Alternative Agriculture: Sorting Out Its Environmental Benefits

Unlike conventional agriculture, alternative agriculture controls weeds and insects by cultivation and crop rotations and provides crop nutrients with animal manure, other organic matter, and legumes. It largely excludes the use of pesticides and inorganic fertilizer. Alternative agriculture thus encompasses the range of practices indicated by terms such as "low-input," "organic," and regenerative" agriculture.

Proponents of alternative agriculture contend that it has significant environmental advantages over the conventional system, particularly with respect to reduced sediment and pesticide damages to water quality, and improved wildlife habitat. However, these advantages mean little to farmers. Like the rest of us, farmers make business decisions on the basis of the costs they bear and the benefits they receive. They receive few of the environmental benefits of alternative agriculture because many of these, such as improved water quality, occur off the farm, or like improved wildlife habitat, cannot be captured in economic terms. Consequently, farmers decide to adopt alternative agriculture or to stay with the conventional system by comparing the economics of the two. Alternative agriculture is at a disadvantage in this comparison because as currently practiced it generally is less profitable to farmers than the conventional system.

This economic disadvantage is not surprising, given that agricultural research and policy over the last forty years have been designed to promote conventional agriculture. Farming systems that offered gains in environmental benefits only at some sacrifice of economic productivity were relatively neglected. As a result, farmers have not adopted alternative agriculture on the scale that would be in the public interest if, in fact, the environmental advantages of alternative agriculture are as great as its proponents contend. Yet continuing uncertainty about the facts indicates that a wholesale shift to alternative agriculture over the next decade or so would not be justified. The economic disadvantages appear to be too great under such circumstances.

A policy to direct more resources into research designed to increase the profitability of alternative agriculture deserves serious consideration, however. Successful research of this kind would provide farmers with an economic incentive to adopt more environmentally favorable agricultural practices, and society as a whole would benefit. The grounds for this assertion need closer scrutiny.

Pesticides and water quality

Chemical pesticides are a key component of conventional agriculture. To the extent that pesticides pose environmental problems, conventional agriculture is the culprit, and alternative agriculture offers potential for eliminating the problems.

Studies of the presence of pesticides in groundwater are relatively few. How-ever, research published by the American Chemical Society in 1986 showed that at least 17 pesticides had been found in groundwater in 23 states—a result of routine agricultural use. The largest number of pesticides was detected in California, New York, and Iowa, but this probably was because these states monitor more closely than others. As other states intensify their monitoring, the number of pesticides found in those states is expected to increase. Monitoring data from Iowa indicate pesticides in the drinking water of more than 25 percent of Iowans.

Concentrations of pesticides in groundwater resulting from agricultural use are usually low, ranging in most cases from 0.1 to 1.0 milligrams per liter. However, in some places where suppliers of pesticides—both insecticides and herbicides—mix or dump them, ground-water concentrations are much higher. In several states the concentrations have been high enough to cause the closing of both public and private wells.

While insecticide use (on a weight basis) is declining, herbicide use is increasing. And given the growing use of more water-soluble herbicides, some increase in pesticide concentrations in groundwater seems likely.

In a 1987 U.S. Department of Agriculture report on groundwater contamination from agricultural chemicals, Elizabeth Nielsen and Linda Lee analyzed the potential of 38 pesticides to pollute groundwater. Combining information about county-level rates of use of these pesticides with other information about their tendency to leach to groundwater and the "leachability" of soils in areas where they are used, Nielsen and Lee ranked counties by their potential for groundwater contamination by these pesticides. They judged 361 counties, approximately 12 percent of the national total, to have high contamination potential because of high rates of pesticide use and soil conditions favorable for leaching. Another 757 counties were judged to have moderate potential. An estimated 12.6 million people live in the counties with high or medium potential for pesticide contamination of groundwater. Another 5.1 million people live in countries where pesticides and nitrates together create high or medium contamination potential.

It should be emphasized that Nielsen and Lee identify counties with potential for pesticide contamination of ground-water. They explicitly do not say that groundwater in these counties in fact contains pesticides. While actual groundwater monitoring data are still quite limited, a study by the U.S. Environmental Protection Agency (EPA), scheduled for completion in 1990, should provide much-needed information about the pervasiveness of pesticides in groundwater.

Data on pesticide concentrations in surface water evidently are even more scarce than data on groundwater concentrations. It is known, however, that surface water concentrations tend to be higher than those in groundwater. This is because only highly soluble pesticides leach to groundwater, while less soluble species can be carried to surface water by runoff and, in some cases, by sediment. In addition, subsurface flow can carry pesticides from groundwater to surface water.

