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SF & PN Test 1
Test 1
843
Agriculture
Undergraduate 4
08/11/2016

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Term
atom
Definition
smallest unit of matter that maintains the distinguishing features of an element.

Example: N (nitrogen)
Term
molecule
Definition
smallest unit of compound or element with stable, independent existence. Example: N2 (N gas), NH3 (ammonia)
Term
ammonia
Definition
NH3
Term
NH3
Definition
ammonia
Term
atomic #
Definition
Number of protons in the nucleus of an atom
Term
atomic mass unit
Definition
1/12 mass of the nucleus of carbon (amu)
Term
atomic weight
Definition
mass of atom in amu

Example:
C → 12 amu
N → 14 amu
H → 1 amu
Term
atomic weight of N
Definition
14
Term
molecular weight
Definition
mass of a molecule in amu
Term
mole
Definition
6.02 x 1023 particles (atoms, molecules)
Term
the weight of 1 mole of atoms
Definition
atomic weight of the atom
Term
valence
Definition
Number of positive or negative charges on an ion
Term
valence of H+
Definition
1
Term
valence of Cl-1
Definition
1
Term
valence of Ca2+
Definition
2
Term
valence of O2-
Definition
2
Term
equivalent
Definition
Quantity that will release, react with, or be equivalent to 6.02 x 1023 hydrogen ions (H+)
Term
molarity (M)
Definition
(moles of solute)/(liter of solution)
Term
normality (N)
Definition
(equivalents of solute)/(liter of solution)
Term
percentage by weight
Definition
percentage of weight made up by element or compound of interest
Term
depth of 1 acre furrow slice
Definition
6in
Term
predicted increase in cereal consumption for food over the next 4 decades
Definition
50%
Term
predicted increase for meat consumption over the next 4 decades
Definition
predicted to double
Term
why it might be costly for agriculture to expand into new areas
Definition
-poor soil fertility
-shallow soil depth
-low rainfall
-etc.
Term
great risks caused by agricultural expansion
Definition
-biodiversity
-soil erosion
-other factors impacting ecosystem health
Term
why per capita cropland assessments are misleading
Definition
because of the changing distribution of human populations in urban and rural areas
Term
current estimates state that ______% of future crop production increases will come from ______ compared to ______.
Definition
90%
intensification
expansion of cropland
Term
the primary causes of soil degradation
Definition
water and wind erosion
Term
why undeveloped and developing nations will continue to rely on food imports
Definition
because this is where the majority of future population growth is gonna be and the soil in these areas that could be converted to cropland is substantially less productive than current croplands
Term
why using corn for ethanol is not sustainable
Definition
because using it for ethanol makes it harder for undeveloped and developing countries to meet their basic food needs
Term
using ethanol as fuel in the future will require this
Definition
use of lignocellulose feedstocks, such as crop residues, forest products, etc.
Term
why there are limits to using field crop residues for ethanol
Definition
because organic residues returned to soils are critical to sustaining soil and crop productivity
Term
meeting future food and fiber demand, while protecting environmental health, will require this
Definition
ag intensification
Term
why meeting future food and fiber demand, while protecting environmental health, will require ag intensification
Definition
-decreasing available land for cultivation
-maintaining and enhancing natural land areas is critical to sustaining ecosystem diversity and health
Term
this is critical to sustaining ecosystem diversity and health
Definition
maintaining and enhancing natural land areas
Term
why advances in ag production technologies must occur
Definition
to enhance productivity per unit of cropland to ensure world food security
Term
the principal factors contributing to higher crop yields
Definition
include:
-development of improved varieties and hybrids
-nutrient and pest management
-soil and water conservation
-cultural practices
Term
why the continued growth of N fertilizers will increase demand for fossil fuel
Definition
because natural gas (CH4) is a primary ingredient in the manufacture of N fertilizers
Term
why improved nutrient management technologies are needed
Definition
to reduce the impact of nutrient use on environmental quality and ecosystem health
Term
one important nutrient management principle discussed throughout the book
Definition
the importance of maximizing crop productivity to increase the quantity of applied nutrient recovered by the crop
Term
why it's important to maximize crop productivity to increase the quantity of applied nutrient recovered by the crop
Definition
because it reduces the quantity of applied nutrient in the soil after harvest and, thus, reduces the impact of nutrient use on the environment
Term
Carl Sprengel and Justus von Liebig
Definition
19th century scientists who developed the Law of the Minimum
Term
the Law of the Minimum
Definition
states that crop yield is proportional to the amount of the most limiting nutrient
Term
some climate factors that affect crop yield potential
Definition
-precipitation -air temp -relative humidity -light -altitude -latitude -wind -CO2 concentration
Term
some soil factors that affect crop yield potential
Definition
-organnic matter
-texture
-structure
-CEC
-pH
-base sat
-slope and topography
-soil temp
-soil management factors
-depth (root zone)
-nutrient supply (soil test)
-element toxicity
Term
some soil management factors
Definition
-tillage
-drainage
-others
Term
some crop factors that affect crop yield potential
Definition
-crop species
-variety
-seeding rate
-geometry
-seed quality
-evapotranspiration
-water availability
-nutrition
-pests
-harvest efficiency
-crop sequence or rotation
-
-
Term
some pests that can affect crop yield potential
Definition
-insects
-diseases
-weeds
Term
the order in which limiting factors should be minimized
Definition
1: the most limiting factor
2: the 2nd most limiting factor
3: so on and so forth
Term
an element is considered essential to plant growth and development if...
Definition
-the element is directly involved in the nutritionof the plant
-a deficiency makes it impossible for the plant to complete its life cycle, and
-a deficiency is specific to the element and can only bee prevented or corrected by supplying the element
Term
why you must use caution when evaluating a visual symptom on a plant
Definition
because there's lots of things that can cause the visual sumptoms
Term
deficient
Definition
when the concentration of an element is low enough to severely limit yield and distinct deficiency symptoms are visible
Term
critical range
Definition
the nutrient concentration in the plant below which a yiield response to added nutrients occurs
Term
where critical range occurs
Definition
somewhere between deficient and sufficient
Term
sufficient
Definition
the nutrient concentration range in which added nutrient will not increase yield but can increase nutrient concentration
Term
luxury consumption
Definition
absorbtion by the plant that does not influence yield
Term
excessive or toxic
Definition
when the concentration of essential or other elements is high enough to reduce plant growth and yield
Term
excessive nutrient concentration can cause this, which can also influence yield
Definition
an imbalance in other essential nutrients
Term
Steenberg effect
Definition
when under severe deficiencyrapid increases in yield with added nutrient cause a small decrease in nutrient concentration
Term
what causes the Steenberg effect?
Definition
dilution of the nutrient in the plant by rapid plant growth
Term
when the concentration of nutrient reaches this range, plant yield is generally maximized
Definition
critical range
Term
how excessive quantities of elements can reduce plant yield directly
Definition
toxicity
Term
how excessive quantities of elements can reduce plant yield indirectly
Definition
reducing concentrations of other nutrients below their critical ranges
Term
essential macronutrients in order of abundance in plants
Definition
1: H
2: C
3: O
4: N
5: K
6: Ca
7: Mg
8: P
9: S
Term
essential micronutrients in order of abundance in plants
Definition
1: Cl
2: Fe
3: B
4: Mn
5: Zn
6: Cu
7: Ni
8: Mo
Term
plant nutrients that are not considered mineral nutrients
Definition
C, H, & O
Term
The p'synth process in green plants converts ______ into ______.
Definition
CO2 and H2O simple carbohydrates
Term
organic compounds that can be synthesized from simple carbohydrates
Definition
-amino acids
-sugars
-proteins
-nucleic acids
-other organic compounds
Term
4 additional elements that have been established as beneficial micronutrients in some plants
Definition
-Na
-Co
-V
-Si
Term
minor elements
Definition
micronutrients
Term
the ash left over from burning plant dry matter contains all the elements except ______ because ______.
Definition
C, H, O, N, & S
they are volatilized as gases
Term
why plants do not absorb all of the nutrients applied
Definition
because many biological and chemical reactions occur w/ nutrients in soils
Term
external factors plants have to deal with
Definition
-CO2 c'tration -light -heat -water -nutrients
Term
wheat the external factors of water, nutrients, heat, light, and CO2 c'tration do to the plant
Definition
regulate plant growth and development
Term
where most of the water and nutrients a plant uses comes from
Definition
the soil
Term
why plant roots are in very close association w/ the soil
Definition
because most of the water and nutrients comes from the soil
Term
Soil Productivity
Definition
Capacity of a soil to support the production of a specific crop
Term
how soil productivity is measured
Definition
in terms of yield/biomass
Term
soil productivity depends on...
Definition
adequate moisture and soil nutrients, as well as favorable climate (temperature, rainfall)
Term
Soil Fertility
Definition
Soils’ capacity to supply elements essential for plant growth
Term
how soil fertility is measured
Definition
- directly (concentration of nutrients)
- indirectly (productive capacity)
Term
how soil fertility is measured directly
Definition
c'tration of nutrients
Term
how soil fertility is measured indirectly
Definition
productive capacity
Term
soil fertility is relative to...
Definition
the plant being considered, that is, how the plant interacts with the nutrients
Term
how soil fertility can be improved
Definition
by adding nutrients
Term
soil fertility is a component of...
Definition
soil productivity
Term
why you can, to an extent, manage soil productivity
Definition
because soil fertility is a component of soil productivity
Term
Importance of Soil Fertility
Definition
-Agriculture depends on soil productivity
-Soil productivity depends in part on soil fertility
Term
agriculture depends on...
Definition
soil productivity
Term
soil productivity depends in part on...
Definition
soil fertility
Term
population could be ______ by 2060
Definition
9 billion
Term
population could be 9billion by ______
Definition
2060
Term
this led to an increase in farming
Definition
mechanization
Term
mechinazation led to an increase in...
Definition
farming
Term
Green Revolution was part of the ______ inprovement of ag.
Definition
scientific
Term
some things the Green Revolution brought to ag
Definition
-fertilizers
-high yielding varieties
-pesticides
Term
what pesticides did for ag
Definition
decreased losses
Term
the fertilizer consumption that seems to be going up the quickest
Definition
N fertilizer
Term
recent trend in global fertilizer use
Definition
seems to be on the rise
Term
trend in U.S. fertilizer use
Definition
might be increasing, but might be leveling off
Term
the largest source of N inputs into the Mississippi River basin
Definition
N fertilizers
Term
the fastest growing source of N inputs into the Mississippi River basin
Definition
N fertilizers
Term
such a large amount of N going into the water so quickly can lead to...
Definition
eutrophication
Term
artificial sources of N cause this
Definition
increased growth of plants, algae, and other stuff
Term
after the excessive growth of plants, algae, and other stuff due to such excessive N, this leads to depleted oxygen supply
Definition
microbes later lead to depleted oxygen supply
Term
how long it naturally takes eutrophication to occur
Definition
centuries
Term
how long it takes eutrophication to occur with such excessive N inputs
Definition
decades
Term
how microbes help in the causing of hypoxia
Definition
they use oxygen to feed on stuff
Term
when the hypoxic zone on the Louisiana coast shows up
Definition
every summer
Term
can phosphate and potash resources get depleted?
Definition
yes
Term
yearly production of phosphate
Definition
224million tons
Term
yearly production of phosphate
Definition
224million tons
Term
yearly production of phosphate
Definition
224million tons
Term
total reserves of phosphate
Definition
~67billion tons
Term
life of phosphate reserves
Definition
~300 years
Term
US phosphate reserves
Definition
1,100 million tons
Term
life of US phosphate reserves
Definition
34 years
Term
the bulk of the phosphate reserves are in...
Definition
Morocco
Term
yearly production of potassium
Definition
35million tons
Term
total reserves of potassium
Definition
6billion tons
Term
life of potasium reserves
Definition
171 years
Term
factors affecting plant growth and yield
Definition
-climate
-crop
-soil
Term
climate factors that affect plant growth and yield
Definition
-rain
-temp
-light
-wind
-etc.
Term
crop factors that affect plant growth and yield
Definition
-variety
-planting date
-pests
-etc.
Term
soil factors that affect plant growth and yield
Definition
-fertility
-structure
-texture
-etc.
Term
Leibig’s Law of the Minimum
Definition
The level of plant production can be no greater than that allowed by the most limiting growth factor
Term
essential nutrient
Definition
nutrient needed to complete life cycle
Term
how to do the water in hydroponics
Definition
mix specific amounts of nutrients in solution with water
Term
how hydroponics can be used to determine which nutrients are essential
Definition
eliminating one nutrient at a time helps identify essential nutrients
Term
criteria for importance of nutrients in plant life cycle
Definition
1: importance in plant growth and development
2: involved in the a plant’s biochemical or physiological process
Term
how plants get most of their carbon
Definition
carbon being fixed in the form of CO2
Term
these nutrients are not considered mineral nutrients
Definition
H, C, and O
Term
distribution of nutrients in plants
Definition
may differ among different parts of the plant
Term
where silicon is in plants
Definition
can sometimes accumulate in the leaves, as much as 10%
Term
one hypothesis about silicon
Definition
says that silicon provides mechanical strength to the plants
Term
does hydroponics use silicon?
Definition
no
Term
yearly production of phosphate
Definition
224million tons
Term
total reserves of phosphate
Definition
~67billion tons
Term
life of phosphate reserves
Definition
~300 years
Term
US phosphate reserves
Definition
1,100 million tons
Term
life of US phosphate reserves
Definition
34 years
Term
the bulk of the phosphate reserves are in...
Definition
Morocco
Term
yearly production of potassium
Definition
35million tons
Term
total reserves of potassium
Definition
6billion tons
Term
life of potasium reserves
Definition
171 years
Term
factors affecting plant growth and yield
Definition
-climate
-crop
-soil
Term
climate factors that affect plant growth and yield
Definition
-rain
-temp
-light
-wind
-etc.
Term
crop factors that affect plant growth and yield
Definition
-variety
-planting date
-pests
-etc.
Term
soil factors that affect plant growth and yield
Definition
-fertility
-structure
-texture
-etc.
Term
Leibig’s Law of the Minimum
Definition
The level of plant production can be no greater than that allowed by the most limiting growth factor
Term
essential nutrient
Definition
nutrient needed to complete life cycle
Term
how to do the water in hydroponics
Definition
mix specific amounts of nutrients in solution with water
Term
how hydroponics can be used to determine which nutrients are essential
Definition
eliminating one nutrient at a time helps identify essential nutrients
Term
criteria for importance of nutrients in plant life cycle
Definition
1: importance in plant growth and development
2: involved in the a plant’s biochemical or physiological process
Term
how plants get most of their carbon
Definition
carbon being fixed in the form of CO2
Term
these nutrients are not considered mineral nutrients
Definition
H, C, and O
Term
distribution of nutrients in plants
Definition
may differ among different parts of the plant
Term
where silicon is in plants
Definition
can sometimes accumulate in the leaves, as much as 10%
Term
one hypothesis about silicon
Definition
says that silicon provides mechanical strength to the plants
Term
does hydroponics use silicon?
Definition
no
Term
the majority of plant nutrient uptake is thru...
Definition
the roots
Term
[image]
Definition
longitudinal section of the root
Term
longitudinal section of the root
Definition
[image]
Term
What's #1?
[image]
Definition
root hair
Term
What's #2?
[image]
Definition
cortex
Term
What's #3?
[image]
Definition
stele
Term
What's #4?
[image]
Definition
xylem
Term
What's #5?
[image]
Definition
phloem
Term
What's #6?
[image]
Definition
endodermis w/ casparian strip
Term
What's #7?
[image]
Definition
epidermis
Term
What's #8?
[image]
Definition
region of rapid cell division
Term
What's #9?
[image]
Definition
quiescent center (few cell divisions)
Term
What's #10?
[image]
Definition
root cap
Term
What's #11?
[image]
Definition
mucigel sheath
Term
What's #12?
[image]
Definition
apex
Term
What's #13?
[image]
Definition
meristematic zone
Term
What's #14?
[image]
Definition
elongation zone
Term
What's #15?
[image]
Definition
maturation zone
Term
meristematic region helps the root do this
Definition
grow
Term
2 purposes of the root cap
Definition
-helps protect the tip of the root
-helps it stay lined up with the force of gravity
Term
in the elongation zone, there’s less ______ and more ______
Definition
division
cell growth
Term
what happens in the maturation zone?
Definition
cells taking up specific nutrients
Term
cells in the maturation zone no longer do this
Definition
grow or divide
Term
what is a root hair?
Definition
modified epidermal cell
Term
parts of the plant that take up nutrients
Definition
[image]
Term
What's #1?
[image]
Definition
shoot
Term
What's #2?
[image]
Definition
root
Term
What's #3?
[image]
Definition
primart root
Term
What's #4?
[image]
Definition
lateral root
Term
What's #5?
[image]
Definition
root hairs
Term
What's #6?
[image]
Definition
root tip
Term
What's #7?
[image]
Definition
root cap
Term
the parts of the roots that don't do very much nutrient and water uptake
Definition
the older parts
Term
the parts of the roots that do the bulk of the nutrient and water uptake
Definition
maturation zone and younger
Term
characteristics of root morphology and architecture that can have effect on nutrient uptake
Definition
-Root length, thickness
-Branching
Term
how variations in root architrture can affect nutrient uptake
Definition
increasing root surface area
Term
Factors affecting root surface area
Definition
-Thinner, multiple roots have more surface area per unit volume
-Root branching, which can be influenced by lateral roots
-Root hairs
-Association with mycorrhizae
Term
Lateral roots increase...
Definition
root mass and surface area
Term
lateral root develop from the...
Definition
pericycle
Term
some root structure
Definition
[image]
Term
[image]
Definition
pericycle
Term
structure of root hairs
Definition
[image]
Term
root hairs
Definition
outgrowths of epidermal cells
Term
length of root hairs
Definition
short, rarely reaching lengths of 1mm
Term
how much of the root surface area is root hairs?
Definition
~75%
Term
primary points where roots absorb nutrients
Definition
root hairs
Term
growth of root hairs affected by...
Definition
nutrient supply
Term
when plants may make more root hairs
Definition
if there's defficiency
Term
mycorrhizae do this for plants
Definition
-contribute greatly to nutrient uptake in most plants (>80% of plants)
-increase surface area
Term
amountof plants that form mycorrhizal associations
Definition
>80% of plants
Term
when mycorrhizae are most effective
Definition
under low nutrient conditions
Term
deveolpment of mycorrhizae can be inhibited by some nutrients such as...
Definition
P
Term
how mycorrhizae can make more nutrients available to plants
Definition
by using organic forms of nutrients and converting them to inorganic forms, thus making more nutrients available to plants
Term
the 2 types of mycorrhizae that plants form associations with
Definition
-Ectomycorrhiza
-Endomycorrhiza
Term
Ectomycorrhiza
Definition
sheath around root tip, hyphae do not penetrate plant cells (mainly trees of temperate zones)

