Midterm Study Guide Flashcards

1
Q

How was soil fertility managed during the Neolithic?

A

Slash and burn

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2
Q

What fertility theory dominated the Middle Ages?

A

Humus theory

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3
Q

What characterizes Humus Theory?

A

The idea that plants “eat” soil particles.

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4
Q

How does the practice of tillage relate to Humus Theory?

A

It was believed that finer soil particles facilitated plant root ingestion of soil for fertility.

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5
Q

What fertility theory arose in the 19th century?

A

Mineral plant nutrition; NPK

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6
Q

Who discovered that plant carbon comes from the atmosphere, not soil?

A

Justus von Liebig

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7
Q

Who discovered N-fixation?

A

Hellriegel and Wilfarth

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8
Q

Approximately half the yield increases from the Green Revolution were from _____.

A

Fertilization

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9
Q

Fertilizer use efficiency is generally ____% or less.

A

40

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10
Q

Sustainable agriculture is related to alternative/organic agriculture. (T/F)

A

F

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11
Q

Sustainable approaches can be incorporated into any agricultural system. (T/F)

A

T

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12
Q

Sustainability of a farming system is only marginally related to fertilizer (organic/inorganic) or other inputs. (T/F)

A

T

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13
Q

Intrinsic soil factors, rainfall or irrigation practices, and management related factors have a greater influence on farm sustainability than soil amendments or other inputs. (T/F)

A

T

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14
Q

What legislation provided for land-grant state colleges and universities for agriculture and mechanical arts?

A

Morrill Act 1862

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15
Q

What legislation gave federal land grants to states in order to create a series of agricultural experiment stations to study soil minerals and plant growth?

A

Hatch Act 1887

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16
Q

What legislation assisted states in carrying on a program of forestry research and for purposes of developing/utilizing resources from forests and related rangelands?

A

McIntire-Stennis Act 1962

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17
Q

Major agricultural research drivers in the last century:

A

-Food supply and safety
-Land expansion
-Population growth
-Limitations on renewable resource availability
-Maintaining productivity

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18
Q

Most funding for research now comes from the ____ sector.

A

Private

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19
Q

The relationship between essential nutrient concentration and plant growth:

A

As nutrient concentration increases towards critical range, plant yield increases. Above the critical range, the plant contains sufficient levels for normal growth and can continue to absorb nutrients without increasing yield (luxury consumption). Excessive absorption can be toxic and reduce yield.

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20
Q

The technological innovation that provides inorganic nitrogen for fertilizers.

A

The Haber-Bosch process

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21
Q

What factors of precipitation affect plant growth?

A

Quantity and distribution

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22
Q

What is the thesis of the Malthusian Population Trap?

A

Population expands geometrically, food production increases arithmetically

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23
Q

What is Liebig’s Law of the Minimum?

A

Plant yield is directly related to the minimum or limiting nutrient; yield will not increase if more nutrients other than the limiting one are added.

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24
Q

What are micronutrients?

A

Nutrients required in smaller amounts and may only be required by certain plants.

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25
Q

What are the essential macronutrients?

A

NPK, Mg, Ca, and S (also C, O, and H)

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26
Q

What are the essential micronutrients?

A

B, Cl, Mn, Fe, Ni, Cu, Zn, and Mo

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27
Q

Mg is a (macro/micro) nutrient.

A

Macro

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28
Q

Ca is a (macro/micro) nutrient.

A

Macro

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29
Q

S is a (macro/micro) nutrient

A

Macro

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30
Q

Fe is a (macro/micro) nutrient.

A

Micro

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31
Q

P is a (mobile/nonmobile) nutrient.

A

Mobile

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32
Q

Mg is a (mobile/nonmobile) nutrient.

A

Mobile

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33
Q

Cl is a (mobile/nonmobile) nutrient.

A

Mobile

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34
Q

Mo is a (mobile/nonmobile) nutrient.

A

Mobile

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35
Q

K is a (mobile/nonmobile) nutrient.

