Plant Nutrients Flashcards
1
Q
How many elements known to be essential
A
17
2
Q
Photosynthesis
A
- Light Energy used, H split off of water
- H combined w/ C and O to make CO2 (diffused through leaf stomata)
- Results in CHO + other organic _______?___________
3
Q
Macronutrients
A
Needed to supply plant so large amounts are needed:
- N
- P
- K
4
Q
Secondary Nutrients
A
- Ca
- Mg
- S
5
Q
Micronutrients
A
Minuscule amounts needed but so critical if below amount needed then it can cause major problems:
- B
- Cl
- Cu
- Fe
- Mn
- Ni
- Zn
6
Q
Mechanisms of Nutrient Uptake
A
- Nutrients reach root surfaces by three mechanisms
- Absorption of Nutrients into roots
- Absorption through leaves
7
Q
Nutrients reach root surfaces by three mechanisms
A
- Mass flow
- Diffusion
- Interception
- all three in constant operation but shift in priority as move through growing season
- root hairs primarily responsible for the uptake
8
Q
Mass flow
A
movement of nutrients in water flowing towards the root
9
Q
Diffusion
A
movement down a concentration gradient from high to low
10
Q
Interception
A
roots explore new soil areas containing unused soil nutrients
11
Q
Absorption of nutrients into roots
A
Mechanism not well understood (hard to see below ground)
- Movement through cell wall easy
- movement into cytoplasm much harder
- nutrient must go through passageway or bond w/ carrier to get through cell membrane
- some actively pulled into cell
- Electrical balance also involved
12
Q
Absorption through leaves
A
Leaf Stomata
- Exchange of H20, )2, CO2
- Some soluble elements can be absorbed in small amounts
* Mostly micronutrients
* Marcos typically need in too high quantities to foliage needs
13
Q
Soil N gains and transformations
A
- N is the key nutrient in plant growth management
- Most Soil N isn’t in a form that can be absorbed
- Unique Nutrient
14
Q
N is the key nutrient in plant growth management
A
- Most commonly deficient nutrient
- controlling factor in plant growth
- Constituent of: proteins, chlorophyll, nucleic acids
- Plants w/ sufficient N have thinner cell walls and are more succulent plants
- N deficiency= poor plant yields
15
Q
Most soil N isn’t in a form that can be absorbed
A
-Most immobile in organic matter
-N2 gas in the atmosphere
-Must be fixed bu soil bacteria
first
16
Q
Unique Nutrient
A
-Can be absorbed soluble organic form
-NH4, NO3
-Soluble, mobile, easily
leached
-can be easily denitrified by
soil microbes
17
Q
2 forms of N available to plants
A
- NH4
- NO3
18
Q
N deficiency symptoms
A
- poor
- spindly
- stunted growth
19
Q
NH4 & NO3 are not necessarily interchangeable
A
- NH4 saves the plant energy (easier for plant to use)
- NO3 is more stable in the soil
20
Q
NH4
A
Ammonium
21
Q
NO3
A
Nitrate
22
Q
Fixation of N gas (N2)
A
- Primary source of soil N
- Taken by soil microbes, converted to NH4
- Wide variation in how much N is fixed
23
Q
Wide variation in how much N is fixed due to:
A
- soil
- fertilizers used
- crops
24
Q
In very productive soil and high amounts of N plants don’t have a relationship with
A
N fixing bacteria, no nodules form on the roots
25
Mineralization of N
-Release of N from decomposition of organic materials
-Conversion of organic N to NH4 form
-Soil OM contains ~5% N
-Only small % of OM
decomposes each year
26
Nitrification of Ammonium
- oxidation of ammonium to nitrate by bacteria and other organisms
- Rapid microbial transformation (1-2 days)
- Most is complete w/in 1-2 weeks
- Some absorbed, some absorbed quickly
- Slowed by anaerobic conditions, dry, cold, toxic chemicals
27
Other Fixation reactions involving Soil N
immobilization
28
immobilization
soluble N held in plant materials or microbes
29
in immobilization N.....
