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Flashcards in SOILS 101 FINAL Deck (189):
1


6 functions of soil


Support plant growth

Control fate of water

Nature's recycling system

Atmosphere modifier

Habitat

Engineering medium

2

6 ways soils support plants


nutrients

water

air

physical support

temperature

protection from toxins

3


Size sand:


1-.05mm

4


size silt:


.05-.002mm

5


size clay


less than .002mm

6


what is weathering?


a biochemical and physical process that involves both destruction and synthesis

7


3 ways to physically weather soils


temperature

freeze/thaw

water, ice, and wind abrasion

8


biochemical processes of weathering


water and acis produced by microbes

rust

9


4 processes of soil formation


transformation

translocation

addition

loss

10


transofrmation


chemical or ohysical alteration

11


translocation


movement of soil by water

12


addition


material input from outside source such as eroded sediment

13


loss


material lost from soil due t water

14


what are the 5 master soil horizion layers?


O

A

E

B

C

15


O horizion


Mainly organic materials above mineral layers

16


A horizion


topmost mineral layer with a bit of organic matter to make it dark. coarse texture

17

e horizion


maximum leaching loss, eluviation of clay, often sandy and white

18


b horizon


zone of illuviation and clays. no longer can see parent material

19


c horizion


unconsolidated material under solum

20


what are the 5 factors that influence soil formation


parent materials

climate

biota

topography

times

21

when do biochemical reactions double


when they are raised 10 degrees CELS

22


Molic Epipedon


Thick Dark High base saturation

23


Melanic Epipedon


Thick Dark mineral horizoon derived from volcanic ash

24

histic epipedon


thick organic horizon forming inw et areas

25


argillic epipedon


high activity silicate clays

26


oxic


veyr highly weather with fe and al oxides

27


spodic


illuvial horizon with accumulation of organic matter and al oxide

28


fragipan


bx horizon of hgihly compacted dense brittle material that resisits any kind of penetration

29

6 soil physical properties


color

texture

structure

density

porosity

compaction

30


where do you find granular aggregates


a horizon

31


where do you find angular or blocky aggregates


b horizon

32


where do you find prismatic aggregates


b and c horizons

33


where do you find massive or structureless aggregates


any horizon

34


particle density


mass of solids/volume of solids

35


bulk density


mass of solids/volume of soil

36


what soil density includes pore space, and which does not?


particle density does not

bulk density does

37


size of macropores


greater than .08mm

38


size of mesopores


between .03-.08mm

39


size of micropores


less than .08mm

40


what percent of the worlds fresh water is in soil


33%

41


cohesion

attraction fpo water molecules to eachother

42


adhesion


attraction of water molecules to other surfaces

43


what is surface tension a result of


qwater molecules having a greater attraction to each other than air

44


name 3 forces that affect potential energy of water


gravity

matric

osmotic

45


matric force


water molecules being attracted to solid surfaces

46


osmotic force


attraction between water molecules and solutes

47


saturated soil


maximum retentive capacity 0kpa

48


field capacity


macropores filled with air -10 to -30 kpa

49


permenant wilting point

all pores filled with air

-1500 kpa

50


volumetric water content


volume of water per dry soil

51


gravimetric water content


mass of water per mass dry soil

52


what are the three types of water movement in soil


saturated

unsaturated

vapor

53


saturated flow


gravitational flow from high to low elevation

54


unsaturated flow


matric flow from high energy to low energy

55


tourtousity


soil pores are not straight like a cappillary

56


plant available water


volume of water present between field capacity and PWP

57


whta is the typical residence time of water in soil


1-2 months

58


evapotranspiration


wtaer lost through evaporation from soil or transpiration from leaves

59


when does infiltration excess occur


the rate of precipiation exceeds the rate of infiltration during hard rains

60


when does saturation xecess occur


amount of precipiation exceeds water holding copacity during long rains

61


acid mine drainage


oxidation of pyrite produces extreme acidity and soluble iron and sulfur

62


the best to the worst way for chemicals to travel through soil


matrix flow

marcopore flow

bypass flow

63


concentration fo what decreases with soil depth?


oxygen

64


what are the 2 methods of soil gas exchange


mass flow and diffusion

65


what makes diffusion happen


concentration gradients

66


oxidation


the loss of electrons in a substance therefore increasing valence charge

67


reduction

gain of electrons therefore a decrease in valence charge

68


what is redox potential?


a measure of how aerobic or anaerobic a system is by measuring the tendency of a substance to give up or take electrons

69


what can anaerobic respiration lead to?


methane ethlyne dentitrification

70


what is a vernalization process?


seeds requiring a cold treatment before germination

71


at what temperature do biological processes cease


5 degrees celsius

72


at what high temperature does microbial activity die?