A

Mobile

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36
Q

N is a (mobile/nonmobile) nutrient.

A

Mobile

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37
Q

Ni is a (mobile/nonmobile) nutrient.

A

Nonmobile

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38
Q

Zn is a (mobile/nonmobile) nutrient.

A

Nonmobile

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39
Q

B is a (mobile/nonmobile) nutrient.

A

Nonmobile

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40
Q

Fe is a (mobile/nonmobile) nutrient.

A

Nonmobile

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41
Q

Ca is a (mobile/nonmobile) nutrient.

A

Nonmobile

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42
Q

Mn is a (mobile/nonmobile) nutrient.

A

Nonmobile

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43
Q

S is a (mobile/nonmobile) nutrient.

A

Nonmobile

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44
Q

Cu is a (mobile/nonmobile) nutrient.

A

Nonmobile

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45
Q

What are the general plant symptoms of mobile nutrient deficiencies?

A

Older leaves will display deficiency symptoms before younger leaves.

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46
Q

What are the general symptoms of immobile nutrient deficiencies?

A

Younger leaves will display deficiency symptoms first, and symptoms may be localized.

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47
Q

The most concentrated nutrients in plants are ___ and ___.

A

O and C (about 45% each)

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48
Q

H concentrations in plants are ____%

A

6

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49
Q

N concentrations in plants are ___%.

A

1.5

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50
Q

K concentrations in plants are ___%.

A

1

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51
Q

P concentrations in plants are ___%.

A

0.2

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52
Q

Ca concentrations in plants are ___%.

A

0.5

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53
Q

Mg concentrations in plants are ___%.

A

0.2

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54
Q

S concentrations in plants are ___%.

A

0.2

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55
Q

Micronutrient concentrations in plants are less than or equal to ___%.

A

0.01

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56
Q

Macronutrient concentrations in plants are greater than or equal to ___%.

A

0.2

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57
Q

What is the Steenberg effect?

A

A rapid yield increase with added nutrients can cause a small decrease in nutrient concentrations in the plant.

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58
Q

What are essential plant nutrients?

A

Mineral elements required for plant growth and development

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59
Q

The criterial for essential elements:

A

-Required for growth and reproduction
-Specific (can’t be replaced)
-Acts directly

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60
Q

Silica is an essential nutrient (T/F).

A

F (beneficial)

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61
Q

Na is an essential nutrient (T/F).

A

F (beneficial)

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62
Q

Co is an essential nutrient (T/F).

A

F ( beneficial)

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63
Q

Se is an essential nutrient (T/F).

A

F (beneficial)

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64
Q

B is an essential nutrient (T/F).

A

T

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65
Q

Cl is an essential nutrient (T/F).

A

T

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66
Q

Mn is an essential nutrient (T/F).

A

T

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67
Q

Fe is an essential nutrient (T/F).

A

T

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68
Q

Ni is an essential nutrient (T/F).

A

T

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69
Q

Cu is an essential nutrient (T/F).

A

T

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70
Q

Zn is an essential nutrient (T/F).

A

T

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71
Q

Mo is an essential nutrient (T/F).

A

T

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72
Q

In the inorganic components of soil, (primary/secondary) minerals provide the greatest ion exchange capacity.

A

Secondary

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73
Q

How to minerals contribute to nutrient availability?

A

Ion exchange; weathering.

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74
Q

The hydrolysis of feldspar yields ____.

A

Kaolinite

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75
Q

The oxidation of biotite yields ____.

A

Iron oxides

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76
Q

The hydrolysis of biotite yields ____.

A

Vermiculite

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77
Q

How is CEC defined?

A

meq/100g soil

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78
Q

1meq/100g = __ cmol/kg

A

1

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79
Q

Equivalent weight =

A

grams/equivalent

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80
Q

For a monovalent ion, equivalent weight =

A

Atomic weight

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81
Q

For a divalent ion, equivalent weight =

A

1/2 atomic weight

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82
Q

How does pH affect CEC?