- is not available to plants
- can be fixated to clay particles
- can be consumed by decomposing microbes and held until they die
30
N losses from the system
- leaching of soil N
| - nitrification inhibitors
31
Leaching of soil N
NO3- readily leached form of N, toxic to young mammals
- Nitrate lost due to negative charge
- Ammonium held due to positive charge
- leaching rates
- losses from crop covered soils usually low
- losses from heavily fertilized, wet soils high
32
Leaching rates _____ as _______ increase, when plant growth rates aren't quick enough to keep up with N production
increase
| percolation rates
33
Nitrification inhibitors
- chemicals used to inhibit nitrification
- N-Serve, DCD, ATC
- Inhibit the first step of nitrification, slow the release of N to the soil
- N-serve more volatile and can evaporate slowly
- DCD, ATC stable, easy to handle, can be applied as coatings to granules
34
What effect does Nitrification inhibitors have and what options does it allow producers?
Completely altering ecosystem, lost of N-fixing microbes which eliminate the process to nitrify in the soil, reliant on the addition because we have eliminated natural bacteria populations from the ecosystems
35
N losses from the system
- leaching of soil N
- nitrification inhibitors
- Gaseous losses of soil N
36
N losses from the system
- leaching of soil N
- nitrification inhibitors
- Gaseous losses of soil N
37
Gaseous losses of soil N
Denitrification: change by bacteria of NH4 to N gas
- biological process
- can be most extensive gaseous N loss (esp. with poorly aerated/wet soils)
- rapid process
- substantial N loss can occur in
38
N losses from the system
- leaching of soil N
- nitrification inhibitors
- Gaseous losses of soil N
- Ammonia Volatilization
39
Three reasons large amounts of N lost:
- lack of adequate free O in the soil
- energy source of organic matter for the bacteria
- Warm, slightly acidic soils
40
Ammonia Volatilization
- occur when ammonium is in alkaline environment
- chemical process
- losses occur from surface applications of ammonium/urea (can be ~30%, normally
41
N loss is most extensive under the following conditions:
- high pH, calcareous soils
- fertilizer left on soil surface
- high temperatures
- Low CEC soils
42
Materials supplying N
- Ammonia and Aqueous N
- Solid fertilizers
- Ammonium Sulfate
- UAN
- Organic Wastes
- Controlled-Release N fertilizers
43
Materials supplying N
- Ammonia and Aqueous N
- Solid fertilizers
- Ammonium Sulfate
- UAN
- Organic Wastes
- Controlled-Release N fertilizers
44
Ammonia and Aqueous N: Anhydrous Ammonia (NH3)
- most common N fertilizer (>90% of all N fertilizers made up of some form of ammonia)
- 82% N
- Manufactured from atmospheric N using natural gas to supply H (Haber process); 1st usable fertilizer product of this process, other N fertilizers require more processing
45
Ammonia and Aqueous N: Anhydrous Ammonia (NH3)
- most common N fertilizer (>90% of all N fertilizers made up of some form of ammonia)
- 82% N
- Manufactured from atmospheric N using natural gas to supply H (Haber process); 1st usable fertilizer product of this process, other N fertilizers require more processing
46
Anhydrous Ammonia
- applied w/ chisels to ~5"
- pressured liquid in the tank, gas at atmospheric pressure
- least expensive N fertilizer (per unit N)
- Very dangerous to handle (burns, blindness, inhalation risks, safety precautions)
47
when using Anhydrous Ammonia
-keeo
48
when using Anhydrous Ammonia
- keep away from flames
- keep away from ammonia clouds
- have water available
- store in proper tanks, don't overfill
- paint tanks white to reflect heat
- inspect tanks regularly for leaks/problems
49
Materials supplying N
- Ammonia and Aqueous N
- Solid fertilizers
- Ammonium Sulfate
- Organic Wastes
- Controlled-Release N fertilizers
50
Solid fertilizers
Uera
| Ammonium Sulfate
51
Solid fertilizers
Uera
Ammonium Sulfate
UNA
52
Solid fertilizers
Uera
Ammonium Sulfate
UNA
53
Solid fertilizers: Uera
- synthetic, organic fertilizer
- cheaper per lb than any other solid N fertilizer
- 45% N
- Must be converted in the soil to NH4
- readily soluble and leachable
- stabilized and can be stored when converted in the soil to NH4
