Chapter 3 soil science Flashcards
The majority of the fine, absorbing roots of a tree are in the _____ and _____ horizons.
O, A
Driving vehicles across wet soil will ________ the soil and destroy soil ________ _________
Compact, pore space
__________ _________ is the soil property that resists changes to the ph.
Buffering capacity
True/false-negatively charged clay particles hold cations near their surface
True
- In 1 ft of clay soil with 4 inches of water in the soil, approximately how many inches of water would be available to the tree?
1 in
________ ________ modifies the effects of soil texture as the soil particles form clumps or aggregates
Soil structure
- True/false-soil can hold water so tightly in micropores that the ability of tree roots to absorb the water is restricted.
True
On the ph scale, less than 7 is _________, 7 is __________ and more than 7 is __________.
Acidic, neutral, alkaline
True/false-over time, mulching can improve soil structure, reduce compaction, and add organic matter to the soil.
True
A ph of 5 is ______times more acidic than a ph of 7.
100
- The process in which ions of essential elements wash down through the soil profile and are lost is called
Leaching
- Many essential elements are dissolved in soil water in the form of positively charged particles called
Cations
- If the soil is too _________, iron and manganese may be in a chemical form that is unavailable to trees.
Alkaline
- The buffering capacity is the resistance of a soil to changes in ph. Clay soils and soils high in organic matter usually have a _______ buffering capacity
High
- The ________is the zone of intense biological activity near the actively elongating roots.
Rhizosphere
- The diversity of organisms living, moving and interacting in the soil is often referred to as the _____ ______ ______.
Soil food web
- Water that drains from the macropores is called ________ water. Following drainage, the soil is said to be at _________ ________.
Gravitational, field capacity
- True/false-most soil organisms cause disease or decay in tree roots.
False
Field capacity
Maximum soil moisture content following the drainage of water due to the force of gravity
CEC-cation exchange capacity
Ability of a soil to adsorb and hold cations. Measures soil fertility, clay composition, engineering characteristics.
Cations
Positively charged ion.
Horizons
Soil profile o,e,a,b,c
O-Organic layer,
A-absorbing roots and inorganic material
B-mix of surface material and parent material
C-weathered parent materia
Aggregate
Cluster or mix of small particles of soil of differ sizes that are bonded.
Bulk density
Mass of dried soil per unit of undisturbed soil volume.
T/f soils with high percentage of fine particles are easily compacted.
True
In acidic soils
Phosphorus maybe not available and other elements (copper and manganese) may become toxic.
In alkaline soils
Iron, zinc and manganese are unavailable but calcium, magnesium and potassium are available
What do you add to raise the soils ph
Lime
To lower the ph, add
Sulfur
T/f organic matter and clay have a high negative charge density
True
Sodic soil
Soils in which cation sodium occupies an unusually high percentage of Cec.
Mineralization
Organic bound plant nutrients are converted into inorganic plant available forms.
Capillary water
Water that remains is held in micro pores
Teacup effect
If plant is planted in clay soil and backfilled with coarser soil, bowl will retain too much water.
Structural soils
Designed soils that can be compacted to meet engineering requirements and still allow root growth and development.
Actinomycetes
Type of bacteria that is symbiotic with some species and helps decompose organic matter to form hummus.
