16 themes of bio
Evolution, biodiversity, systems, info flow, energy / matter transf., structure / function relationships
2Skills learned in BIOL110
Apply process of science, communicate science, apply quantitative reasoning to bio questions, connect themes wiology @all org levels +tie in other fields
3Theme of course
Microbial biodiversity and the role of orgs. in soil
4Anecdotal evidence
personal experience
5Scientific method
Obs / question > research > hypothesis > experiment > analysis > report conclusions
6What is soil
a mixture of solids liquids and gasses
7how much organic matter in soil
5%
8if soil is moist, what % of pore space is filled?
25%
9How does soil form?
interaction of:
climate
living organisms
topography
parent material
10how does clmate effect the formation of soil
temp and rainfall, water can freeze in cracks, expanding the crack
11how do living organisms effect the formation of soil?
vegetration, roots break rocks etc.
12how does topography effect the formation of soil?
elevation, slope
13how does parent material effect the formation of soil?
the minerals being broken up are the ones that end up in soil
14components of soil and their proportions
45% mineral particles
25% air
25% water
5% organic matter
15prop mineral particles in soil
45%
18prop org matter in soil
5%
19components of org matter in soil and props
80% humus
10% roots
10% organism
20% humus in org matter of soil
80%
21% roots in org matter of soil
10%
22% organisms in org matter of soil
10%
23Physical characteristics of soil
texture - particle size
density - weight and volume
pore size - small or lrg
structure - presence or absence of aggregates
24how desc texture of soil
by particle size
25how desc density of soil
mass over volume
26how desc pores of soil
small or large
27how desc structure of soil
presence or absence of soil aggregates
28types and sizes of soil particles
clay, less than .002mm
silt, .002mm to .05mm,
Sand, 0.05mm to 2.0mm
29Soil horizons
O- organic layer
A- topsoil
E - Eluciation layer
B - subsoil
C - Parent rock
R- bedrock
30what is soil horizon O
organic layer - humus
31what is soil horizon A
Topsoil - minerals with humus
32what is soil horizon E
eluviation layer - leached minerals and org matter
33what is soil horizon B
Subsoil - deposited minerals and metal salts
34what is soil horizon C
semi altered parent material
35what is soil horizon R
bedrock - unaltered parent material
36soil type that makes up most of the worlds soils, has high inorganic material content
mineral soil
37types of rock
sedimentary
metamorphic
igneous
38rock hardened by heat and pressure, ex marble
metamorphic rock
39rock crystalized by slow cooling after some heat and pressure, ex. granite
igneous rock
40rock formed when sediment is laid down over time, ex. shale
sedimentary
41what is coal
carbon from organic matter
42mineral composition top 10 miles from earth crust
mostly oxygen and silicon atoms (O and Si)
Quartz is SiO2
Lots of Aluminum atoms as well (Al)
Minerals that dominate are silicates and aluminosilicates
43wher4e does soil organic matter come from?q
plants
metabolism
decomposition
humus
mineralization
44what particle typoes make up soil
silt, sand, clay
45which particles types do you want to have "good" soil
a combination of all three: silt, clay, and sand
46surface area of sand vs surface area clay
sand has a relatively low surface area compared to clay which has a relatively high surface area
47how many particles in a gram of sand
90-700 thousand
48how many particles in a gram of clay
about 9 trillion
49Clay properties
layer silicate clays are ordered crystalline sheets of Si, Al, Mg or Fe
Layers should have a neutral charge
50what can change clay charge
isomorphous substitution causes permenant charge (Si4+ replanced w Al3+ = -1)
pH can lead to a variable charge (hydroxyl (OH) groups can add or release H+)
51Important chemical characteristics of soil
cation exchange capacity
pH
52What is cation exchange
holding and release of cations by clay and humus (clay and humus have weak negative charge)
53What cations are held by clay and humus
H+, K+, Al3+, Mg2+, Ca2+,
54why is cation exchange capacity important
plants need the cations because theyre nutritious, but if soil cant hold them they leech away and plants dont get em
55how many exchange sites in a g of soil
1.2 quintillion
56what is CEC
cation exchange capacitty
57relative CEC of sand, clay, and humus
Sand very low, clay medium, humus very high
58ph scale
1 acid
7 neutral
14 basic
60typical agricultural pH
5.5 to 8
61do agro soils typically drop or raise pH
they drop in pH naturally
62why is it diff to grow crops in pH lower than 5.5
lack available nutrients
toxic ions (ex. Al)
reduced microrganism activity
63how increase soil pH
add lime (CaCO3)
64what is buffering capacity
pH change resistance
65phigher CEC = higher or lower buffering capacity
higher
66stunted/purple plants
phosphorous defficiency
67how phosphorous defficiency happen
low pH make phosphorous unavailabke to plants
68Bright leaves, yellowish green, veins still dark green
iron defficiency
69how iron defficiency happen
high pH make iron unavailable to plants
70what is SOM stand for
soil organic matter
71what is soil organic matter
every org compound ion soil (ex. humus, a stable degraded form of soil)
72what % of soil bulk is SOM
5%
73what % of CEC comes from SOM
80%
74sources of SOM
humus - 80%
biosolids (sewage sludge)
animal manure
microrganisms
animals
plant residues from agro and nat ecosyustem
other orgs
75can biosolids be used interchangably instead of manure/plant residue
no, there's a limit to how often biosolids can be used because of the toxins in the sewage sludge
76abiotic soil factors
Soil aeration
-Many microbes need O2 as do roots of plants
-Soil lacking O2 is anoxic (anaerobic)
Soil water
-Limits microbial activity
-Gas exchange and chemical reactions
Soil temperature
-Influences microbial growth
-Greatest swings at soil surface