“It’s more than just dirt” -Mr. Shefferly 3.4 The Soil System.

Its more than just dirt -Mr. Shefferly 3.4 The Soil System

The Soil System Soil is a complex mixture of Eroded rock Mineral nutrients Decaying organic matter Water Air Billions of living organisms (DECOMPOSERS!!)

Soil Formation Over Time

Soil Formation Very Slow Process 1. Weathering of rock (mechanical) 2. Deposition of sediments by erosion (mechanical) 3. Decomposition of organic matter (chemical)

Soil System Food Web

Soil horizons (layers) Soil Layers O - (Organic) Freshly fallen leaves, twigs, animal waste, fungi A- Mixture of partially decomposed organic matter B- (Subsoil) Nutrients leached from A Plant Roots C- (Parent Material) largely inorganic material

Important Cycles (Nitrogen Cycle)

Nitrogen Cycle Terms Nitrogen Fixation: Atmospheric N2 is made available to plants Nitrification: Bacteria in soil convert ammonium to nitrates Denitrification: Bacteria in soil nitrates to nitrogen gas Assimilation: Living organisms take in the nitrogen to make proteins

Carbon Cycle

Soil Content Clay (very fine particles >0.002mm) Silt (fine particles 0.05mm-0.002) Sand (medium-sized particles 2mm-0.05mm) Gravel (large coarse particles < 2mm) Soil Texture is determined by the relative amounts of the different types and sizes of mineral particles Smallest Largest

Soil Texture Triangle

Soil Permeability Rate at which air and water flow from upper layers of soil to lower layers of soil

Soil TextureNutrient Capacity InfiltrationWater Holding Capacity AerationWorkability ClayGoodPoorGoodPoor SiltMedium SandPoorGoodPoorGood LoamMedium

Soil Erosion Movement of soil, especially surface litter and topsoil Two main agents of erosion Wind Flowing water Occurs due to loss of plant in soil from: Overgrazing Deforestation Irrigation

Global Soil Erosion Stable or nonvegetative Some concern Serious concern

Top Soil Erosion and Run Off from Farm

Gully Erosion In Bolivia

Wind removes topsoil

Erosion Continued Erosion is harmful 1. Leads to loss of soil fertility and ability to hold water 2. Increases runoff of sediment that pollutes water and kills fish.

Desertification Enlargement of deserts through human activities Causes: Overgrazing, deforestation, irrigation, and erosion Consequences: Worsening drought, famine, economic losses

Other Soil Issues SalinizationWaterlogging Irrigation water contains small amounts of dissolved salts Evaporation and transpiration leave salts behind Salt builds up in soil Precipitation and irrigation water move downward Water table rises

Soil Issues SalinizationWaterlogging

Toxification An increase in soil acidity ( low pH = more acidic) Caused by leaching of metals Burning of plant material increases soil pH Can be counteracted by using lime stone to raise the pH and reduce acidity Large problem in the Ohio valley in the USA due to coal power plants