-these act kinda like root hairs
Term
how ectomycorrhiza act
Definition
kinda like root hairs
Term
endomycorrhiza
Definition
extends surface area of roots; penetrates plant cells (widespread)

-hemps move the nutrients inside the cell
Term
what hemps do inside plant cells
Definition
move nutrients inside plant cells
Term
when plants don't make many mycorrhizal associations
Definition
when there's lots of nutrients available
Term
illustration of the importance of mycchorizae to corn
Definition
[image]

-left w/ mycorrhizal associations
-right w/o mycorrhizal associations
Term
some anatomical features roots have to regulate nutrient uptake
Definition
-root hairs (epidermis)
-cortex
-endodermis
-pericycle
-phloem
-xylem
Term
function of the root hairs (epidermis)
Definition
facilitate uptake
Term
function of the cortex
Definition
nutrients can be taken up into the symplast
Term
function of the endodermis
Definition
barrier for uncontrolled uptake; kinda limits the uptake of unneccessary substances

also limits leakage of nutrients
Term
function of the pericycle
Definition
generates lateral roots
Term
function of the phloem
Definition
transport from the shoot (flows down)
Term
function of the xylem
Definition
transport to the shoot (flows up)
Term
location of the vascular tissue (xylem and phloem) in the root
Definition
center of the root
Term
anatomy of a dicot root
Definition
[image]
Term
[image]
Definition
anatomy of a dicot root
Term
anatomy of a monocot root
Definition
[image]
Term
[image]
Definition
anatomy of a monocot root
Term
what's #1?
[image]
Definition
stele
Term
what's #2?
[image]
Definition
root hair
Term
what's #3?
[image]
Definition
epidermis
Term
what's #4?
[image]
Definition
endodermis
Term
what's #5?
[image]
Definition
xylem
Term
what's #6?
[image]
Definition
pericycle
Term
what's #7?
[image]
Definition
phloem
Term
what's #8?
[image]
Definition
cortex
Term
what's #1?
[image]
Definition
epidermis
Term
what's #2?
[image]
Definition
xylem
Term
what's #3?
[image]
Definition
phloem
Term
what's #4?
[image]
Definition
cortex
Term
what's #5?
[image]
Definition
pericycle
Term
what's #6?
[image]
Definition
endodermis
Term
why nutrient supply to plant roots is a very dynamic process
Definition
because plants adsorb cations and anions and exude H+, OH-, and HCO3-
Term
how plants get nutrients from the soil
Definition
by absorbing them from the soil solution by plant roots
Term
what plant roots release into the soil solution
Definition
small quantities of H+, OH-, and HCO3-
Term
what nutrient uptake by plants causes to happen in the soil
Definition
several chemical and biological rxns to buffer or resupply these nutrients to the soil solution
Term
what happens to ions adsorbed to the surface of clay minerals when the soil solution needs to be buffered?
Definition
they desorb from these surfaces to resupply the soil solution
Term
what fertilizer does to the soil solution
Definition
increases ion concentration in the soil solution
Term
what can happen to ions from fertilizers if they don't remain in solution?
Definition
some get adsorbed to mineral surfaces and some precipitate as solid minerals
Term
some soil components that influence nutrient concentration in the soil solution
Definition
-nutrient uptake
-soil air
-OM/microbes
-rainfall evaporation/drainage management
-mineral solubility
-surface exchange (that is, in the surface of soil particles)
Term
microbial activity is dependent on...
Definition
-adequate energy supply from organic C, such as crop residues
-inorganic ion availability
-numerous environmental conditions
Term
why CO2 concentration in the soil air is greater than in the atmosphere
Definition
because plant roots and sil organisms use O2 and respire CO2
Term
ion exchange in soil occurs where?
Definition
on the surfaces of clay and other minerals, organic matter (OM), and plant roots
Term
why cation exchange capacity is generally considered to be more important
Definition
because the CEC is much larger than the AEC
Term
why it's essential to understand the origin of the surface charge of soil minereals and OM
Definition
because ion exchange rxns are very important to plant nutrient retention and availabvility in soil
Term
why nutrient supply to plant roots is a very dynamic process
Definition
because plants adsorb cations and anions and exude H+, OH-, and HCO3-
Term
the composition of aluminosilicate minerals
Definition
sheets of layers of silica tetrahedra and alumina octahedra
Term
the structure of a silica tetrahedra
Definition
one Si+4 cation bonded to 4 O-2 anions
Term
the structure of the Al octahedra
Definition
one Al+3 cation bonded to 6 OH- anions
Term
forns that clay minerals exist in
Definition
-1:1
-2:1
-2:1:1
Term
the most common type of 1:1 clay
Definition
kaolinite
Term
the composition of 2:1 clays
Definition
Al octahedral layer between 2 Si tetrahedral layers
Term
the most common 2:1 clays
Definition
-mica (aka illite)
-smectite (aka montmorillonite)
-vermiculite
Term
illite aka...
Definition
mica
Term
montmorillonite aka...
Definition
smectite
Term
a type of 2:1:1 clay mineral
Definition
chlorite
Term
composition of 2:1:1 clay minerals in acid soils
Definition
interlayer Al hydroxide sheet in addition tho the 2:1 structure
Term
composition of 2:1:1 clay minerals in basic soils
Definition
interlayer Mg hydroxide sheet in addition tho the 2:1 structure
Term
isomorphic substitution
Definition
cation replacement in minerals, predominantly in 2:1 minerals and very little in 1:1 minerals

occurs during the formation of these minerals
Term
the type of isomorphous substitution that contributes to montmorillonite having such a high CEC ad the ability to readily expand and contract based on moisture
Definition
isomorphous substitution in the octahedral layer instead of the tetrahedral layer

this is the only isomorphous substitution that occurs in montmorillonite
Term
in chlorite, the interlayer space is occupied by...
Definition
Mg(OH)x in basic soils and Al(OH)x in acid soils
Term
why isomorphous substitution occurs in both the octahedral and tetrahedral layers in the 2:1 vermiculite
Definition
because it's commonly weathered from micas
Term
why vermiculite has a higher CEC, but lower interlayer expansion compared to smectites
Definition
because although isomorphic substitution (Al+3 for Si+4) is less than in mica, the tetrahedral charge attracts hydrated cations (Ca+2, Mg+2), which limits expansion of the interlayer compared to smectites
Term
brucite
Definition
chlorite w/ a Mg hydroxide layer
Term
gibbsite
Definition
chlorite w/ an Al hydroxide layer
Term
why the CEC of chlorites is extremely low
Definition
because the surface of the hydroxide layers is + charged and is attracted to the - charged tetrahedral surface
Term
description of intergrade 2:1 minerals
Definition
-similar to smectites and vermiculites except the interlayer area contains discontinuous "islands" of chlorite
-non-expansive and exhibit a much lower CEC than than vermiculites and smectites
Term
the charge on clay minerals that's unaffected by solution pH
Definition
permanent charge
Term
the pH-dependent charge on clay minerals
Definition
the edge charge
Term
why the edge charge of clay minerals is + under low pH
Definition
because of the excess H+ ions associated with exposed SiOH and Al-OH groups
Term
why the edge charge becomes more negative when the pH increases
Definition
because some of the H+ on the clay particles is neutralized
Term
what inbcrteasing the soil pH above 7 does to the charges on the clay particles
Definition
nearly completely removes the the H+ ions from the Al-OH and Si-OH groups
Term
the amount of - charge on 2:1 clays that's pH dependent
Definition
5-10%
Term
the amount of negative charge on 1:1 clays that's pH dependent
Definition
50%
Term
2 sources of pH dependent charge
Definition
broken edges on clay minerals and soil OM
Term
where most of the pH dependent - charge from soil OM comes from
Definition
-carboxylic acid
-to a lesser extent, phenolic acid groups
Term
why the CEC of soil OM increases as pH increases
Definition
because some of the H+ ions are neutralized, increasing the - surface charge
Term
CEC of pure soil OM
Definition
estimated to be 100-300 meq/100g soil
Term
the CEC of the whole soil is strongly affected by...
Definition
the nature and quantity of clay minerals and OM in the soil
Term
which type of clay mineral tends to have a higher CEC? 1:1 or 2:1?
Definition
2:1
Term
the CEC of most SE soils (ultisols) is mostly ______ while the CEC of most MW soils (mollisols) is mostly ______
Definition
pH dependent
permanent charge
Term
3 rxns from which pH dependent CEC originates
Definition
-neutralization of H+ on sesquioxide (Al, Fe(OH)x) by way of liming -neutralization of H+ associated with the interlayer Al(OH)x as pH increases -neutralization of Al3+ and Al(OH)x+n as pH increases with liming
Term
most of the exchangeable cations in soils are plant nutrients except for...
Definition
Al3+ and Na+
Term
the principal cations in acid soils
Definition
-Al3+ -H+ -Ca2+ -Mg2+ -K+
Term
the predominant cations in neutral and basic soils
Definition
-Ca2+ -Mg2+ -K+ -Na+
Term
this influences the ease with which cations can be replaced or exchanged with other cations
Definition
cations being adsorbed to the CEC with different adsorption strengths
Term
lyotropic series
Definition
series that shows cations in order of how strongly they are adsorbed onto CEC sites Al3+ > H+ > Ca2+ > Mg2+ > K+ = NH4+ > Na+
Term
the strength of adsorption is directly proportional to...
Definition
the charge on the cations (>charge>adsorption strength) exception: H+
Term
what makes the H+ ion unique?
Definition
its very small size and high charge density
Term
the adsorption strength of cations with similar charges is determined by...
Definition
the size or radii of the hydrated cation
Term
why smaller cations of different charge are adsorbed more strongly
Definition
because larger hydrated cations can't get as close to the exchange surface as smaller cations
Term
some factors that affect which cations are preferentially adsorbed onto mineral surfaces
Definition
-mineral type
-solution pH
-dominant anions present
-electrical potential of the charged surface
-other factors beyond the scope of this text
Term
soil CEC
Definition
represents the total quantity of - surface charges on minerals and OM available to attract cations in solution

expressed in meq/100g oven dried soil
Term
why meq is used for CEC instead of mass
Definition
CEC represents both the meq/100g of - charge and the total meq/100g of cations adsorbed to the CEC
Term
base saturation (BS)
Definition
% of total CEC occupied by Ca2+, Mg2+, K+, and Na+
Term
soil factors that may affect %BS
Definition
-BS of cultivated soils higher for arid than for humid regions
-BS of soils formed from limestone or basic igneous rock is greater than that of soils formed from sandstone or acidic igneous rock
Term
the relation betwen BS and cation availability is modified by...
Definition
the nature of the soil colloids
Term
soils with ______ can supply nutrient cations to plants at a much lower BS than soils with ______
Definition
large amounts of OM or 1:1 clays
2:1 clays
Term
BS vs. soil pH
Definition
BS increases with increasing soil pH
Term
why the influence of pH on CEC is highest in soils high in OM
Definition
because increasing pH has a greater effect on increasing CEC in the OM fraction in soil compared to montmorillonite, which exhibits little pH dependent charge
Term
why weathered, acidic soils containing hydroxyl-Al vermiculites (ultisols) exhibit strong pH-dependent CEC
Definition
because of the large quantity of Al(OH)x in the interlayer space of these clays
Term
this displacement mechanism in soil is an important mechanism for anion exchange
Definition
displacement of OH from hydrous Fe and Al oxides
Term
AEC vs. soil pH
Definition
AEC incereases as soil pH decreases
Term
soils where AEC is greatest
Definition
acid soils containing 1:1 clays and those containing Fe and Al oxides

