Introduction to Soil! (Review, 15 minutes)
To begin your lesson, take some time to discuss and introduce the concept of soil science - the study of soil. According to the USDA, there are over 50,000 different varieties of soil in the United States alone! The type of soil is dependent upon the soil’s parent material, topography, climate, the organisms in and around the soil, and the amount of time it takes for these to all interact. Since these characteristics vary worldwide, soil profiles also vary worldwide.
The above map of the United States illustrates just a few of the diverse soil types that can be found across the country.
Soil starts with a process called weathering. Physical and chemical weathering processes erode parent material like rocks into mineral particles. These materials are then transported by volcanoes, wind, water, ice, and waves and deposit these minerals around the landscape. The minerals are then influenced by gravity, and upon deposition create landforms from which soil formation begins.
There are a couple of important minerals to consider:
- Sand: The major mineral in sand is called quartz and it is composed of silica and oxygen (SiO2).
- Clay: Silicates, mica, iron, and aluminum hydrous-oxide minerals are found in clay. The silicate clay group is primarily located in the mid-latitudes, while the iron and aluminum clays are found in the tropic zones.
There are many other concepts you can expand on here including: nutrient cycling, soil chemistry, geology, rock formations etc.
To help students better understand soil, you can lead some simple hands-on activities and experiments in the classroom.
Example: Building Soil
Setup an activity for student design teams to make different soil profiles. Each team can represent a different part of the world. Asia, North America, Europe and South America for instance. Supply students with the three main ingredients for soil (sand, clay and compost) and a beaker of water.
Team Asia - 1 cup of clay, ¼ cup of compost and ½ cup of sand
Team South America - 1 cup of compost, ½ cup of clay and 1 cup of sand
Team North America - 1 cup of compost, ¼ cup of sand, ¼ cup of clay
Team Europe - ½ cup of compost, ½ cup of sand and ¼ cup of clay
Assemble all the elements at proper ratios and add a splash of water to each.
Soils for Greenroofs
Greenroofs are vegetated roof covers, with plants taking the place of typical roofing material like shingles or tiles. Greenroofs help to reduce energy costs by keeping in heat and air conditioning, while providing a habitat for insects, animals and birds, helping to improve air quality and collect water from storms. The soils or “mediums” used to grow plants on a greenroof are usually much different than the potting soil mix or soil you would find in your backyard.
Many organizations are designing special kinds of greenroof soils that will work better for the conditions of a building. One major issue is weight. The weight of the greenroof is a concern for any structure. Because of this greenroof soils are lightweight and are able to retain water much more easily than normal soils. The thin layer in which they must be applied to roof toops reuires that they be extremely absorbant. The Gaia Institute has developed a soil that works great for these conditions called GaiaSoil™. The main ingredient in GaiaSoil™ for is a non-toxic recycled expanded polystyrene foam coated with an organic pectin (pectin is the main ingredient in gelatin), and mixed with high-quality finished compost (a fertilizer for plants).
https://www.gaiasoil.com/
This kind of soil avoids additional reinforcement on the roof of the building, allows a more diverse plant selection and can capture stormwater easily, making it possible for greater soil depth and easier transport.
Soil in Relationship to History and the Environment (Investigate 10 minutes)
Now that students have a basic understanding of soil, discuss the role of soil in relationship to a current history lessons you may be conducting. Ask students to think about how soil affected the development of agriculture an
During the expansion of the 13 colonies and into the Civil War Era - soil type and quality had a lot of influence on the formation of cities, towns and what kinds of industries flourished in a certain area. Include lessons about local d industry in the United States. In the south, for instance, soils can be more clay-like - but the climate is better for growing crops more months out of the year than in the New England.
history - was your region of the country heavy in agriculture or mining? How did the soil type affect what kinds of structures were built and used throughout history? Bring up relevant examples and discuss as a class.
After talking about some historical influences, discuss some of the major environmental challenges associated with soil quality in the past and currently:
- Agriculture and farming - Industrial farming and monoculture crops rapidly deplete the soil of nutrients, which are replaced each year with chemical fertilizers. The soil is then damaged beyond repair taking upwards of 50-75 years to restore.
