Agriculture
Ecosystems can normally cope with most types of disturbance. However, human disturbance often occurs too quickly for the environment to respond, negatively affecting the soils and the plants and animals that depend upon them. Soils are living environments, providing habitat for a host of microorganisms necessary for plant growth. Impacts on soils, therefore, can affect the entire ecosystem.
History
The human invention that probably has had the greatest impact on soils is the John Deere self-scouring steel plow, introduced in 1837. The once impenetrable prairies were plowed and tilled, becoming vast farm lands. Today, only 5 percent of the original native prairie remains in the United States. Similar losses occurred in other habitat types such as wetlands, negatively impacting their water-loving soils and disturbing layers of buried sediment. According to the U.S. Geological Survey, more than 50 percent of the aquatic habitats of the lower 48 states have been drained.
Dust Bowls
The greatest human impact to soils in the 20th century was the 1930s Dust Bowl Drought, which lasted 8 years overall. The drought, along with improper farming practices, created a deadly scenario, resulting in the loss of tons of precious topsoil. Soils whirled around in the air, creating the so-called "black blizzards." Texas, Kansas, Oklahoma and Colorado saw losses of over 30 million hectares of farmlands alone.
Soil Erosion and Urban Development
Agriculture is the primary source of negative human impact on soils. However, the urban landscape is not exempt. Urban environments include vast regions of impervious surfaces which water cannot penetrate. During a severe weather event, water washes over these impenetrable surfaces, eroding stream banks and displacing soils. Depending upon the adjacent land use, these soils may contain toxins which can negatively impact surface water and groundwater resources. Soil erosion feeds upon itself. As stream banks erode, water flow increases during floods, causing more soil erosion in the process.
Pollution
Even human activity not directly associated with soils can affect these natural resources. Air pollution releases contaminants such as sulfur dioxide into the atmosphere. This compound combines with moisture present in the air to create acidic precipitation. Soils receiving this acid rain become acidic. Microorganisms die off, impacting the health of the soils. Left unchecked, soils become ecological dead zones, unable to support neither plant nor animal life.
Prevention/Solution
Many human impacts on soils can be prevented. For example, planting grass or other clumping vegetation along stream banks can prevent soil erosion. More stringent pollution control regulations can mitigate the environmental effects by preventing the introduction of toxins into the environment and soils. Finally, individuals can lessen their impact on soils by the proper use of pesticides and fertilizers.
Tags: impact soils, stream banks, human impact