exception: soils that contain hydroxyl-Al vermiculites common to the SE US
Term
the order of adsorption strength for anions
Definition
H2PO4- > SO4-2 > NO3- > Cl-
Term
the primary anion adsorbed in most soils
Definition
H2PO4-
Term
how Al and Fe oxide minerals can adsorb H2PO4-
Definition
thru rxns that result in chemical bonds that are non-electrostatic
Term
the macronutrients are
Definition
-Carbon
-Hydrogen
-Oxygen
-Nitrogen
-Phosphorous
-Potassium
-Calcium
-Sulfur
-Magnesium
Term
the micronutrients are
Definition
-Iron
-Zinc
-Boron
-Molybdenum
-Copper
-Manganese
-Chloride
-Nickel
Term
types of solute transport mechanisms
Definition
passive and active
Term
Passive transport occurs along...
Definition
concentration and electrical (electrochemical) gradients
Term
Active transport can occur against...
Definition
electrochemical gradients
Term
passive vs. active transport
Definition
-Passive transport occurs along concentration and electrical (electrochemical) gradients
-Active transport requires energy, and can occur against electrochemical gradients.
Term
types of proteins that can facilitate passive transport
Definition
channel and carrier proteins
Term
types of active transport
Definition
primary and secondary
Term
mechanisms of Primary active transport (PAT)
Definition
-ATP hydrolysis generates energy
-Energy used for ion/solute transport
Term
mechanisms of Secondary active transport
Definition
-Special proteins (Integral membrane proteins)
-Co-transport involved
-Energy indirectly derived from PAT
Term
depiction of primary active transport in plants
Definition
see slide 7 of the powerpoint titled "Nutrient Uptake - II", but be sure to remove that white block
Term
how plants bring Pi into the cell
Definition
using ATP to send protons outside of the cell so they can bind with Pi so the Pi can come into the cell this is an example of a symporter
Term
how plants get Na+ out of their cells
Definition
pumping protons out of their cells so they can reenter and cause the Na+ to leave
Term
function of ATPase
Definition
pumps hydrogen ions across the plasmalemma
Term
Nutrient transporters are present in these zones of roots
Definition
uptake related zones of roots
Term
Two possible routes for apoplastic uptake
Definition
-Elongation zone
-Emerging laterals
Term
examples of Adaptations in Nutrient Uptake
Definition
-Adaptations in Nutrient Uptake
-Regulation of Nutrient Uptake
-Increase in nutrient transporters in roots under nutrient deficiency
Term
ways roots can modify themselves
Definition
-Altered root hair density
-Proteoid root formation
Term
mechanisms nutrient uptake may follow
Definition
single- or a multi-phasic mechanism
Term
Rate of uptake dependent on...
Definition
nutrient availability
Term
when plant uses Low Affinity Transport System (LATS)
Definition
high nutrient concentration
Term
when plant uses High Affinity Transport System (HATS)
Definition
low nutrient concentration
Term
when plants may Increase the number of nutrient transporters in roots
Definition
under nutrient deficiency
Term
depiction of the difference between roots under nutrient deficiency and roots not under nutrient deficiency
Definition
see slide 16 of the powerpoint titled "Nutrient Uptake - II"
Term
why a plant root may form proteoid roots
Definition
to increase Pi uptake
Term
examples of regulation of uptake in plants
Definition
-High N uptake rates result in high N levels in the leaves
-Leaves contain high levels of amino acids
-Amino acids are transported back to the roots
-Amino acids inhibit nitrogen uptake by the roots
Term
Two separate long distance transport systems in plants
Definition
xylem and phloem
Term
what the xylem transports
Definition
-water
-nutrients
-some amino acids
Term
what the phloem transports
Definition
-water
-sugar
-many nutrients
Term
what nutrients can be transported in the xylem?
Definition
all nutrients
Term
direction of transport in the xylem
Definition
unidirectional (roots to shoots for nutrients)
Term
transport in the phloem
Definition
-Bidirectional, although mainly from leaves to growing plant parts (roots, fruits, meristems, young leaves)
-From old, senescing leaves to younger plant parts (retranslocation)
-Mobility of nutrients in the phloem varies
Term
plants remobilize nutrients thru the...
Definition
phloem
Term
when plants remobilize nutrients
Definition
when leaves senesce
Term
where nutrients in plants go when remobilized
Definition
Many nutrients are removed from senescing leaves and transported to younger leaves or fruits
Term
where nutrients can be stored if not used right away
Definition
central vacuole
Term
the older part of the roots don’t do very much...
Definition
nutrient and water uptake
Term
these parts of the roots do the bulk of the nutrient and water uptake
Definition
maturation zone and younger
Term
these factors have an effect on nutrient uptake
Definition
-Root morphology and architecture
-Root surface area
Term
factoirs of Root morphology and architecture that have an effect on nutrient uptake
Definition
-Root length, thickness
-Branching
Term
root branching can be influenced by...
Definition
lateral roots
Term
lateral roots start forming from ______, not the ______
Definition
the inside of the pericycle
epidermis
Term
how much root surface area is in the root hairs?
Definition
75% of it
Term
how Mycorrhizae can make nutrients more available to plants
Definition
by using organic forms of nutrients and converting them to inorganic forms, thus making more nutrients available to plants
Term
plants don’t make many mycchorrizal associations when...
Definition
there’s lots of nutrients avilable
Term
some functions of the cortex
Definition
-nutrients can be taken up into the symplast
-can also act as storage; nutrients can be stored in the vacuoles of cortical cells
Term
what the endodermis limits
Definition
-kinda limits the uptake of unnecessary substances
-also limits the leakage of nutrients
Term
why pericycle can generate lateral roots
Definition
has new cells that can make lateral root
Term
apoplast
Definition
space outside plasma membrane, even the space costituted by dead functioning xylem tissue
Term
symplast
Definition
inside cells
Term
depiction of plant cells
Definition
[image]
Term
all the plant cells are connected by...
Definition
plasmodesmata
Term
something inside plasmodesmata that might help regulate traffic thru them
Definition
plasmodesmata have some amount of endoplasmic reticulum in there and plasmodesmata are pretty tightly controlled; there’s regulatory mechanisms inside plasmodesmata
Term
depiction of cells in the endodermis
Definition
[image]
Term
casparian strip found in...
Definition
endodermis
Term
casparian strip is (hydrophobic or hydrophilic)
Definition
hydrophobic
Term
simple diffusion
Definition
movement of ions from one side of the membrane to the other
Term
this happens when ions bind to carrier proteins
Definition
they change shape to bind to ions
Term
these proteins have a higher transport rate
Definition
channel proteins
Term
these proteins have to undergo more changes than channel proteins
Definition
carriers
Term
these proteins can be gated
Definition
channels
Term
what ATPase does with hydrogen
Definition
pumps hydrogen ions across the plasmalemma, against normal gradient and uses energy
Term
normal charge outside cell
Definition
slight positicve
Term
normal charge inside cell
Definition
slight negative
Term
the only known proteins that directly use primary active transport
Definition
H+ and Ca2+ proteins
Term
depiction of Primary Active Transport in Plants
Definition
[image]
Term
what happens in 2ndary active transport
Definition
carrier proteins couple the transport of protons with other ions from outside the cell to inside the cell; energy used by proton pump, not nitrogen pump, for example
Term
depiction of 2ndary active transport
Definition
[image]
Term
an important function of antipiorters in plant cells
Definition
can help mitigate toxicities inside the cells
Term
depiction of a Sodium-proton antiporter
Definition
[image]
Term
phosphate transporter mostly in these zones of the root
Definition
mesomatic and elongation zones
Term
regulation of calcium inside plant cells
Definition
the c’tration of Ca in the plant cells is tightly regulated and kept pretty low
Term
what plants do to their carbohydrates when they don't put out root hairs
Definition
they partition more of the carbohydrates towards the shoots
Term
this might stunt plant growth
Definition
severe nutrient deficiency
Term
at the cellular level, plants can do this in response to nutrient deficiencies
Definition
make more of certain kinds of transporters and increase the concentration of them, such as the specific one for P when there's a shortage of P
Term
plants make this in response to Pi defficiency
Definition
proteoid roots
Term
plants make proteoid roots in response to...
Definition
Pi defficiency
Term
some details about proteoid roots
Definition
-they are dense clusters of lateral roots, but very short, about 1-2mm long
-they can form tertiary roots
-these roots can send out certain enzymes to change rhizosphere and increase P uptake
Term
how plants respond to nutrient excess
Definition
plants respond to nutrient excess by slowing down uptake or storing it
Term
an example of regulation of nitrogen uptake
Definition
-High N uptake rates result in high N levels in the leaves
-Leaves contain high levels of amino acids
-Amino acids are transported back to the roots
-Amino acids inhibit nitrogen uptake by the roots
Term
what happens to leaves before they fall off
Definition
N from leaves goes back into plants for next season
Term
the difference between storage and sequestration
Definition
storage is when it’s intended to be used later, but sequestration is dead end for it
Term
how well boron is stored in plants
Definition
boron typically doesn’t get stored very well
Term
acid
Definition
donates protons (H+)
Term
base
Definition
accepts protons (H+)
Term
how HCl acts in water
Definition
HCl + H2O <--> H3O+ + Cl- HCl is the acid and H2O is the base
Term
buffer solution
Definition
mix of equal amounts of conjugate acid and conjugate base that resists pH changes; this is the important concept for soil
Term
what buffer does when the pH is too low
Definition
some of the conjugate base becomes part of the conjugate acid, making the conjugate acid increase and the conjugate base decrease
Term
what buffer does when the pH is too high
Definition
some of the conjugate acid becomes part of the conjugate base, making the conjugate acid decrease and the conjugate base increase
Term
pH scale regarding soils
Definition
[image]
Term
Regions with predominantly acidic soils
Definition
[image]
Term
some sources of soil acidity
Definition
1. Acids in Precipitation
2. Dissociation of H+ from Soil Organic Matter
3. Dissociation of H+ from broken edges
4. Al and Fe hydrolysis
5. Microbial respiration
6. Nutrient Transformations
Term
the rxn that causes water to become more acidic after being exposed to air
Definition
H2O + CO2 ←→ H2CO3 ←→ H+ + HCO3-
Term
pH of rainfall
Definition
5.7 (only CO2)
Term
where the rainfall is <4.3
Definition
many industrial areas
Term
Natural Causes of Acid Rain
Definition
-Lightning
-Volcanoes
-Decomposing plant biomass
Term
Man-Made Causes of Acid Rain
Definition
-Exhaust from cars, trucks, and buses
-Power plants that burn coal
-Pollution from industry
Term
when organic matter releases H+
Definition
when the soil is a certain pH
Term
when the H+ on broken edges starts to come off
Definition
when the pH increases
Term
series of rxns of aluminum hydrolysis
Definition
Al3+ + H2O → Al(OH)2+ + H+ Al(OH)2+ + H2O → Al(OH)2+ + H+ Al(OH)2+ + H2O → Al(OH)3 + H+ Al(OH)3 + H2O → Al(OH)4- + H+
Term
how hydroxy Al ions reduce CEC
Definition
bvy combining to form large polymers, which are so big, that they're non exchangeable
Term
a type of soluble Al that's toxic
Definition
Al(OH)4-
Term
the equation of microbial respiration
Definition
CO2 + H2O → H2CO3 ←→HCO3- + H+
Term
the pHa of microbial respiration
Definition
6.35
Term
pKa
Definition
the pH where half of the acid is dissociated
Term
some transformations of N that cause soil acidity
Definition
-immobilization -nitrification -volatilization -NH4+ uptake
Term
a transformation of S that causes soil acidity
Definition
mineralization
Term
immobilization of N
Definition
ammonium being converted to organic form
Term
effect of immobilization of N on soil pH
Definition
pH decreases 1 unit for each mole of N
Term
nitrification of N
Definition
ammonium being converted to nitrate
Term
effect of nitrification of N on soil pH
Definition
pH decreases 2 units for each mole of N
Term
volatilization of N
Definition
ammonium being converted to ammonia
Term
effect of volatilization of N on soil pH
Definition
pH decreases 1 unit for each mole of N
Term
ammonium uptake
Definition
to me, it seems to be a type of immobilization
Term
effect of ammonium uptake on soil pH
Definition
pH decreases 1 unit for each mole of N
Term
mineralization of S
Definition
organic S being converted to inorganic S
Term
effect of mineralization of S on pH of soil
Definition
pH decreases 1 unit for each mole of S
Term
effect of a rxn consuming H+
Definition
increasing pH
Term
N rxn that produces the most acidity
Definition
nitrification
Term
active acidity
Definition
H+ in soil solution
Term
how active acidity is measured
Definition
measured by pH in soil-water mixture
Term
methods by which to measure active acidity
Definition
-Electrometric method (pH meter)
-Dye methods (pH indicator)
-Test probe (not reliable)
Term
the most reliable pH meter
Definition
bench pH meter
Term
what dilution does to soil pH
Definition
increases pH
Term
what suspended particles do to soil pH
Definition
-decrease soil pH (negatively charged soil)
-increase soil pH (positively charged soil)
Term
how the probe can affect the pH reading
Definition
because the soil particles interact with how the probe works
Term
what salts do to soil pH
Definition
-decrease soil pH (negatively charged soils)
-increase soil pH (positively charged soils)
Term
this might cause seasonal variations in the soil's pH
Definition
the soil's salt content
Term
the UGA method for measuring pH avoids...
Definition
the seasonal variation in pH caused by differences in the soil’s salt content
Term
an advantage of the UGA method for measuring soil pH
Definition
this gets you close to the true pH, no matter how much salt
Term
potential acidity
Definition
undissociated acids
Term
some sources of potential acidity
Definition
- Al3+ in soil solution (all species) - Hydroxy-Al polymers - H+ and Al3+ in exchange sites - H+ in broken edges of clays, oxides - H+ in organic matter (ROOH, ROH)
Term
when undissociated acids release H+
Definition
when you try to increase the pH
Term
diagram of potential and active adidity in soil
Definition
[image]
Term
amount of potential acidity vs. rate of change in active acidity
Definition
the more potential acidity, the slower the change in active acidity

