Land and Water Use - Environmental Science - page 82

This is considered subsistence agriculture, in which enough food is created for the family but not for others.
In contrast, agriculture on a large scale, with crop production for many people, and including the use of fertil-
izer, pesticides, irrigation, seeds, fossil fuels, monoculture (growing one single crop), and human power is con-
sidered industrialized agriculture, also called conventional agriculture. (For more information about indus-
trialized agriculture, see the upcoming section "The Green Revolution.")
The Dust Bowl
Soil erosion, in which soil is transported from a location via wind or water, has an impact both at the site
from which it was taken and the site at which it is deposited. Erosion is a natural process, but human inter-
vention has led to its rapid increase to the point that we are losing nutrient-rich topsoil faster than it is cre-
ated. One source of this erosion is the removal of trees and undergrowth to clear land for crops, rangeland,
construction, and roadways. The roots of plants and trees are especially important as they trap soil and
prevent wind and water from carrying it away. This erosion or other factors including overgrazing,
drought, soil compaction, can lead to desertification, which is loss of soil productivity. In extreme cases,
desertification can, as its name implies, lead to expansion of deserts and giant dust storms. Today, dust
storms are common in areas of China and Africa, where the land has been overworked, but desertification
also led to a dust storm in the United States that dated several years and devastated many states.
Due to the food needs of human expansion into the western United States in the late 1920s and early
1930s, natural land was cleared and replaced with crops and rangeland. The removal of vegetation, includ-
ing grasses, trees, shrubs, and plants, exposed the soil to wind and water. To this newly overworked land,
nature added a drought. This combination in the southern Great Plains, along with the stock market crash
of 1929, led to the environmental, agricultural, and economic catastrophe known as the Dust Bowl. In
hopes of averting another Dust Bowl, the United States created the Soil Conservation Act of 1935, the
Soil Conservation Service (now the Natural Resources Conservation Service), and new guidelines for bet-
ter farming practices.
The Green Revolution
The advent of industrialized agriculture in the mid- and late 20th century became known as the Green Revolu-
tion. This revolution included combining more effective farming techniques with the science of newly created
crops to increase yields and efficiency. Developments during the Green Revolution included the following:
• High-yield crop varieties (mainly wheat, maize, and rice) created through breeding and crossbreeding
techniques (selective breeding)
• Increased irrigation infrastructure
• Wide use of pesticides and fertilizers
The enormous benefit of the Green Revolution was the ability to produce more food on less land. Instead of
feeding only the local population, crop excesses led to international markets in which food is exported and im-
ported.
That said, more output requires more input. In the case of industrialized agriculture, inputs include fossil fuels
for machinery and transportation, water, fertilizers, and pesticides. The environmental impacts of industrial ag-
riculture can include pollution, contaminated waterways and drinking water, decreased available freshwater, re-
duced soil quality, and increased erosion, desertification, and salinization.