There is considerable uncertainty about how pesticide concentrations in ground and surface waters affect animal, plant, and human health. Pesticide concentrations in fish have declined significantly since the more persistent pesticides such as DDT and dieldrin were banned by the EPA in 1971. In most fish, the concentrations now are within limits the EPA considers safe for human consumption. Cancer and birth defects in humans, caused by pesticides, have been clearly demonstrated only in cases of relatively high exposure, such as may occur in occupational situations. High pesticide concentrations in water supplies appear to be fairly infrequent and localized, and by the time water reaches a user's tap, pesticide concentrations are seldom, if ever, at levels thought to produce health effects.

Caution is needed in interpreting these findings because much remains unknown about the long-term health effects of even very small concentrations of pesticides. Nor is much known about synergistic effects among various pesticides and between pesticides and other substances.

The issue of just how much pesticide in water is too much is highly controversial. For some people, the presence of any amount of pesticide in ground or surface water is sufficient evidence to justify public action to remove the offending material and to prevent its further use. Agencies concerned with the use of pesticides, however, should not—and in fact do not—take this extreme position. As Alice Ottoboni suggests in The Dose Makes the Poison, not all concentrations of pesticides are equally threatening, and some may not be threatening at all.

All of this suggests that if one word can be used to describe the current situation about pesticides and water quality, it is "uncertainty." It is therefore impossible to judge whether the reduced use of pesticides with alternative agriculture would generate enough water quality benefits to offset the higher economic costs of the system relative to conventional agriculture. However, some offset seems likely.

Nutrients and water quality

Some of the nitrogen and phosphorus applied to the soil in fertilizer and manure is carried through runoff and sediment to surface waters, where it promotes algae growth. Decay of the algae reduces the water's oxygen supply and thus impairs the quality of the water for recreational and other uses. In addition, nitrogen in the nitrate form is leached into groundwater, where it may pose a threat to human and animal health.

It is not clear that alternative agriculture has an advantage relative to conventional agriculture in reducing nitrate damages to water quality. Heavy manuring, a characteristic of alternative agriculture, has been shown to cause the same nitrate problems as heavy chemical applications. The Council for Agricultural Science and Technology (CAST) asserted in 1980 that the nitrate in fertilizer is more readily available to the crop than that in manure or leguminous crops. This suggests that these sources may contribute more to nitrate pollution than inorganic nitrogen fertilizer, since the amount of the nutrient remaining in the soil after harvest might be greater. Other analysts also point out that mismanagement of manure and other organic wastes can result in the same problems of nitrate pollution as with inorganic fertilizers. Proponents of alternative agriculture counter by arguing that organic farmers use various soil management techniques that give them better control over the availability and release of nitrogen.

Although the issue is unsettled, present evidence does not indicate that the environmental benefits of alternative agriculture in reducing nitrate pollution of ground and surface water contribute much toward offsetting the economic disadvantages of the system.

Alternative agriculture, however, does appear to have a potential advantage relative to conventional agriculture in reducing eutrophication of lakes and reservoirs where phosphorus is the limiting nutrient. This is because much of the phosphorus delivered to surface water is carried by sediment, and the use of crop rotations in alternative agriculture on sloping, erosive soils generally produces much less erosion than conventional agriculture. How significant this advantage may be is uncertain, however, because information about the amount of eutrophication damage, its link to agricultural sources of phosphorus, and the effect of alternative agriculture in reducing the damage is limited.

Sediment and water quality

Sediment in surface water costs the nation $4 billion to $16 billion annually (in 1985 prices), according to estimates by Edwin Clark II and his colleagues at the Conservation Foundation. They have estimated that cropland erosion is responsible for about one-third of this damage. The erosion-reducing characteristics of alternative agriculture on sloping, erosive land would appear to give it a clear advantage over conventional agriculture in reducing these sediment damages. Still, alternative agriculture is not the only system that enhances water quality through reduced sediment damage. Conservation tillage—defined as any tillage system that leaves at least 30 percent of the previous crop residue on the soil surface after spring planting—reduces erosion on sloping, erosive land by 50 to 90 percent relative to conventional tillage. It is more economically competitive with conventional agriculture than alternative agriculture, and is practiced on roughly one-third of the nation's cropland—far more acreage than is farmed by alternative systems.

Yet conservation tillage has its own drawbacks. As typically practiced, it relies on herbicides at least as much as, and often more than, conventional tillage. Thus, while conservation tillage may economically reduce sediment damage, its benefits might be bought at a higher environmental price with respect to herbicide pollution. Alternative agriculture would reap erosion reduction benefits without paying this price.

There is little documented evidence that pesticide residues in food are a serious threat to human health. A 1987 report by the National Research Council (NRC) estimated that pesticide residues in food consumed by Americans would increase the probability of contracting cancer over a 70-year lifetime from 25 percent to 25.1 percent, an increase of .4 percent. The estimate is low by comparison with other health risks in American society. It should be noted, however, that the council's estimate refers only to cancer risks from pesticide residues in food. Other risks, such as birth defects, were outside the purview of the study.

