1
Q
What number range does the pH scale follow?
A
0-14
2
Q
If something has a pH between 0-6, it is…
A
acidic
3
Q
if something has a pH between 8-14, it is…
A
basic
4
Q
if something has a pH of 7, it is…
A
neutral
5
Q
2 ways to determine soil pH:
A
pHw: water suspension test.. water measures H+ ions attached to soil
pHs: lab field kit
6
Q
4 ways that pH governs productivity:
A
- Nutrient Availability
- Strong acidic soils have low CEC occupied by K, Mg, &Ca
- Affects pesticides
- Affects microbial activity
7
Q
Factors causing pH to change? (9)
A
- Depletion of bases by erosion
- Amount of rainfall/percolation
- Absorption of bases by plants
- chemical fertilizers
- tillage
- acid rain
- waste & sewage sludge
- irrigation
- plant roots
8
Q
What is buffer capacity?
A
The resistance of the soil to changes in pH
9
Q
what is active acidity?
A
H ions in solution
10
Q
What is reserve acidity?
A
Absorbed H+ & Al+
11
Q
Reserve acidity depends on…
A
the higher the CEC, the greater the buffer capacity
12
Q
Why correct soil pH? (acidic levels)(5)
A
- Elements can reach toxic levels (deadly)
- Microbial activity and population will be low
- Ca & Mg may be deficient
- Lose more potassium
- low pH can mobilize heavy metals (deadly)
13
Q
POSSIBLE TEST QUESTION: If on a budget, what should you fix before adding nutrients?
A
pH
14
Q
Liming materials
A
Calcitic Limestone Dolomitic Limestone Burned Lime: Made by heating limestone Hydrated Lime: Burnt lime with water added Marl: freshwater deposit in swamp areas Ground seashells Lime-rich industrial waste wood ash
15
Q
What is burned lime?
A
a liming material made by heating limestone
16
Q
what is hydrated lime?
A
burnt lime with water added
17
Q
what is marl?
A
freshwater deposit in swamp areas
18
Q
Quantities of lime are determined by?:
A
Current pH
Desired pH
Buffer capacity
chemical makeup and fineness of liming material used
19
Q
5 factors influencing liming frequency?
A
- soil texture
- rate of N fertilization
- rate of crop removal
- amount of lime applied
- pH desired range
20
Q
When is the best time to lime? (2)
A
- soil test for lime needed every 3 years
2. 3-6 mos. before planting legumes
21
Q
What is ENM?
A
Effective Neutralizing Method
22
Q
ENM tells us
A
how many tons per acre of material to apply
23
Q
ENM on soil test says 850, quarry has calculated ENM to be 475…. how much per acre needs to be applied?
A
850/475=1.78 tons per acre
24
Q
Alkaline soils have a pH above…
A
7
25
What is a saline-sodic soil?
high levels of both soluble salts and sodium
26
what is a sodic soil
mostly sodium, called black alkali or slick spots
27
what is a saline soil?
mainly chlorides and sulfates of Ca, Na, Mg, and K
28
Causes of alkaline soils (3)
1. minimal leaching
2. carbon dioxide and carbonates precipitate
3. the amount of Na + Ca ions in the soil
29
About ____ of the soils in the USA are affected by salinity
1/3
30
Measuring salinity in 2 ways...
Total dissolved solids (TDS)
| Electrical conductivity: the more salts in solution, the more current can be passed between them
31
Problems associated with alkaline soils (4)
1. Nutrient deficiencies
2. CEC levels tend to be higher
3. Calcium Rich Layer (duripan)
3. water supply ----> dry soils
32
2 ways to reclaim a saline soil
irrigate and attempt to leach
| gypsum
33
Soil microorganism groups (5)
1. Macrofauna
2. Macroflora
3. Microfauna
4. Microflora
5. Mesofauna
34
What is functional resiliency in a soil?
