- Micas (CEC=0 cmolc/kg) release K when introduced to water / weathering... - As this process continues, illite (CEC=30-50 cmolc/kg) begins to form. Particles become smaller and more K+ is released. - Soil 'degrades' into vermiculite (CEC=150 cmolc/kg) with much more available K+ than before.

FINAL Flashcards by Leah Black

Plants take up potassium in what form?

K+

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Name the forms of potassium commonly found in soils.

Mineral
Non-exchangeable
Exchangeable
Solution (taken up by plants)

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What are the relative amounts of potassium found in soil?

Least to greatest plant availability…

Mineral: 90 - 98% (5,000 - 25,000 ppm)
Non-exchangeable: 1 - 3% (50 - 750 ppm)
Exchangeable / Solution: 0.2 - 2% (40 - 600 ppm … 1 - 10 ppm)

Pssst! % = ppm / 10,000 !

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Draw the K cycle!

Doodle time.

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Discuss K fixation.

Micas (CEC=0 cmolc/kg) release K when introduced to water / weathering…
As this process continues, illite (CEC=30-50 cmolc/kg) begins to form. Particles become smaller and more K+ is released.
Soil ‘degrades’ into vermiculite (CEC=150 cmolc/kg) with much more available K+ than before.

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In what clays does K fixation occur?

micas, vermiculite

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In which soil situations can K leaching be a concern?

Only sandy soils.

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What are the basic functions of K in a plant?

NOT a component of biological compounds!

Function related to ionic strength in cells… regulation of turgor pressure

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What is the relationship between K and stomates?

K provides osmotic ‘pull’… opens stomates with influx of K.

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What is the K content in plant tissue (dry matter basis)?

1 - 3%

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Define organic fertilizer.

With C

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Define inorganic fertilizer.

Without C.

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Define soluble fertilizer.

Readily available for plant use.

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Define slow release fertilizer.

Nutrients metered out over time…

two types!

physically slow-release
chemically slow-release

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What’s the difference between chemically-slow and physically-slow release fertilizers?

Chemical composition ‘resists’ degradation.

Physical coatings prevent excessive solution.

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Define guaranteed analysis.

% nutrient content and source of said nutrients.

This MUST be on the product to be considered a fertilizer (AL state law).

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Discuss the Haber-Bosch process… what is produced? from what?

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Formula / nutrient content of ammonium sulfate?

(NH4)2SO4 … 21-0-0

sometimes reported as 21-0-0-24(S)

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Formula / nutrient content of ammonium nitrate?

NH4NO3

… 34-0-0

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Nutrient content of UAN?

urea ammonium nitrate

… 28~32-0-0

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Formula / nutrient content of DAP?

diammonium phosphate – (NH4)2HPO4

… 18-46-0

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Formula / nutrient content of MAP?

monoammonium phosphate – NH4H2PO4

… 11-52-0

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Formula / nutrient content of urea?

CO(NH2)2

… 46-0-0

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What is the most widely used N source in the world?

Urea! (NH4+ / NH4- forming)

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What are biurets and why do we care?

Chain of NH2-CO-NH2-CO... etc. Phytotoxic byproducts from manufacture of urea. Citrus is sensitive, but generally not an issue with most crops(1.5 - 2% okay).

Physical state of UAN?

Liquid.

Physical state of anhydrous ammonia when transported?

Liquid only under pressure.

How is anhydrous ammonia applied?

Applied to surface as a gas... knifed in. Slits must close or gas escapes.

What are some safety issues with anhydrous ammonia?

Very irritating to lungs, eyes, skin. Can blow up. Used in meth manufacture.

Formula / nutrient content of anhydrous ammonia?

82-0-0 ... highest N content of any fertilizer!

What is aqua ammonia?

NH3 in H2O Usually locally made (too heavy to transport due to water content)

Where are ammonium chloride and ammonium bicarbonate used more?

Asia, esp. China

UF / MU stands for...

urea formaldehyde ... shorter chain, faster release methylene urea ... longer chain, slower release

What makes UF / MU slow release?

chemically slow release ... longer chains take longer to degrade!

How is N availability controlled in UF / MU?

Microbial activity

What is a triazone?

Circular MU ... not a chain! Foliar, slow-release source of N.

Give some examples of physically slow-release fertilizers. What makes N slow release?

Coated with sulfur, resin, wax, or other components to SLOW degradation process. Sulfur coat urea (SCU) Polymer coat urea (PCU)

Urease inhibitors slows down what process?

stops urease from forming... helps prevent volatilization losses!

Nitrification inhibitors slow down what process?

affects enzymatic activity of Nitrosomonas...