50-60 degrees celsius

73


frost heaving


soil freezing and pushing objects in it upward

74


what does rain do to the soil in the spring?


warms cool soils

75


what does rain do to soils in the summer?


cools hot soils

76


albedo


the fraction of sunlight reflected by land surface

77


aspect


how the slope of land affects solar radiation

78

What makes a charge variable?


ph levels

79


what makes permanent charge


isomorphus subsitution

80


cations


positive and attracted to negatively charged sites

81


anions

negative and attracted to positively charged sites

82

cation selectivity


some cations bind more strongly than others

83


what is cec


the amount of cations a soil can contain per unit mass

84


what happens to cec as soil ph increases


the cec increases

85


what happens to anion exchnage as ph increases


anioon exchange decreases

86


anions are _________

cations are _________

negative and attracted to positives in low ph

positive and attractued to negatives in high ph

87


what is ph


the concentration of H+ in soil solution

88


what happens to H+ concentration as ph increases


the H+ concentration goes down

89


What is a ph buffer


Something that is resistant to change in ph

90


At what ph do metals become very readily available


low ph

91


What is calcitic limestone vs dolomitic limestone?


When little Mg is present in liming materials it is calcitic

When high levels of Mg are in liming material it is dolomitic

92


What neutralizes acidity in liming material?


The carbonates, not the Mg and Ca

93

What are 4 factors to take into consideration when liming a soil?


Change in ph required

Buffering capacity of the soil

The type of liming material to be used

The fineness of the liming material

94


What is CCE?


The neutralizing value of liming materials.

CALCIUM CARBONATE EQUIVALENCY

95


What is Alkalinity?


The concentration of OH+
 inverse to acidity which is the concentration of H+

96


Where do most alkaline soils exist?


In soils where evapotranspiration exceeds precipitation.

 

DRY SOILS

97


What is often deficient in alkaline soils? Which nutrient?

Microsutrients and Phosphate

98


Where do saline soils reside?


In arears where water runs through the profile and takes up salt. This runoff eventually resides somewhere and concentrates the salts afetr evaporation

99


How is salinity in soil measured?


Electrical Conductivity

100


How do you correct a saline soil?


Flush it with irrigation water that can actually run off without concetrating

 

GYPSUM can be used as a chemical alternative to lower Na

101


What do protists and nematodes prey on?


The primary decomposers

102


What 4 factors in soil that affect microorganism growth?


Organic Matter

Aeration

Moisture and Temperature

Soil fertility an ph

103


What are the 3 things that make up Organic Matter and what does OM contain in general?


Plant Residue

Animal remains and excretes

Living soil microbes

REDUCED CARBON

104


What compounds decompose fast in soil and have a quikc nutrient release?


Sugars and proteins of green cover crop and manure

105


what compounds have a very slow rate of decomposition?


Lignin humus that comes from wood and compost

106


Name 4 ways to increase input of OM


return crop residue

add cover crop

diversifiy crop rotations

add other sources of OM

107


Name 4 internal providers of nutrients


mineral weathering

biological nitrogen fixation

atmospheric deposition

internal recyling of nutrients such as manure

108


What are 2 external nutrient providers


organic and inorganic fertilizers

109


what nutrient is affected by freeze thaw

K Potassium

110


What are 3 essential plant ELEMENTS


Carbon obtained from CO2

Oxygen obtained from O2 and H2O

Hydrogen obtained from H2O

111


When does volitalization occur?


When levels of ammonium are high

112


When does denitrification occur?


By biological means (bacteria) under anaerobic conditions

113


Of the macronutrients, which has very low concentrations?


P

114


What greatly increases P uptake?

Mycorrhizal fungi

115


What is the primary root of P to water systems?


Runoff and erosion

116


what nutrient is most abundant in soils, but not readily availabale?


Potassium

117

Where is K held in soils?


Feldspars and Micas

118


Enrichment ratio


Eroded sediments are enriched with NPK and OM more so than they soil from which they were eroded

119

Contaminant


A material or chemical present in soil greater than normal concentration

120


Pollutant


A material in soil present at a high enough concentratiuon to cause harm

121


Name 8 common types of contaminants

Nutrients

Pesticides

Hazardous organic chemicals

Hazardous Materials

Trace Elements

Acidification

Salinity

Sediments

122


5 peices of technical information when soil contaminants are studied


Normal Background levels

How long the contaminant will persist

Bioavailability

Transport

Toxicity to what organisms?

