As problems with industrial agriculture become more apparent, alternatives are gaining more attention. Some of the newer techniques have actually been used in the developing world for thousands of years. In this module, we will examine some of these alternative farming practices. We will also look at the large-scale farming of meat and fish.

Learning Objectives

After reading this module, you should be able to

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Industrial agriculture has been so successful and widespread that it has come to be known as conventional agriculture. However, in situations in which the cost of labor is not the most important consideration, traditional farming techniques may also be economically successful. Small-scale farming is common in the developing world where labor is less expensive than are machinery and fossil fuels. In these countries, there are still many farmers who grow crops on small plots of land. Traditional farming methods that differ from those of industrial agriculture include shifting agriculture and nomadic grazing, which are not always sustainable, and more sustainable methods such as intercropping and agricultural forestry.

Shifting Agriculture and Nomadic Grazing

In locations with a moderately warm climate and relatively nutrient-poor soils, such as the rainforests of Central and South America, a large percentage of the nutrients is contained within the vegetation. In these places, farmers sometimes use shifting agriculture, in which the land is cleared and used for only a few years until the soil is depleted of nutrients. This traditional method of agriculture uses a technique sometimes called “slash-and-burn,” in which existing trees and vegetation are cut down, placed in piles, and burned (FIGURE 33.1).The resulting ash is rich in potassium, calcium, and magnesium, which makes the soil more fertile, although these nutrients are usually depleted quickly. If the deforestation occurs in an area of heavy rainfall, nutrients may be washed away, along with some of the soil, which further reduces the availability of nutrients. After a few years, the farmer usually moves on to another plot and repeats the process.

If a plot is used for a few years and then abandoned for a number of decades, over time the soil may recover its organic content and nutrient supplies and the vegetation may have a chance to regrow. However, population pressures may cause the land to be used too frequently to allow for its full recovery. In that case, soil productivity can decrease rapidly, leaving the land suitable only for animal grazing. In addition, the burning process oxidizes carbon, meaning that it converts it into the oxide compounds carbon monoxide (CO) and carbon dioxide (CO₂). In this way, carbon from the vegetation and the soil is released into the atmosphere and ultimately contributes to higher atmospheric CO₂ concentrations.

In semiarid environments, dry, nutrient-poor soils can be easily degraded by agriculture to the point at which they are no longer viable for any production at all. Irrigation can cause salinization, and topsoil is eroded away because the shallow roots of annual crops fail to hold the soil in place. The transformation of arable, productive land to desert or unproductive land due to climate change or destructive land use is known as desertification. The world map in FIGURE 33.2 shows the parts of the world that are most vulnerable to desertification. Today, desertification is occurring most rapidly in Africa, where the Sahara is expanding at a rate of up to 50 km (31 miles) per year. Unsustainable farming practices in northern China are also leading to rapid desertification.

The only sustainable way for people to use soil types with very low productivity is nomadic grazing, in which they move herds of animals, often over long distances, to seasonally productive feeding grounds. If grazing animals move from region to region without lingering in any one place for too long, the vegetation can usually regenerate.

Shifting agriculture and nomadic grazing worked well under the conditions in which they were first developed—namely, low human population densities and subsistence farming—but as populations increase, both these forms of traditional agriculture become less sustainable. Sometimes the relocation of people for political or other reasons can cause traditionally sustainable agricultural techniques to become unsustainable. For example, in the early part of the twentieth century, many subsistence farmers in Central America were relocated away from rich floodplains to mountainous areas where the plowing methods that had worked in the flat areas caused severe erosion in the mountains and could not be sustained.

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Sustainable Agriculture

Is it possible to produce enough food to feed the world’s population without destroying the land, polluting the environment, or reducing biodiversity? Sustainable agriculture fulfills the need for food and fiber while enhancing the quality of the soil, minimizing the use of nonrenewable resources, and allowing economic viability for the farmer. It emphasizes the ability to continue agriculture on a given piece of land indefinitely through conservation and soil improvement. Sustainable agriculture often requires more labor than industrial agriculture, which makes it more expensive in places where labor costs are high. But practitioners of sustainable agriculture consider the improved long-term productivity of the land to be worth this extra cost.

