Module 3: Soil

Topics addressed in this module include: introducing soil, identifying soil as distinct from dirt, identifying the various types of soils and soil horizons, and understanding soil formation and the nutrient cycle.

Updated Oct. 29, 2019

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Table of Contents Section 3.1: Soil 101 ...... 3 What is Soil? ...... 4 How is Soil Different from Dirt? ...... 5 How Does Soil Form? ...... 5 What Factors Influence Soil Formation? ...... 6 Are All Soils the Same? ...... 8 Section 3.2: Soil Horizons ...... 10 What is a Soil Profile? ...... 11 What is a Soil Horizon? ...... 11 How do Soil Horizons Form? ...... 12 How do Soil Profiles Compare Across Canada? ...... 13 Labelling Soil Horizons ...... 14 While Sampling ...... 15 Section 3.3 The Nutrient Web ...... 17 What is the Nutrient Web? ...... 18 How Does the Nutrient Web Work? ...... 18 What Factors Influence the Nutrient Web? ...... 20 Glossary ...... 28

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Section 3.1: Soil 101

Original image by Mesaytesegaye

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Section Overview

Outcomes Students will:

• Describe what soil consists of and its four main functions. • Investigate factors and processes that influence soil formation (i.e. addition, removal, transfer, and transformation). • Differentiate soils based on their characteristics (i.e. texture, structure, porosity, and colour).

Key Terms

Acid Rain Dirt Parent Material Texture Acidification Eluviation Pedosphere Topography Addition Erosion pH Transfer Bioavailable Groundwater Porosity Transformation Climate Humans Removal Water Table Colloids Leaching Solutes Weathering Colour Organisms Structure

What is Soil? To most, soil is just the ground beneath our feet, but soil is a complex mixture of minerals, organic matter, and organisms. With the TREE program, you will need to provide samples of soil near the trembling aspen you are sampling from. Soil is collected because it helps correlate data from the tree cores because as we know, soil is composed of many nutrients and minerals that find their way into the tree. By analyzing the soil, we are able to potentially make these connections and see the impact the environment has on the tree. Soil contains the three common states of matter: solid, liquid, and gas. Roughly 50% of soil is solid and is composed of minerals (~45%) and organic matter (~5%). Soil is porous though which allows for water and gases to seep through (see Figure 1).

Figure 1 shows the pores or spacing between sand grains. Image by klaber.

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Soil has four main functions. It acts as a medium for plant growth. It also stores and filters water. It modifies the atmosphere by emitting and absorbing various gases and dust and finally, soil is also a habitat for countless organisms. These functions continuously alter the composition and structure of soil. All of the soil on Earth is collectively called the pedosphere. As outlined in Figure 2, the pedosphere connects to the four other spheres: the lithosphere (Earth’s crust and upper mantle), the hydrosphere (Earth’s water and ice), the atmosphere (Earth’s Figure 2 shows the interconnectedness of Earths many spheres. gases), and the biosphere (Earth’s living creatures). Original image by Jojndon.

How is Soil Different from Dirt? The terms soil and dirt are used interchangeably but they are, in fact, different and should be used separately. Dirt is distinct from soil in that dirt is soil that has been displaced from its native environment in a way that is unusable. Dirt is incapable of supporting plant growth, so it is sometimes referred to as dead soil. You can identify dirt from soil by adding water to it. If the mixture compacts well together, it is soil. If the mixture does not pack together, then it is most likely dirt. How Does Soil Form? Soil formation, or pedogenesis, happens through a variety of complex processes but simply put, it is formed by the breakdown and movement of rocks and sediments called parent material. The processes impacting the parent material can be simplified to just their effects: addition, removal, transfer, and transformation. Addition ● This effect refers to adding material into soil. Anything or anyone can add material to soil. For example, adding compost from your kitchen or through weathering of larger rocks will impact soil formation (Figure 3).

Removal ● With removal, this effect takes material out of soil. Anything can remove material from soil, such as simply digging a hole in the ground, or through erosion from wind or water. Figure 3 shows weathering and erosion of a boulder. Image by UCL Mathematical & Physical Sciences. Transfer ● In this process, soil materials are moved between locations. Anything can transfer material between locations, such as simply tilling the ground or through leaching and eluviation of minerals (Figure 4).