Acidity of precipitation measured by the National Atmospheric Deposition Program in 2006. Notice that precipitation is most acidic downwind of the large concentration of power plants in the Ohio Valley. Effect on Soils Neutralization: The effect of acid rain on the environment depends greatly on the ability of soils to neutralize the acid. Limestone and other rocks and soils containing calcium carbonate are most effective. Acids react with calcium carbonate to produce neutral compounds and carbon dioxide. For example, sulfuric acid and hydrochloric acid react with calcium carbonate: CaCO 3 + H 2 SO 4 > CaSO 4 + H 2 CO 3 H 2 CO 3 > CO 2 gas + H 2 O 2HCl + CaCO 3 -> CO 2 + CaCl 2 + H 2 O The extent to which soils can neutralize acid rain depends on several factors: type of soil, thickness, weather, and water flow patterns. If the ground is frozen, as in the winter, soil process cannot work, the acid is not neutralized. If the soil is mainly quartz, such as sand, it is resistant to weathering and no bases are present to neutralize acid. If the soil has very little base such as limestone, the acid is neutralized only slightly or with the passage of time, not at all. In the slightly acidic soils in typical evergreen forests in the Northeastern U.S., Canada, and Europe, two other effects can neutralize the acid rain. The acid can be immobilized as the soil or vegetation retains the sulfate and nitrate ions (from sulfuric and nitric acids). Very deep soils have a large capacity to retain sulfate and nitrate ions. From Virtual ChemBook, Elmhurst College: Acid Rain Soil Interactions.Acid Rain Soil Interactions Mature forest soils are also able to neutralize the acids in rain. Such soils are acidic and rich in humic acids. Krug (1983) reports that mature soils in New England or Norwegian forests have a pH of 3.8, and they may contain as much acid as would fall in 1000 years of rain at 1m/year with a pH of 4.3. These soils are highly resistant to acid rain. In contrast, thin alpine soils lacking carbonates and humic acid and overlying granite rocks are not able to neutralize acid rain. The same is true for disturbed forests where forest fires and logging have reduced the organic material in the soil, which also make the soil more susceptible to damage by acid rain. Leaching of Nutrients Acids leach nutrients from the soil. They are carried deeper into the ground or into streams, depriving plants of essential elements calcium, potassium, magnesium and trace metals. Normally, metals are attached to clay particles produced by weathering of rocks. The H + anion of the acid replaces the metal ions in the clay in a process called ion exchange. The metals occur in groundwater as sulphates and nitrates. Two H + anions displace one Ca 2+ or Mg 2+ anion or two K + anions. Release of Aluminum Aluminum in soils and rock is very insoulable if the pH is greater than 5. More acidic solutiona dissolve aluminum from the soil, and the aluminum is carried into streams and lakes by runoff and groundwater. Effect on Vegetation Bavaria, Germany, high-altitude forest damaged by acid rain. Photo by Spitzbergler. From AccuWeather. More photos of Bavarian forest by Spitzbergler.AccuWeatherSpitzbergler In some regions, especially regions where granite is close to the surface and where soils have been degraded by logging and forest fires, the soil has little ability to neutralize the acid. In these regions, acid deposition depletes the available plant- nutrient cations Ca 2+, Mg 2+, and K +, it increases the leaching of aluminum, and it increases the amount of sulfur and nitrogen in the soil. All lead to weakening of trees, leading to their death by bark beetle infestations and disease. Some of the most dramatic effects on forests have been observed in Europe. In 1983, a survey in West Germany showed that 34% of the country's total forest is damaged by air pollution. This included about one half of the famous Black Forest. Switzerland has recorded damage to 14 % of her forest trees... Vogelmann, measured the reproductive capacity of the forest by counting the total trees in an area. Red spruce dropped from 6,000 trees to 1,000 trees, a decline of 80 % from 1965 to 1983. Very few pine cones and young trees were found. Sugar maple tree counts dropped 84 % and beech tree counts dropped 63% over the same time period... Acid rain or acid cloud droplets that fall on the leaves and needles of trees leaches the nutrients from them. Calcium, magnesium, and potassium ions may be removed from the leaves faster than the roots can resupply them. Acid rain in combination with ozone may damage the waxy coating on leaves and needles. This may weaken, damage them, and provide opportunities for diseases to enter the tree. From Virtual ChemBook Elmhurst College Charles E. Ophardt Acid Rain Effects on Forests.Acid Rain Effects on Forests Effect on Aquatic Animals When nutrients and metals, including heavy metals and aluminum, are leached from the soil, they are carried by runoff and groundwater into streams and lakes where they kill aquatic life. Aluminum dissolved by acid rain is highly toxic to many aquatic animals, especially young animals including eggs and larvae. Not all species of animals are equally sensitive to acids and aluminum. Some fish species (such as (brown bullhead, yellow perch, golden shiner, brook trout, and white sucker) are tolerant of water with pH < 6, while others (such as Atlantic salmon, tiger trout, redbreast sunfish, bluegill, tiger musky, walleye, and alewife) cannot tolerate such waters. Most fish are killed if pH falls below 5.2 (Driskoll, 2001). In areas where soils have little capacity to buffer acids in water, acidic precipitation can be a problem because the infiltrating acidic water can increase the solubility of metals, which results in the flushing of high concentrations of dissolved metals into surface water. Increased concentrations of naturally occurring metals such as aluminum may be toxic to aquatic organisms. Studies of watersheds have indicated that the length of subsurface flow paths has an effect on the degree to which acidic water is buffered by flow through the subsurface. For example, studies of watersheds in England have indicated that acidity was higher in streams during storms when more of the sub-surface flow moved through the soil rather than through the deeper flow paths. Moreover, in a study of the effects of acid precipitation on lakes in the Adirondack Mountains of New York, the length of time that water was in contact with deep subsurface materials was the most important factor affecting acidity because contact time determined the amount of buffering that could take place. US Geological Survey. Circular 1139, Ground Water and Surface Water A Single Resource. Effects of Atmospheric Deposition on the Quality of Ground Water and Surface Water.Effects of Atmospheric Deposition on the Quality of Ground Water and Surface Water Further Reading 1.A good review article article on acid rain in North America by Driscoll (2001) in BioScience. This is a 700kByte PDF file.review article article on acid rain in North America 2.For information on acid rain deposition check the acid rain web pages at the EPA. More information is at the National Atmospheric Deposition Program web pages.acid rain web pagesNational Atmospheric Deposition Program 3.To understand how emissions trading works and how it has led to a reduction of acid rain in the US, read Clearing The Air: The Truth About Capping and Trading Emissions (a 0.6 MByte PDF file).Clearing The Air: The Truth About Capping and Trading Emissions 4.The USGS has a site on acid rain with examples from Washington DC, especially the effects of acid precipitation on buildings. There is an active monitoring program in the US called the National Acid Precipitation Assessment Program (NAPAP) and they have a brief summary on their web site. Environment Canada has also a very informative web page on acid rain (as well as other environmental issues including ozone hole over the Arctic Ocean).acid rain active monitoring programacid rain 5.The EPA publishes Emission Reports listing the amounts of pollutants emitted by individual power plants.Emission Reports 6.A European perspective with many good links can be found at the Swedish NGO Secretariat on Acid Rain.European perspective References DRISCOLL, C. T., G. B. LAWRENCE, et al. (2001). Acidic Deposition in the Northeastern United States: Sources and Inputs, Ecosystem Effects, and Management Strategies. BioScience 51(3): 180--198. Krug, E. C. and C. R. Frink (1983). Acid Rain on Acid Soil: A New Perspective. Science 221 (4610): 520-525. Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has also occurred in regions undergoing acidification. There is evidence that acidification by acid rain is superimposed on long-term acidification induced by changes in land use and consequent vegetative succession. Thus, the interactions of acid rain, acid soil, and vegetation need to be carefully examined on a watershed basis in assessing benefits expected from proposed reductions in emissions of oxides of sulfur and nitrogen. Revised on: 5 January, 2009