A 1980 CAST report noted an earlier National Research Council study of the acute toxicity of pesticide residues in food. That study found that U.S. per-capita consumption of these residues was about 40 milligrams, over half of which was from pesticides no longer in use. CAST concluded that pesticide residues in food did not present a threat of acute toxicity.

Adoption of alternative agriculture would appear to do little to reduce threats of acute toxicity or of cancer from pesticide residues in or on food because these threats already are small.

Knowledge of the effects of handling pesticides is more definitive. Deaths from pesticides by accident, homicide, and suicide are estimated to have been several hundred per year in the 1970s. Estimated illnesses from pesticide poisoning at that time were in the tens of thousands. These numbers are subject to considerable error because state reporting of the data is sometimes spotty. Nonetheless, there seems little doubt that the cost of pesticide poisoning of farmers, their families, and their hired workers is significant. Indeed, the fact that alternative agriculture would drastically reduce if not eliminate these human costs of handling pesticides probably is its most important environmental advantage relative to conventional agriculture.

Wildlife habitat

The evidence about the effects of conventional and alternative agriculture on wildlife habitat is contradictory. In Competition for land in the American South (1987), Robert Healy says that on balance, the land-use changes that have taken place in the South since about 1935 have probably improved carrying capacity for many game species by creating a more diverse local habitat. He says field abandonment, more frequent timber harvest, and the change from cotton to soybeans, for example, have helped more than harmed. Even activities such as establishment of pine plantations and clearing of hardwood forests did not have much long-term impact on game.

Healy clearly is writing about more than crop production. However, the period of which he writes encompasses that in which crop production in the South shifted to the high-energy and chemical-based system we now call conventional agriculture. Healy's conclusion is that this shift was accompanied by favorable changes in habitat of game animals.

Terry Cacek arrived at a much less favorable conclusion about the Midwest. Writing on the "Impacts of Organic Farming and Reduced Tillage on Fish and Wildlife" in Sustainable Agriculture and Integrated Farming Systems, Cacek considered the effects of conventional agriculture from the mid-1950s to the mid-1970s on wildlife habitat in 12 mid-western states. He cited a study indicating that during this period wildlife populations in these states declined 40 to 80 percent, pheasant in Ohio being particularly hard hit. Cacek attributed these declines to the transformation of crop production in this period, particularly the dramatic increase in the use of agricultural chemicals, a decrease in crop diversity, reductions in fencerows as the size of fields was increased, and reduced acreage in cropland set-aside programs. Cacek went on to recount major advantages of alternative agriculture in improving wildlife habitat, such as providing nesting places for birds and reducing the possibility of pesticide poisoning.

Urbanization will continue to take land from agriculture and other rural land uses as it has throughout most of the nation's history. This will gradually diminish the supply of wildlife habitat, since many plant and animal species cannot survive in an urban environment. If Cacek is right about the benefits of alternative agriculture for wildlife habitat, a large-scale shift to these methods would tend to offset some of the prospective loss of habitat resulting from urbanization.

Healy's work and that of others indicates that many people in the United States place a high value on wildlife, both as hunters and as non consumptive users such as bird watchers. With continued growth in population, income, and leisure over the next fifty years, demand for these various uses of wildlife is sure to grow, probably quite substantially. The benefits of alternative agriculture relative to those of conventional agriculture in providing wildlife habitat could be expected to grow correspondingly.

What to do

Although some of the environmental advantages of alternative agriculture probably are not as great as its proponents contend, the human health and habitat benefits appear real and significant. To assure that society captures these benefits, policymakers should support increased research to overcome the economic disadvantages of the system. A main source of the disadvantages is the difficulty of controlling weeds without herbicides. Consequently, a key objective of the research should be development of techniques that adequately control weeds without sacrifice of the environmental benefits of alternative agriculture. Policymakers should also support collection and analysis of data on pesticide use and consequences for environmental quality to reduce the present high uncertainty in this area.

The animal habitat benefits of alternative agriculture relative to conventional agriculture deserve additional research attention, as well. Analytical techniques have been developed to estimate unpriced benefits of this general sort, but the techniques have not been systematically brought to bear on study of the relative habitat benefits of the two contending agricultural systems. Alternative agriculture appears to be particularly favored in this respect, and growing future demand for wildlife services is likely to strengthen that advantage even more. Hence, the payoff to research along this line could be high.

If these several lines of research succeed, farmers will have increasing economic incentive to adopt alternative agriculture and the system will spread. Farmers will gain economically, and society in general will reap rewards in environmental improvement.