Transformation ● Transformation refers to altering the chemical composition of soil materials. Many things can cause soil materials to change their chemical composition, such as simply adding fertilizer to the soil or through acidification from acid rain. Figure 4 shows iron leaching out from a stone wall. Image by Ashley Van Haeften.

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Examples of Soil Forming Processes ● Weathering is the breakdown of soil, rocks, minerals, wood, and man-made materials through contact with wind, water, ice, and organisms. Products of weathering remain in the same place. ● Erosion is the breakdown and movement of soil, rocks, minerals, wood, and man-made materials by wind, water, ice, gravity, and organisms. Products of erosion do not remain in the same place. ● Leaching is the loss of dissolved material due to flowing water. ● Eluviation is the loss of solid material due to floating on flowing water. ● Acidification is the build-up of hydrogen in the soil, decreasing the pH or the measure of the acidity of a solution. This build up can be from adding in acidic materials or solutions, or removing basic ones.

What Factors Influence Soil Formation? Soil is the product of parent material, climate, organisms, topography, groundwater, and humans all interacting with each other. Most importantly, soil is the product of time. Parent material refers to the rocks and sediments that are broken down to form soil (see Figure 5). • The composition and structure of soil is highly dependent on the composition of the parent material. Iron rich parent material will produce iron rich soil. o The rate at which soil forms is also dependent on the parent material. Easily weathered parent material will produce soil faster than stronger, more resistant material.

Figure 5 shows layers of parent sediment. Image by Figure 6 shows a pothole full of water. Image by Matt RF TheusiNo. Webb. The climate refers to the long-term trend in weather. • The rate at which soil forms is dependent on the local climate. • Climates with a trend for rain will experience rock and soil erosion which will create and relocate soil faster than soil in dry climates. Climates with a trend for freezing and thawing will experience rock and soil weathering, creating soil faster than soil in climates without the freezing and thawing. • The effects of freezing and thawing can be seen every spring when potholes on the road start to appear. As shown in Figure 6, potholes are due, in part, to spring melt-water making its way into road cracks during the day, where the water then freezes and expands as it becomes ice overnight.

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The term organism refers to any living creature: plants, fungi, animals, insects, and microbes alike. • The rate at which soil forms and the composition and structure of the soil are dependent on the organisms inhabiting the soil. • Burrowing animals are able to erode rocks and mix around the soil, creating soil faster than soil without these animals nearby (Figure 7). • Smaller microbes consume and concentrate nutrients from the gases and water within the soil. They also mobilize these nutrients as they move and when the microbes die, the nutrients are deposited to the new location. o Nitrogen, for example, is not readily available in the soil. Microbes must consume nitrogen, convert it to be bioavailable (able to be absorbed by a body), and then die off to deposit it for plants. • Plants alter the composition of soil by absorbing and storing nutrients within it. Some plant roots are capable of splitting boulders in half, eroding them into soil over Figure 7 show how Cathedral Termites will remove large time. amounts of soil to create their homes, called termite mounds. Image by J Brew.

Topography is used to describe the elevation, slope, and orientation of the terrain. • The topography of the terrain impacts the rate at which soil forms and the composition and structure of the soil. • Elevation is the height above or below a fixed reference point when talking of a geographical location. Elevation will impact how water travels through the landscape. • Slopes, a type of elevation, encourage water to flow quickly. This occurrence causes landslides that erode rocks into soil and helps mix the soil up. Depending on the direction the slopes face as well, the soil may receive more sunlight causing weathering and/or drier conditions.

Groundwater refers to the water stored within the ground or soil. The depth where the pores in soil become saturated with water is called the water table (see Figure 8). • Groundwater affects the rate at which soil forms by weathering and eroding parent material. • Fast flowing groundwater will erode the parent material Figure 8 shows where the water table is defined. Image faster than still groundwater. by Geoff Ruth.

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Humans have a diverse effect on the composition and structure of the soil. Human activity is another factor that influences soil formation. • Industrial and agricultural activities (Figure 9) change the features of soil either to have the properties needed for a specific task or as part of the resource extraction process. • Gardening even alters the composition of the soil through fertilizers and the plants absorbing nutrients.

