O horizon: the O-horizon is made up of organic material. The horizon is found at the soil surface.

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A Good Dirty n Soil Lab: References: Wagner & Sanford. Environmental Science. Wiley & Sons, 2005. Molnar. Laboratory Investigations for AP* Env. Science. Peoples Ed, 2005.

1 A Good Dirty n Soil Lab: References: Wagner & Sanford. Environmental Science. Wiley & Sons, Molnar. Laboratory Investigations for AP* Env. Science. Peoples Ed, Soil Porosity & Permeability Kit. Carolina Biological. Introduction Soil composes a very thin layer, called the pedosphere, on top of most of Earth s land surfaces and is one of the most precious natural resources on Earth. Soils so deeply affect every other part of the ecosystem that they are often called the great integrator. Soils hold nutrients and water for plants and animals. Water is filtered and cleansed as it flows through soils. Soils affect the chemistry of the water and the amount of water that returns to the atmosphere to form rain. The foods we eat and most of the materials we use for paper, buildings, and clothing are dependant on soils. Understanding soil is important in knowing where to build our houses, roads, and buildings as well as understanding environmental impacts. Soils are composed of three main ingredients: minerals; organic materials from remains of dead plants and animals; and pores that may be filled with air or water. A good quality soil for growing plants should have about 45% minerals, 5% organic matter, 25% air, and 25% water. Soils are dynamic and change over time. Some properties, such as soil moisture content, change very quickly (over hours), while other changes, such as mineral transformations, occur very slowly (over thousands of years). Soil formation (pedogenesis) and the properties of the soils are the result of five key factors. These factors are: 1. Parent material: the material from which the soil is formed. Soil parent material can be bedrock, organic material, or surficial deposits from water, wind, glaciers, or volcanoes. 2. Climate: heat and moisture break down the parent material and affect how fast or slow the soil processes go. 3. Organisms: all plants and animals living on or in the soil. The dead remains of plants and animals become organic matter in the soil, and the animals living in the soil affect the decomposition of organic materials. 4. Topography: the location of a soil on the landscape can affect how climatic forces impact it. For example, soils at the bottom of a hil will be wetter than those near the top of the slopes. 5. Time: all the above soil-forming factors assert themselves over time, from hundreds to tens of thousands of year. Soil Profiles Due to the interaction of the five soil-forming factors, soils differ greatly. Each soil on the landscape has its own unique characteristics. The way a soil looks if you dig a hole in the ground is called a soil profile. The soil profile can be used to determine the properties of the soil and the best use of the soil. Every soil profile is made up of layers called soil horizons. Horizons can be identified by changes in color or texture compared to adjacent horizons. Horizons are labeled based on their properties. See the figure on the next page.

2 O horizon: the O-horizon is made up of organic material. The horizon is found at the soil surface. A horizon: the A-horizon is commonly called the topsoil and is the first mineral horizon in the soil profile. The A-horizon is mostly made up of sand, silt, and clay particles, but also contains some decomposed organic material. B horizon: the B-horizon is composed of mineral material which is undergoing chemical and physical weathering. Weathering causes changes in soil color, texture, and structure. The B-horizon is often rich in clays, iron, and aluminum. C horizon: the C-horizon (bedrock) is the parent material from which the horizons above have formed. Soil Characterization In the field, soil pits are routinely dug, and soil horizons are characterized according to color, texture, structure, consistence, amount of roots and rocks. The color of the soil changes depending on how much organic matter is present and the kinds of minerals it contains. Soil color will differ depending on moisture content, and the color can often indicate if the soil has been saturated with water. The texture is the amount of sand, silt, and clay particles in the soil and can be determined by how the soil feels. Sand is the largest size particle in the soil and feels gritty. Silt feels smooth and floury. Clay feels sticky. Soil Porosity & Permeability Throughout the hydrologic cycle, water is in motion. It falls from the sky as precipitation. Then, the water might run off the land surface into streams that feed lakes and oceans, it might evaporate back into the atmosphere to be precipitated again, or it might infiltrate the land surface to become groundwater. Groundwater moves slowly through the subsurface, between grains of soil and sediment and fractures in bedrock. A layer of sediment or rock that yields enough water for human to use is called an aquifer. Aquifers are important natural resources; they supply over half of the US population with drinking water. Aquifers are the only source of drinking water in many rural areas. The amount of usable groundwater in an aquifer and the rate of groundwater flow both depend upon factors involving the void space between grains of soil and sediment and fractures in the bedrock. This void space is also referred to as pore space. The greater the ratio of pore space to material, the higher the porosity and the more water the material can hold. If the pore spaces are interconnected, then the material is permeable, meaning that water can flow through the material from one pore to another. The greater the concentration of interconnected pores (i.e., the higher the permeability of the material), the more easily water can flow through the material from one pore to another. Certain