the less potential acidity, the faster the change in active acidity
Term
potential acidity vs. lime requirement
Definition
the higher the potential acidity, the higher the lime requirement
Term
why midwest soil has high potential acidity
Definition
because it has high buffering capacity and has organic matter that has hydrogen attatched to it
Term
part of the acidity tolerance is...
Definition
aluminum tolerance
Term
some plants with very low acidity tolerance
Definition
-Alfalfa
-Cotton
-Soybean
-Spinach
Term
some plants with moderate acidity tolerance
Definition
-Peanut
-Rice
-Strawberry
-Watermelon
Term
some plants with high acidity tolerance
Definition
-Azalea
-Blueberry
-Cranberry
-Rhododendron
Term
above the critical pH, you don’t see much...
Definition
aluminum
Term
do this to the critical listed pH
Definition
add 0.6 to it
Term
why we now recommend pH 6 instead of pH 6.5
Definition
because there’s the chance of overshooting the target pH
Term
chart showing pH related to nutrient supply
Definition
[image]
Term
apply lime based on...
Definition
pH
Term
methods of determining lime requirement
Definition
1. Titration
2. Buffer Solution
Term
titration
Definition
add a base and measure pH
Term
UGA method of titration
Definition
Add Ca(OH)2 in 1:1 mix -20 g soil (0.02 kg) -20 mL 0.01 M CaCl2 (measure pH1) -this is shaken for 30 minutes because you need that reaction time I think 1:1 means 1mg/mL
Term
why it's not a good idea to use Ca(OH)2 as lime
Definition
because it's caustic such that it burns plants
Term
why lime requirement (LR) is often multiplied by 1.5
Definition
because they assume you’re not using pure calcium carbonate
Term
buffer solution method of determining lime requirement
Definition
add a buffer, measure pH
Term
this determines how much the pH goes up
Definition
buffer capacity
Term
some liming materials
Definition
-Ca
-Mg oxides
-hydroxides
-carbonates
-silicates
Term
H+ must be neutralized by...
Definition
OH- or HCO3-
Term
liming materials have to produce...
Definition
OH- or HCO3-
Term
why CaO is very caustic
Definition
because it reacts very fast
Term
why soil tersting lab uses Ca(OH)2
Definition
because it reacts so fast
Term
the solubility of CaCO3
Definition
15 mg/L
Term
how long it takes to see the effect of calcium carbonate
Definition
about 6 months after application
Term
this isn used to express the purity of liming material
Definition
Calcium Carbonate Equivalent (CCE)
Term
in Georgia, you need at least ______% Calcium Carbonate equivalent to sell it as lime
Definition
85%
Term
is fgineness factor measured in Georgia?
Definition
no