Time is the last main factor that impacts soil formation. Time refers to the duration that the above factors have to act on the parent material. It is by far the most important factor in soil formation. With enough time, even mountains can be eroded into pebbles.

Figure 9 shows a farmer tending to his crops. Image Are All Soils the Same? by Jean Beaufort. No. Soils are characterized by many factors. The main ones include: texture, structure, porosity, and colour. These factors are intricately related as changing one factor will change many others.

Texture Structure Texture refers to the feel, appearance, and consistency Structure refers to the clumping of the textural of the soil. Soil’s texture is determined by the ratio of components. Small clumps are called aggregates, while mineral components of soil (the ratio between sand, silt, clumps of aggregates are called peds. The structure of and clay). soil can make it more or less erosion resistant.

Porosity Colour Porosity is a measure of the porous space in a material. Colour refers to the different colour of the soil horizons It is the ratio between the volume of pores to the total (see Figure 10). Colours give a visual indication of the volume. Porous soil allows materials to flow easier, elements present and the processes acting on the soil. making it susceptible to weathering. Non-porous soil Soils from different location can be completely different withstands weathering better, but inhibits plant root colour or be completely identical. Soil can change growth. colours as you increase depth, making it easy to identify soil horizons which is outlined in the next section.

Figure 10 shows differently coloured soil horizons. Image by HolgerK.

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Additional Resources Soils of Canada: https://www.soilsofcanada.ca/ Webpage created through the help of soil scientists from across Canada that provides information on Canadian soil, how it forms, what it is made of, the different types of soil, and much more. Also has helpful links for further exploration.

Soil vs. Dirt, You’ll be Surprised to Know the Difference: https://www.tinyplantation.com/soil-fertilizers/soil-vs-dirt An online blog post that covers the difference between soil and dirt, how soil becomes dirt, and the different types within each. Informative read to help students distinguish between these two commonly associated words.

Virtual Soil Science Learning Resources: http://soilweb.ca/ A webpage full of resources for soil science courses and national resource programs across Canadian and other Northern American universities. This webpage has a lot of soil resources, lessons, activities, research papers, and other resources that can be adapted for the classroom.

References Annenberg Learner. (2017). Earth & space science: Session 1. Retrieved from https://www.learner.org/courses/essential/earthspace/session1/closer2.html National Research Council of Canada. (1998). The Canadian system of soil classification (3rd ed.). Ottawa: Research Branch, Canada Dept. of Agriculture. Soils of Canada. (n.d.). Welcome. Retrieved from https://www.soilsofcanada.ca/index.php Soil Science Society of America. (n.d.). Soils overview. Retrieved from https://www.soils.org/files/about-soils/soils- overview.pdf

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Section 3.2: Soil Horizons

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Section Overview

Outcomes

Students will: • Investigate the characteristics and formation of surface geology, specifically soil. • Differentiate soil profiles across Canada, and understand the mechanical, chemical, and biological processes that contribute to their formation.

Key Terms

Humic Material Peat Plate Tectonics Soil Horizons Mesic Material Permafrost

What is a Soil Profile? A soil profile is a vertical cross section of the ground. Soil profiles can show distinct or indistinct layers called soil horizons (see Figure 11). Soil profiles can be used to quickly compare ground characteristics between different locations and to assess whether or not a location is suitable for tasks such as farming.

Figure 11 shows a deep soil profile with a few distinct horizons. Image by Mike Kolman.

What is a Soil Horizon? Soil horizons are layers of soil parallel to the soil surface whose appearance, structure, and/or composition are distinct from soil horizons above and below. Colour is the easiest way to distinguish separate horizons as they can be vastly different from each other. Textures and physical composition are also ways to distinguish separate horizons by sight and by touch, as one horizon can contain large rocks, while another can contain no rocks. When distinguishing by sight and by touch fails, horizons can be distinguished based on their chemical compositions.

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Figure 12 shows distinct soil horizons. Original image by HolgerK.

How do Soil Horizons Form? Soil horizons form through a variety of physical, biological, and chemical processes that impact varying materials to at different depths within the soil. These processes include weathering, erosion, leaching, eluviation, illuviation, acidification, (de)calcification, (de)salinization, decomposition, mineralization, and many others. A few examples of these processes are listed below. ● Physical ○ Water flowing down horizons will transport solid and dissolved materials to lower horizons through eluviation and leaching respectively. ○ Weathering and erosion in the soil will break down rocks, altering the texture and appearance.