- Brownfields and superfund sites - Many areas of the United States have been contaminated because of their proximity to chemical waste sites or industry runoff. These sites have been designated Brownfield or superfund sites because of the degree of toxicity that remains in the soil - commonly the site of oil, chemical or biological spills.
- Erosion and mudslides - Development for housing/buildings have caused unprecedented amount of erosion and mudslides to occur around the world. Removing plant life loosens the soil making it easy for wind, water or other forces to erode the soil or cause a mudslide.
How are designers thinking through some of these environmental challenges in the architecture or city planning?
• Soil Lamp- A number of designers today are integrating objects with alternative means of clean power to create self-contained, self-sustaining systems. For Dutch designer Marieke Staps, the power source is mud. Her Soil Lamp makes use of the metabolism of biological life in dirt to produce enough energy to power a small LED light. The soil, enclosed in cells containing zinc and copper, acts as an electrolyte—an electrically conductive medium—and requires only a simple splash of water to keep it from drying out. The more cells there are, the more electricity can be generated. Staps’s design and naming of the Soil Lamp celebrates the transparency and simplicity of its process: the earth battery is housed in a clear bulbous base, with power carried along a thin conductor leading to a bare bulb. Exposing the possibilities of another source of abundant, renewable energy, the lamp serves to invigorate future innovation for small, contained power systems.
Design Challenge: Saving Our Soils…! (Frame/ReFrame)
After discussing some potential challenges and historical connection, talk about some of the recent solutions being developed by designers to address soil conservation and quality:
- Remediation Techniques - Many scientists and designers are thinking of innovative ways to remediate (or improve) soil quality. One method is Mycoremediation or the use of mushrooms to absorb toxins in certain soil types. Oyster mushrooms are commonly used in oil spills for instance, accumulating the oil in a metabolic process. Other materials like wetlands plants and other hyper accumulators can help to remediate soils naturally.
- Conservation/Preservation - A straightforward technique to preserving soils and their quality is open space preservation and conservation of sensitive lands.
- Organic/Sustainable Farming - Sustainable farming techniques that reduce or eliminate the use of pesticides, fertilizers and other harmful chemicals used to “enrich” soils can improve soil fertility many fold.
- Composting - Composting, or the process of recycling organic wastes like dead leaves, food scraps and other wastes into a fertilizer can be used to naturally restore nutrients to soil.
Now its time for a design challenge! In this exercise, encourage students to use design thinking to problem-solve a scenario presented to each team. The scenario will setup a design problem and students will work as a team to develop a solution based on their knowledge of soil science.
Scenario One: The mayor has asked you to look into fixing up a former industrial site along a major river that cuts through downtown. He wants to turn the site into a park. The site used to be home to the Miller-Smith Corporation. Unfortunately the site is now designated a brownfield site because of chemical runoff that has accumulated in the soil. What can you do to fix the site and what kind of a park would you design?
Scenario Two: A developer wants you to be the lead architect on a new housing development. The development site is partly on a steep slope with lots of sandy soil. Design a house that would be able to constructed on the site that would adapt to the kinds of soil there and the steep conditions.
Scenario Three: A big farm recently went out of business. This left over 40 acres of land that had grown just one crop - lots of corn! The soil now looks kind of orange and dusty. When the wind picks up a lot of the soil blows away. You’ve been asked to divide the land into 20 smaller farms. What kind of a farm would you design and how would you fix the soil?
Scenario Four: You live down by the beach. Every year more and more condos are being built along the shoreline. You’ve noticed that the beach keeps getting smaller each year, but still more houses are built. As a town planner you’ve been asked to help save some of the beach from eroding into the ocean. What kind of conservation plan would you come up with? How would you save the beach and what would a preservation site look like?
Sketch and Brainstorm (Generate, 10-15 minutes)
After presenting scenarios to each design team, ask them to brainstorm and create sketches that respond to their situation.
Model Making (Edit and Develop, 25-30 Minutes)
After each design team generates sketches, provide students with modeling materials. Ask each team to develop 3D representation of their design with the corresponding soil type as a base.
After each team completes their model, share your design solutions as a class. Tie in historical and environmental discussions previously held in class and encourage students to talk about their designs from the perspective of the soil. (Share and Evaluate)