not even given a weight
Term
why repeated applications of lime are needed in Southeastern soils
Definition
to maintain appropriate chemical balances in the soil
Term
the recommended pH is usually...
Definition
6-6.5
Term
the main process that acidifies soil
Definition
nitrification
Term
is Ca(NO3)2 a lime?
Definition
no
Term
test soil how often?
Definition
every 3 years
Term
apply lime how long in advance?
Definition
3-6 months
Term
do this with lime for a faster rxn
Definition
mix it with the soil
Term
why you can't mix lime with the soil in pasture
Definition
because it ruins your pasture
Term
rxn of elemental S that acidifies soil
Definition
S + H2O + 3/2 O2 → 2H+ + SO4- -biological rxn -Thiobacillus sp. -sulfur oxidizes and forms sulfuric acid -you need the bacteria for this reaction to occur
Term
how sulfuric acid has been used to acidify soil
Definition
has been used in midwest where there are some very calcareous soils
Term
how alum (Al2(SO4)3) can be used with poultry litter
Definition
can be mixed in with poultry litter to tie up the phosphorus so that it don’t run off
Term
preferred pH for blueberries
Definition
about pH 4
Term
how manures can contribute to soil being salty
Definition
manures have a lot of salt, so if there’s little or no rain with the manure there, the soil could become saline
Term
this can cause soils to become saline or sodic
Definition
-Water evaporation
-salt accumulation
Term
come cations in saline and sodic soils
Definition
-Na+ -Ca2+ -Mg2+
Term
some anions in saline and sodic soils
Definition
-Cl- -SO4- -HCO3- -CO3-
Term
salt content of sodic soils
Definition
sodic soils don't have much salt
Term
pH of sodic soils
Definition
sodic soils tend to be very basic
Term
when the pH of soil is above 8.5 or 9, this happens to the dissolved organic matter
Definition
the dissolved organic matter is deposited on the surface
Term
chart showing some details of normal, saline, sodic, and saline-sodic soils
Definition
[image]
Term
how EC and exchangeable Na affect plant growth
Definition
[image]
Term
the black stuff is...
Definition
the dissolved organic matter
Term
what saline soils can do to plants
Definition
-water imbalance in the plant
-ionic imbalance
Term
how to remediate the effects of saline soils on plants
Definition
leach with low-salt water
Term
water in soils moves from ______ negative to ______ negative
Definition
less
more
Term
why too much salt in the soil is bad for plants
Definition
-too much salt in the soil draws water away from plant roots because salt has so much negative charge on it -toxic levels of Na+ and Cl-
Term
why saline and sodic soils have bad physical properties
Definition
poor structure, resulting in dispersive clay
Term
why the clay in saline and sodic soils is dispersive
Definition
because some of the negative charge on the clay pushes against each other
Term
amount of exchangeable sodium vs. dispersiveness of the clay
Definition
the more exchangeable sodium, the more dispersive the clay
Term
dispersiveness of the clay vs. hydraulic conductivity
Definition
the more dispersive the clay, the less the hydraulic conductivity
Term
why more dispersive clay has lower hydraulic conductivity
Definition
when the clay is more dispersive, the hydraulic conductivity declines because small particles clog pores in the soil
Term
how to fix dispersiveness of clay in saline and sodic soils
Definition
by replacing the sodium with calcium
Term
how calcium fixes clay dispersiveness in saline and sodic soils
Definition
by neutralizing the negative charges and causing aggregation
Term
problems with saline and sodic soils
Definition
-bad physical properties -dispersed clay -toxic levels of Na+ and Cl-
Term
how to remediate saline and sodic soils
Definition
add gypsum (CaSO4) and leach
Term
how gypsum remediates saline and sodic soils
Definition
Ca2+ replaces Na+ in CEC
Term
some transformations of N that increase soil pH
Definition
-mineralization -denitrification -urea hydrolysis -NO3- uptake
Term
N mineralization
Definition
organic N being turned into NH4+
Term
effect of N mineralization on soil pH
Definition
1 mole N increases pH 1 unit
Term
denitrification
Definition
NO3- turning into N2
Term
effect of denitrification on soil pH
Definition
1 mole N increases pH 1 unit
Term
urea hydroysis
Definition
urea turning into nitrate
Term
effect of urea hydrolysis on soil pH
Definition
1 mole N increases pH 1 unit
Term
NO3- uptake
Definition
NO3- turning into NH2
Term
effect of NO3- uptake on soil pH
Definition
1 mole N increases pH 1 unit
Term
a transformation of S that increases soil pH
Definition
SO4-2 uptake
Term
effect of SO4-2 uptake on soil pH
Definition
1 mole S increases pH 2 units
Term
why fertilizing can be inefficient
Definition
because plant roots are always competing w/ microbes and minerals for nutrients
Term
how nutrients can get out of soil other than by plant uptake
Definition
leaching
Term
Nutrients in solution controlled by
Definition
-Microbial processes (N, S, etc.)
-Chemical processes (P, K, etc.)
-Physical processes (P, etc.)
Term
Microbial processes control these nutrients
Definition
-N
-S
-etc.
Term
Chemical processes control these nutrients
Definition
-P
-K
-etc.
Term
Physical processes control these nutrients
Definition
-P
-etc.
Term
one form in which organic nitrogen can occur
Definition
microbial biomass
Term
why our soils here in Georgia don’t expand and contract very much based on wetness
Definition
because of the H bonds between the sheets of kaolinite
Term
2 Origins of Charge in clay minerals
Definition
-Isomorphic substitution
-Broken edges
Term
example of isomorphic substitution in the tetrahedral layer
Definition
Al3+ replacing Si4+
Term
example of isomorphic substitution in the octahedral layer
Definition
Mg2+ or Fe2+ replacing Al3+
Term
why clays that undergo isomorphic substitution have charges on them
Definition
because each link tries to compensate half a charge
Term
when the charge on clays disappears
Definition
when it breaks down into its elements
Term
the part of clay charge that's pH dependent
Definition
the charge along the broken edges
Term
why the point of no charge is bad
Definition
because it means no nutrient retention
Term
one reason it's important to maintain pH
Definition
because the pH at which there's no charge means no nutrient retention
Term
point of no charge
Definition
the pH at which there's no charge on the clay particles
Term
when gibbsite develops negative charge
Definition
at very high pH, maybe 8
Term
the charge on our soil here in Georgia
Definition
here in Georgia, we have lotta positive soil in the profile
Term
for which type of clay is pH more important? 1:1 or 2:1?
Definition
1:1
Term
amount of charge on 2:1 clays that's permanent due to isomorphic substitution
Definition
90-95%
Term
amount of charge on 1:1 clays that's permanent due to isomorphic substitution
Definition
<50%
Term
amount of charge on 2:1 clays that's pH dependent due to broken edges
Definition
5-10%
Term
amount of charge on 1:1 clays that's pH dependent due to broken edges
Definition
>50%
Term
the point of zero charge for our soils
Definition
about 4
Term
you need this to retain cations
Definition
negative charges
Term
the charge of oxic soils
Definition
just positive
Term
the types of clays in oxic soils
Definition
iron and aluminum oxides
Term
how organic matter adds negative charge to soil
Definition
dissociation of carboxylic acid and phenolic acid