● Biological ○ Decomposing materials introduce new nutrients into the topsoil that will eventually make its way into lower horizons. ○ Plants absorb nutrients out from the upper layers of soil, changing the soil chemistry and possibly colour, depending on the nutrients remaining.

● Chemical ○ Acidic solutions in the water can react with minerals and rocks, altering the appearance, texture, and chemistry of that horizon. ○ Leaching can remove salts and calcium, among many other chemicals and elements, which alters the appearance, texture, and chemistry of the soil.

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How do Soil Profiles Compare Across Canada? Soil profiles from different regions can have similar features but no two profiles will be identical, as no two regions will experience the exact same soil altering conditions year in and year out. Figure 13 shows a general overview of some of the unique regions found across Canada. It is important to note that the lines are not distinct between the various soil profiles. They provide a general sense of where these profiles can be found.

Figure 13 shows the five major regions of Canadian soil. Original image by Wikirictor.

● Canadian Shield The landscape of this profile extends from Newfoundland on the east coast of Canada, to the majority of Ontario and Manitoba, to northern portions of Saskatchewan and Alberta, to much of the Northwest Territories and Nunavut. ○ In the past, the Canadian interior was covered with massive glaciers. About 15,000 years ago these glaciers receded north and they stripped away the top layers of soil, leaving behind very little soil and exposing bedrock, forming the Canadian Shield as we know it. ○ Soil profiles throughout the shield exhibit shallow horizons (if any) as there is very little soil and it has not had enough time to develop.

● Mountains and Islands This profile covers all of British Columbia and the Yukon as well as parts of the Northwest territories and the maritime provinces (excluding Newfoundland). Also known as the Cordilleran and Appalachian Orogens. ○ The Earth beneath our feet is not stationary; in fact, quite the opposite. Huge continental and oceanic plates are constantly moving according to the theory of plate tectonics. Quite frequently (and geologically speaking) they crash into each other, causing one plate to rise up and the other to sink below. ○ The rising side forms mountains. If the conditions at the top of the mountain are just right, soil will erode away, exposing the bedrock at the top, while burying the soil at the bottom. This rising can also reorient the horizons, making them less horizontal.

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○ The sinking side forms islands due to water flowing in and eroding the larger landmasses into smaller islands. This can either expose the bedrock below or bury it below a beach.

● Prairies The soil profile for the prairies or the Interior Platform, covers the majority of Alberta, Saskatchewan, Manitoba as well as parts of the Northwest Territories, Nunavut, Ontario, Quebec, and Newfoundland & Labrador. ○ The prairies are safe away from the effects of plate tectonics meaning their soil profiles are more like what was described throughout this section. ○ Soil in this region has had plenty of time to develop relatively undisturbed, making the bedrock much deeper down than in mountainous regions.

● Arctic This profile includes the Innuitian Orogen which is mainly the most northern parts of the Northwest Territories and Nunavut. ○ The arctic region regularly experiences freezing conditions which keeps part of the ground permanently frozen, which is referred to as permafrost (Figure 14). ○ This inhibits the weathering of parent material, making for shallow soil profiles, and making it difficult for leaching to develop horizons. Figure 14 shows permafrost exposed from erosion of the soil above. Image by Finavon. Labelling Soil Horizons Soil horizons are given alphabetical letters that are shorthand for their characteristics and are separated into two main categories: organic and mineral horizons. Soil horizon labels start with a capital letter indicating which category the horizon belongs to and roughly where the horizon is with respect to the surface layer. This is followed by a suffix that gives a more specific description of the horizon characteristics. ● Organic Horizons ○ O - refers to the organic horizon, a layer of grass and moss referred to as peat. ■ Of - refers to fibric or organic materials with easily recognizable origins. ■ Om - refers to mesic material, partially decomposed organic material which contains moderate amounts of moisture. ■ Oh - refers to humic material, highly decomposed organic material that arise from the decomposition and transformation of plant, animal, and microbial residues. ■ Oco - refers to a layer of waste material deposited by aquatic creatures. ○ L - refers to an organic horizon of leaf, twig, and wood litter. ○ F - refers to an organic horizon of partially decomposed litter. ○ H - refers to an organic horizon of highly decomposed litter.