Many of the practices used in sustainable agriculture are traditional farming methods (FIGURE 33.3). Subsistence farmers in India, Kenya, and Thailand typically use animal and plant wastes as fertilizer because they cannot obtain or afford synthetic fertilizers. Such traditional farmers may also practice intercropping (FIGURE 33.3a), in which two or more crop species are planted in the same field at the same time to promote a synergistic interaction between them. For example, corn, which requires a great deal of nitrogen, can be planted along with peas, a nitrogen-fixing crop. Crop rotation achieves the same effect by rotating the crop species in a field from season to season. For example, peas can be planted in a field for one year, leaving excess nitrogen in the soil to nourish the corn crop that is planted there in the following year.

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Intercropping trees with vegetables—a practice that is sometimes called agroforestry—allows vegetation of different heights, including trees, to act as windbreaks and to catch soil that might otherwise be blown away, greatly reducing erosion (FIGURE 33.3b).The trees not only protect the vegetable crops and the soil, but also provide fruit and firewood.

Alternative methods of land preparation and use can also help to conserve soil and prevent erosion. For instance, contour plowing—plowing and harvesting parallel to the topographic contours of the land—helps prevent erosion by water while still allowing for the practical advantages of plowing (FIGURE 33.3c). Some farmers plant an autumn crop, such as winter wheat, that will sprout before frost sets in, so that the land does not remain bare between regular plantings.

No-Till Agriculture

Perennial plants live for multiple years, and there is usually no need to disturb the soil. In contrast, annual plants, such as wheat and corn, live only one season and must be replanted each year. Conventional agriculture of annual plants therefore relies on plowing and tilling, processes that physically turn the soil upside down and push crop residues under the topsoil, thereby killing weeds and insect pupae. Critics argue that plowing and tilling have negative effects on soils. As we learned in Chapter 8, soils may take hundreds or even thousands of years to develop as organic matter accumulates and soil horizons form. Every time soil is plowed or tilled, soil particles that were attached to other soil particles or to plant roots are disturbed and broken apart and become more susceptible to erosion. In addition, repeated plowing increases the exposure of organic matter deep in the soil to oxygen. This exposure leads to oxidation of organic matter, a reduction in the organic matter content of the soil, and an increase in atmospheric CO₂ concentrations. Tilling, in addition to irrigation and overproduction, has led to severe soil degradation in many parts of the world. The world map in FIGURE 33.4 indicates areas of severe soil degradation.

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No-till agriculture is an agricultural method in which farmers do not turn the soil between seasons and is used as a means of reducing topsoil erosion. No-till agriculture is designed to avoid the soil degradation that comes with conventional agricultural techniques. Farmers using this method leave crop residues in the field between seasons (FIGURE 33.5).The intact roots hold the soil in place, reducing both wind and water erosion, and the undisturbed soil is able to regenerate natural soil horizons. No-till agriculture also reduces emissions of CO₂ because the intact soil undergoes less oxidation. In many cases, however, in order for no-till agriculture to be successful, farmers must apply herbicides to the fields before, and sometimes after, planting so that weeds do not compete with the crops. Therefore, the downside of no-till methods is an increase in the use of herbicides.

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Integrated Pest Management

Another alternative agricultural practice, integrated pest management (IPM), uses a variety of techniques designed to minimize pesticide inputs. These techniques include crop rotation and intercropping, the use of pest-resistant crop varieties, the creation of habitats for predators of pests, and limited use of pesticides.

Crop rotation and the use of pest-resistant crop varieties prevent pest infestations. Crop rotation can foil insect pests that are specific to one crop and that may have laid eggs in the soil. It can also hinder crop-specific diseases that may survive on infected plant material from the previous season. Intercropping, as stated earlier, also makes it harder for specialized pests that succeed best with only one crop present to establish themselves. Farmers can also provide habitat for species that prey on crop pests (FIGURE 33.6). Agroforestry encourages the presence of insect-eating birds (although birds can also damage some crops). Many herbs and flowers attract beneficial insects.

