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Monday (1/23/2012) Let’s Get Dirty

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1 Monday (1/23/2012) Let’s Get Dirty
Today’s Agenda: 1. Journal Question: Why is soil composition important? 2. *Lecture I: Soil – Foundation of Land Ecosystems 3. Final Exam next Monday (100 Questions) – Good Luck! 4. Free Response Questions next Tuesday (2 Questions) –Good Luck! 4/12/2017

2 2004 AP Environmental Exam Report for Perspective
Multiple-Choice Portion of Exam Fundamental Principles & Concepts: 25 Questions Human Population: 12 Questions Resource Distribution & Use: 13 Questions Environmental Quality: 24 Questions Global Changes: 12 Questions Social & Economic Forces: 13 Questions 4/12/2017

3 2004 AP Report Environmental Exam for Perspective
Free-Response Heavy Metals In Seafood Wind Power Cost Analysis Radioactive Isotopes-Waste Soils-Analysis & Conservation 4/12/2017

4 Soil Particles are Quite Small
In fact, one could say they are mini 4/12/2017

5 Soil: Foundation for Land Ecosystems
A. Soil & Farmland 1. 90% of the world’s food comes from land-based agricultural systems, and the percentage is growing as the ocean’s fish and natural ecosystems are increasingly depleted. 2. As the world’s population moves beyond 7 billion, croplands and grazing lands are being increasingly pressed to yield more crops and other products. 4/12/2017

6 Agriculture Practices
A. The poor agricultural practices of the past 50 years have led to the degradation of 23% of land used for crops, grazing, or forestry. 4/12/2017

7 Agriculture Practices
B. Throughout the world, agricultural soils have been (and continue to be) degraded by erosion, the build up of salts, and other problems that can only undermine future productivity. 4/12/2017

8 4/12/2017

9 Loss of Prime Farmland A. In the United States, another kind of agriculture land loss has occurred: The loss of prime farmland. B. This is happening because farmlands are usually easy to develop and farmers can often sell their land to developers at huge profits. 4/12/2017

10 Productive Soil A. Detritus feeders and decomposers constitute a biotic community of organisms that not only facilitate the transfer of nutrients, but also creates a soil environment that is most favorable to the growth of roots. B. A productive topsoil involves dynamic interactions among the organisms, detritus, and minimal particles of the soil. 4/12/2017

11 Soil A. Soil covers much of the land on Earth. It is made up of minerals (rock, sand, clay, silt), air, water, and organic material (matter from dead plants and animals). B. Soil provides a substrate for plants (roots anchor in soil), a source of food for plants, and a home for many animals (insects, spiders, centipedes, worms, burrowing animals, bacteria, and many others). 4/12/2017

12 Someone that studies soil is called…
Pedologist 4/12/2017

13 Soil Formation A. Soil Formation: Soil is formed slowly as rock (the parent material) erodes into tiny pieces near the Earth's surface. Organic matter decays and mixes with inorganic material (rock particles, minerals and water) to form soil. 4/12/2017

14 Soil Horizons A. Soil Horizons (layers): Soil is made up of distinct horizontal layers; these layers are called horizons. B. They range from rich, organic upper layers (humus and topsoil) to underlying rocky layers ( subsoil, regolith and bedrock). 4/12/2017

15 Soil Profiles: The process of soil formation creates distinct horizontal layers of soil: O Horizon: Humus (surface litter, decomposing plant matter). Humus = residue of partly decomposed organic material. A Horizon: Topsoil. (mixed humus and leached mineral soil) E Horizon: Zone of leaching (less humus, minerals resistant to leaching) B Horizon: Subsoil (accumulation of leached minerals like iron and aluminum oxides) C Horizon: Weathered parent material (partly broken-down minerals; glacial deposits, etc.) -A vertical slice through the different horizons is called the soil profile. 4/12/2017