each acid has its own dissociation constant
Term
pH of soil vs. negative charge
Definition
increasing the pH of the soil causes more negative charge
Term
amount of organic matter vs. places for nutrient retention
Definition
increasing organic matter increases places for nutrient retention
Term
how roots add negative charge to the soil
Definition
carboxylic acid dissociation
Term
effective CEC (ECEC)
Definition
what’s actually working in the soil
Term
change in CEC of clay vs. change in CEC of organic C as pH increases
Definition
CEC of OM increases faster than the CEC of clay with increasing pH
Term
why organic matter is critical to increasing CEC
Definition
because its CEC increases with pH at a faster rate than the CEC of clay does
Term
this part of soil contributes the most in terms of increasing CEC
Definition
OM
Term
CEC of sands
Definition
3-10 meq/100g
Term
CEC of loams
Definition
10-15 meq/100g
Term
CEC of silt loams
Definition
15-25 meq/100g
Term
CEC of clays
Definition
20-50 meq/100g
Term
CEC of organic soils
Definition
50-100 meq/100g
Term
CEC of soils in MW
Definition
15-30 meq/100g
Term
CEC of soils in Piedmont
Definition
3-10 meq/100g if lucky
Term
CEC of Sphagnum peat moss
Definition
80-100 meq/100g
Term
CEC of zeolite
Definition
100-300 meq/100g
Term
what determines the CEC of the roots?
Definition
the amount of negative charges in the roots; the more negative charges in the roots, the higher the CEC
Term
CEC of grass roots
Definition
10-30 meq/100g
Term
CEC of legumes
Definition
40-100 meq/100g
Term
these 2 factors affect how strongly an ion is held
Definition
-hydrated radius
-charge
Term
which type of clay, 1:1 or 2:1, can supply nutrients to plants at a lower pH?
Definition
1:1
Term
anion exchange capacity (AEC)
Definition
Total amount of positive charges
Term
important mechanism for AEC in many soils of tropics and subtropics
Definition
displacement of OH-, often from Al and Fe hydroxides
Term
pH where you start developing CEC
Definition
above the point of zero charge
Term
pH where you start developing AEC
Definition
below the point of zero charge
Term
why oxisols have lots of AEC, but not much CEC
Definition
because all they have left is Fe oxides with lots of positive charge
Term
the key to oxisols and why
Definition
increasing organic matter because it increases the CEC
Term
pH vs. depth here in Georgia
Definition
decreases as you go down
Term
pH vs. depth in Midwest
Definition
increases as you go down
Term
at this depth, you retain nitrate
Definition
below a meter or so
Term
why you want a soil that's well buffered
Definition
so the pH don’t change much when you drain it
Term
Mechanisms of nutrient movement to roots
Definition
1: Mass flow
2: Diffusion
3: Root Interception
Term
mass flow
Definition
soluble ions move to root with soil water
Term
mass flow vs. transpiration
Definition
mass flow increases as transpiration increases
Term
diffusion as a mechanism of nutrient movement to roots
Definition
low solubility ions move only by random thermal motion
Term
speed of diffusion as a mechanism of nutrient movement to roots
Definition
very slow, only 1-2cm/season
Term
root interception
Definition
root hair grows until it can reach ions and exchange then takes place
Term
in soil, Ca can accumulate here
Definition
around old root channels
Term
why temp is critical for diffusion of water
Definition
because the diffusion coefficient for water is temp dependent
Term
why lots of of the early corns show purplish color
Definition
because of P deficiency due to the temp being insufficient for diffusion of nutrients
Term
tortuosity
Definition
basically the difficulty of a path; length can be a factor
Term
buffering capacity vs. nutrient adsorption
Definition
when you have a bigger buffering capacity, you have more nutrients being adsorbed onto the soil particles
Term
how much the P moves in soil
Definition
in most soils, not much more than an inch
Term
diffusion of K vs. diffusion of P
Definition
-potassium diffuses much faster than phosphorus
Term
key nutrient uptake mechanism for corn
Definition
diffusion
Term
Root interception can be enhanced by...
Definition
mycorrhiza
Term
Ectomycorrhiza
Definition
sheath around root tip – do not penetrate plant cells (mainly trees of temperate zones)
Term
Endomycorrhiza
Definition
extends surface area of roots – penetrate plant cells (widespread)
Term
depiction of ectomycchoriza
Definition
[image]
Term
depiction of endomycchoriza
Definition
[image]
Term
corn does better on fumigated or unfumigated soil?
Definition
unfumigated
Term
the biological N fixation by legumes
Definition
80-90 million tons of N
Term
how much of the world's N the U.S. uses
Definition
10-15%
Term
the N-P-K nutrients in order of greatest consumption to least consumption
Definition
1: N
2: P
3: K
Term
how much of our atmosphere is N?
Definition
78%
Term
microbes tend to prefer ______ for immobilization
Definition
ammonium
Term
lightning's role in nitrogen
Definition
fixing it, which later comes down as rain
Term
what happens when urea decomposes in the soil?
Definition
raises the pH of the soil
Term
why terrestrial systems are getting enriched with nitrogen
Definition
because the rate of fixation turns out to be greater than the rate of denitrification
Term
soils contain how much N?
Definition
0.02-2.5% N
Term
How much of the soil N is organic?
Definition
about 95%
Term
types of organic N in soil
Definition
-amino acids
-proteins
-complex compounds
Term
how much of the soil N is inorganic?
Definition
about 5%
Term
types of inorganic N in the soil
Definition
-NH4+ (ammonium) -NO2- (nitrite) -NO3- (nitrate)
Term
gaseous forms of N
Definition
-N2O -NO -N2
Term
Nitrogen Mineralization
Definition
Org N --> NH4+ organic N turning into ammonium
Term
the 2 steps of N mineralization
Definition
-Aminization
-Ammonification
Term
Aminization
Definition
Org N --> R-NH2 (amines) organic N turning into amines R is organic residue
Term
Ammonification
Definition
R-NH2 + H+ + H2O --> R-OH + NH4+ amines turning into ammonium
Term
the plant leaves with the most cumulative N mineralized after 160 days
Definition
clover leaves
Term
Nitrogen mineralization from broiler litter varies depending on...
Definition
litter characteristics
Term
2 N compounds that are in broiler litter
Definition
-Water-soluble organic N
-Uric acid
Term
why it's good to know the amount of N Mineralized in all parts of the field
Definition
because if you can estimate these numbers, you can use precision ag
Term
Nitrogen Immobilization
Definition
ammonium turning into organic N NH4+ + R-OH --> R-NH2 + H+ + H2O
Term
Nitrogen Immobilization is controlled by...
Definition
C/N ratio
Term
C/N ratio that leads to immobilization
Definition
C/N > 30
Term
C/N ratio that leads to mineralization
Definition
C/N < 30
Term
the C/N ratio is based on...
Definition
mass
Term
most residues contain this much C
Definition
38-42%C
Term
C:N ratio is an indicator of...
Definition
the stability of the soil supplement
Term
what a lower C:N ratio means for plants
Definition
Lower ratios mean the supplement is very stable and will not draw down nutrients from the soil that plants need to grow.
Term
the best C:N ratios
Definition
30:1 or lower
Term
what residue with a high C:N ratio does
Definition
soaks up water and nutrients, robbing plants of what they need
Term
compost has a 30:1 ratio, but what's the disadvantage?
Definition
it breaks down quickly in the soil
Term
peat moss, being 50:1, draws down a small amount of nitrogen fertilizer such that it won't hurt the plant, but what's an advantage of it?
Definition
it lasts for years in the soil
Term
why the ideal C:N ratio isn't always 30:1
Definition
because the C:N ratio of 30 is a rule of thumb; it really depends on where the N is in the material
Term
why you gotta know the C:N if you want to use compost
Definition
because not all compost will give you the desired N
Term
how much the N immobilizes depends on
Definition
the microbial biomass that’s there
Term
C:N ratio of bacteria
Definition
uaually 6-8
Term
C:N ratio of fungi
Definition
usually 10-12
Term
microbial efficiency refers to...
Definition
C
Term
nitrification
Definition
ammonium turning into nitrite that then turns into nitrate NH4+ + 3/2 O2 --> NO2- + 2H+ + H2O NO2- + ½ O2 --> NO3- only the first rxn acidifies soil
Term
you usually don’t have accumulation of nitrite unless...
Definition
something inhibits the second rxn, such as lots of ammonia
Term
the strain of bacteria that works best at any given pH
Definition
the strain that’s best adapted to that pH
Term
Optimum pH for nitrification
Definition
7.5-8.5
Term
Applying fertilizer in a band can lead to...
Definition
bacteria being dehydrated
Term
nitrification needs...
Definition
aeration and water
Term
aluminum starts to appear in the exchangeable process at this pH
Definition
4.8
Term
in soils with too much ______, nitrification stops
Definition
aluminum
Term
nitrification is very sensitive to...
Definition
pH
Term
if you don’t control the ______, nitrification stops
Definition
pH
Term
problem in soils with 2:1 clay minerals
Definition
fixed NH4+ this is called ammonium fixation
Term
some minerals that can fix ammonium
Definition
-illite
-vermiculite
Term
how much of the ammonium in fertilizer can be fixed in certain soils?
Definition
up to 75%
Term
heating soil does this to the edges of 2:1 minerals
Definition
warps the edges
Term
how 2:1 minerals fix ammonium
Definition
ammonium gets stuck in between the sheets of 2:1 minerals binding to the CEC sites
Term
some N lossses from soil
Definition
-nitrate leaching
-denitrification
-runoff and erosion
-ammonia volatilization
-crop harvest
Term
amount of nitrate leaching depends on...
Definition
- Rate, timing of N fertilization
- Nitrification inhibitors; some fertilizers come with these and they last for about 2 weeks
- Crop uptake; reduces nitrate leaching
- Soil characteristics
- Precipitation patterns
Term
why we have negative charges in the lower levels
Definition
