Soils 210 chapter 4 review

T/F biopores are large, continuous channels that begin at or bear the surface and lead deeper into the soil
T
T/F chunks of soil caused by tillage are called clumps
F
T/F soil scientists divide mineral particles into size groups called soil separates
T
T/F gravel and other pieces of stone larger than two millimeters are not considered to be part of the soil texture
T
T/F wet, moist, and dry are descriptive terms for soil consistence moisture levels
T
T/F tilth is a general term for the physical condition of tilled soil and takes into account texture, permeability, structure, and consistence; how easy the soil is to till; how good a seedbed can be made; how easily seedlings can emerge; how easily roots can grow
T
T/F soil temperature is fairly static and not subject to the influences of many factors
F
T/F in soil, there are 14 textural classes
F
T/F a smart grower will approach using soils by taking the following things in to account
1. selecting a crop that will fit the soil
2. managing the soil in a manner that fits the texture
3. improving texture by adding organic material
T
In the ribbon or feel test for determine soil texture, what indicates loamy sand?
no ribboning
total pore space is a measure of soil volume indicating how much it?
holds water and air
what physical property is least likely to be altered by growers?
texture
if soil texture were the same, which soil would be most permeable?
one with granular structure
a soil that is 20% clay and 20% sand is
silty loam
Y/N does pressure applied to the soil surface cause compaction
Y
Y/N does soil particle size affect soil features other than specific surface area and the number and size of pores?
N
Y/N is it true that texture in large areas of soil can be modified easily?
N
Y/N does total pore space measure soil volume that holds air and water?
Y
Y/N are the three groups of traits scientists use to falsify soil structure type, class and grade?
Y
Particle density varies according to the type of ______ in the parent material and the amount of organic matter in the soil
minerals
the most fundamental soil property that influences other soil traits is _____
texture
Sand, silt, and clay make up the fine earth ______ of soil used to determine texture
fraction
_____ soils are easiest to use for landscapes and gardens
loamy
soil structure refers to the way soil particles clump together into larger units. these large units are called _____
aggregates
sand behaves as individual grains and is considered a ____ soil
structureless
occurs where extreme illation has caused a very high clay content in a subsoil layer
claypan
layers of soil in which chemicals cement soil particles together
caliche
layers of soil cemented by a special type of clay common to the tropics
plinthite
clay binds soil particles into a hard, brittle layer
fragipan
tend to occupy lower B and C horizons; peds are 1/5 to 4 inches, forming angular columns that stand upright in the soil
prismatic structure
usually found in E horizons; peds are large but thin, plate-like, and arranged in overlapping horizontal layers
play structure
commonly found in A horizons; peds are 1/25 to 2/5 inch; rounded in form; considered the most desirable of structures
granular structure
typical of many B horizons; peds are 1/5 to 2 inches
blocky structure
small particles; many small pores; consisting mostly of tiny sheet-like crystals
clay
a soil in which sand, silt, and clay contribute equally to the soils properties
loam
large particles; composed mainly of weathered grains of quartz or other minerals
sand
medium-sized particles; silky or powdery to the touch
silt
the mass of a volume of undisturbed of undisturbed oven-dry soil
bulk density
the ease with which air, water, and roots move though soil
permeability
the measure of the rate of water movement through a soil
infiltration
soil characteristics that can be seen or felt
physical property
may indicate that chemicals have leached out or may be due to accumulations of lime, gypsum, or other salts
white to light grey
result from oxide iron minerals
light brown, yellow to red
result from high levels of organic matter
dark brown to black
patches of different colors that suggest the soil is waterlogged for part of the year
mottled
result from reduced iron compounds
blueish-grey
soil particles coming together to form aggregates
flocculation
distinctness of structure; sometimes referred to strength of structure
grade
a measure of soil response to pressure
soil consistence
substance produced by fungi an bacteria that helps form aggregates
glomalin
how easily soil can be molded
plasticity