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● Mineral Horizons ○ A - refers to the top mineral horizon called topsoil. Topsoil is located in the zone of leaching and eluviation, where minerals are washed down to lower horizons, and in the zone of maximum organic matter accumulation, where decomposing material from the O horizon washes down to. ○ B - refers to the horizon directly below the A horizon called subsoil. Subsoil is located in the zone of accumulation, where majority of the minerals are leached or eluviated to through the process of illuviation. ○ C - refers to the horizon directly below the B horizon called parent rock or substratum. This horizon is hardly affected by the processes affecting A and B, and contains a lot of parent material. ○ R - refers to the lowest and hardest soil horizon known as bedrock. ○ W - refers to a layer where water starts to appear. Figure 15 shows the major soil horizons. Image by Wilsonbiggs.

It is not uncommon for horizon boundaries to blur together, making them harder to distinguish. As well, it may be difficult to distinguish the boundary between the O and A horizons, making them look like one horizon.

While Sampling While collecting your soil samples, record the following information on the TREE Sample Form and send it back with your samples:

● The start and end of the A and B horizons as measured from the soil surface. o For example, say the soil horizon starts at 1 cm below the surface and ends at 11 cm, this depth will be recorded as 1-11 cm on the returned information sheet. ● The total depth of the pit dug to collect your soil samples.

TREE Video: Digging a Soil Pit Learn about soil horizons and how to dig a soil pit from this TREE video: http://bit.ly/TREE_SoilPit

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Additional Resources Canadian System of Soil Classification Handbook: http://sis.agr.gc.ca/cansis/publications/manuals/1998-cssc-ed3/cssc3_manual.pdf An in-depth information booklet (1998 edition) on the various soils found within Canada and what comprises the different soil horizons.

Synchrotron-Based Techniques in Soils and Sediments: Developments in Soil Science Volume 34 (Textbook), 2006, Edited by Balwant Singh & Markus Grafe, Published by Elsevier A textbook that covers the chemistry, physics, and mineralogy of soils and sediments analyzed using synchrotron- based research techniques. Similar techniques will be used when analyzing your soil at the Canadian Light Source. See Module 6 for more information on this!

References Bastedo, J., James-Abra, E., & Barrett, D. (2017). Canadian shield. Retrieved from https://www.thecanadianencyclopedia.ca/en/article/shield National Research Council of Canada. (1998). The Canadian system of soil classification (3rd ed.). Ottawa: Research Branch, Canada Dept. of Agriculture.

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Section 3.3 The Nutrient Web

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Section Overview

Outcomes

Students will: • Define the nutrient web and describe how it works. • Examine the various processes of the nutrient web, as well as the factors that influence the nutrient web.

Key Terms

Absorption Bioturbation Desorption Perturbation Bioavailability Decomposition Pedoturbation Sedimentation

What is the Nutrient Web? The nutrient web is the exchange of elements and minerals between living and nonliving things. Various physical, chemical, and biological processes help create nutrients, move the nutrients around, and change the bioavailability of the nutrients. All life on Earth depends on the nutrient web in some form or another.

How Does the Nutrient Web Work? The nutrient web is an interconnected set of processes that happen in no particular order; in fact, these processes happen at the same time. Formation • Parent materials form through the sedimentation of nutrients, like minerals and elements, over a period of time and leads to the formation of bedrock and the larger rocks in the soil.

Figure 16 shows the process of sedimentation, where heavier particles fall to the bottom faster than lighter particles.

Perturbation • Perturbation covers all processes that alter soil and comes from the root word perturb, which means to alter from its original condition. • The break down and mixing of parent material and soil is called pedoturbation. Pedo refers to soil. o Everything from a landslide to plate tectonics is included in pedoturbation.

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• Bioturbation is the process when living creatures break down and mix the soil. The prefix bio refers to living creatures. o Bioturbation includes larger burrowing animals such as prairie dogs or moles, to smaller creatures such as worms eating their way through the soil.

Absorption • Nutrients released from the parent material can stay in the soil in either a solid state, in a liquid solution, or in a gaseous mixture. • The nutrients can be consumed or absorbed by plants and animals.