A

Low pH decreases; high pH increases

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83
Q

(1:1/2:1) clays are non-expanding.

A

1:1

84
Q

(1:1/2:1) clays are pH dependent.

A

1:1

85
Q

(1:1/2:1) clays are low CEC.

A

1:1

86
Q

(1:1/2:1) clays are non-sticky.

A

1:1

87
Q

(1:1/2:1) clays are expanding.

A

2:1

88
Q

(1:1/2:1) clays are constant charge.

A

2:1

89
Q

(1:1/2:1) clays are high CEC.

A

2:1

90
Q

(1:1/2:1) clays are sticky.

A

2:1

91
Q

(1:1/2:1) clays are low surface area.

A

1:1

92
Q

(1:1/2:1) clays are high surface area.

A

2:1

93
Q

What is the source of permanent charges in clays?

A

Isomorphous substitution

94
Q

What is isomorphous substitution?

A

Substitution of the central atom of a clay sheet with a similarly sized atom.

95
Q

What soil particles have mainly pH dependent charge?

A

1:1 clays, OM, oxides.

96
Q

How is CEC estimated?

A

The sum of: (CEC x percent composition) of the constituents.

97
Q

How is CEC determined in the lab?

A

NH4 used to replace all other cations on exchange complex, ethanol rinse to remove excess, then Ba2Cl OR KCl used to extract NH4 ions. Filtrate analyzed to determine CEC.

98
Q

ppm =

A

mg/L

99
Q

How do clay type and SOM influence buffering capacity?

A

Higher CEC –> higher buffering capacity

100
Q

What is buffering capacity?

A

The ability to resupply nutrients to soil solution.

101
Q

CEC: OM (>/<) clay

A

>

102
Q

Base saturation is defined as:

A

% of CEC occupied by Ca, Mg, K and Na.

103
Q

How does base saturation affect soil pH?

A

Higher base saturation –> less acid cations –> higher soil pH

104
Q

Do plants have ion exchange properties?

A

Yes, the roots.

105
Q

Monocots have (higher/lower) plant root CEC.

A

Lower

106
Q

Dicots have (higher/lower) plant root CEC.

A

Higher

107
Q

Why have dicots evolved more CEC?

A

Roots have less surface area; must compensate to remain competitive.

108
Q

Lyotropic series:

A

Al>H>Ca>Mg>K=N>Na

109
Q

Adsorption strength of an ion depends on ____ and ____.

A

Valence and hydrated radius size.

110
Q

Greater valence —> _____ adsorption strength.

A

Greater

111
Q

Greater hydrated radius size –> ____ adsorption strength.

A

Weaker

112
Q

Anion lyotropic series:

A

PO4>SO4>NO3

113
Q

(Sandy/clay) soils require higher rates of fertilizer application to maintain the same solution concentration.

A

Clay

114
Q

How does soil water content affect the solubility of minerals?

A

Less water —> more precipitation/less solubility

115
Q

How are nutrients within SOM released?

A

Mineralization by microorganisms.

116
Q

C/N/P/S =

A

100/10/1/1

117
Q

What is the difference between mass flow and diffusion?

A

Mass flow occurs by evapotranspiration, while diffusion occurs by movement along a concentration gradient.

118
Q

How do dry soil, low soil temperatures, and hot afternoons affect mass flow?

A

Reduces transpiration –> reduces mass flow

119
Q

Finer textured soils have a (lower/higher) effective diffusion coefficient.

A

Higher

120
Q

At a given level of saturation, (1:1/2:1) clays will supply more of a nutrient.

A

1:1

121
Q

High CEC –> (more/less) diffusion

A

Less

122
Q

What mainly determines the mobility of a nutrient in the soil solution?

A

Quantity in soil solution in relation to quantity needed by crop.

123
Q

Nutrient mobility (increases/decreases) as nutrient deficiency increases.

A

Decreases

124
Q

SO4 has ___ mobility in the soil solution.

A

High

125
Q

Cl has ___ mobility in the soil solution.