16 O Horizon O Horizon - The top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter). 4/12/2017

17 A Horizon A Horizon - The layer called topsoil; it is found below the O horizon and above the E horizon. (1) Seeds germinate and plant roots grow in this dark-colored layer. (2) It is made up of humus (decomposed organic matter) mixed with mineral particles. 4/12/2017

18 E Horizon E Horizon - This eluviation (leaching) layer is light in color; this layer is beneath the A Horizon and above the B Horizon. (1) It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation). 4/12/2017

19 Tuesday (January 24) Today’s Agenda:
(1) Journal Question: What is humus? (2) What is eluviation *(3) Soil Horizons Continued & Soil Textures 4/12/2017

20 B Horizon B Horizon - Also called the subsoil - this layer is beneath the E Horizon and above the C Horizon. (1) It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above. 4/12/2017

21 C Horizon C Horizon - Also called regolith: the layer beneath the B Horizon and above the R Horizon. (1) It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer. 4/12/2017

22 R Horizon R Horizon - The un-weathered rock (bedrock) layer that is beneath all the other layers. 4/12/2017

23 Soil Horizons 4/12/2017

24 Soil Texture A. All soils exist in layers and can be characterized by their texture. B. Soil texture; as rock weathers, it breaks down into smaller and smaller fragments. 4/12/2017

25 Soil Texture C. You can see the individual rock particles in sand, and you can see finer particles in silt, and clay is a gathering of the smallest particles. D. Sand, Silt, Clay (large to small) E. Sand, silt, and clay particles constitute the mineral portion of the soil. 4/12/2017

26 Soil Properties A. Soil texture, porosity (a measure of the volume of pores or spaces per volume of soil), and permeability (1) The rate at which water and air move from upper to lower layers of soil, determines a soil’s water holding capacity, aeration or oxygen content (the ability of air to move through the soil), and workability (how easily the soil can be cultivated). 4/12/2017

27 Loam A. A portion that is commonly found in soil consists of roughly 40% sand, 40% silt, and 20% clay. B. A soil with these proportions is called loam. C. Loams are the best soils for growing most crops because they hold lots of water, but not too tightly for plant roots to absorb. 4/12/2017

28 Sandy Soils A. Sandy soils are easy to work, but water flows rapidly through them. B. They are useful for growing irrigated crops or those with low water requirements, such as peanuts and strawberries. 4/12/2017

29 Soil & Plant Growth A. For their best growth, plants need a root environment that supplies optimal amounts of: 1. Minerals 2. Water 3. Oxygen 4. The pH (relative acidity) and salinity (salt concentration) of the soil are also critically important. 4/12/2017

30 Acidic Soils A. The uptake of nitrogen and phosphorus by plants is reduced in acidic soils with a pH below 5.5 and severely reduced in soils with a pH of 4 or lower. B. When soils are too acidic, the acids can be partially neutralized by an alkaline substance, such as lime. 4/12/2017

31 Alkaline Soils A. In dry regions such as much of the western and southwestern United States, rain does not leach away calcium and other alkaline compounds, so soils in such areas may be too alkaline (ph above 7.5) for some crops. 4/12/2017

32 Acid Rain’s Effect on Soil
A. Burning fossil fuels, especially coal, releases sulfur dioxide and nitrogen oxides into the atmosphere. B. These gases form acidic compounds that return to the earth’s surface as acid deposition. C. As acidic rain or melted acidic snow infiltrates the soil, the result is a loss of soil fertility, which can reduce crops and tree growth, making them more vulnerable to drought, disease, and pests. 4/12/2017

33 Soil Fertility A. Soil fertility, the soil’s ability to support plant growth, often refers specifically to the presence of proper amounts of nutrients. B. Farmers speak of a given soil’s ability to support plant growth as the tilth of the soil. 4/12/2017

34 Leaching A. Nutrients may literally be washed from the soil as water moves through it, a process called leaching. B. Leaching not only lessens soil fertility, but also contributes to pollution when materials removed from the soil enter waterways. 4/12/2017