Desorption • The nutrients absorbed by plants and animals will eventually be released, or desorbed, through the exhaling of gases, expelling of solid and liquid waste, or upon the creature’s death and decomposition.

Figure 17 shows the interconnectedness of the nutrient web. Original image by tom.

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What Factors Influence the Nutrient Web? The nutrient cycle is affected by the same factors that influence soil formation from Section 3.1 and they are: parent material, climate, organisms, topography, groundwater, humans, and time. Parent material refers to the rocks and sediments that are broken down to form soil. • The chemical composition of the parent material determines what nutrients are available in the nutrient cycle. • The physical structure of the parent material determines how easily it is weathered into soil. This affects how quickly the nutrient cycle can replenish the nutrients absorbed or lost (see Figure 18).

Figure 18 shows an iron rich sedimentary rock. These are Figure 19 shows a desert climate, where the soil is easily very weather resistant. Image by Andre Karwath. eroded away. Image by Luca Caluzzi.

Climate refers to the long-term trend in weather. • Climate affects the rate of weathering and erosion of soil and parent material (Figure 19). • Erosion of parent material can add nutrients to the cycle, while erosion of the soil can remove nutrients from the cycle.

Any living plant, animal, fungi, insect, and microbe is referred to as an organism. • Organisms absorb and release nutrients, as well as help with the breakdown of parent material (Figure 20). • While the organism still has the nutrients within, it can transport the nutrients to new locations, making it easier or harder to access when released. • Organisms can also change the bioavailability of nutrients, making the nutrients easier or harder for other organisms to absorb. Figure 20 shows prairie dogs emerging from their burrow. Image by Gunnar Ries.

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The term topography refers to the slope, elevation, and orientation of the terrain (see Figure 21). • Having a higher elevation may limit access to key nutrients for plant and animal growth, hindering key steps in the cycle. • Having a large slope may cause a landslide, exposing new parent material, but washing away majority of the nutrients to the bottom of the hill.

Figure 21 shows a landslide and exposed bedrock at the top of Figure 22 shows the flow of groundwater, which can a mountain. Image by Sheri Terris. erode the surrounding soil. Image by USGS.

Groundwater refers to the water stored within the ground. • Groundwater helps dissolve nutrients, making them easier to absorb by plants and animals. • Fast flowing groundwater can also wash away the nutrients, removing them from the local cycle as shown in Figure 22.

You may recall that when the term human is used, it refers to human activity that affects soil and parent material. • Industrial and agricultural activities, such as in Figure 23, alter soil chemistry through fertilizers or resource extraction, affecting what nutrients are available in the cycle. • Pollution in the air, water, and on the ground can add nutrients and toxins to the nutrient cycle.

Figure 23 shows excavators mining for ammolite. Image by Hadal~commonswiki.

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Finally, time refers to the duration that the above factors have to act on the parent material and influence the nutrient cycle (see Figure 24).

• Over long periods of time, a lot of parent material can be broken down to enter the nutrient cycle. Alternatively, a lot of nutrients can sediment into parent material, making them unavailable for absorption. • As a whole and over a long period of time, there is a unique balance between all of the factors affecting the nutrient cycle.

Figure 24 shows the top of a mountain being weathered into smaller rocks. Image by Luis Paquito.

A Dirty Crossword Lesson Identify soil terminology from this section in a fun crossword. Lessons can be downloaded and adapted from here: http://bit.ly/TREE_TeachingResources

Additional Resources Canadian System of Soil Classification Handbook: http://sis.agr.gc.ca/cansis/publications/manuals/1998-cssc-ed3/cssc3_manual.pdf An in-depth information booklet (1998 edition) on the various soils found within Canada and what comprises the different soil horizons.

References National Research Council of Canada. (1998). The Canadian system of soil classification (3rd ed.). Ottawa: Research Branch, Canada Dept. of Agriculture. Soils of Canada. (n.d.). Welcome. Retrieved from https://www.soilsofcanada.ca/index.php

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A Dirty Crossword

Time: 30 minutes or used as part of another lesson. Grade Level: 8 Concepts Covered: Soil vocabulary used through Module 3 Materials Needed: Writing utensils, copies of A Dirty Crossword

KEY QUESTIONS CURRICULUM OUTCOMES (General)

• What do we know about soil? • Identify soil terminology • What terminology is associated with soil? • Understand soil formation processes • What are the different processes in soil • Understand soil horizons formation? • Understand the nutrient web • What are soil horizons and what are the different layers? • What is the nutrient web and how does it impact soil?

