16 Soil Erosion and Conservation
It takes up to 2,000 years to form one inch of soil. Under the right conditions, that inch of soil can be eroded by wind or water in a single storm. Thus, if not conserved, soil that developed over millennia can be lost within a single human generation. However, soils can be used over and over again using appropriate conservation practices. In this lab, several videos will be used to demonstrate the mechanics underlying soil erosion. In addition, a model will be used to estimate the impact of common soil conservation practices on soil erosion.
Learning Objectives
- Identify conditions under which soil is most susceptible to erosion by water.
- Identify conditions under which soil is most susceptible to erosion by water.
- Utilize the RUSLE equation to estimate the erosion rates of a given hillslope.
- Compare estimated erosion rates to “tolerable” rates of erosion, commonly known as T values.
- Name and describe conservation practices that reduce water and wind erosion.
- Become familiar with the federal, state, and local agencies associated with soil and water conservation.
Materials
- Computer with internet access and a projector
*Note*
For this lab you will need to bring your textbook for lecture, and a laptop or tablet. If you do not have a laptop or tablet, please share with a partner.
Recommended Reading
- Module 3 – Managing for Soil Erosion (McCauley and Jones, 2005a)
- Soil Quality Resource Concerns: Soil Erosion (USDA NRCS, 1998)
Prelab Assignment
Using the recommended reading and the introduction to this lab, consider the questions listed below. These definitions/questions will provide a concise summary of the major concepts to be addressed in the lab. They will also serve as the basis for the post-lab quiz and are useful study notes for exams.
- Describe the difference between geologic erosion rates, and erosion rates exhibited by managed soils.
- Identify the soil particle size most susceptible to erosion by wind.
- Identify the soil texture class size is most susceptible to erosion by water.
- Identify and describe the three methods of sediment transport by wind.
- Define sheet, rill, and gully erosion by water.
- Name the factors included in RUSLE.
- Identify and describe three conservation practices used to reduce water erosion
- Identify and describe two conservation practices used to reduce wind erosion.
Introduction
Worldwide there are approximately five billion hectares of degraded land, which is approximately 43% of the Earth’s land surface. Of those five billion hectares, the most common cause of degraded land (two billion hectares) is soil degradation due to erosion, compaction, surface crusting, acidification, or salt accumulation. Most of that degradation (85%) comes from water and wind erosion.
However, erosion is a natural process. Geologic erosion is a process that transforms soil into sediment. It takes place naturally without the influence of any human activities. Geologic erosion rat