What are the two common nitrification inhibitors mentioned in class?

- Nitrapyrin | - Dicyandiamide

Is rock phosphate suitable to use within a cropping year? Why or why not?

NO. Takes a while to degrade and become available. Rose growers

Nutrient content of Triple Super Phosphate (TSP)?

0-46-0

Nutrient content of ammonium polyphosphate (APP) ... two different kinds.

10-34-0 11-37-0 Both are liquids!

Formula / nutrient content of potassium chloride?

KCl ... highly soluble 0-0-60 to 0-0-63

Potassium chloride, aka...

muriate of potash (KCl)

Formula / nutrient content of potassium sulfate?

K2SO4 ... 0-0-50

Formula / nutrient content of potassium magnesium sulfate?

"K Mag" ... 0-0-22-22(S)-11(Mg)

Formula / nutrient content of potassium nitrate?

KNO3 ... specialty crops 13-0-44

Formula / nutrient content of potassium thiosulfate?

K2S2O3 ... liquid, foliar apps ... 0-0-25-17(S)

Formula / nutrient content of potassium carbonate?

K2CO3 ... foliar ?

What is the salt index, and why do we care?

Ratio of increase in osmotic pressure produced by fertilizer to that produced by same weight of NaNO3

If a fertilizer has a high salt index, what damage can be done?

reduced germination, inhibited seedling growth, foliar burn

Fertilizer with highest salt index?

Muriate of potash ... KCl

P fertilizers have high or low salt indexes?

Low.

What can we do with P fertilizers that we cannot do with most N and K fertilizers?

Overapply without worry!

The salt index uses which fertilizer as its comparison? (100)

NaNO3

Draw the S cycle!

Doodle time.

In the soil, what percentage of S is in the organic form?

~90%

In which forms do plants take up S?

SO4 2-

What is the role of S in plants?

Important in N relations... amino acid conversion to plant proteins.

In what soil situation do sulfides exist?

Compacted, waterlogged soils.

Until the Clear Air Act, how was a lot of our needed soil S applied?

Blanket deposition

Formula / nutrient content of ammonium sulfate?

21-0-0-24S

Is gypsum a liming source? Why or why not?

No! No carbonates.

What Ca / Mg sources are used when soil pH is low?

Lime!

Plants take up Ca in what form?

Ca2+

Plants take up Mg in what form?

Mg2+

When no lime is needed, what Ca sources are used?

CaSO4 Ca(NO3)2 ... calcium nitrate, specialty crops CaEDTA ... synthetic chelate

What is grass tetany?

specialized Mg issue... low Mg in forages -> low Mg in blood of grazing animals... twitching, staggering, nervous. High rates of NH4+ or K+ fertilizer can depress Mg uptake.

How do we fix grass tetany, economically?

Add supplement (SweetLicks)

When no lime is needed, what Mg sources are used?

Epsom salts (MgSO4) ... 0-0-0-13(S)-10(Mg) ... rose growers. magnesium nitrate, Langbeinite in horticulture

Discuss examples of specialty situations where we apply micronutrients. (four)

1. very sandy soils 2. high pH * 3. early in season with cold, wet soils * 4. specialty crops * = typically together

What is a chelate?

latin for 'claw' ... inorganic / organic structure which holds metal ions within it. Makes ion plant available.

Is Zn deficiency an issue anywhere in the world?

HUGE issue in many parts of the world, but not in US. Commonly seen in cool, wet weather, early in the season.. then disappears.

Why do we talk about K as a nutrient for stress?

Related to water relations, charge balance, osmotic pressure in cells, and membrane continuity

Factors of K availability

1. clay minerals and CEC 2. exchangeable K 3. environment 4. K leaching

Why are nutrient contents (N-P2O5-K2O) reported in different forms than what plants uptake?

Old vestige - nutrients reported on oxide basis.

%N in UF/MU?

~38%

%N in IBDU?

~31%

IBDU stands for...

isobutylidene diurea

How is N availability controlled in physically slow release fertilizers?

Microbial activity and water content

Most commonly applied micronutrient in turf?

Iron! via chelates... gives green without excess growth associated with N application

How are chelates normally applied?

Foliar spray at low rates

Plants take up Fe in what form?

Fe2+ or Fe3+

Plants take up Zn in what form?

Zn2+

Plants take up Cu in what form?

Cu2+

Plants take up Mn in what form?

Mn2+

Plants take up B in what form?

H3BO3+ ... can be taken up as anion, but not typical.

Plants take up Mo in what form?

MoO4 2-

FINAL Flashcards

(89 cards)