- Popular; cheapest solid N source, soluble in water, convenient for application in sprinkler, spray, solution
54
Solid fertilizers: Uera
- synthetic, organic fertilizer
- cheaper per lb than any other solid N fertilizer
- 45% N
- Must be converted in the soil to NH4
- readily soluble and leachable
- stabilized and can be stored when converted in the soil to NH4
- Popular; cheapest solid N source, soluble in water, convenient for application in sprinkler, spray, solution
55
Solid fertilizers: Ammonium Sulfate
- 21% N
- high cost
- less popular
- commonly used in rice
- Ammonium is all available to plant
- sulfate keeps it from being denitrified quickly
- Strongest acidic N fertilizer
56
Solid fertilizers: Ammonium Sulfate
- 21% N
- high cost
- less popular
- commonly used in rice
- Ammonium is all available to plant
- sulfate keeps it from being denitrified quickly
- Strongest acidic N fertilizer
57
Solid fertilizers: UAN
- Urea-Ammonium Nitrate solution
| - 28% N or 32% N
58
Organic Wastes
- considered controlled-release fertilizers
- nutrient concentration is low
- depends on decomposition rates
- may carry undesirables (wees seed, diseases, soluble salts, etc.)
59
Controlled-Release N Fertilizers
- Standard N fertilize crop use rates ~40-70% (rest is leached, denitrified etc.)
- Slow-release N fertilizers used to control proportion of fertilizers available at one time
- More efficient use of N means more cost saving & less pollution
60
Controlled-Release N Fertilizers
- Standard N fertilize crop use rates ~40-70% (rest is leached, denitrified etc.)
- Slow-release N fertilizers used to control proportion of fertilizers available at one time
- More efficient use of N means more cost saving & less pollution
- slow release N products most commonly used in turf grass
61
Controlled-Release N Fertilizers: Urea-Formaldehyde
- varying rates of urea & formaldehyde (greater urea, more available N
- Environmental conditions must favor microbe activity to release N (losses may be ~20%)
62
Controlled-Release N Fertilizers: Polymer-coated N
- soluble form of N (urea) diffuses through polymer membrane
- reliable, consistent control of N release
63
Soil Phosphorus
- Traditionally, 2nd most prescribed nutrient in the soil (K has now passed in use)
- Essential part of nucleoproteins in cell nuclei (carry DNA)
- Main component of cell energy currency (ATP)
64
Soil Phosphorus: Roles
- cell division
- root growth
- plant maturation
- energy transformation w/in cells
- Fruit/seed production
- Animal/human nutrition (growth of bones and teeth)
65
Young plants absorb soil P readily
- most critical for plants to have available P sources early in development
- Wheat from tillering to flowering
- corn ~3 weeks into growing season
66
Problems with P
- soil forms of P very low solubility
- P applied through fertilizer often combines w/ substances to reduce solubility
- major problem to keep P soluble and available to the plants in the soils
- soil P doesn't leach
67
Most P supplied to plants by ________ in the soil
diffusion
| -diffusion rares extremely slow (.02-.1mm/hr)
68
The P Problem:
- Mineral P
- Phosphates in Anaerobic soils
- Organic Soil P
69
The P Problem: Mineral P
- available P critical: supply P in soils is low, P in soils not readily available
- While there is lots of P in the soil, minute fractions actually available
- Original natural source of P: apatite (rock phosphate), along with others, these can be used as low-quality fertilizers sources
- Soluble P often reacts w/ other soil substances to form insoluble compounds (also readily absorbs other molecules, explains soil P buildup
- Soil P most available at pH ~6.5
70
The P Problem: Phosphates in anaerobic soils
- phosphates more soluble than in aerated soils
- iron phosphates are soluble in flooded soils, less tie-up for P
- works out well for rice growers
71
The P Problem: Organic soil P
- phosphates used by plant roots and some microbes to split P from organic residues-making it available for absorption
- P in organic residues tends to be more soluble therefore, more useful to plants (may comprise >50% of soluble soil P)
- the more favorable conditions are for microbe decomposition, > available soil P
72
Managing Soil P
