Packet 2

Question 1

Soil Composition

Answer 1

Soil is composed of mineral particles, organic matter, and living biomass.

Question 2

Fine Earth Fraction

Answer 2

Mineral particle < 2 mm diameter.

Question 3

Coarse Fragments

Answer 3

Mineral particle 2 > mm diameter.

Question 4

Sand Particles

Answer 4

Mineral particle within the size range of 0.05 to 2 mm and visible without microscope.

Question 5

Clay Particles

Answer 5

Mineral particle having effective diameters less than 0.002 mm.

Question 6

Silicate Clays

Answer 6

Those containing crystalline, silicate (SiO4) minerals.

Question 7

Oxide Clays

Answer 7

Those composed solely of oxides of iron or aluminum.

Question 8

Amorphous Clays

Answer 8

Those composed of non-crystalline silicate minerals (i.e. like glass).

Question 9

Soil Colloid

Answer 9

Extremely small mineral and organic particles, with large external and internal surface area.

Question 10

Clay Flocculation

Answer 10

The process of soil aggregation.

Question 11

Specific Surface Area

Answer 11

The surface area per unit mass of a collection of mineral soil particles (cm2 g-1).

Question 12

Soil Texture

Answer 12

The relative proportion of sand, silt, and clay particles in a soil.

Question 13

Soil Organic Matter

Answer 13

Non-living organic carbon in the soil and on the soil surface.

Question 14

Biomass

Answer 14

Living organic carbon compounds in the soil.

Question 15

Dissolved Organic Matter (DOM)

Answer 15

Compounds that are readily assimilated by soil organism. Can be readily leached through the soil.

Question 16

Particulate Organic Matter

Answer 16

The primary carbon and energy source for heterotrophic soil organisms.

Question 17

Humus

Answer 17

Colloidal, gel-like, chemically amorphous and poly-cyclic organic matter that is resistant to decomposition.

Question 18

Black Carbon Organic Matter

Answer 18

Soil carbon from incomplete combustion of plant litter, such as charcoal left from fires.

Question 19

Soil Aggregation

Answer 19

The association of soil particles together with organic matter, into larger sized units called aggregates or peds.

Question 20

Soil Structure

Answer 20

When soil particles, mineral, and organic particles are assembled into aggregates.

Question 21

Granular Structure

Answer 21

Roughly spherical, loosely packed granules.

Question 22

Platy Structure

Answer 22

Relatively thin, horizontal aggregates found in surface and subsurface horizons.

Question 23

Blocky Structure

Answer 23

Irregular but roughly cube like, found in well developed B horizons.

Question 24

Prismatic Structure

Answer 24

Vertically oriented columns of different heights found in subsurface horizons and more commonly in arid and semi arid regions.

Question 25

Single Grained Soil

Answer 25

A soil without aggregates or structure composed mostly of sand sized particles.

Question 26

Massive Soil

Answer 26

Virtually all particles within a soil body are associated, with no separating cracks or voids.

Question 27

Soil Total Porosity

Answer 27

The proportion of the total soil volume that is pore space.

Question 28

Macropores

Answer 28

Large diameter pores (greater than 0.08 mm). present either as inter-aggregate spaces or as biospores.

Question 29

Microspores

Answer 29

Small diameter pores (pore diameters less than 0.08 mm) formed between individual soil particles and component micro aggregates.

Question 30

Inter-Aggregate Pores

Answer 30

Cracks and fissures in a soil profile.

Question 31

Silt Particles

Answer 31

Mineral particle within the size range of 0.002 to 0.05 mm.