Download Structure of Soil Horizons - Environmental Biology - Lab Handout and more Exercises Biology in PDF only on Docsity! Environmental Biology Rev 9/07 1 Lab 2 Soils: The environment under your feet Today’s exercises A. Become familiar with the structure of soil horizons and be able to identify soil textures. B. Become familiar with the tools and methods for sampling forest vegetation A. Today we will visit two forest stands at William Kain County Park. 1) A broad-leafed deciduous forest 2) A confer (pine & spruce stand) You will examine some properties of soil, including ⇒ Learn to identify soil horizons. ⇒ Characterize the soil texture using a ‘texture by feel’ flow chart. ⇒ Compare the soil development under two different forest types. ⇒ Collect organic matter from each forest stand for next week’s lab: Life Under Your Feet. 1. Using the photocopied page from the York County gazetteer and the soil survey map, determine the soil series of the two locations at today’s field site. Then find the soil series description and read it 2. Horizon identification. We will use a nursery shovel to dig some small diameter soil pits. Try to identify the different soil horizons. It is not always apparent to the untrained eye where one horizon stops and the next one begins, or which horizon is which, and they are not always all present. Does our soil match the soil series description? Based on the soil series descriptions, would you expect to reach the C horizon? Look at the litter on the soil surface. What is it comprised of? Peel it back lay by layer to the depth where its botanical structure is indistinct. Can you identify where the coarse organic layer turns into the humus layer? Do you see mycelia (pale yellow to white threads) in it? Roots? Is there a distinct boundary between this organic layer(O) and the mineral soil (A horizon)? Measure the thickness of the O horizon where it has not been trampled. Your instructor will show you how. 3. What color is the soil? Smear some on a piece of white notebook paper. Soil scientists (pedologists) use standard color notation from a Munsell color charts to name soil colors. Here it is sufficient to compare color. Does the soil color differ from among the layers? Where there is iron in the soil, as there is in much of North America, well-drained soil has a yellow or red tone due to oxidized iron, while soil that is poorly drained (though perhaps seasonally dry) has a light gray cast from reduced iron. (This characteristic is used to assist in identifying wetlands.) Organic material typically makes the soil dark brown or black. ( I used to live in a town in Wisconsin called Black Earth.) 4. Soil texture. Feel the soil. Is it gritty? Smooth? Sticky? The sand feels gritty or grainy. Silt particles feel smooth and silky, while clay particles makes soil sticky and colors your hands. Use the ‘texture by feel’ chart to characterize the soil texture. Docsity.com