INTRODUCTION (Motivational Set)

Ask students the following questions: what is dirt and what is soil? Discuss with students their answers and inform them they will be completing a crossword to further check their understanding of soil terminology that was presented in the Module 3 of TREE.

TASKS

1. Hand out a crossword to each student and with the aid of the module, have them complete the crossword. Students could work in pairs/group. 2. Using the answer sheet provided, have your students either mark their own crossword or trade off with another student. Go over the answers with the entire class, explaining why the answer is what it is to further instill the material.

CONCLUSION

Ask students if there are still any terms they are not quite grasping. Make a note of any they suggest and be sure to review these terms.

SUGGESTIONS FOR ASSESSMENT

- Use the number of correct and incorrect answers to determine a grade/percentage.

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- Or do not use this as an objective assessment but rather a check-for-understanding piece to see if students understand the content.

LESSON EXTENSIONS

- Have students create their own crosswords on any terminology found in the modules and have their classmates complete them.

RESOURCES

- Module 3 of TREE Program

ADDITIONAL NOTES

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A Dirty Crossword: Descriptions Down 1. The depth where the soil is completely filled with water. 2. The state of matter where volume doesn't change, but can take the shape of any container. 3. The slope, elevation, and orientation of the terrain is known as ______. 4. The theory describing the constant movement of continental and oceanic plates. 5. ______refers to the long-term trend in weather. 6. ______is soil that has been removed from the ground. 7. The third planet from the Sun. 8. The lowest and hardest soil horizon. 9. ______refers to human activity that affects soil or parent material. 10. The process of taking away material from soil. 11. The breakdown of soil and rocks where the products remain in the same place. 12. The process of changing the chemical composition of soil. 13. The state of matter where volume doesn't change, but can't take the shape of any container. 14. ______describes how much of a substance is absorbed into a living system. 15. Known as soil formation. 16. Soil permanently frozen for 2 or more years. 17. A ______encourages water to flow quickly, causing landslides. 18. Loss of material by being dissolved in water. 19. The process of depositing leached and eluviated material at a lower horizon. 20. The build-up of hydrogen in soil is a process known as ______. 21. ______refers to any living creature, like plants, animals, fungi, insects, and microbes alike.

Across 1. The feel, appearance, and consistency of soil. 2. Another name for the materials that make up the organic horizon. 3. The material that soil is formed from. 4. The soil profile known for exposed bedrock due to the movement of massive glaciers in the past. 5. The breakdown and movement of soil where the products end up in a new location. 6. ______refers to the clumping of the textural components of soil. 7. The set of processes that alter soil is known as ______. 8. The process of adding material to the soil. 9. Water stored within the soil. 10. The ______connects the hydrosphere, the lithosphere, the atmosphere, and the biosphere. 11. The state of matter where volume can change and can take the shape of any container. 12. The measure of the porous space in a material. 13. A measurement of the acidity of a solution. 14. The process by which parent material forms. 15. A vertical cross section of the ground. 16. Eluviation, Loss of material by floating on water. 17. When talking about geographical location, ______is the height above or below. 18. The easiest way to distinguish soil horizons. 19. A complex mixture of minerals, organic material, and organisms 20. Layers distinct in colour, texture, structure, and or chemical composition from those above and below. 21. Microbes must change ______s bioavailability for plants to use. 22. The most important factor in soil formation.

