Causes and Consequences: Soils
Soil erodes naturally, but human activities can greatly speed the rate of soil erosion, leading to
diverse ecological effects and to potentially severe impacts on agricultural production.
Fortunately, farmers, scientists, and policymakers have devised a number of ways to conserve
soil and prevent or mitigate erosion.
Write in two causes of soil erosion in the spaces provided. Then write in two consequences
(impacts on the environment, human health, or quality of life) that result from soil erosion.
Finally, offer two solutions to this issue and its consequences. One cause, one consequence,
and one solution have been filled in for you, providing examples.
CONSEQUENCES
CAUSES
Erosion by wind
Soil
Erosion
Loss of topsoil
SOLUTIONS
Planting shelterbelts to block wind on farmland
Sometimes solutions can have unintended consequences. Can you think of an undesired
consequence that one solution to this issue might have? How might we deal with that
consequence?
Calculating Ecological Footprints
In the United States, approximately 6 pounds of topsoil are lost for every 1 pound of grain
harvested. Erosion rates vary greatly with soil type, topography, tillage method, and crop
type. For simplicity let us assume that the 6:1 ratio applies to all plant crops and that a typical
diet includes 1 pound of plant material or its derived products (sugar, for example) per day. In
the first two columns of the table, calculate the annual topsoil losses associated with growing
this food for you and for other groups, assuming the same diet.
Assume Washington State has a population size of 6,500,000 and the US has a population size
of 305,000,000 people (data from census.gov)
You
Your class
WA state
United States
Plant products
consumed (lb)
Soil loss at 6:1
ratio (lb)
Soil loss at 4:1
ratio (lb)
365
2190
1460
Reduced soil loss
at 4:1 relative to
6:1 ratio (lb)
730
1. Improved soil conservation measures reduced erosion by one-third from 1982 to 1997.
If additional measures were again able to reduce the current rate of soil loss by a third
the ratio of soil lost to grain harvested would fall from 6:1 to 4:1. Calculate the soil
losses associated with food production at a 4:1 ratio and record your answers in the
third column of the table.
2. Calculate the amount of topsoil hypothetically saved by the additional conservation
measures in question 1, and record your answers in the fourth column of the table.
3. Define a “sustainable” rate of soil loss. Describe how you might determine whether a
given farm was practicing sustainable use of soil.