because of low pH
Term
if you have this soil, you’ll have leaching
Definition
bare
Term
denitrification
Definition
nitrate turning into nitrogen gas or nitrous oxide 2NO3- + 2H+ --> N2 + 21/2 O2 + H2O
Term
pH effect of denitrification
Definition
1 mole of N raises the pH by 1 unit
Term
nitrification needs...
Definition
- Nitrate or intermediate product
- Carbon source
- Anoxic conditions (no oxygen)
- Temperature
Term
amount of N gas vs. pH
Definition
amount of N gas increases as you become more alkaline
Term
there’s bacteria that have the ability to switch to nitrification when...
Definition
there’s no oxygen
Term
bacteria can also use this for reduction
Definition
ferric iron
Term
other than soil, denitrification can occur in...
Definition
streams
Term
the majority of global emissions of non-CO2 GHGs are from...
Definition
nitrous oxide from soils and methane from enteric fermentation and livestock
Term
ammonia volatilization
Definition
ammonium turning into ammonia that gets into the air
Term
if there’s lotta ammonium in ______, there’s lotta ammonium in CEC
Definition
solution
Term
the pKa of the ammonia volatilization rxn
Definition
about 9.3; above it, you got mostly ammonia, below it, you got mostly ammonium
Term
ammoniacal nitrogen
Definition
nitrogen in the form of ammonium and ammonia; can be used to determine pH
Term
this form of N can be used to determine pH
Definition
ammoniacal nitrogen (ammonium and ammonia)
Term
the direction the ammonia volatilization rxn goes at higher temperatures
Definition
to the right
Term
some factors that affects ammonia volatilization
Definition
temp and wind
Term
best conditions for ammonia volatilization...
Definition
windy and hot
Term
pH effect of ammonia volatilization
Definition
lowers pH
Term
some conditional details about ammonia volatilization
Definition
-Important at pH > 7.5 and surface application
-Slow at < 5 oC
-N source (contains or generates NH4+)
-Increases with temp
-Increases with wind speed
Term
you get more denitrification from these ecosystems
Definition
wetlands and such
Term
why ammonia can get absorbed by the water
Definition
because it has a very high affinity for water
Term
other than water, ammonia can also be absorbed by...
Definition
soil
Term
how ammonia can lead to soil acidification
Definition
ammonia gets into the atmosphere, reacts with water, becomes ammonium, and acidifies soil
Term
recalcitrant
Definition
resistant to decomposition
Term
what compost will do to soil
Definition
improve the physical conditions of the soil, but won’t give you much N
Term
how much N legume residues can cupply to soil
Definition
20 to 150 kg N/ha
Term
some organic N sources
Definition
-manure
-compost
-legume residues
-sewage sludge
-feather meal
-blood meal
-bone neal
Term
one use of composted sludge
Definition
potting media
Term
why too much nitrate is bad
Definition
toxic to cattle
Term
some inorganic N sources
Definition
-Ammonia
-Urea
-Ammonium Nitrate
-Ammonium Sulfate
Term
the world's largest fertilizer N consumer
Definition
east Asia, followed by S. Asia and N. America
Term
the principal N fertilizer used in most of the world
Definition
urea
Term
IFA
Definition
international fertilizer association
Term
the primary N fertilizer in the US
Definition
urea ammonium nitrate (UAN) solutions
Term
N loss pathways and cropping systems around the world
Definition
they differ
Term
how management to improve crop N recovery and to reduce the risks of environmental loss will vary
Definition
-geographically
-site-specifically
-the N source used
Term
NH3 is compatible with...
Definition
- Carbon steel
- Stainless steel
- Fiberglass, rubber, PVC, polyethylene
Term
NH3 is not compatible with...
Definition
- Aluminum [Al(OH)3] - Copper [Cu(NH3)4]2+ - Zinc [Zn(NH3)4]2+ because it binds with these materials and forms a precipitate
Term
Fertilizers containing NH3
Definition
-Anhydrous NH3 -Aqua NH3
Term
some details about Anhydrous NH3
Definition
- 82% N
- about 6% of world N fertilizer use
Term
some details about Aqua NH3
Definition
- 20 to 25% N
- not used much in Midwest
Term
Overall Effect of NH3 on soil pH
Definition
1 mole of NH3 decreases pH by 1 unit
Term
why ammonia is bad for plants
Definition
because it's toxic to roots
Term
management of Anhydrous NH3 and Aqua NH3
Definition
- Knife into the soil
- Preferably moist soil
- Apply several weeks before planting
- Observe safety recommendations
Term
toxic contaminant in urea fertilizer
Definition
biuret
Term
amount of biuret that can be tolerated
Definition
up to 2%
Term
urea hydrolyzed by...
Definition
urease enzyme
Term
urea effect on pH
Definition
increases pH
Term
why the urea usually has to go to the clays
Definition
because most of the urease is bound to the clays
Term
CRH
Definition
critical relative humidity
Term
critical relative humidity (CRH)
Definition
relative humidity at which urea dissolves
Term
surface application of urea can result in loss of...
Definition
NH3
Term
how to avoid ammonia loss after applying urea
Definition
Irrigate (0.5 to 1 inch) after surface application to incorporate and avoid NH3 losses; this much irrigation needed to make it go down and make it not volatilize
Term
N content of ammonium nitrate
Definition
33 to 34 % N
Term
how much of the world's fertilizer use is ammonium nitrate?
Definition
about 3%
Term
when ammonium nitrate causes ammonia loss
Definition
when the pH is above 7.5
Term
Behavior of Ammonium Nitrate in Soil
Definition
NH4NO3 --> NH4+ + NO3- NH4+ + 2O2 --> NO3- + H2O + 2H+
Term
this is a big problem in ammonium nitrate
Definition
caking up
Term
why you should not stack many bags of ammonium nitrate in hot weather
Definition
risk of explosion
Term
why it's hard to sell ammonium nitrate
Definition
because it can be used to make bombs
Term
N content of ammonium sulfate
Definition
21% N
Term
ammonium sulfate is how much of world's fertilizer usssssssseeeee?
Definition
about 3%
Term
why ammonium sulfate is a very convenient fertilizer
Definition
because it has a significant amount of fertilizer
Term
Behavior of ammonium sulfate in soil
Definition
(NH4)2SO4 --> 2NH4+ + SO42- 2NH4+ + 4O2 --> 2NO3- + 2H2O + 4H+
Term
when ammonium sulfate doesn't cause any ammonia loss
Definition
when the pH <7.5
Term
N content of ammonium chloride
Definition
25% N
Term
how much of world fertilizer use is ammonium chloride?
Definition
about 3% of it
Term
pH effect of ammonium chloride
Definition
1 mole N causes pH to decrease by 2 units
Term
why you have to wash your equipment after using ammonium chloride
Definition
because it's corrosive
Term
why P and K are expressed on an oxide basis in fertilizer grades
Definition
because back in the day, they had to precipitate it and go a gravimetric measure
Term
ammonium phosphates account for how much of world N fert use?
Definition
about 5%
Term
Monoammonium phosphate (MAP)
Definition
NH4H2PO4
Term
N content of Monoammonium phosphate (MAP)
Definition
11-12%
Term
pH effect of Monoammonium phosphate (MAP) on soil pH
Definition
1 mole N causes soil pH to decrease 2 units
Term
pH at which Monoammonium phosphate (MAP) has no ammonia loss
Definition
pH<7.5
Term
Diammonium phosphate (DAP)
Definition
(NH4)2HPO4
Term
N content of Diammonium phosphate (DAP)
Definition
18-21% N
Term
why Diammonium phosphate (DAP) is a very commonly used fertilizer
Definition
because it provides lotsa N and lotsa P
Raises the pH pretty high
Term
pH effect of Diammonium phosphate (DAP) on pH of the soil
Definition
1 mole N makes pH go down 1.5 units
Term
what Diammonium phosphate (DAP) can do to seeds
Definition
Can cause seed germination damage because of high pH (NH3 damage)
Term
amount of Diammonium phosphate (DAP) that should be used with seed
Definition
Use < 10 kg N/ha with seed
Term
some Fertilizers containing only nitrate
Definition
-calcium nitrate
-potassium nitrate
-sodium nitrate
Term
advantage of Fertilizers containing only nitrate
Definition
no soil acidification
Term
how Urea-Ammonium nitrate (UAN) is produced
Definition
Dissolve ammonium nitrate and urea in water
Term
what Urea-Ammonium nitrate (UAN) does in soil
Definition
behaves as ammonium nitrate and urea
Term
UAN solutions are corrosive to these materials
Definition
Cu and Zn alloys, and to an extent, Al alloys
Term
UAN soluytions are OK with these substances
Definition
-PVC
-fiberglass
-stainless steel
-carbon steel
Term
why UAN must not be used with brass nozzles
Definition
because it'll complex with the copper, leading to plugging up
Term
this may happen when UAN ius applied to surface
Definition
ammonia loss
Term
effect of UAN dribbling
Definition
leaves a yellow streak where it burned it, but didn‘t kill it; disappears soon after
Term
composition of UAN
Definition
about half urea and half ammonium nitrate
Term
use of Slow release N fertilizers
Definition
mainly used by turf industry, horticulture, high-value crops
Term
advantages of Slow release N fertilizers
Definition
-release rate more closely matches plant requirements
-no extra N in soil (less leaching)
-less frequent applications
Term
disadvantage of Slow release N fertilizers
Definition
cost
Term
particle size vs. release rate
Definition
the bigger the particle size, the lower the release rate
Term
solubility vs. chain length
Definition
Solubility increases with decrease in chain length
Term
the reason urea releases N so quickly
Definition
because the bond in urea between the C and the ammonium is a single bond
Term
why N release from Triazone compounds is slow
Definition
because of closed-ring structure
Term
why Triazone compounds have lower N loss
Definition
lower solubility
Term
Sulfur-coated urea (SCU)
Definition
Sulfur shell around each urea granule
Term
Sulfur-coated urea (SCU) designed to...
Definition
reduce leaching and denitrification
Term
Polymer-coated compounds (Osmocote)
Definition
Coated N-P-K fertilizer granules
Term
how Polymer-coated compounds (Osmocotes) release fertilizer
Definition
by osmotic exchange with moisture from the soil