There are several organisms that carry out similar tasks
more overlapping microbes=more stable and resilient
35
4 examples of macrofauna:
gophers, ants, mice, beetles
36
2 broad examples of macroflora:
Mosses and vascular plants
37
3 examples of mesofauna:
mites, springtails, worms
38
5 primary producers:
1. vascular plants
2. mosses
3. lichens
4. algae
5. photosynthesizing bacteria
39
3 primary consumers
1. herbivores
2. saprophytes
3. detritivores
40
what is an herbivore
a plant eater
41
what is a saprophyte
organism that lives on dead material (fungi)
42
what is a detritivore?
an ANIMAL that feeds on dead material
43
Secondary consumers:
Predators-carnivores
| Microbivore feeders
44
Tertiary consumers
Feed on secondary consumers: moles, robins, ants, spiders, mites
45
there are over ___ different genera of bacteria
200
46
POSSIBLE TEST QUESTION: what is the role of bacteria in the soil?
Breakdown!
47
5 types of bacteria
1. arthrobacters
2. streptomycetes
3. pseudomonas
4. sporulating bacilli
5. cyanobacteria
48
what bacteria is predominant in the soil?
arthrobacters
49
What bacteria gives soil a smell?
streptomycetes
50
What bacteria is used in pesticides?
pseudomonas
51
which bacteria fix Nitrogen?
sporulating bacilli
52
which bacteria contain chlorophyll?
cyanobacteria
53
what is the rhizosphere?
millimeter of soil closest to the root surface
54
The rhizosphere is the most...
biologically active area in the soil
55
Plants produce the ____ that microbes feed on
organic matter
56
there are over ______ species of nematodes
15,000
57
Are nematodes exclusively good or bad?
no. there are good and bad nematodes. can be parasitic or free living
58
what do nematodes do?
consume bacteria, important for the release of N in the soil
59
Fungi are important in...
humus formation, nutrient cycling, and stabilizing soil aggregates.
60
Fungi produce...
penicillin and mycotoxins
61
6 types of fungi
1. acraciomycetes
2. myxomycetes
3. flagellated fungi
4. sugar fungi
5. higher fungi
6. imperfect fungi
62
Mycorrhizae are
a fungi that grow in a symbiotic relationship with a plant
63
advantages of mycorrhizae (2)
extends root zone
| puts nutrients in a plant available form
64
what is bioremediation?
using microorganisms to convert organic contaminants to less harmful products
65
what 3 points are on the disease triangle?
susceptible host, pathogen and favorable environment.
a disease cannot exist without all 3
66
functions of o.m. (3)
nutrient and water storage
soil aggregation--resist compaction
prevent erosion
67
Labile means
easy to decay material: starches, cellulose, hemicellulose
68
recalcitrant means:
difficult to decay material: lignin
69
Process of decay (4)
solution
fragmentation
decay
humification
70
solution is...
nutrients dissolving out of litter into nearby soil water
71
Fragmentation
shredding up and breaking up
72
Decay
labile material broken down by microbes
| recalcitrant slowly broken down by fungi
73
Humification
Occurs when N is released from labile decay and re-used to break down C
74
Humus has...
50% C and 5 % N
75
Humus has a C:N ration of
10:1
76
Humus is ____ in color and ____ to decay
dark in color, resistant to decay
77
factors affecting O.M. (5)
Vegetation, climate, soil texture, drainage, tillage
78
Prairies generate the most ____ __
soil O.M.
79
Fine textured soils have more _____ than coarse textured soils
O.M.
80
Poorly drained soils have _____ ____
more O.M.
81
Decay is a primarily ____ process
aerobic
82
Decay is influenced by (4)
1. tillage
2. amount of water
3. amount of life organisms
4. structure and texture
83
2 undesirable effects of O.M.
1. N can be tied up
| 2. some plant residues are toxic to other plants (phytotoxins)
84
```
What happens to soil organic matter decomposition when you...
add mulch?
clear cut?
no till into corn stover?
Use hairy vetch as a green manure crop?
```
add mulch?..... slows dow
clear cut?......... speeds up @ first then slows down
no till into corn stover?...... slows down
Use hairy vetch as a green manure crop?...... speeds up
