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Soils and Mineral Nutrition - Coggle Diagram
Soils and Mineral Nutrition
Nitrogen Metabolism
most abundant as gas N2
inert chemically
useless in almost all organisms
converted to chemically active forms
Nitrogen Fixation
conversion of N2 to nitrate, nitrite, or ammonium
all forms substrates to enzymes
human manufacturing
Nitrogen Reduction
reducing nitrogen in the nitrite ion
oxidation state from +5 to -3
Nitrogen Assimilation
actual incorporation of ammonium
reduced nitrogen passes through carriers
do not change
acceptor molecule: glutamate
transamination: transfer of amino group from 1 molecule to another
Soils and Minerals Availability
derived by weathering
2 fundamental processes
Physical weathering
physical forces
wind
water movement
temperature changes
ice
variety of sizes
coarse sand
large particles
important
2.0 to 0.2 mm
fine sand
1/10 coarse sand size
0.2 to 0.002 mm
silt
1/10 fine sand size
clay particles
smaller than 0.002 mm
AKA micelles
finest particles
field capacity
water remaining in soil
adhesion/ cohesion
available to roots
Cation Exchange
freely dissolved
cations loosely bounded
disrupted by proton presence
Soil Acidity
soil pH
important to cation exchange
acidity increases, cations released
solubility change
factors that affect soil acidity
rainfall
chemical nature of rock
The Endodermis and Selective Absorption of Substances
enter roots by
crossing plasma membrane
entering symplastic protoplasm phase
diffusing along the cell walls and intercellular spaces in the apoplectic phase
Essential Elements
Mineral Nutrition
derived of rock
experiments to plants
supply single elements
withheld, or
excessive quantity
hydroponic solution
Julius von Sachs, 1860
supports plant growth
trial and error
absorbed elements
essential elements
major or macro
needed in large quantities
no particular element= nonessential
trace elements
minor or micro
Fe, B, and Zn
extremely low concentrations
Criteria for Essentiality
element necessary to complete plant development through full life cycle
element required for any aspect
element itself necessary
no substitute effective
acting within the plant, not outside
Mineral Deficiency Diseases
Causes of Deficiency Diseases
elevated levels of single minerals causes toxicity
low concentration of certain elements makes some plants unable thrive
undergone human arficial selection
soil depletion
Symptoms of Deficiency Diseases
symptom related to particular element lacked
chlorosis
leaves lack chlorophyll
leaves are yellowish
brittle and papery
necrosis
death of patches of tissue
bacterial, viral, and fungal infections
spot depends on element
Mobile and Immobile Elements
immobile elements
B, Ca , and Fe
remain in place after incorporated
grow well until ions have been absorbed
mobile elements
Cl, N, P, K, and S
translocated to younger tissue
salvaged and moved to growing regions
Storage of Minerals Within Plants
cannot be certain that essential minerals will be available
storage mechanisms
animals: large reservoirs
Plants: all parts but seeds
