HSC Study guide for exam 2ans-2

HSC Study guide for exam 2ans-2 - Soil ecosystems, food...

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Soil ecosystems, food production and food safety 1. What makes soil fertile? o A root environment with oxygen, proper pH (near neutral), low salt, proper nutrients o Mineral nutrients: phosphate, potassium, and others o No leaching 2. Explain how soil texture affects water holding capacity o The texture determines permeability or porosity of soil and this increases or decreases its holding capacity 3. The best type of soil for growing crops is a combination of what three things and what is the combination called? o Sand, clay and slit mixture is called loam. 4. What are the root causes of erosion? 1. Over cultivation 2. Overgrazing 3. Deforestation 5. How do you prevent erosion? 1. Crop rotations 2. No-till agriculture (actually requires the use of herbicides) 3. Use organic fertilizer 4. Contour strip cropping 5. Shelter belts 6. What are salinization and water-logging? Salinization is adding too much salt to the soil and it is caused by trying to irrigate using well water that is too high in minerals in areas with high evaporation, poor drainage Water-logging - crops are irrigated in an area where the subsoil is less permeable. Instead of 7. Goals of sustainable agriculture: 1. Maintain productive topsoil 2. 3. 4. Keep farms economically viable viii. Benefits of organic verse inorganic fertilizer Inorganic is easy to apply but does nothing to build topsoil Organic adds humus to the soil Inorganic contributes to water pollution and a condition called Blue Baby Syndrome ix. What is Blue Baby Syndrome? – Short answer = chemical fertilizer poisons babies  If chemical fertilizer enters the water system, babies may get acute nitrate poisoning because of certain bacteria that may live in their digestive system during the first few months of life. These bacteria change nitrate into toxic nitrite (NO2). The nitrite reacts with hemoglobin (which carries oxygen to all parts of the body) to form methemoglobin, which does not carry oxygen. The level of oxygen being carried throughout the body decreases in proportion to the amount of hemoglobin converted to Methemoglobin. As the oxygen level decreases, the baby is suffocated. This condition is called methemoglobinemia. x.
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This note was uploaded on 04/13/2008 for the course SED Developmen taught by Professor Terivoss during the Spring '08 term at Illinois State.

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HSC Study guide for exam 2ans-2 - Soil ecosystems, food...

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