Soil Conservation Reduce Erosion by Wind Reduction: Plant trees or bushes as windbreaks near edges of open fields Improving irrigation: Prevent evaporation of water Soil Conditioners : Add lime to raise the pH and prevent the soil from become too acidic Soil Fertility: Rotate crops to prevent the depletion of nitrogen in the soil and add natural manure as fertilizer

Soil Conservation Improve farming Methods: Terracing Contour planting Strip cropping with cover crop Alley cropping, agroforestry Windbreaks or shelterbelts Conservation-tillage farming No-till Minimum tillage

Terracing Reduces soil erosion by controlling water runoff by holding water at each level

Contour Planting/ Strip Cropping Each row acts as a small dam to help slow water runoff and reduce soil erosion

Alley Cropping Crops are planted in alleys between trees/shrubs Provides shade and helps to slow down the release of soil moisture

Windbreak in field Barrier of trees planted around the edge of the crop Prevents wind erosion, provides habitat for birds, and a supply of fuel wood

A soil Lab Must!! Simpsons Diversity Index Review Use the Simpsons diversity index below D = ____________N (N-1)___________________ n1(n11) + n2(n2 1) + n3(n3 1) +nk(nk 1) D = Diversity N = Total number of organisms of all species n = number of individuals of a particular species The higher the D value the more diverse the sample is!!!!!

Now You Try Abundance of Organism Ecosystem AEcosystem B species 135 species 274 species 32612 species 497 species 575 Diversity3.27

Vermicomposting Vermicomposting is the process of having redworms and other decomposer organisms process our organic waste and turn it into a great natural fertilizer (called worm castings). Worm cast = worm poop Creates Healthy Topsoil from waste that would end up in a landfill.

“It’s more than just dirt” -Mr. Shefferly 3.4 The Soil System.

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