Soil Science

Question 1

Parent Material

Answer 1

Underlying bedrock, soils are formed from the breakdown of parent material through biological, chemical, and physical weathering.

Question 2

Horizons

Answer 2

Layers of varying soil components below the surface. O, A, B, C

Question 3

Soil Profile

Answer 3

The nature, arrangement, depth, and number of horizons.

Question 4

Organic Layer

Answer 4

The top horizon level, unaltered soil of thin, decomposing organic material. Contains most of the fine absorbing roots of trees and very biologically active.

Question 5

Aggregates

Answer 5

Organic matter that binds together, which improves soil structure.

Question 6

Soil Texture

Answer 6

Relative fineness or coarseness of the inorganic mineral articles, proportions of clay, sand, and silt.

Question 7

Loam

Answer 7

A mixture of the three different soil sizes and ideal texture for growing plants.

Question 8

Soil Structure

Answer 8

Shape, size, strength and arrangement of soil aggregates.

Question 9

Macropores

Answer 9

Large spaces between soil aggregates, too large to hold water against the force of gravity.

Question 10

Micropores

Answer 10

retain water and are the source of available water to plants between rainfalls.

Question 11

Bulk Density

Answer 11

The mass weight of dried soil

Question 12

Soil Compaction

Answer 12

defined as an increase in bulk density, and a decrease in pore space.

Question 13

pH

Answer 13

Acidity scale, high acidity is 8/9 low is 6/7

Question 14

Buffering Capacity

Answer 14

A high buffering capacity or resistance to changes in pH is found in soils with high clay or organic matter.

Question 15

Ions

Answer 15

Charged particles in water/mineral solutions that are available to the trees through root absorption.

Question 16

Anions

Answer 16

Negatively charged particles

Question 17

Cations

Answer 17

Positively charged particles.

Question 18

Cation Exchange Capacity

Answer 18

A measure of the soil’s capacity to retain, and exchange positively charged cations. CEC can be used as a gauge of soil fertility. Clay and organic matter normally have a high negative charge density this negative charge attracts and holds cations, giving the soils high in clay and organic matter a high CEC.

Question 19

Leach

Answer 19

Wash through the soil

Question 20

Sodic Soils

Answer 20

the cation sodium Na+ occupies an unusually high percentage of the CEC. have the tendency to crust and are associated with high pH. can amend by adding gypsum.

Question 21

Available Water

Answer 21

Capillary water, held in the micropores of the soil and is generally available for plant uptake.

Question 22

Hygroscopic Water

Answer 22

forms a film on the soil particles and is held tightly by the soil for uptake by plants.

Question 23

Water-holding capacity

Answer 23

The total amount of water held by a soil after drainage occurs. varies with soil texture; clay has a higher water holding capacity than sand.

Question 24

Infltration

Answer 24

Used to describe water movement downward in the soil.