Lesson 15: Soils
This is our fourth and final lesson to focus on Earth's resources and in it you'll learn about
the structure, properties and erosion of soils (like those of the Missouri grasslands, at right). Part of the importance of soils
can be understood in their relation to agriculture. Remember that old adage I mentioned a couple of weeks ago, "If it's not grown, it's mined." During our two previous lessons we've considered mineral and energy resources that are "mined"; this week, however, we'll look at soils which are the basis for all the food and timber that are "grown". The significance of soils in environmental geology goes beyond agriculture, however, because, as you saw in the landslide hazard exercise a few weeks ago the nature of a soil plays a big role in determining how suitable a site will be for construction or other uses.
As you read through the introduction to soils in our text and study the accompanying websites it will be helpful to take careful notes. Writing out key facts in your own words or making neatly labeled drawings will help you better understand the significance of what you've read and spot any gaps in your knowledge. Having complete notes will also make it easier for you to review for this week's quiz and and access what you've learned when you want to refer back to it for future assignments. Be sure that you are prepared to meet the learning objectives outlined below before you move on to the quiz at the bottom of the page. This week's exercise, which comes from Hazard City, looks at how a variety of factors (which in real-life would also include soil characteristics) influence our ability to site waste disposal sites.
Weekly Learning Objectives
Upon successful completion of this week's lesson, a student is expected to be able to:
- Contrast how a soil would be defined by a soil scientist versus an engineer and descirbe the general basis for the different soil classifications used by the two groups (Tables 17.1 and 17.2).
- Identify the different horizons in a soil profile and explain what they indicate about the conditions under which the soil formed (e.g., arid or humid, well or poorly-drained, and so on.)
- Determine the texture of a soil given information on how much sand, silt, and clay it contains by referring to a copy of the soil texture classfiication diagram (Fig. 17.4).
- Predict the likely properties of a soil (strength, compressibility, hydraulic conductivity, and shrink-swell potential) from a knowledge of its composition and moisture content.
- Use the universal soil loss equation to predict qualitatively how changes in slope, runoff, or vegetative cover are likely to affect average the soil loss rate for a site.
Reading and Browsing Assignment
- Read Chapter 17, focusing on the topics outlined in the learning objectives above.
- Check out what type of soil is found in an area where you live or work using the National Resource Conservation Service's Web Soil Survey. For example, if you check you'll learn that the COS campus is built on Deetz gravelly loamy sand.
- Learn about the meaning of any soil-related term using the Soil Society of America's online glossary. There are also links here to tables and figures similar to those in our text that help you classify soil structures and textures.
- Finally, you can find links to dozens of online resources on soil science on the National Society of Consulting Soil Scientists soil science sources page. In addition to sites here in the U.S., this site has links to many international soil science sites.
Exercise 15: Landfill Siting exercise (Due by 9:00 AM on 28-Nov-2011)
Please point your browser to the Hazard City website and work through version 2 of the Landfill Siting exercise. This is one of the more "interactive" Hazard City assignments because you'll be using a simplified GIS (geographic information system) to turn on and off map "layers" so that you can determine which—if any—of several sites might be suitable for a landfill. The project will probably take about an hour to complete, but be sure not to rush through it or you'll risk missing important details about the siting requirements. It may be helpful to take notes on key facts as you read through the introduction (e.g., the population of Hazard City is critical because it dictates which type of municipal landfill is being proposed as described in §330.2 of the regulations). Also, I recommend that you fill out the project's final report before you go to the "Assignments, Tests, and Surveys" tool in Etudes to submit your answers for Exercise 15.
Quiz 15: Soils (Due by 9:00 AM on 28-Nov-2011.)
After you feel you have met the learning outcomes outlined above, please complete Quiz 15 in the Etudes "Assignments, Tests, and Surveys" area. There are ten questions, each worth one point. If you can answer all of them correctly it means that you know your way around the basics of soil resources pretty well and are ready to move on to a more detailed look at recycling and waste management next week. Remember, answers will be available for review after 10:00 AM on the Tuesday after the quiz closes, so please look over the results of your quiz and contact me if you have any questions about either content or scoring.