Agricultural Practice Impacts

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Agricultural Practice Impacts

Introduction

Using land to grow crops has occurred for thousands of years. When agriculture involved family farms and the care of land involved manual labor, the effect of agricultural land on the environment was minimal.

However, as farms have become larger and more mechanized, and as the use of pesticides has grown more prevalent, agricultural practices have become more damaging to the environment. Clearing the land can increase the erosion of soil, and the runoff of pesticides can poison watercourses and even contaminate underground water supplies.

Even areas not as agriculturally developed as North America experience agriculture-related environmental damage. For example, the deforestation of the Amazon rain forest is being driven largely by the creation of agricultural and grazing land. Not only does this damage the local ecosystems, but the massive loss of forest is affecting the global climate.

As unwise agricultural practices are environmentally damaging, wise use of land can enable the raising of crops in a way that minimally affects the environment.

Historical Background and Scientific Foundations

Farming can be traced back over 10,000 years to regions of present-day Turkey and the Middle East. The shift from a nomadic lifestyle to more permanent dwelling centered around rivers, which supplied the water for human agricultural needs.

During the height of the Industrial Revolution, around the 1850s, mechanization was introduced to farming, which increased crop production markedly. At around this time fertilizers and pesticides began to be manufactured, but they were not extensively used until the early twentieth century.

In 1950s and 1960s, agriculture in North America became a highly mechanized process. As well, the use of fertilizers and pesticides increased. The need to raise large amounts of food to support the growing population and the growth of rail and truck transport encouraged the development of huge farms, including factory farms—livestock and poultry facilities capable of housing tens of thousands and more animals. Agriculture changed from being a supplier to local markets to a national and even international source of food.

Concern with the environmental impacts of agricultural practices in the United States dates back to the 1930s, when drought combined with agricultural practices that encouraged erosion caused massive dust storms in the midwest of the United States and Canada. Following the publication in 1962 of Silent Spring by Rachel Carson, more concern developed over the adverse effects of pesticide and antibiotic use on farms and of the environmental impact of factory farms.

Although the use of pesticides and fertilizers has been reduced by some farmers, they are still commonly employed. Runoff of these chemicals into adjacent watercourses can poison the water, and the presence of nitrogen (N) and phosphorus (P) can cause the explosive increase in algal growth. The algal bloom can deplete oxygen (O) from the water so much that the water cannot support fish.

Beginning in the 1990s, the environmental impacts of factory farms were more widely recognized. The facilities, which house 10,000-100,000 poultry or live-stock, require a great deal of drinking water. This can deplete local surface water and groundwater supplies. Furthermore, a factory farm that can be the size of several football fields generates huge amounts of feces—10,000 hogs produce as much waste in one day as a

WORDS TO KNOW

EROSION: The wearing away of the soil or rock over time.

FACTORY FARMS: Enclosed or open-air facilities that house thousands to tens of thousands of poultry, swine, or cattle.

MONOCULTURE: Single species.

community of 25,000 people, according to the U.S. Environmental Protection Agency (EPA). Often, wastewater and feces are stored in holding ponds up to 7 acres (2.8 hectares) in size. The accidental leakage or outright release of the contents can contaminate surrounding water sources. Dozens of these spills have been documented by the EPA since the 1970s. For example, in 1999 North Carolina was struck by hurricanes Dennis and Floyd within one week. Lagoons damaged in the first hurricane ruptured during

Hurricane Floyd. One spill alone released 25 million gallons (95 million liters) of feces-laden water, killing an estimated 10 million fish.

As well, the foul odor from open-air holding ponds is objectionable, and aerosols given off by the ponds can be a source of heavy metals and hydrogen sulfide to those downwind.

Another adverse environmental impact of agriculture is erosion—the removal of soil by wind and flowing water that does occur naturally but is increased by agricultural practices such as deforestation and surface vegetation loss due to the overgrazing of cattle. As well, the practice of tilling—where the surface land is turned under—can disturb roots of grass and other vegetation that helps hold soil in place.

Clearcutting is another agricultural practice that can increase erosion, since the stabilizing effect of the tree roots is eliminated. As well, massive deforestation can affect climate, since trees can trap carbon dioxide (CO₂), restricting the release of this greenhouse gas into the atmosphere.

Impacts and Issues

The adverse environmental effects of agriculture can be huge. As one example, the EPA estimates that waste from chicken, hog, and cattle factory farms has polluted 35,000 miles (56,000 km) of waterways in 22 U.S. states, and that the polluted water has leached into the ground and contaminated groundwater in at least 17 states.

Although in 2008 such concerns about agricultural practices remain, positive changes are taking place. Organically raised crops and the lessened use of antibiotics as a growth supplement in cattle have reduced environmental damage in developed countries. In addition, agricultural practices such as planting different crops in different growing seasons, having fields lay fallow for a time, and planting stands of trees to act as a wind block help maintain soil fertility.

However, in other countries agricultural practices that include deforestation are becoming even more of a concern, especially given the influence that massive tree loss can have on the increased release of carbon dioxide to the atmosphere.

For example, the Brazilian rain forest makes up about 30% of all rain forests on Earth. Over 5 million acres (2 million hectares) of this rain forest are being cut down each year, mainly to generate land for agriculture and the raising of livestock. If the deforestation continues at this rate, the Brazilian rain forest could be gone by 2050.

Ironically, the cleared land is agriculturally productive for only a limited number of growing seasons, since the treeless land no longer can cycle nutrients into the soil. Only with the addition of fertilizers is continued agriculture possible, which further degrades the soil and surrounding watercourses.