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Glossary

Absorption - Step in the nutrient cycle that refers to when nutrients that are released from parent material stay in the soil to be consumed or absorbed by plants and animals. Acid Rain - Any form of precipitation that has an unusually low pH. Acid rain increases the rate of weathering on materials like rocks and cement. Acidification - The build-up of hydrogen in the soil, decreasing the pH of a solution (example of soil transformation). This build up can be from adding in acidic materials or solutions, or removing basic ones. Addition - Process that effects soil formation and refers to adding material into the soil. This could be done through adding food compost to soil or through the weathering of larger rocks. Bioavailable/Bioavailability - Refers to how much of a substance is absorbed into a body. The easier the substance is to absorb, the more bioavailable it is. The same element in a different oxidation state will have different bioavailabilities. Bioturbation - The breakdown and mixing of parent material and soil due to plant and animal activities. Climate - The long-term trend in weather. The rate at which soil forms is dependent on the local climate. Colloids - Substances that suspended, but not dissolved, in another substance. The colloid and the substance are suspended exist in separate phases (ex. solids floating in liquid). Colour - In the context of TREE and this module, colour refers to the different colour of the soil horizons. Colours give a visual indication of the elements present and the processes acting on the soil. Decomposition - Decomposition is the process of rotting or decaying, where organic materials break down into simpler materials. Desorption - Step in the nutrient cycle that refers to when absorbed nutrients are released, or desorbed, through the exhaling of gases, expelling of solid or liquid waste, or upon a creature’s death and decomposition. Dirt - Soil that has been displaced from its native environment in a way that is unusable. Not to be used to refer to soil. Eluviation - The loss of solid material due to floating on flowing water (example of soil transfer). Erosion - The breakdown and movement of soil, rocks, minerals, wood, and man-made materials by wind, water, ice, gravity, and organisms (example of soil removal). Products of erosion do not remain in the same place. Groundwater - Refers to the water stored within the ground or soil. Humans - In the context of TREE and this module, humans refer to the human activities that impacts the composition and structure of the soil such as industrial and agricultural activities. Humic Material - Highly decomposed organic material that arises from the decomposition and transformation of plant, animal, and microbial residues. Leaching - The loss of dissolved material due to flowing water (example of soil transfer). Mesic Material - Partially decomposed organic material which contains moderate amounts of moisture. Organisms - Refers to any living plant, fungi, animal, insect, and microbe alike. The rate at which soil forms and the composition and structure of the soil are dependent on the organisms inhabiting the soil.

TREE: Module 3: Soil Page 29

Parent Material - The rocks and sediments in which soil horizons are formed from. Peat - A layer of grass and moss. In terms of soil horizons, peat is part of the organic horizon. Pedosphere - Layer or sphere of Earth the is composed of soil. Pedoturbation - Pedoturbation is the breakdown and mixing of parent material and soil. Permafrost - permafrost is rock or soil that has been below the freezing point of water, 0° C, for two or more years. Perturbation - In a geological context, perturbation is a set of processes that alter the soil. The root word is perturb, which means to alter from its original state. pH - pH stands for the Power of Hydrogen and is a measure of the acidity of a solution. Acidic solutions have pH’s lower than 7, basic solutions have pH’s greater than 7, while neutral solutions have a pH of 7. Plate Tectonics - A theory describing the large-scale movement of the Earth’s continental and oceanic plates. Porosity - The measure of the porous space in a material. It is the ratio between the volume of pores to the total volume. Porous soil allows materials to flow easier, making it susceptible to weathering. Removal - Process that effects soil formation as it that takes material out of the soil. Examples of removal are when someone digs a hole in the ground and removes soil or through the erosion process from wind or water. Sedimentation - Sedimentation is the process of a substance being deposited to form sedimentary rock. Soil Horizons - Layers of soil parallel to the soil surface whose appearance, structure, and/or composition are distinct from soil horizons above and below. Solutes - Substances dissolved in another substance, called the solvent. The solute and solvent exist in the same phase (such as in a liquid). Structure - Refers to the clumping of the textural components. The structure of soil can make it more or less erosion resistant. Texture - The feel, appearance, and consistency of the soil. Soil’s texture is determined by the ratio of mineral components of soil, the ratio between sand, silt, and clay. Topography - Term used to describe the elevation, slope, and orientation of the terrain. The topography of the terrain impacts the rate at which soil forms and the composition and structure of the soil. Transfer - Process that effects soil formation where soil materials are moved between locations such as when the ground is broken up (tilling the ground) or through leaching and eluviation of minerals. Transformation - Process that effects soil formation and refers to altering the chemical composition of soil materials such as when fertilizer is added to soil or through acidification from acid rain. Water Table - The depth where the pores in soil become saturated with water. Weathering - The breakdown of soil, rocks, minerals, wood, and man-made materials through contact with wind, water, ice and organisms (example of soil addition). Products of weathering remain in the same place.