Final Exam Review

Question 1

Aluminosilicates

Answer 1

Mineral particles made of silicon, oxygen, and aluminum. Weathered rocks can also change into clay minerals (hydrated aluminosilicates) - have water molecules and platy structure.

Question 2

Smectite

Answer 2

2:1 clay, sandwich-like layer of silica/aluminum/silica. Includes montmorillonite; swells when wet, holds plant nutrients and water well - cations in between layers hold water.

Question 3

Hydrous mica

Answer 3

From weathering of mica, 2:1lattice structure - layers held together by potassium ions. Includes illite; K bonds minimize swell/shrinking, good bearing strength.

Question 4

Kaolinite

Answer 4

1:1 silica/aluminum (least silica). From intense weathering, doesn’t hold nutrients well. Fixed space between layers from hydrogen bonding - less sticky, good bearing strength.

Question 5

Bauxite

Answer 5

Found where aluminum oxide concentrated. Mostly aluminum ore, mined - yields pure aluminum metal

Question 6

Soil capacity

Answer 6

(Cation exchange capacity) The weight of nutrient ions that a given weight of soil can hold. Soil tests determine soil’s nutrient needs. More clay = more capacity.

Question 7

Buffering capacity

Answer 7

Soil’s pH is not easily altered significantly (resistant to pH change). Given by cation exchange capacity. (expl.)

Question 8

Montmorillonite

Answer 8

Smectite group, 2:1, holds nutrients well. Swell when wet, shrink when dry. Troublesome - clay layer slip, low bearing strength; dry - cracks, wet - sticky.

Question 9

Hydrous Mica Group

Answer 9

Mica with water, 2:1 lattice - held together by mutual bonds with K ions between layers (reduces swell/shrink). Good bearing strength, low capacity for plant nutrients - K takes up space.

Question 10

Kaolinite Group

Answer 10

1:1, least silica, in weathered areas, low capacity for nutrients/water absorption. Has fixed space between layers - H (alumina) bonds to O (silica) - less sticky, greater bearing strength.

Question 11

Explain the importance of soil pH to growth of crops

Answer 11

Crops do better in slight acidic to mod. alkaline soil (5.5-8.3, 6.5-7.5 desirable). Helps determine amount of lime/sulfur to add to soil. If soil far from neutral pH: lack of nutrients, nutrients fixed to form unavail. for plant, beneficial microbes diminished.

Question 12

Explain the process of soil aggregation

Answer 12

Colloids cluster into flocc. condition, dispersion (opp. of flocc.) - soil particles don’t cluster when wet. Sodium ions disperse well - leads to hardpan, soil flows together and impermeable to water.

Question 13

Hydrology

Answer 13

The study of the movement of water on Earth. Includes hydrologic cycle.

Question 14

Infiltration

Answer 14

Water moving into the soil.

Question 15

Runoff

Answer 15

Water runs across the soil surface to a stream, marsh, or lake. Happens when the rate of rainfall exceeds the water infiltration rate.

Question 16

Percolation

Answer 16

Water moving down, deeper into the soil (out of the root zone). Water moves towards groundwater.

Question 17

Adhesion

Answer 17

Attraction of soil to water. Helps hold water between soil particles, with cohesion.

Question 18

Cohesion

Answer 18

Attraction of water to other water molecules. Helps hold water between soil particles, with adhesion.

Question 19

Capillary movement

Answer 19

Water moves from particles with thicker films to those with thinner films, next to plant roots. Because of adhesion and cohesion, water always moves toward the root.

Question 20

Xerophytes

Answer 20

Plants with low water requirements.

Question 21

Hydrophytes

Answer 21

Plants with high water requirements.

Question 22

Mesophytes

Answer 22

Plants with moderate water requirements.

Question 23

Field capacity

Answer 23

The maximum amount of water in the soil held against the force of gravity.

Question 24

Wilting point

Answer 24

When the attraction between soil and water is greater than the plant’s capacity for absorption. The plant can no longer absorb water for transpiration and to sustain life.

Question 25

Identify water conservation techniques now in common use.

Answer 25

- Improved timing of watering based on soil moisture. - Plastic lining in ditches to prevent infiltration. - Proper crop selection and plant density. - Attention to plant nutrition. - Better application techniques giving water more directly to roots.

Question 26

Conduction

Answer 26

Kinetic energy transferred from particles in one molecule to an adjacent, cooler molecule. In soil, depends on proportion of solid, liquid, and gaseous phases. Takes more energy to warm soil.

Question 27

Convection

Answer 27

Movement of heated fluid/air involved in heat transfer. Convected in soil by warm rain or wind blowing over soil. Forced - cool air blows over soil. Free - heat rising out of soil to cool air.

Question 28

Radiation

Answer 28

Energy radiated in form of invisible electromagnetic waves. Through sun/core of Earth.

Question 29

Net radiation

Answer 29

Amount of solar radiation reaching earth minus amount reflected by earth. Positive in daytime, negative at night.

Question 30

Soil heat storage

Answer 30

During day, soil is warmed by solar radiation. At night soil radiates energy stored back to colder atmosphere.

Question 31

Latent heat

Answer 31

Solar energy used to evaporate water in soil. Large amount pf energy needed. Positive latent transfer - during condensation, energy released back (dew).

