Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Water pollution wikipedia , lookup
Composition of Mars wikipedia , lookup
Deep sea community wikipedia , lookup
Surface runoff wikipedia , lookup
Soil horizon wikipedia , lookup
Soil governance wikipedia , lookup
Soil salinity control wikipedia , lookup
Canadian system of soil classification wikipedia , lookup
ENVR SCI Nov. 2012 Ch 13. Soil and its Uses. Geologic Processes Earth’s Composition – Core (Fe, Ni) Solid Inner Mantle (Silicate ) Solid inner, Plastic-like outer. Crust – Fragmented, solid (plates): Continental 4.5 BY, light color, relatively light weight. Max. thickness 70 Km; Oceanic Crust 200 MY, dark color, heavy weight, Max thickness 10 Km. Plate Tectonics – 12 major fragments (Plates) many small pieces, in motion (Tectonics). Plate boundaries- Divergent (Pull apart) , example Mid Ocean Ridge ; On land examples East Africa ,and Baja California. Convergent (Collision) example on land – Ural Mts, Himalayas, Where Ocean crust collides with Continental crust – Subduction occurs, example Trenches in the western Pacific. Transform boundaries. Where plates move horizontal relative to each other. Example San Francisco. Plate movement results from the transfer of asthenosphere matter by convection cells, and gravity pull. Soils. Loose (unconsolidated) material on the surface of the land. Importance of the soil is due to its influence on (a) Crop yield. (b) what crops are grown and (c) the method of farming practiced. Soil type is a function of (a) the parent rock. (b) the climatic and (c) the topography. Soil formation can be (a) Physical- the fragmentation of rock by any means. (b) Chemical – (1) Hydrolysis resulting from water infiltrating into the rock and subsequently causing its disintegration. (2) Oxidation from oxygen entering into the rock pores leading to its disintegration. (3) Dissolution caused by water dissolving the solid rock. (c) Biological – when an organism ingests a rock and emits finer grain sizes or when it extracts calcium carbonate or silica from the surrounding waters and produces solid rock material. Soil Properties – Texture – grain size (Pebbles/sand/silt/clay) Structure – ability to clump worst case; best texture soil is loam. Composition – the chemical material present in the rock. Porosity - pore space in the soil. Biotic Content – organic material in the soil. Soil Profile is observed in the color changes with depth. The Zone of leaching is the uppermost horizon, otherwise called the A Horizon; The Zone of Accumulation is the B Zone; The deeper Zone or C Horizon is the weathered zone. Below the C horizon is the Parent Rock. Additionally, there is an Organic zone (O Zone) on the ground surface. An E Horizon is a thin brightly colored E Zone at the base of the A horizon. Soil Types of particular interest are Desert soil called Pedocal; and Rain forest soil is a Pedalfer. Prairie soil is particularly fertile because of its content of organic matter, and good porosity. Soil Erosion is the wearing away and removal of the soil by Ice or Water or Wind. As a consequence of erosion, soil fertility is reduced, air and water pollution is increased, dredging of waterways becomes critical for barge and ship transportation in land, and fish habitats are destroyed. Soil Conservation is maintained by several methods, but the most common is by (a) enhancement of organic matter in the soil. (b) No Till farming. (c) Efficient pest’s management. (d) Prevention of Compaction. (e) Crop diversity and or rotation. (f) Maintain ground cover. Presently, US soils are used 20% crops, and 24% pasture. Europe uses 30% for crops and 17% for pasture. Africa has 6% in cropland and 3% in pasture. The Methods of Farming The major influencing factors are : Climate, Plot size, soil texture, Topography, Drainage, and Fertility. Contour farming (Tilling direction) Strip farming (alternating ridges tilled) Terracing (does not accommodate heavy machinery) Use of wind breaks and sodded waterways. Conservation Practices: Mulch tillage Strip Tillage No Till Conventional Farming generally follows the procedure of Plow, Disc and Harrow – three times before planting. Benefits to conservation practices are: Less erosion less fuel use; less soil compaction; more free time; Drawbacks to conservation practices: lower production; more fertilizer use; more pesticide use; US Federal land use classification: 8 groups Grazing; lumber harvesting; wild life protection; watershed protection; Urban; industrial; crop land and Recreation.