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Soils > Test 2 > Flashcards

Test 2 Flashcards

0
Q

Hydrologic cycle

A

All life depends on and involves run off and excess water

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1
Q

Water balance

A

P=et+ss+d

Et=evapotranspiration
Ss=soil storage
D=discharge

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2
Q

Soil plant atmosphere continuum

A

Water moves from soil to plants to the atmosphere and back to soil

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3
Q

Water deficit

A

Potential water evaporation - evapotranspiration

Is considered a measure of plant stress

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4
Q

Conservation tillage

A

Leaving plant residues on surface to minimize both evaporation loses and erosion

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5
Q

Two ways water leaves the soil

A

Through percolation or drainage that carries with it plant nutrients, pesticides and other dissolved chemicals that can move into groundwater and nearby streams

Through runoff water that carries with it plant nutrients as well as the finer fractions of the soil itself through soil erosion

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6
Q

Preferential flow

A

Percolating water moving rapidly through very large macro pores such as those formed by root holes and earth worms

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7
Q

Vadose zone

A

The unsaturated zone above the water table

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8
Q

Capillary fringe

A

Zone of unsaturated material directly above groundwater table and part of vadose Zone

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9
Q

Problems with preferential flow

A

Brings chemicals and solubles down farther in the soil profile

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10
Q

Open ditches

A

Drainage method used to lower the water table in a poorly drained soil

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11
Q

Buried tile lines

A

Perforated plastic pipe that acts in the same way as an open ditch yet it is not visible and doesn’t provide an obstacle.

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12
Q

Footer drain

A

Used around foundation of the house to keep water level lower and prevent flooded basements. Topsoil is angled away and a drainage pipe is present.

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13
Q

Septic tank

A

Wastewater from homes is piped to a concrete box where the solids settle out and decompose. The liquid effluent overflows into a series of perforated pipes buried which operate in the opposite way of the drainage system

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14
Q

Perc test

A

Used to check for permeability for septic tank

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15
Q

Micro irrigation

A

Trickle or drip systems that apply very small quantities of water directly onto the plant and is the most efficient method

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16
Q

Soil aeration

A

Influences most chemical physical and biological processes in soils

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17
Q

Hydrophytic plants

A

Plants that can adapt to saturated conditions due to aerenchyma tissues that allow them to thrive in water saturated conditions by getting oxygen from the atmosphere

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18
Q

Gases in soil air

A

Nitrogen, oxygen and carbon dioxide

Nitrogen is about 78 percent
Oxygen is about 21
Co2 is definitely higher than that of atmosphere at .035

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19
Q

Aeration status of soil can be determined by:

A

The O2 content in the soil
The proportion of the pores pace filled with air
The oxidation reduction potential of the soil

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20
Q

Redox potential

A

Gives an indication of the tendency of the soil to accept or donate electrons which infuences the ionic species of several elements in the soils.
Measures in Millivolts
400-700 indicates oxidizing conditions
300 to -300 suggest reducing conditions

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21
Q

Colors of redox status

A

Red and brown colors indicate oxidized Fe and Mn compounds

The Blues and Grays predominating under reduced conditions

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22
Q

Factors influencing soil temperature

A

Soil radiation
The specific heat of a soil
Energy needed to evaporate soil water

23
Q

Colloidal particles

A

Very small in size at less than 2 micrometers in diameter and are made up of clay and/or humus.
Carry negative or positive changes that attract particles
The absorbed ions are subject to exchange with plant roots thereby providing plants with most of their essential mineral elements

24
Q

4 colloidal particles

A

Crystalline silicate clays
Allophane and associated non-crystalline silicate clays
Hydrous iron and aluminum oxide clays
Humus

25
Q

Silicate clays

A

Found all over the world but most prominently in temperate regions

26
Q

Allophane

A

Most prominent in volcanic regions

27
Q

Oxide clays

A

Prominent in soils of the tropics

28
Q

Humus

A

Found wherever organic residues are

29
Q

Kaolinite

A

1:1 as in one tetra to octa
Non expanding and no swelling
.7nm
Little isomorphous substitution and therefore low cation exchange

30
Q

Smectite

A

2:1 T/O/T
Expanding and max swelling
1-2 nm between groups

31
Q

Vermiculite

A

2:1
Expanding and some swelling
1.0-1.5 nm
Expansive cation holding capabity

32
Q

Fine grained mica

A

2:1
Non expanding
Minimum swelling
Has higher cation exchange is higher than 1:1 but lower than other 2:1 clays

33
Q

Chlorite

A

2:1
Non expanding
Minimum swelling
1.4nm

34
Q

Tetrahedral

A

Silica sheet called a tetra hedral sheet because of the four sides configuration and associated oxygen atoms.
4 SIDED

35
Q

Octahedral

A

Aluminum and magnesium sheets comprise eight sided building blocks

36
Q

Isomorphous substitution

A

Ions having nearly the same radius as a silicon atom can fit in the tetrahedral sheet.
Once this occurs the crystal is negatively charged attracting cations which then exchange with plant roots

37
Q

Soil acidity or alkalinity

A

Expressed as soil ph, it determines which plants dominate natural landscape and which crops can be grown

38
Q

Natural ph levels in different environments

A

Acidity in humid environments and alkalinity in arid environments.

39
Q

pH scale

A

Natural rain and souls are 5.5 to 6 and pure water is 7

Battery acid is 1 and bleach is 12

40
Q

Causes of alkalinity

A

Caused when hydroxyl ions from carbonates and biocarbonates react with water

41
Q

Role of aluminum

A

Another principle acid cation besides hydrogen, it’s hydrolysis reactions produce H- ions and its toxicity comprise one of the main detrimental effects of soil acidity.

42
Q

Active acidity

A

A measure of the H + ion activity in the soil solution. Quantity of H+ ions in this form is very small.

43
Q

Salt replaceable acidity

A

Gives an indication of the exchangeable Al3- and H+ present on the exchange complex and is equivalent to 200-2000 kg CaCO3 per hectare furrow slice

44
Q

Remaining acidity

A

Mostly associated with aluminum and hydrogen ions that are tightly bound by the organic matter and silicate clays. The amount of residual acidity is commonly much higher than even the salt replaceable form and may be as high as 5000-20000 kg CaCO3 per hectare

45
Q

Total acidity

A

Must be overcome to raise soil ph to a desired value

46
Q

Total acidity definition

A

Sum of active, exchangeable and residual pools of soil acidity (salt replaceable)

47
Q

Acidifying agents

A

This can be done by applying quantities of organic material, sulfur

48
Q

Liming

A

Used to balance the loss of calcium and magnesium in the soil to decrease soil acidity

49
Q

Saline soils

A

pH value of 8,5 or less

50
Q

Sodic soils

A

Have the sodium levels of Saline-sonic soils without the moderating influences of the neutral salts. PH greater than 8.5

51
Q

Flocculation

A

Ability for colloids to form and stick together

52
Q

Primary producers

A

Higher plants and algae

53
Q

Nematodes

A

Highly diverse tiny roundworms. A few species attack plant roots

54
Q

Rhizosphere

A

Populated by a greater abundance and diversity of microorganisms than is the bulk soil

Soils (2 decks)

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