Although IPM practitioners do use pesticides, they limit applications through very careful observation. Farmers regularly inspect their crops for the presence of insect pests and other potential crop hazards to catch them early so they can be treated using natural controls or smaller doses of pesticides than would be needed at later stages of an infestation. These more-targeted methods of pest control can result in significant savings on pesticides as well as improved yields. FIGURE 33.7—a case study from IPM training in Indonesia—shows the difference IPM can make. Farmers who learned how to determine whether a pesticide application was warranted were able to cut their pesticide applications, and their expenditures on pesticides, in half. Yields also improved after farmers learned IPM methods.

When farmers take time to inspect their fields carefully, as required by IPM methods, they often notice other crop needs, and this additional attention improves overall crop management. The trade off for these benefits is that farmers must be trained in IPM methods and must spend more time inspecting their crops. But once farmers are trained, the extra income and reduced costs associated with IPM often outweigh the extra time they must spend in the field. IPM has been especially successful in many parts of the developing world where the high-input industrial farming model is not viable because labor costs are low and farmers lack financial resources.

Organic Agriculture

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Organic agriculture is the production of crops without the use of synthetic pesticides or fertilizers. Organic agriculture follows several basic principles:

In the developed world, organic farming has increased in popularity over the past 3 decades. The U.S. Organic Foods Production Act (OFPA) was enacted as part of the 1990 farm bill to establish uniform national standards for the production and handling of foods labeled organic. “Science Applied 5: How Do We Define Organic Food?” on page 392 discusses organic food labeling in more detail.

For a long time, all organic farms were small, but today this is not necessarily the case. However, because most organic farmers plant diverse crops and encourage beneficial insects, it is common for them to keep their farms relatively small. Organic farmers also must manage the soil carefully because if they lose soil nutrients and see a decline in the health of their crops, they have fewer options than conventional farmers. These practices usually increase labor costs significantly. However, farmers can recoup extra labor costs by selling their harvest at a premium price to consumers who prefer to buy organic food (FIGURE 33.8).

Organic agriculture is not without some adverse environmental consequences. Because organic farmers typically do not use herbicides, they are less likely than conventional farmers to be able to use no-till methods successfully. And alternative pest control methods are not always environmentally friendly. For example, in order to keep crops such as carrots free of weeds, organic farmers may treat the soil with a flame fueled by propane before planting. While this technique protects carrots without the use of herbicides, it does use propane, a fossil fuel.

Animals and fish are in general more energy intensive to raise and prepare for eating than vegetable crops, but there are methods for animal and fish production that have a lower environmental impact. This section covers some of those processes.

Not all meat comes from CAFOs. Free-range chicken and beef are becoming increasingly popular in the United States. Some people find it more ethically acceptable to eat a chicken or cow that has wandered free than one that has spent its entire life confined in a small space. Free-range meat, if properly produced, is more likely to be sustainable than meat produced in CAFOs. Because these free-range animals are not as likely to spread disease as those that are kept in close quarters, the use of antibiotics and other medications can be reduced or eliminated. The animals graze or feed on the natural productivity of the land, with little or no supplemental feeding, so less fossil fuel goes into the raising of free-range meat. Finally, manure and urine are dispersed over the range area and are naturally processed by detritivores and decomposers in the soil. As a result, there is no need to treat and dispose of massive quantities of manure. On the negative side, free-range operations use more land than CAFOs do, and the cost of meat produced using these techniques is usually significantly higher.

More Sustainable Fishing

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In the interest of creating and supporting sustainable fisheries, many countries around the world have developed fishery management plans, often in cooperation with one another. International cooperation is particularly important because fish migrate across national borders, some marine ecosystems span national borders, and many of the world’s most important fisheries lie in international waters.