Question 32

Sensible heat

Answer 32

Warms air layer just above soil surface. Negative - heat used to warm air, positive - air already warm, heats surroundings.

Question 33

Leaching

Answer 33

Plant nutrients move down and potentially out of root system.

Question 34

Eluviation

Answer 34

Small clay particles move from topsoil to subsoil. Illuviation - accumulated clay particles.

Question 35

Identify the factors affecting soil temperature.

Answer 35

Soil color - Darker absorbs more heat. Moisture content - How fast soil warms/cools. Direction of soil slope - Facing sun warms faster. Depth of soil - Varies more near surface. Part of the world - determines range in temp.

Question 36

Identify methods of managing soil temperature.

Answer 36

Tilling soil to make rough surface - reduces albedo. Adding vegetation to shade soil - reduces soil temp. Modify slope aspect - increases soil temp.

Question 37

Identify effects of freezing and thawing

Answer 37

Cracks in rocks/minerals - freezing expands water, breaks rock, wears rock down.

Question 38

Identify the forms in which plant nutrients exist in the soil.

Answer 38

Minerals, cations/anions, complex chemical compounds, soluble ions, organic matter

Question 39

Identify the three elements that make up the basic building blocks of all plant compounds.

Answer 39

Carbon, hydrogen, oxygen

Question 40

Identify typical nutrient deficiency symptoms.

Answer 40

Poor or stunted growth, lack of green color (chlorosis), browning tissue (necrosis), yellowing leaves (lack of nitrogen).

Question 41

Identify the nutrients present (in order) in a fertilizer labeled 16-16-16.

Answer 41

Nitrogen, phosphorus, potassium/

Question 42

Macronutrients

Answer 42

Nutrients a plant uses in relatively large quantities. N, P, K, S, Mg, Ca

Question 43

Micronutrients

Answer 43

Nutrients a plant uses in relatively small quantites. Fe, Cl, Mn, Cu, B, Mo, Zn, Ni

Question 44

Beneficial elements

Answer 44

Nutrients/elements a plant can use if missing an essential element (have same VE). V, Co, I, F, Sr

Question 45

Symbiotic nitrogen fixation

Answer 45

Bacteria live in the root system of a plant - mutual benefit for plant and bacteria. Bacteria convert nitrogen to ammonium to be used by plant.

Question 46

Green manure

Answer 46

Crops grown to be plowed under soil, they improve fertility and physical condition of the soil. Legumes (alfalfa/clover) work best - high in nitrogen, Non legumes (wheat/sudan grass) also used.

Question 47

Tilth

Answer 47

Physical condition of soil.

Question 48

Tillage

Answer 48

Incorporating crop residue into soil.

Question 49

Saline Soils

Answer 49

When enough soluble salts are accumulated in the soil to affect plant growth. Shows as white caps in soil.

Question 50

Sodic Soils

Answer 50

When too much sodium is in the soil. Shows as a dark soil, called "black alkaline".

Question 51

Plow Pan

Answer 51

Compacted soil just below till depth, usually from disk tilling. Prevents plant roots from growing down in the soil.

Question 52

Understand the importance of residue management.

Answer 52

Crop residue positively impacts soil, it's organic matter which turns into humus. Can be tilled into the soil immediately after harvest or used as cover for a year to prevent erosion.

Question 53

Erosion

Answer 53

Accelerated washing and blowing of soil as a result of disturbance by humans. Natural process, accelerated by humans.

Question 54

Watershed

Answer 54

The land area that yields water from rain and snow to a particular river (all drains to same body of water).

Question 55

Gullying

Answer 55

Water concentrates in a channel and deepens it rapidly. Starts at the outlet of a channel.

Question 56

Rill erosion

Answer 56

Removal of soil on a side slope by small channels. Leads to the loss of a large amount of soil.

Question 57

Sheet erosion

Answer 57

Soil planes off of land surface by water action without forming channels. Essentially flattens land.

Question 58

Saltation

Answer 58

Bouncing of soil particles after rolling has started by wind. Mostly sand and loosened fine particles, damages plants.

Question 59

Surface creep

Answer 59

Rolling of soil particles on soil surface from wind.

Question 60

Suspension

Answer 60

Fine soil particles (silt and clay) are suspended in the air. Carried long distances, loss of fertile top soil, led to Dust Bowl in 1930s.

Question 61

Mass wasting

Answer 61

Masses of soil moving under the force of gravity.

Question 62

Identify the three main types of water erosion

Answer 62

Gully erosion, rill erosion, sheet erosion.

Question 63

Identify the three main types of wind erosion

Answer 63

Surface creep, saltation, suspension.

Question 64

Understand the basic principles associated with water erosion control

Answer 64

Keep particles from detaching by having stable aggregates with high humus, and adding a vegetative cover. Reduce the rate of flow (attenuate) - water has less energy to transport sediments, more time to infiltrate.

Question 65

Understand the basic principles associated with wind erosion control

Answer 65

Slow down the impact of wind with vegetative cover or a roughened soil condition, they create obstacles to deter or stop erosion. Examples: strip cropping, wind breaks, soil stabilizers.

Question 66

Understand why sediment is viewed as a pollutant

Answer 66

Eroded soil is carried by water until flow slows and sediments drop. Depleted channels from increased sediments increase flood risk, and dams lose value as capacity of the reservoirs decrease.