Chapter 2 Inorganic Solids in Soil. Soil Chemistry includes: Components of soil –Inorganic (soil minerals, salts, metals) –Organic (aggregates, humus,

Download Chapter 2 Inorganic Solids in Soil. Soil Chemistry includes: Components of soil –Inorganic (soil minerals, salts, metals) –Organic (aggregates, humus,

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<ul><li> Slide 1 </li> <li> Chapter 2 Inorganic Solids in Soil </li> <li> Slide 2 </li> <li> Soil Chemistry includes: Components of soil Inorganic (soil minerals, salts, metals) Organic (aggregates, humus, plant residues) Solution Gases Processes important to plant growth and environmental applications Ion exchange capacity Sorption/Complexation </li> <li> Slide 3 </li> <li> Composition Soils are: porous open systems (to atmosphere, hydrosphere, biosphere) multi-component products of weathering dynamic, constantly changing, not static </li> <li> Slide 4 </li> <li> Soil Solids &gt;90% solids are inorganic in most soils. USDA major size fractions used by soil scientists in U.S.: clay ( </li> <li> Common elements O and Si are two most common elements by weight and volume O &gt; Si &gt;&gt;&gt; Al &gt; Fe &gt;&gt; C, Ca, Mg, K, Na aluminosilicates and silicates minerals that are made up of Si-O-Al and Si-O molecular framework </li> <li> Slide 7 </li> <li> </li> <li> Slide 8 </li> <li> Essential and toxic ions Macronutrients: H, C, N, O, Mg, P, S, K, Ca Animals also need Na, Cl Micronutrients: B, Cl, V, Mn, Fe, Cu, Zn, Mo Animals also need F, Si, Cr, Ni, Co, As, Sn, Se, I The list changes with progress in experimental techniques </li> <li> Slide 9 </li> <li> </li> <li> Slide 10 </li> <li> Nutrients in plants and animals Light atomic weight, concentrated at earths surface (heavier metals form the core of earth). Evolution took advantage of elements abundant at the surface. Plants can tolerate a much wider range of mineral concentrations than animals. Chemical spatial variability of soils causes variations in mineral concentrations of plants animals should eat a variety of plants and plants grown on different soils. </li> <li> Slide 11 </li> <li> Minerals in Soil as Sources of Elements and Ions Mineral: "natural, inorganic homogenous compound with definite chemical composition and ordered atomic arrangement </li> <li> Slide 12 </li> <li> Examples of ionic crystalline solids </li> <li> Slide 13 </li> <li> Unit Cell Smallest repeating 3-D array of atoms in a crystal. Minerals are often reported in half-cell formulas for simplification be aware! Ex: Kaolinite Unit cell = Si 4 Al 4 O 10 (OH) 8 Half-cell = Si 2 Al 2 O 5 (OH) 4 </li> <li> Slide 14 </li> <li> html </li> <li> Slide 15 </li> <li> </li> <li> Slide 16 </li> <li> Soil clay minerals Silica Tetrahedrons one building block of soil minerals Crystal pictures are from Bob Harter at Univ. of New Hampshire </li> <li> Slide 17 </li> <li> Figure 1: Single silica tetrahedron (shaded) and the sheet structure of silica tetrahedrons arranged in a hexagonal network. </li> <li> Slide 18 </li> <li> Aluminum Octahedrons another building block or layer in minerals </li> <li> Slide 19 </li> <li> Single octahedron (shaded) and the sheet structure of octahedral units. </li> <li> Slide 20 </li> <li> Various linkages of the tetrahedra create classes of silicates: week2/sillmin.jpg </li> <li> Slide 21 </li> <li> </li> </ul>