The northwestern Atlantic fisheries, for example, comprise several continental shelf ecosystems that stretch from the northeastern United States to southeastern Canada. Historically, these fisheries were among the most productive in the world. However, overfishing by international fleets of factory ships led to a catastrophic depletion of fish stocks, particularly of cod and pollock, by the early 1990s, as FIGURE 33.9 shows. The fisheries were forced to close because of the depleted stocks, and the Canadian and U.S. governments imposed a moratorium on bottom fishing in the area. The majority of the Atlantic Canadian fisheries are still closed today. Most fisheries in the United States are now open, at least for part of the year.

In response to the fishery collapse, and in order to restore the depleted stocks and manage the ecosystem as a whole, the U.S. Congress passed the Sustainable Fisheries Act in 1996. This act shifted fisheries management from a focus on economic sustainability to an approach that increasingly stressed conservation and the sustainability of species. The act calls for the protection of critical marine habitat, which is important for both commercial fish species and nontarget species. For many commercial species considered to be in danger, such as cod, a sustainable fishery means that no fishing will be permitted until populations recover.

One successful fishery management plan was developed in Alaska, where the commercial salmon fishery declined rapidly between 1940 and 1970. Managers first tried to increase salmon populations by limiting the fishing season, but by 1970, when the season was restricted to less than a week, so many fishers participated that populations continued to drop.

In 1973, fishery managers introduced a system of individual transferable quotas (ITQs), a fishery management program in which individual fishers are given a total allowable catch of fish for a season that they can either catch themselves or sell to others. Before the start of each salmon season, fishery managers establish a total allowable catch and distribute or sell quotas to individual fishers or fishing companies, favoring those with long-term histories in the fishery. Fishers with ITQs have a secure right to catch their quota so they have no need to spend money on bigger boats and better equipment in order to outcompete others. If fishers cannot catch enough salmon to remain economically viable, they can sell all or part of their quota to another fisher. FIGURE 33.10 shows the results: Since the beginning of the ITQ program, the salmon population and harvest have increased—at times very rapidly—and costs to fishers have been reduced.

In Alaska, ITQs are sold primarily to small family-run fishing operations. In New Zealand, however, ITQs have been used effectively to control overfishing by large fishing companies. The ITQ system is being used successfully in many other fisheries around the world.

Not all fisheries are declining, but it is often difficult for consumers to know which fish are being overharvested and which are not. To help consumers choose more sustainable fish, the Environmental Defense Fund and other organizations have compiled lists of popular food fish, dividing them into three categories, depending on how sustainable their stocks are. “Best” choices include wild Alaskan salmon and farmed rainbow trout. “Worst” choices include shark and Chilean sea bass.

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Aquaculture

The demand for fish has increased even as wild fish catches have been falling. In response, many scientists, government officials, and entrepreneurs have been developing ways to increase the production of seafood through aquaculture: the farming of aquatic organisms such as fish, shellfish, and seaweeds. Aquaculture involves constructing an aquatic ecosystem by stocking the organisms, feeding them, and protecting them from diseases and predators. It usually requires keeping the organisms in enclosures (FIGURE 33.11), and it may require providing them with food and antibiotics. Almost all of the catfish and trout eaten in the United States, as well as half of the shrimp and salmon, are produced by aquaculture.

Proponents of aquaculture believe it can alleviate some of the human-caused pressure on overexploited fisheries while providing much-needed protein for the more than 1 billion undernourished people in the world. Aquaculture also has the potential to boost the economies of many developing countries.

Critics of aquaculture, though, point out that it can create many environmental problems. In a typical aquaculture facility, clean water is pumped in at one end of a pond or marine enclosure, and wastewater containing feces, uneaten food, and antibiotics is pumped back into the river or ocean at the other end. The wastewater may also contain bacteria, viruses, and pests that thrive in the high-density habitat of aquaculture facilities and this can infect wild fish and shellfish populations outside the facility. In addition, fish that escape from aquaculture facilities may harm wild fish populations by competing with them, interbreeding with them, or spreading diseases and parasites. Overall, however, aquaculture has many promising characteristics as a means of sustainable food production.