3 materials such as sand and gravel have both high porosity and high permeability. On the other hand, if there are no pores between grains or if the pores are not interconnected, the material is impermeable. Materials such as clay or crystalline bedrock are impermeable because they have small or poorly connected pore spaces. Lab Overview This lab will consist of multiple parts. Part 1 will consist of determining the soil moisture of the JBS prairie topsoil and JBS lawn. Part 2 will consist of determining the mineral content of the JBS prairie topsoil and JBS lawn. Part 3 will consist of determining the soil texture of the JBS prairie topsoil and JBS lawn. Part 4 will consist of determining the porosity and specific yield of different soil grains, the JBS prairie, and the JBS lawn. Part 5 will consist of determining the permeability of different soil grains, the JBS prairie, and the JBS lawn. Part 6 will consist of making a soil core to determine the depth of the A horizon in the JBS prairie and the JBS lawn. Part 7 will consist of determining the biodiversity index of macroinvertebrates in the soil samples from the JBS prairie topsoil and JBS lawn. Part 1. Soil Moisture 1. Your instructor collected soil for you earlier this week. Your instructor weighed the soil sample and then placed in the oven overnight. Ask your instructor for the original soil weight. 2. Weigh the dried soil to determine percent moisture. Part % Moisture 2. Mineral Content 1. Have someone in your assigned group grind up the dried soil provided into a fine powder. 2. Use the ground soil to determine the ph of the soil and the concentration of phosphorus, nitrogen, and potassium in the soil. Follow the instructions provided in the kits. ph Phosphorus Nitrogen Potassium Part 3. Soil Texture 1. Take a small moist wad of your undried soil sample and squeeze it between your thumb and forefinger. If it feels gritty, then you have mostly sand. If it feels sticky, then you have mostly clay. If it feels neither gritty nor sticky, then you have mostly silt. 2. Try to squeeze out a long, unbroken ribbon of soil from your fingers. If you can then you have mostly clay. If you can squeeze out only a short ribbon, you

4 have silt or loam. If you cannot form a ribbon, then you have sand or sandy loam. Your Qualitative Results: 3. Have someone in your assigned group grind up the dried soil provided into a fine powder. 4. Place about 100 ml of soil into the top of the soil sieve system. Put the lid on the soil sieve system and shake for one minute in an up and down motion. Shake for an additional minute in a swirling motion. Clay, Silt, and Sand can be separated based on their different particle sizes. Chart 1 Particle Size Sand 0.05 mm to 1.00 mm Silt mm to 0.05 mm Clay less than mm 5. Weigh each of the soil sieve screens to determine the percent composition of sand, silt, and clay of the soil sample and record in the data table on the next page. 6. Use the soil triangle to determine the soil texture type. % Clay % Silt % Sand Soil Type Part 4. Porosity & Specific Yield See the attached student guide for instructions and data tables. Part 5. Permeability See the attached student guide for instructions and data tables.

5 Part 6. Core Samples Determine the depth of the O and A horizons from core samples taken. O Horizon Part A Horizon 7. Biodiversity of Soil Macroinvertebrates 1. Take a trowel and resealable bags to each of your sites. Collect enough soil to fill your funnel, being careful to sample the detritus and the underlying soil. Place your sample in a resealable bag labeled with a description of the site and your name. 2. Return to the lab and place your soil sample in the funnel. Label the funnel to indicate your group and the site from which the sample was taken. 3. Place your funnel under a light source and place cup ½ full with alcohol under the funnel. 4. Leave the Berlese funnel under the light source for several days, or until the soil has dried out completely. Replenish the alcohol solution if it begins to evaporate. As the soil dries from the top, the soil arthropods will migrate down into moister soil, until they fall through the mesh into the alcohol solution. After a week 5. Remove the funnel from one bottle and dispose of the soil. 6. Swirl the cup to mix, and then pour the contents into the Petri dish. Rinse any remaining arthropods into the dish using a small amount of the alcohol solution. 7. Place the Petri dish on white paper and, using the hand lens and toothpicks, sort the arthropods by morphology (color, shape, type, and structure). Your group and entire class should get together to characterize the morphotypes so that your data comparisons will be accurate. 8. Record the morphotypes on a sheet of paper and then return the contents of the Petri dish to the cup. 9. All data from the habitat should be combined and all data from the JBS lawn habitat should be combined. 10. Calculate the biodiversity of each habitat by using the Simpson s Biodiversity Index. Enter your data in the table below. Biodiversity Index Reference Chart Soil Type Characteristics Soil Textu re Nutrient- Holding Capacity Waterinfiltration Capacity Water- Holding Capacity Aeratio n Work abilit y Clay Good Poor Good Poor Poor Silt Medium Medium Medium Medium Medium Sand Poor Good Poor Good Good Loam Medium Medium Medium Medium Medium

6 Analysis & Questions (Use the links page for additional help) 1. Why is soil ph important? 2. Why is nitrogen in soil important? 3. Why is phosphorus in soil important? 4. Why is potassium in soil important? 5. Given equal volumes of material, what effect do grain size, grain shape, and sediment uniformity have on the porosity of sediment? Explain your answer. 6. Given equal volumes of material, what effect do grain size, grain shape, and sediment uniformity have on the specific yield of sediment? Explain your answer. 7. Given equal volumes of material, which type of aquifer would produce more water: a sand aquifer or a gravel aquifer? Why?

7 8. How does grain size affect permeability? 9. How are porosity and permeability related? 10. In terms of permeability, how does the mixed sediment compare with the single-size (well-sorted) sediments? 11. Does the soil moisture data and specific yield data correlate? Explain why or why not. 12. Does the soil texture and porosity data correlate? Explain why or why not. 13. Does the soil texture and permeability data correlate? Explain why or why not.

8 14. Which habitat had a greater O and A horizon depth? Why? 15. What correlations did you find between soil quality and the organisms you found in your samples? Why? 16. Which soil do you think would be best for agricultural use? Why? Why not the other sample?

DIRT! APES Laboratory Activity

Name: Part I: Soil Texture DIRT! APES Laboratory Activity Can one determine the texture of soil by examining the particles found in a particular sample? The purpose of this activity is to determine the