- major pollutant of surface waters
| - Mycorrihzae helps plants access soil P (fumigated soils, non-healthy microbe population soils
73
P Problem
-~6.5 pH optimal for P availability
74
Phosphate fertilizer effectiveness
- most efficient use when banded (row of plants and then right next to it a row of P application)
- only 10-30% of soil applied P is actually used
75
Excess P retained in the soil
- can cause Zn deficiency
| - P pollution from runoff
76
Maximizing P efficiency
- maintain soil pH 6-7
- Promote healthy soil organic matter content
- Band P fertilizer for row crops, broadcast and incorporate for non-row crops
77
Places supplying P
- U.S is world's largest producer (estimated our supply may run out in 20 years at current usage, most comes from FL or western US)
- Western Africa has 6x more supply than U.S
78
Materials supplying P: Phosphate ores and deposits
- rock phosphate mined, ground
- mixed w/ sulfuric acid to form superphosphate (8-9% P, 48% gypsum)
- Mixed w/ phosphoric acid to from tripled superphosphate (20-22% O (40-45% phosphate)
79
Materials supplying P: Mixed N-P fertilizers
-Monoammonium and Diammonium Phosphate fertilizers (apply N and P with same product)
80
Soil K ranks _____ to N in plant use and fertilizer applied
2nd
81
Soil K
Chemical compounds of K very soluble, but mineral form is not
- can see considerable soil amounts of K, but much of it may not be available
- Decomposition of plant residues provides much soluble K
82
Roles of soil K
- cell division
- Formation of CHO's
- Movement of sugars
- Enzyme actions (>60 enzymes known to need K for activation)
- Disease resistance
- Cell permeability
- Important for water balance
83
Forms of Soil K
- Most K used by plants in exchangeable or soluble from
- exchangeable K forms as micas & feldspars weather, or as plant residues release
- Exchangeable soil K in root zone may be small amount (often must supply 150-180lb/ar)
84
K losses and Gains
- K may be taken up in excess amounts by plants (Luxury Consumption)
- May be expensive waste of K fertilizer
- May inhibit Mg absorption
- May not increase crop yield
85
Soluble K losses
- immobilized by microbes
- leached
- trapped in soil clay layers
- Eroded
86
K gains
- Mineralization of organic matter K (can be used ~ as fast as water moves through soils)
- held on cation sites in the soil
87
Soil K is relatively ______ and ________ with temperature changes
stable and not volatile
88
Supplying K to plants
- K fertilizers usually very soluble (may not be very mobile in the soil)
- Is held on cation sites, or will replace other ions on those sites
- needs to be supplied in the root zone to be most effective
- acidic soils often result in K deficiencies
- Abundance of soil Ca, Mg, or K may antagonize uptake of one of the others (competition for plant absorption)
89
KCl
cheapest K fertilizer source
| -can choose sulfate or nitrate forms to add additional nutrients.... but more costly
90
Managing Soil K
- hay harvesting removes much K from the soil each year
| - Highest K requirement during vegetative growth
91
K management Keys
- Maximize efficient use of added K
- Minimize luxury consumption (split applications-especially in sandy soils)
- Maximize use of natural K (organic matter sources)
- Maintain soil pH 6-6.5, reduces leaching losses
92
Materials supplying K
- Potash
- Most potash imported from Canada
- Muriate of potash (KCl)-principle source (60%) potash
- Potassium sulfate-2nd most used K fertilizer
- Potassium-magnesium sulfate- provides 3 nutrients
- Potassium nitrate- adds N with K
93
Soil Ca
Occurs in many minerals, more plentiful in soils than any other plant nutrient
-Ca deficiency is rare due to wide range of Ca sources in soils
94
Mobility of Ca
- taken up as Ca
- Strongly adsorbed to cations
- large amounts may be leached simply due to large supply in the soil
- mass flow usually supplies enough Ca to root zone
- only absorbed through root tips
95
Plant need for Ca
- dividing cells-forms Ca pectate which cements cells together
- Physical integrity and normal cell function
96
Symptoms as Ca deficiencies
- deformation of new leaves/necrotic appearance
| - death of buds
97
Ca is used more than _____ and less than ____
-Mg, K
98
Ca needs ....
