Ch. 5 Roots Part 3

Question 1

Describe 3 soil components from largest to smallest

Answer 1

sand –> silt –> clay in soil

Question 2

Describe soil pH

Answer 2

 Extreme pH can kill mycorrhizae
* Acidity inhibits growth of nitrogen-fixing bacteria
* Counteract by adding calcium or magnesium compounds
o Example: liming
 Affects nutrient availability
 Alkalinity causes some mineral to become less available
* Example: copper, iron, manganese
 Counteracted by sulfur
* Converted to sulfuric acid by bacteria
 Counteracted by adding nitrogenous fertilizers

Question 3

Describe the human relevance of roots

Answer 3

o Roots Human Relevance
 Food
* Carrots, beets, turnips, sweet potatoes
 Spices
* Sassafras, licorice
 Dyes
 Drugs
* Aconite, ipecac, gentian
 Insecticide
* Rotenone

Question 4

Soil

Answer 4

 Formed through interaction of climate, parent material, topography, vegetation, living organism, and time
 Solid portion of soil consists of minerals and organic matter
 Pore spaces: fill with air or water, between solid particles

Question 5

Describe soil climate

Answer 5

• Varies around globe, effects weathering of rocks
• Desert: little weathering by rain, soil poorly developed
• Moderate rainfall: well-developed soils
• High rainfall: excessive water flow through soil leaches out important materials

Question 6

Describe interactions between soil living organisms and organic composition

Answer 6

• Organisms, roots, and other plant parts
• Bacteria and fungi decompose material from dead materials (plants, animals, etc.)
• Roots produce carbon dioxide, combines with water to form acid and increases mineral dissolve rate

Humus in soil

small animals alter soil through activity and waste

Question 7

Humus

Answer 7

partially decomposed organic matter, gives soil dark color
o Holds minerals and water like sponge
o Plants have less limitations, better environment

Question 8

Topography for soil

Answer 8

• Steep areas: soil may erode (wind, water, ice)
• Flat, poorly drained areas: pools/ponds disappear, negative soil development
• Ideal topography: permits drainage without erosion!

Question 9

Soil Texture and mineral composition

Answer 9

relative proportion of sand, silt, and clay in soil
o Sand: many small particles bound together chemically
o Silt: particles too small to be seen without microscope
o Clay: only seen with electron microscope

Question 10

Field capacity

Answer 10

water remaining in soil after water drains way by gravity
* Determined by soil texture, structure, organic content of soil

Question 11

Permanent wilting point

Answer 11

rate of water absorption insufficient for plant needs

Question 12

Available water

Answer 12

soil water between field capacity and the permanent wilting point