Soils

Question 1

Topsoil

Answer 1

Upper mineral horizon in soil profile that has organic matter incorporated in it

Question 2

Subsoil

Answer 2

The mineral horizons that are below the topsoil horizon

Question 3

Soil Fabric

Answer 3

Solid particles from fragmented rock

fabric is the element of the structure which deals with arrangement of the solid particles

Question 4

Soil Texture

Answer 4

Distribution in size of the mineral particles

Soil textural triangle: amount of clay, sand, & silt

Soil texture significantly influences soil moisture, soil structure, porosity, & chemical activity of the soil.

Question 5

Soil Structure

Answer 5

The arrangement of solid particles in the fabric.

the arrangement, size & shape of the solid parts of the soil and of the pore space located between them.

Question 6

Waterholding Capacity/Available Water

Answer 6

Plant available status of the soil water

Question 7

Aeration

Answer 7

refers to the amount of void space occupied by air

Question 8

Permeability

Answer 8

The rate at which water moves through the soil

Question 9

Infiltration

Answer 9

The rate at which water enters the soil

Question 10

Bulk Density of Soil

Answer 10

Weight of a unit volume of soil

Question 11

Sand

Answer 11

Loose & single-grained.

Squeeze when Dry: fall apart when release pressure

Squeeze when Moist: will cast, but crumble when touched

Question 12

Sandy Loam

Answer 12

Much sand, but enough silt & clay to make somewhat coherent. Can see sand grains.

Squeeze when Dry: a cast that falls apart easily

Squeeze when Moist: a cast that can handle careful handling

Question 13

Loam

Answer 13

Relatively even mixture of sand, silt, & clay. Somewhat gritty yet fairly smooth & slightly plastic.

Squeeze when Dry: a cast that can bear careful handling

Squeeze when Moist: cast can be handled quite freely without breaking

Question 14

Silt Loam

Answer 14

Moderate amount of fine sand, small amount of clay, & over half the particles being silt. When dry it feels soft & floury and lumps are easily broken.

Squeeze when Dry: casts can be freely handled

Squeeze when Moist: casts can be freely handled; but won’t ribbon, rather has broken appearance

Question 15

Clay Loam

Answer 15

Fine textured soil that breaks into clods/lumps when dry.

Squeeze when Moist: cast that bears much handling; forms thin ribbon that breaks easily, barely sustaining its weight

Question 16

Clay

Answer 16

Fine textured soil.

When Dry: forms very hard lumps & clods

When Wet: Very plastic & sticky. It will form a long flexible ribbon

Question 17

Soil Depth

Answer 17

Refers to the portion of soil that is favorable to root development.

Question 18

Clay

Answer 18

• have good water and nutrient holding capacity

- lack of large pore space restricts water and air movement.

Question 19

Silt

Answer 19

• adds little to the characteristics of a soil

- water holding capacity is similar to clay

Question 20

Sand

Answer 20

• Sandy soils have good drainage & aeration
• low water and nutrient holding capacity

Fine sands add little to the soil characteristic & do not significantly increase large pore space
For a soil to take on the characteristics of a sandy soil it needs greater than 50-60% medium to coarse size sand particles.