35 Wednesday (1/25/2012) Today’s Agenda: A. Silent Period: B. Work on Study Guide Questions C. AP Exam on Monday (100 Questions) 1/30/12 D. Two Essay Prompts on Tuesday 1/31/12 4/12/2017

36 Thursday (1/26/12) Today’s Agenda: (1) No Talking (-5 or +5)
(2) Be in your assigned seat. (-5) (3) What is loam? (4) Finish Soil Lecture III (5) Work on Revised Study Guide for Final Exam on Monday –Prepare to stay late (make appropriate travel arrangements) 4/12/2017

37 In the News 2012 Solar flare is a bright and bold ball of energy that is released from the surface of the sun A solar flare produces radiation that is hazardous to humans. 4/12/2017

38 Soil Development A. Soils develop and mature slowly.
B. It can take 200 to 1,000 years to develop an inch (2.5 cm) of topsoil (A horizon). 4/12/2017

39 Soil Development C. Well-developed soil profiles, in which distinct O,A,B, and C horizons are visible, are characteristic of older, well-established terrestrial ecosystems. 4/12/2017

40 Soil Fertility A. A fertile soil that produces high crop yields has a thick topsoil layer with lots of humus, which helps topsoil hold water and nutrients taken up by plant roots. 4/12/2017

41 Topsoil Color Indications
A. The color of the topsoil often tells a lot about how useful a soil is for growing crops. B. Dark brown or black topsoil is nitrogen rich and high in organic matter. (Indicative of fertile soil) C. Gray, bright yellow, or red top soils are low in organic matter and need nitrogen enrichments to support most crops. 4/12/2017

42 To support a good crop, the soil must have the following:
1. Have a good supply of nutrients and a good nutrient holding capacity. 2. Allow infiltration, have a good water-holding capacity, and resist evaporative water loss. 3. Have a porous structure that permits good aeration. 4. Have a pH near neutral (pH 7) 5. Have a low salt content. 4/12/2017

43 Soil Degradation A. When key soil attributes required for plant growth or soil ecosystem services deteriorate over time, the soil is considered degraded. B. How is topsoil lost? The most pervasive and damaging force is erosion, the process of soil and humus being picked up and carried away by water or wind. 4/12/2017

44 4/12/2017

45 Soil Degradation C. Farming, logging, construction, overgrazing by livestock, off-road vehicles, deliberate burning of vegetation, and other activities that destroy plant cover leave soil vulnerable to erosion. D. Such human activities can speed up erosion and destroy in a few decades what nature took hundreds and thousands of years to produce. 4/12/2017

46 Soil Erosion A. Most soil erosion is caused by moving water.
B. Three types of water erosion: 1. Sheet Erosion: occurs when surface water moves down a slope or across a field in a wide flow and peels off fairly uniform sheets or layers of soils. 2. Rill Erosion: the surface water forms fast-flowing little rivulets that cut small channels in the soil. 3. Gully Erosion: Rivulets of fast-flowing water join together and with each succeeding rain cut the channels wider and deeper until the become ditches or gullies. 4/12/2017

47 The five golden rules for soil conservation
A. Keep the soil covered. B. Using minimal or no tillage. C. Use mulch to provide nutrients for crops (not fertilizers) D. Maximizing biomass production. E. Maximizing biodiversity. 4/12/2017

48 4/12/2017

49 4/12/2017

50 4/12/2017

51 4/12/2017

52 Evaluating Ecosystem Services (ES)

53 Soil Profiles in Various Ecosystems

54 What do you think? A. How do the soil profiles in plowed farmland differ from those of unplowed natural areas? B. What properties of soils change by the act of plowing, both in the short term and in the long term? 4/12/2017

55 The Rock Cycle 4/12/2017

56 The Rock Cycle 4/12/2017

57 Make Sure You Clearly Understand:
A. Soil and Soil Dynamics (Rock cycle; formation; composition; physical and chemical properties; main soil types; erosion and other soil problems; soil conservation) 4/12/2017

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