-Water moves in, dissolves N, N goes into soil
-Bacteria decompose the plastic coat
Term
uses for Polymer-coated compounds (Osmocote)
Definition
Used in turf, floriculture, high-value crops
Term
the Most common nutrient limiting crop growth and yield
Definition
N
Term
why N is Applied in greater amounts than any other nutrient
Definition
becaus it's used in such large quantities
Term
dry weight content of plants
Definition
normally 1-5%
Term
the primary inorganic forms of N in most plants
Definition
ammonium and nitrate
Term
how urea is often taken in to plants
Definition
thru leaves and such
Term
some organic forms of N that can be taken up
Definition
amino acids; small proteins (peptides)
Term
how plants can take in organic forms of N
Definition
some microbial enzymes help the plant do this
Term
what mycchorrizae help plants access
Definition
more nutrients than just P; they can help turn organic N into inorganic form
Term
plants seem to be able to take up this form of organic N from the soil by themselves
Definition
amino acids
Term
primary mechanism by which nitrate is taken in
Definition
2ndary active trrransport, in the form of a symporter
Term
depiction of symporter
Definition
[image]
Term
the force used to bring nitrate into the cell
Definition
proton motive force
Term
how symporter creates proton motive force
Definition
using energy from the ATP to move protons across the membrane to create a proton motive force
Term
Nitrate transport mechanisms in plants
Definition
low affinity transport system (LATS) and high affinity transport system (HATS)
Term
NRT
Definition
nitrate transport
Term
when LATS is activated
Definition
at high nitrate c'tration
Term
when HATS is activated
Definition
at low nitrate c'tration
Term
Multiple nitrate transporters needed for nitrate movement...
Definition
withiun plant
Term
plants that have both HATS and LATS
Definition
so far, this is all plants that have been categorized
Term
an example of N remobilization within plants
Definition
some N stored within older leaves gets remobilized to where it's needed
Term
one possible use of fluorescence in plants
Definition
to detect where a particular protein is present
Term
is it easier for ammonia or ammonium to get into plant cells?
Definition
ammonia
Term
uniporter
Definition
type of transporter that is specifically for ammonium; this is a passive process based on e'chem gradient
Term
depiction of a uniporter
Definition
[image]
Term
AMT
Definition
ammonium transporters
Term
where ammonium transporters are found in plants
Definition
some present in the root hairs and some functional in the roots
Term
the type of gradient ammonium toxicity can affect
Definition
can dissipate pH gradients
Term
parts of the plant that can have high pH
Definition
-stroma
-matrix
-cytoplasm
Term
parts of the plant that can have low pH
Definition
-lumen
-intermembrane space
-vacuole
Term
cytoplasm needs pH of...
Definition
7.2
Term
why pH is important
Definition
because it helps with the movement of ions and keeps hundreds of enzymes working properly
Term
vacuole needs pH at...
Definition
5.5
Term
the transition of ammonium to ammonia depends on...
Definition
pH
Term
when ammonia in the cytoplasm turns into ammonium...
Definition
after it gets into the vacuole
Term
ammonium gets taken up thru...
Definition
the roots
Term
do animals have mechanisms to manage ammonium?
Definition
yes
Term
lots of plants tend to do better on (ammonium or nitrate)
Definition
nitrate
Term
why do lots of plants do better on nitrate than on ammonium?
Definition
unknown
Term
N transported by...
Definition
xylem
Term
the direction in which the xylem transports nutrients
Definition
roots to shoots
Term
this usually happens to ammonium before transport
Definition
generally incorporated into organic molecules before transport
Term
plant can do this with nitrate
Definition
transport it or assimilate it in the roots
Term
some organic forms of N plants can take up
Definition
-Amino acids
-Amides
-Ureides
Term
how nitrate uptake increases the pH of soil
Definition
Nitrate is taken up together with H+ This increases the pH of the soil or growing medium. Ammonium has the opposite effect
Term
Nitrate reduction requires...
Definition
energy
Term
some plants that seem to prefer ammonium over nitrate
Definition
-Ericaceous plants, such as blueberries, azaleas, rhododendron -rice -Chenopodium album (lambsquarters)
Term
the biologically active form of N
Definition
the reduced form of N
Term
Nitrate needs to be ______ before it can be used
Definition
reduced
Term
reduction of nitrate depends on...
Definition
energy
Term
enzyme used to reduce nitrate
Definition
nitrate reductase (NR)
Term
why plants need Mo
Definition
because nitrate reductase contains Mo. Without Mo, this enzyme does not function, and nitrate cannot be reduced and incorporated into biological molecules.
Term
function of nitrate reductase (NR)
Definition
Catalyzes the reduction of nitrate to nitrite
Term
nitrate reduction occurs in...
Definition
cytoplasm
Term
activity of nitrate reductase depends on...
Definition
-nitrate
-light
-carbohydrates
Term
what happens in plants w/o Mo?
Definition
nitrate reductase (NR) does not function, and nitrate cannot be reduced and incorporated into biological molecules
Term
nitrate reductase (NR) activated by...
Definition
light
Term
why there's no nitrate reduction under low light conditions
Definition
conserves energy
Term
where nitrate can be stored for later use
Definition
vacuole
Term
function of nitrite reductase (NiR)
Definition
Catalyzes the reduction of nitrite to ammonium (light dependent)
Term
nnnnitrite reductase (NiR) is dependent on...
Definition
light
Term
why ammonium has to be incorporated into amino acids (or other compounds) immediately
Definition
because it's highly toxic to plants
Term
this cycle used to incorporate ammonium
Definition
GS-GOGAT
Term
function of the GS-GOGAT cycle
Definition
used to incorporate ammonia
Term
Summary of nitrate Assimilation
Definition
[image]
Term
plants that use GS-GOGAT cycle
Definition
higher plants
Term
GS
Definition
Glutamine synthetase
Term
GOGAT
Definition
Glutamine: 2-oxo-glutarate amido transferase (Glutamate synthase)
Term
GS-GOGAT uses how many ATP?
Definition
1 ATP
Term
GS-GOGAT pathway
Definition
[image]
Term
ammonium can be incorporated into various amino acids, such as...
Definition
-glutamate
-aspartate
-glutamine
-asparagine
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