123


Volitalization


conversion to gaseous forms

124


3 fates of organic chemicals


volitalization

decomposition

sorption

125


What are 3 ways a chemical can decompose and which is the most common


BIOLOGICAL MOST COMMON

Photo

Chemical

126


in situ soil remidiation


treatment of soil without removal

127


ex situ remediation


physical removal of soil.

favored in site with high concentrations in small areas

128


2 methods of ex situ remediation


solidification

vitrification

129


solidification


mixing soil with solidifying agent to produce concretet like product

130


vitrification


heating soil to a high temp like 2000 degrees celcius to produce a melt that is glasslike material

131


4 methods of in situ remediation


solidification

electrokinetics

encapsulation

attenuation

132


can solidification and vitrification be done both in situ and ex situ


yes

133


electrokinetics


appliation of electrical field to mobilize contaminant toward cathode or anode

134


encapsulation

covering a site with a layer of low permeability material

135


attenuation


dillution with an uncontaminated material to reduce concentration

136


Phytostabilization


vegetate a site in order to prevent contaminant from being transported via water or wind erosion

137


phytoextraction


removal of contaminant by plant uptake

138


What do chelates do?


increase metal solubility for phytoextraction via hyperaccumulators

139


What does a triple superphosphate do to soil in AMENDING SOIL


Makes contaminants very NOT bioavailable

140


What is an in vitro bioavailablity test do?


Mimics the human GI track

141


What is a bioreactor ex situ method?


soil introduced usually as slurry to allow complete control of environmental factors

142


what is a land farming?


Spreading contaminated soil over large areas to dilute concentrations and allow indigenous soil microbes to degrade contaminants

143


what microorganism ahs the greatest biomass?


fungi

144


organic to inorganic

inorganic to organic


mineralization

immobilization

145


what is the smallest pool of p


soil solution

146


what are the 2 primary ways to lose SOM


erosion and decomposition

147


what favors net mineralization


a low C:N ratio less than 20:1

148

microorganism with greatest number in soils


bacteria

149


3 properties of plant residue that affect decomposition


chemical content

surface area

C:N ratio

150


reduction of nitrogen to its gaseous form


denitrification

151


ammonia to ammonium


volitalization

152


does a high C:P ratio cause greater than 300:1

 


Immobilization

153


what are stable organic materials highly resistant to change


the passive pool

154


what process adds most notrogen to soil


biological nitrogen fixation

155


name 2 ways to limit p from agriculture to waterways


limit p accumulation and erosion

156


what type of n is not susceptible to leaching, denitrification, and volitalization?


organic N

157


an alkaline soils much p is held in this pool?


Calcium phosphates

158


What are the three steps of soil testing?


obtain example

test

interpret

159


classification of mineral soils based on sand silt or clay


textural class

160


what are the two factors that drive weathering


water and soil microbes

161


the attraction of water to a hydrophillic surface


adhesion

162


what are the three steps of water erosion


detachment, transport, deposition

163


water in this pool has a residence time of 1-2 months


soil solution

164


arrangement of soil particles in large aggregates


granular

165


name 5 factors that determine soil formation


parent material, climate, bioto, time, topography

166


difference between water added and lost


soil water storage

167


void spaces between large soil particles that allow infikltration and aeration


macropores

168


what is removal of material from a zone or horizion?


elluviation

169


What is it called when you add material to a horizion/zone?


illuviation

170


weight of water in a given soil weight


gravimetric sil water content

171


what force primarily acts onw ater in saturated soil


gravity

172


from what does orange and red oxisols come


iron oxides

173


what do you call soil material weathered in place


residual parent material

174


what force moves soil water in unsaturated soils?


matric force

175


soil compacytion causes this parameter to increase


bulk density

176


chemicals dissolved in water move fast to groundwater


bypass flow

177

178

179


what is effective precipitation?


water that infiltrates

This is better in flat areas than sloped areas

180


What are the three pools of acidicty


Acitive

Exchangeble

Residual

181


What form of aluminum is most toxic to plants


Al3+

182


chemoheterotroph


organisms that obtain their carbon and energy from sources previously produced by other organisms

183


chemoautotroph


Organisms that get their carbon and energy from minerals

184


photoheterotroph

organisms that get their carbon from materials previously produced by other organisms and their energy from the sun

185


photoautotroph


organisms that get their carbon from CO2 and their energy from the sun

186


What macronutrient does manure contain a TON of

p

187

188

What is the main force behind soil detachment?


RAINDROPS

189

Why are erosion rates in forest soils slow?


Good O horizon and ground cover