A

High

126
Q

NO3 has ___ mobility in the soil solution.

A

High

127
Q

Na has ___ mobility in the soil solution.

A

High

128
Q

Ca has ___ mobility in the soil solution.

A

Intermediate

129
Q

Mg has ___ mobility in the soil solution.

A

Intermediate

130
Q

K has ___ mobility in the soil solution.

A

Intermediate

131
Q

NH4 has ___ mobility in the soil solution.

A

Intermediate

132
Q

MoO4 has ___ mobility in the soil solution.

A

Low

133
Q

PO4 has ___ mobility in the soil solution.

A

Low

134
Q

Micronutrient metals have ___ mobility in the soil solution.

A

Low

135
Q

Why do some cations that adsorb strongly to the CEC move primarily by mass flow?

A

High prevalence on CEC causes constant exchange, increasing concentration in soil solution

136
Q

(Mobile/Immobile) [in soil] nutrients have larger zones of depletion.

A

Mobile

137
Q

(Mobile/Immobile) [in soil] nutrients have stronger sorption on soil colloids.

A

Immobile

138
Q

(Mobile/Immobile) [in soil] nutrients have larger soil reserves.

A

Immobile

139
Q

(Mobile/Immobile) [in soil] nutrients have higher buffering capacity.

A

Immobile.

140
Q

(Mobile/Immobile) [in soil] nutrients have higher availability to plants.

A

Mobile

141
Q

(Mobile/Immobile) [in soil] nutrients have greater accumulation at soil surface.

A

Immobile

142
Q

(Mobile/Immobile) [in soil] nutrients have greater leachability.

A

Mobile

143
Q

(Mobile/Immobile) [in soil] nutrients have greater short-term crop recovery.

A

Mobile

144
Q

(Mobile/Immobile) [in soil] nutrients have greater competition between plants.

A

Mobile

145
Q
A

Mobile

146
Q
A

Immobile

147
Q
A

Mobile

148
Q
A

Immobile

149
Q
A

Immobile

150
Q

What is the difference between passive and active nutrient uptake by roots?

A

Cell must use energy to use active uptake.

151
Q

How do different types of clay supply nutrients to the soil solution differently?

A

1:1 clays will supply more of a nutrient at a given level of saturation.

152
Q

Nutrient mobility (increases/decreases) as a nutrient deficiency (in the plant) increases.

A

Decreases

153
Q

Diffusion is a type of (active/passive) cellular transport.

A

Passive

154
Q

Facilitated diffusion is a type of (active/passive) cellular transport.

A

Passive (What about transporter proteins?? Active!)

155
Q

Apoplastic pathways are (actively/passively) driven.

A

Passively

156
Q

The drivers of apoplastic pathways:

A

-Diffusion
-Capillary action
-Osmosis

157
Q

In apoplastic pathways, nutrient selection occurs at the ______, and unselected nutrients are deposited in the _____.

A

Casparian strip; cortex

158
Q

Symplastic pathways are (actively/passively) driven.

A

Passively

159
Q

Symplastic pathways include transportation by ____ and _____.

A

Plasmodesmata; xylem

160
Q

What is a uniporter?

A

A transporter protein that moves one molecule at a time down an electrochemical gradient.

161
Q

What are symporter proteins?

A

A transporter protein that catalyzes movement of a molecule against its electrochemical gradient by coupling it movement with an oppositely charged molecule moving down its gradient in the same direction.

162
Q

What is an antiporter?

A

A transporter protein that a catalyzes movement of a molecule against its electrochemical gradient by coupling its movement with a similarly charged molecule moving down its chemical gradient in the opposite direction.

163
Q

What is the relationship between nutrient concentration in solution and the rate of nutrient passive uptake?

A

Slow, linear increase in uptake with increasing concentration.

164
Q

What is the relationship between nutrient concentration in solution and the rate of nutrient active uptake?

A

Sharp increase with initial increase in concentration, leveling out at maximal rate of uptake (Vmax).