to be supplemented in greenhouses
| -Ca deficiency common due to not enough fertilization with higher Ca Sources
99
Ca fertilizers
- Limestone
- Usually only used on soils if they've become acidic
- can use gypsum if pH raise not needed
100
Mobility of Mg
- Readily mobile in the soil
- Most soluble/exchangeable forms supplied in the soil
- reacts similar to Ca
- Lower total leaching loss, less present
101
Plant need for Mg
- most supplied to the roots by mass flow
- 1/5 of Mg used by plants for chlorophyll
- stabilizes ribosome structure
- enzyme activator
102
Symptoms of Mg deficiency
-interveinal chlorosis of older leaves
103
Soil Mg
- Hypomagnesia (grass tetany); can occur in livestock grazing soils low in Mg
- Mg can be tied up by heavy applications of K and/or ammonium fertilizers
104
Mg fertilizers
- Dolomitic limestone (Ca w/Mg)
| - Can also use Mg salts
105
Soil S
- Constituent in 2 of the 20 amino acids
- essential part of proteins
- Also found in vitamins, oils
- Much overlooked
106
Factors increasing need for S fertilizers
- Lower amounts of sulfate added incidentally with other nutrients
- Lower pollution from sulfur oxide into air
- Higher plant yields, greater demands on soils
107
Sources of S
- Availability of soil S hard to determine-major portions come from organic matter (depends on decomposition, climate, temperature, etc.)
- Rainfall (can be toxic to fish, if S is too high)
- S also supplied as part of other fertilizers (rarely need to supply S separately, but the need has been observed)
108
Characteristics of Soil S
- decomposition can release much S
- Exists in many chemical forms, depending on the soil
- Easily leached
- Waterlogged soils can cause soil S source to convert to sulfide-toxic gas to plants
109
Managing soil S
- reduced air pollution,purer fertilizers, better understanding=reduced incidental S additions
- Some increased reports of S deficiencies
110
Sulfur Fertilizers or Amendments
- Select ammonium sulfate or potassium sulfate
| - Gypsum
111
Soil B (Boron) is essential for
- cell wall formation
- sugar movement
- pollination
112
Symptoms of B deficiencies
- terminal bud death
- reduced flowering, retention of flowers
- reduced pollen germination
- less fruiting
113
Soil Chemistry of B
- Forms a weak acid
- deficiencies common in high rainfall areas
- various borates (forms) may exist in different soils
114
Sources for B
- Primary rocks and minerals
- combined in soil organic matter
- adsorbed in soil clays
- Boric acid
115
Boron Deficiency and Amendments
- deficiency in grapes greatly reduces yield
- cost to supplement relatively inexpensive (if over-supplemented can be toxic; fine line between adequate and excess amounts)
- Supplemental B supplied by borax (very soluble, 11% B)
116
Soil Cl
found in soil as Cl^-
- very soluble, mobile
- Not very reactive in the soil
117
Cl role
osmotic role-maintains/equalizes cell charges
118
Unique Features of Cl
- cycles easily
| - Supplied by manures, KCl, rainfall, etc.
119
Cl can....
