pesticides and nitrogen in groundwater
Over the last forty or fifty years the quantities of pesticides and fertilizers that American farmers apply to their fields have increased manyfold. Many people have been concerned about the environmental consequences of these materials, particularly for human health and wildlife. The human health concerns have focused largely on pesticide and nitrate contamination of groundwater used for human consumption. A survey of such contamination undertaken by EPA and published in 1992 suggests that these concerns are less well-founded than is commonly believed. The survey found that about 1 percent of the nation's wells had pesticide concentrations high enough to pose a threat to human health. It also showed that some 4.5 million people (2 percent of the U.S. population) drink wellwater in which nitrate concentrations exceed the U.S. Public Health Service's standard of 10 parts per million. About 67,000 of this 4.5 million are babies under one year old—the population most threatened by methemoglobinemia ("blue baby syndrome"), which is caused by high nitrate concentrations in drinking water. Before 1960, infant deaths from methemoglobinemia attributable to nitrates in farm wells were occasionally recorded. Today, occurrences of blue baby syndrome are so rare that major health organizations no longer keep statistics on it.
If sediment damage to water quality were charged against the farm income account, the performance of the agricultural sector would appear less favorable than it now does.
Sediment damage to water quality
This damage includes the loss of water's value for recreation, the loss of fish spawning sites as a result of sediment deposition, the cost of dredging ports and navigable rivers, and the cost of cleaning water for industrial and household users. According to a 1989 USDA study, the annual costs of damage to water quality from sediment originating on farmers' fields was $4–5 billion in the mid-1980s. This amount was 20–25 percent of net farm income exclusive of direct government subsidies paid to farmers. These percentages suggest that, if the sediment damage to water quality were charged against the farm income account, the performance of the agricultural sector would appear much less favorable than it now does.
Moreover, the costs of sediment damage likely rose over the last forty or fifty years. The quantity of sediment delivered to waterways probably did not increase and may have decreased. However, the real (inflation-adjusted) value of surface waters was much greater in the 1980s than in the earlier years because the growth of the population and the economy greatly stimulated the demand for the various services of the water, the supplies of which were little changed. Consequently, the environmental cost of sediment damage per unit of sediment delivered probably rose over the last several decades. My guess is that the rise in unit costs of damage probably was greater than the possible decline in quantity of sediment delivered, so that the total cost of the damage rose.
It is worth pointing out that if I am right about the two kinds of erosion costs—losses of soil productivity and off-farm damage from sediment—then the costs of sediment damage are a substantially greater threat to the sustainability of American agriculture than the costs of productivity loss. The balance of the evidence, as I read it, indicates that the costs of productivity loss are both trivial and under socially acceptable control by farmers. In contrast, the costs of sediment damage are much higher, and farmers have little incentive to control them because they are borne mostly by nonfarmers. The policy implications seem clear: leave farmers to deal with the soil productivity problem and focus publicly funded efforts on dealing with the sediment damage problem.
Environmental costs—future performance
Charting the future of the three kinds of environmental costs discussed here—losses of wildlife habitat, pesticide and nitrogen contamination of groundwater, and sediment damage to water quality—must be highly speculative. But, again, the three scenarios of future agricultural performance I have explored make some tentative judgments possible.
In the environmentally friendly scenario, all three environmental costs decline over the period 1990–2010 because of small increases in production and the increasing adoption of environmentally friendly technologies, such as integrated pest management. But this environmentally benign future is built into the scenario. Of greater present interest are the business-as-usual and competitive edge scenarios. Both scenarios hold the potential for increased environmental costs. But present trends in policy, and in the environmental thinking reflected in policy, suggest that, even in the competitive edge scenario (under which agricultural production is relatively high), the environmental costs of habitat loss and of pesticide and fertilizer damage to groundwater will be held within socially acceptable limits. The Endangered Species Act and strong policies to control drainage of wetlands already are in place. These policies reflect the nation's awareness of the importance of protecting wildlife and the habitat on which it depends. To be sure, these policies are not always enforced to everyone's satisfaction, but they are evidence of the country's commitment to protecting wildlife values.
The country has expressed high and sustained concern about the potential environmental costs of pesticides. Present trends toward reduced use of these substances and adoption of integrated pest management reflect this concern. I expect these trends to continue.
In contrast, the environmental community is not much exercised by present and potential threats of sediment damage to surface water quality. Muddy water does not arouse moral indignation, even though its damage to the social welfare may be considerably greater than some other environmental threats. I do not expect amounts of sediment delivered to surface water to increase much, if any, under either the business-as-usual or competitive edge scenarios. I do expect the cost of sediment damage to increase, however, because of continuing increases in the economic and environmental value of water and because of the absence of effective policies to deal with the damage.
Is U.S. agriculture sustainable?
As I indicated at the outset, the question of whether the U.S. agricultural system is sustainable has no clear answer. In my judgment, however, U.S. agriculture has met and will continue to meet the economic criteria of sustainability. The much harder part of the question concerns the environmental part of the equation.
Environmental costs almost surely rose over the last forty or fifty years, thus becoming a greater proportion of total costs (since economic costs declined). The American people decided at least a couple of decades ago that, in the absence of controls, the agriculturally imposed environmental costs of habitat loss and pesticide damage would be socially unacceptable, and control policies were adopted. I believe the policies will continue to do the job over the next several decades. No comparable policies have been adopted to control sediment damages. The public evidently is prepared to accept this damage even though its costs, present and prospective, arguably are substantially higher than the costs of habitat loss and pesticide damage. If so, then, by the definition of sustainability adopted here, the costs of the damage are consistent with the sustainability of the country's agricultural system. Whether acceptance reflects full public awareness of the relative size of the sediment costs remains, for me, an open question.
Pierre R. Crosson is a senior fellow in the Energy and Natural Resources Division at Resources for the Future.
A version of this article appeared in print in the October 1994 issue of Resources magazine.
A version of this article appeared in print in the October 1994 issue of Resources magazine.
