AC-Ch. 3 Soil Science

Question 1

Actinomycetes

Answer 1

Group of soil bacteria resembling fungi. They play a role in the decomposition of organic matter and the release of mineral elements.

Question 2

Aggregate

Answer 2

(1) Close cluster or mix of small particles of soil and/or organic matter of varying sizes that are bonded together. (2) Sand, gravel or small rocks in soil and/or used under paved surfaces. (3) Clusters of flowers or fruits that appear as a single unit. (4) Individual tree crowns that form a canopy.

Question 3

Anion

Answer 3

Negatively charged ion.

Question 4

Buffering capacity

Answer 4

Ability of a soil to maintain its pH.

Question 5

Bulk density

Answer 5

Mass of soil per unit volume. Often used as a measure of compaction.

Question 6

Capillary water

Answer 6

Water held in the capillary pores of the soil much of this water can move in any direction and is readily available to plant roots.

Question 7

Cation

Answer 7

Positively charged ion.

Question 8

Calcium. Magnesium. Potassium. Sodium. Aluminum.

Answer 8

What are the most abundant cations in soil?

Question 9

CEC

Answer 9

Cation Exchange Capacity: The ability of a soil to attract, retain, and exchange positively charged cations. Affected by soil pH and particle size. A measure of soil fertility and clay composition.

Question 10

Clay

Answer 10

Soil particles with a typical grain size less than .004 mm.

Question 11

Field capacity

Answer 11

Maximum soil moisture content following the drainage of water due to the force of gravity.

Question 12

Food Chain

Answer 12

A linear network of links in a food web, often starting with an autotroph, also called a producer, and typically ending at an apex predator, detritivore, or decomposer.

Question 13

Gravitational water

Answer 13

Water that drains from the larger soil macropores due to the force of gravity.

Question 14

Horizon

Answer 14

Layer of soil within the soil profile.

Question 15

Humus

Answer 15

Dark colored, stable form of organic matter formed by the decomposition of plant and animal matter, and a rich source of nutrients improving soil health.

Question 16

Hydroxide

Answer 16

Polyatomic anion of hydrogen and oxygen present in alkaline substances that attracts the monoatomic hydrogen cations in acids.

Question 17

Ion

Answer 17

Atom or a group of atoms with a positive or negative charge.

Question 18

Leach (leaching)

Answer 18

Tendency for elements or compounds to wash down through or into the soil.

Question 19

Loam

Answer 19

Soil texture classification based on a certain ratio of sand, silt, and clay. Considered ideal for plant growth.

Question 20

Macropore

Answer 20

Relatively large space between soil particles (mainly betweeen aggregates) that is usually air filled and allows for water movement and root penetration.

Question 21

Micropore

Answer 21

Space between soil particles that is relatively small and likely to be water filled.

Question 22

Mineralization

Answer 22

Process in which an organic substance is converted to or trapped in inorganic substance.

Question 23

Nematode

Answer 23

Microscopic roundworm. Many are beneficial organisms, but some feed on plant tissues and may cause disease or damage.

Question 24

Nutrient cycling

Answer 24

Movement of mineral elements within an ecosystem as organic matter decomposes, releasing bound nutrients back to plants.

Question 25

Organic layer

Answer 25

Layer of organic at the soil surface.

Question 26

Parent material

Answer 26

Soil bedrock or base material from which a soil profile develops.

Question 27

Permanent wilting point

Answer 27

Point at which a plant cannot pull any more water from the soil and suffers permanent damage.

Question 28

pH

Answer 28

Unit of measure that describes the alkalinity or acidity of a solution. Negative log of the hydrogen ion concentration.

Question 29

Rhizosphere

Answer 29

Soil area immediately adjacent to and affected by plant roots. Typically has a high level of microbial activity.

Question 30

Root exudates

Answer 30

Sugar and other substances that are released into the soil as the root caps and external layers are sloughed off.

Question 31

Saline soil

Answer 31

Soil with a high concentration of soluble salts. Can cause poor plant growth.

Question 32

Sand

Answer 32

Soil particles with a size between.06 and 2.0 mm in diameter.

Question 33

Silt

Answer 33

Soil particles with a grain size between .004 and .062 mm.

Question 34

Sodic soil

Answer 34

Soil with relatively low levels of soluble salts and a concentration of sodium high enough to adversely affect soil structure.

Question 35

Sodic soil

Answer 35

Symptoms include waterlogging erosion soil surface crusting and poor plant growth.

Question 36

Soil compaction

Answer 36

Compression of the soil often as a result of vehicle or heavy equipment traffic that breaks down soil aggregates and reduces soil volume and total pore space especially macropore space.

Question 37

Soil food web

Answer 37

(1) Complex network of interconnected food chains within the soil ecosystem. (2) The diversity of organisms living, moving, and interactng in the soil.

Question 38

Soil profile

Answer 38

Vertical section through the soil and all of the soil horizons.

Question 39

Soil structure

Answer 39

(1) Arrangement of soil particles into aggregates. (2) The shape, size, strength, and arragement of the aggregates within the soil.

Question 40

Soil texture

Answer 40

Relative fineness or coarseness of the inorganic, mineral, soil particles—specifically the relative proportions of sand, silt, and clay.

Question 41

Structural cells

Answer 41

Modular system consisting of units of soil and integrated support structures that serves as both a foundation for paved surfaces and a hospitable environment for tree root growth.

Question 42

Structural soil

Answer 42

Pavement substrate that can be compacted to meet engineering specifications yet remains penetrable by tree roots in the urban environment.

Question 43

Structural soil

Answer 43

Composed of angular crushed stone clay loam and hydrogel mixed in a weight ratio of 100:20:0.03

Question 44

Suspended sidewalk

Answer 44

Sidewalk that is reinforced and supported with piers or other structures so that it does not rely on compacted subgrade or soil for support.