accumulate to toxic amounts
| -especially in soils high in soluble salts
120
Symptoms of Cl deficiencies
- some diseases linked to Cl deficiencies
- stripe rust
- take-all root rot
- leaf rust
121
Cl Amendments
- deficiencies rarely seen in the field
| - Cl typically supplied incidentally with other fertilizers
122
Soil Cu
- essential for many enzymes
- very low solubility (solubility related to soil pH)
- Strongly adsorbed to soil clays
123
Problem Soils and Susceptible plants: Deficiencies
- Common in organic soils (bonds strongly to organic substances and won't become soluble)
- Sandy Soils
- Calcareous soil-pH8-8.4
- High competition w/ other metals
-less common than other micro deficiencies
124
Symptoms of Cu deficiency
- yellowing of younger leaves
- off-color (bluish/green)
- small dead spots
- leaf curling
125
Sensitive plants to Cu deficiency
- Alfalfa
- Rice
- Wheat
- Oats
126
Cu amendments and their use
- Successful, when applied
- often only needed supplement few ppm/ac
- CuSO4
- Can be applied as foliar treatment
127
Soil Fe
- Important part of energy-providing reactions (Much Fe association w/ chloroplasts)
- Very low solubility (difficult to keep Fe soluble for plants to absorb)
- Very low amounts needed for plants
128
Fe in soil solution- Chelates and availability
- pH has dominant effect of iron solubility
- Fe needs mostly provided by soil organic matter, stays bonded to something else to keep it soluble
- some supplied in chelate form
129
Fe in soil solution- Chelates and availability: pH has dominant effect of iron solubility;
very soluble at pH 3, solubility decreases by factor of 1000pH unit rise , at normal pH, soluble iron very low
130
Fe in soil solution- Chelates and availability: some supplied in chelate form
- Keep metals in a mobile/soluble form
| - move to plant roots by diffusion or mass action
131
Problem Soils, Susceptible plants, & Fe amendments
- deficiencies common in calcareous soils
| - high P levels also antagonize Fe
132
Symptoms of Fe deficiency
-interveninal chlorosis
133
Soluble _____ supplementation will often correct deficiencies
chelate
- Foliar sprays (may need to be repeated)
- Soil applications have longer residual, but much slower acting
- keep organic matter high
134
Soil Mn
- Involved in enzyme systems
- Solubility increases w/ pH increases
- Organic matter decomposition aids Mn solubility
135
Toxicity, Problem soils
- Toxic concentrations more common than any other micro nutrient (soils may naturally have high Mn, conditions can cause Mn toxicity easily)
- High Mn soils may show toxicities at pH just below 6, excessive water, or even at high pH's
136
Toxicity, Problem soils of Mn somewhat common in
Hawaii
| treatment w/ lime and gypsum
137
Symptoms of Mn deficiencies
chlorosis of younger leaves
138
Soil Mo
- exists and needed in minute amounts
- important for enzyme function and N fixation
- Strongly adsorbed, yet soluble
139
Mo: Problems soils and susceptible plants
-deficiencies common in acid/sandy soils
-susceptible crops:
soybeans, alfalfa, corn, tomatoes, etc.
140
Mo: Toxicities usually only show up in grazing animals
- Known to happen on soils w/ high organic matter and neutral/alkaline pH
- Problem related to imbalances of Cu and Mo
- Stunted growth, bone deformation (feed, inject Cu will often correct)
141
Mo amendments
- Foliar sprays
| - Lime acidic soils
142
Soil Zn
essential for enzyme systems
143
Zn in the soil solution
- quite immobile in the soil (+ charge)
| - can become deficient in flooded soils
144
Problem soils and susceptible plants: Deficiencies:
- occur in basic soils, limed soils, cropping with high Zn demand crops (corn, fruits, etc.)
- most expected at high soil pH
cotton responds to Zn supplementation in SW US
145
Symptoms of Zn deficiencies
- interveinal chlorosis in young and old leaves
- reduced stem elongation
- bunched leaves
- small, thick leaves
- early defoliation
146
Zn amendments
- ZnSO4 most commonly used to cure deficiencies
- Foliar application for treatment
- Soil application if problem is anticipated
147
Co
- essential for microbes involved w/ N fixation
| - can be deficient in high Ca soils, sandy, leached soils
148
Si
- very abundant in the environment
- can be deficient in very weathered soils
- appears to strengthen cell walls
149
Na
- essential for desert species to maintain turgor
| - growers usually reluctant to add
150
V (Vanadium)
- essential for algae, microbes
| - may substitute for Mo en enzyme activation
151
Ni
- raised to essential status in 1983
- scientists still argue over its roles
- suspected roles in plant metabolism (enzyme activator)
- No fertilizer w/ Ni currently available
- Soybeans have demonstrated a positive response to Ni treatment