165
Q

Water and ions move into epidermal and cortical cells via (apoplastic/symplastic) pathways.

A

Apoplastic

166
Q

Ions cross the Casparian strip via (active/passive) transportation.

A

Active.

167
Q

What nutrient do mycorrhizae primarily help to absorb?

A

Phosphorous

168
Q

How does nutrient uptake affect pH?

A

Uptake of cations is facilitated by the release of another cation, usually a proton. Uptake of anions is facilitated by the release of another anion, usually a hydroxyl.

169
Q

What is the liming equation?

A

CaCO3 + H –> Ca + CO2 +H2O

170
Q

What is the site of nutrient uptake in plant roots?

A

The apoplastic pathway.

171
Q

What is the site of nutrient selection in plant roots?

A

The Casparian strip

172
Q

What is the pH of a solution in equilibrium with the atmosphere?

A

5.65

173
Q

Kw=

A

10^-14

174
Q

pK:

A

the pH at which an acid is 50% dissociated

175
Q

pH in a buffered system =

A

pK + log([A-]/[HA])

176
Q

The nitrification equation:

A

NH4 + 2O2 <–> NO3 + H2O +2H

177
Q

How do clays, oxides, and SOM contribute to pH buffering?

A

Dissociation of exterior protons.

178
Q

How can soluble salts contribute to acidification?

A

Base cations can displace acid cations on the exchange complex.

179
Q

Potential acidity includes ___ and ___.

A

Exchangeable acidity and titratable acidity.

180
Q

What is titratable acidity?

A

H and Al that are bound to the exchange complex, not in their ionic state.

181
Q

The equivalent weight of pure calcium carbonate =

A

50g/Eq

182
Q

How is base saturation related to pH?

A

Base saturation increases with pH

183
Q

How does liming affect Al and Mn toxicity?

A

Reduces. Both are highly soluble at low pH.

184
Q

Why do rice fields rarely require liming?

A

Anaerobic processes consume protons.

185
Q

What are the most common methods of acidifying alkaline soils?

A

Elemental sulfur and sulfuric acid.

186
Q

How does sulfur acidify soil (reaction)?

A

2S + 3O2 +2H2O <–> 2SO4 +4H

187
Q

How is phosphate availability affected by pH?

A

Fixes to Fe and Al at low pH and Ca at high pH

188
Q

How is N availability affected by pH?

A

Low pH inhibits N fixation (most effective above 6.0).

189
Q

What effect does sodium have on soil structure?

A

Dispersion between Na ions on exchange complex causes dispersion of colloids, destroying structure.

190
Q

EC of saline soils:

A

> 4mmho/cm

191
Q

pH of saline soils:

A

<8.5

192
Q

ESP of saline soils:

A

<15%

193
Q

EC of sodic soils:

A

<4mmho/cm

194
Q

pH of sodic soils:

A

> 8.5

195
Q

ESP of sodic soils:

A

> 15%

196
Q

EC of saline-sodic soils:

A

> 4mmho/cm

197
Q

pH of saline-sodic soils:

A

pH<8.5

198
Q

ESP of saline-sodic soils:

A

> 15%

199
Q

How does sodium in sodic soils result in high pH?

A

Water molecules split to produce protons in solution that preferentially displace sodium, producing hydroxyls.

200
Q

SAR =

A

Na/sqrt[(Ca+Mg)/2]

201
Q

ESR =

A

Na/(Ca+Mg)

202
Q

Relationship between SAR and ESR

A

ESR= 0.015(SAR)

203
Q

Relationship between ESP and ESR

A

ESP= (100 ESR)/(1+ESR)

204
Q

How does sodicity affect infiltration?

A

Colloids disperse, destroying structure and reducing permeability.

205
Q

Crops in nutrient-(poor/rich) soils are more salt tolerant.

A

Poor. Slower growth.

206
Q

Why is clean water unsuitable to leach a sodic soil?

A

There is nothing to displace Na on the exchange complex.