Environmental Science - Chapter 11 Test 2

A loam soil is a mixture of

40 percent sand, 40 percent silt, and 20 percent clay

Most plants grow best when the pH value of the soil is at or near

6.0

Topsoil, the layer of soil composed of mineral soil particles mixed with humus, is found in the

A horizon

In a temperate deciduous forest, which soil horizon contains the leaf litter, twigs, seeds, and humus of the forest surface

O horizon

Humus us (or refers to)

a residue of organic matter that remains after most of the rotting and decomposition has occurred

Of the following choices, the smallest-sized soil particles are

clay

The nutrients supporting the lush growth in tropical rainforests are provided by

decaying biomass on the forest floor

Sheet erosion occurs as a result of

decreased infiltration and increased runoff

The process of soil being washed or blown away is called

erosion

Which of the following soil conservation methods would reduce losses due to wind erosion

establishment of shelterbelts

Which of the following would produce the least amount of sediments that could enter bodies of water

forested areas

Which of the following is a characteristic of sandy soils

good drainage but poor water retention

As far as agricultural applications are concerned, the main distinction between topsoil and the underlying subsoil is that topsoil

has a higher humus content

Deforestation is more damaging to tropical soils than temperate zones soils because

high rainfall, uniform warm temperatures and rates decomposition cause rapid loss of humus

Nutrient-holding capacity of the soil is a measure of

how readily nutrients may be leached from the soil

The spongy, dark brown or black material that remains from rotting dead log is called

humus

The process of water soaking into soil is known as

infiltration

The aspect of a soil which determines its fertility is

ion exchange capacity

Some forest plants can obtain nutrients from a symbiotic association with:

mycorrhizal fungi

A method of agriculture that reduces soil disturbance from cultivation is

no-till planting

A soil that allows very little leaching has good

nutrient-holding capacity

Leaching is a term that refers to

nutrients or other chemicals being removed from the soil by water percolating through the soil

Soil texture is a measurement of the

proportion of sand, silt, and clay-sized particles

Which of the following would result from soil compaction

reduced infiltration of water

Which of the following is an effect of plant cover

reduction in wind and water erosion

Which of the following is a symbiotic relationship found in soils

roots of certain plants and fungi

When soils that lack adequate subsurface drainage are heavily irrigated that

salinity increases

leaf litter on a forest floor helps protect underlying soils from

splash erosion

The best agricultural soils in the world are

temperate grassland soils (mollisols)

Mineralization of a type of soil refers to

the loss of its humus content through oxidation

Most land plants require substantial quantities of water to replace water lost through

transpiration

The major source of minerals that cause soil salinization is

use of irrigation water containing dissolved salts

The gradual breakdown of rock into soil particles by physical and chemical processes is called

weathering