Fertilizers

Fertilizers



Chapter 14

Scott’s Starter Fertilizer

Scott’s Turf Builder

Fertilizers



 A materials applied to soil or plants to

provide essential elements.

Fertilizers can be:

 Mineral



 Organic



 Inorganic



 Synthetic organic

Seaweed Extract Fertilizer

(Liquid)

Mineral fertilizers

 Ground rocks, such as dolomitic lime

 Contains calcium

 Magnesium

 Low nutrient content

 Dissolve slowly

 Usefulness as a fertilizer is limited

Mineral Fertilizer

Organic fertilizers

 Animal manure

 “Slow release”

 Composted leaves

 Activated sewer sludge

 Low nutrient content

 Air/water benefit: improves aeration

and drainage and moisture retention

Well Rotted Manure/ O.M.

Release of Nutrient Ions

Organic



Dried

Sheep

manure







Mineral Decay inorganic





Lime 10-10-10

Nutrient ions

Dissolved in the soil

solution Synthetic organic

Synthetic Organic

 Manufactured, but chemically organic

 Urea readily available

 Most other organics are slow release

 Nutrients high compared to natural

Urea Fertilizer

Inorganic Fertilizers

 Mined or manufactured

 Dissolve quickly

 High in nutrients

Fertilizer Forms

 Pressurized liquid

 Fluids

 Dry fertilizers

 Slow release fertilizers

Slow Release Fertilizers

Pressurized Liquids

 Anhydrous ammonia is primary

 Gas at normal temp and pressure

 Liquid at –27 degrees F

 Stored in refrigerated tanks

 Injected into soil, evaporates

 Combines with waterbreaks down

Anhydrous Ammonia



Tank of

Direction of travel Liquid

ammonia









Soil line



Chisel NH3

Fluid Fertilizers

 Liquid, but not under pressure

 Solutions do not settle out

 Suspensions will settle out, so must be

stirred

 Popular, easy to hand, many ways to

apply

Dry Fertilizers

 Applied to soil

 Dissolve quickly

 Pulverized, dusty, absorb moisture

 Granules, large evenly sized grains

 Prills, smooth round, dust free superior

flow, coated

Slow-Release Fertilizer

 Dry release slowly several weeks to

months

 Too costly for agricultural use

 Used in greenhouse and nurseries

 Little lost from leaching

 Osmacote

Greenhouse Slow Release

Fertilizers

Nitrogen Carriers

 Guano (bird and bat manure)

 Sodium nitrate

 Haber process gets N from the air

 3H2+N22NH3

 Anhydrous ammonia=82% N

 Aqua ammonia

 Ammonium nitrate

Guano: A Source of Nitrogen

Nitrogen Carriers (cont’d)

 Ammonium sulfate

 Nitrate of sodium

 Urea

 Urea-ammonium nitrate UAN

 Urea-formaldehyde UF, IBDU, SCU

Nitrogen Carriers

Anhydrous ammonia

 82% N



 From Haber process



 Anhydrous means without water



 Cheapest strongest form of N



 Must be injected deep or will evaporate



 Dangerous for lungs

Anhydrous Ammonia Application

Nitrogen Carriers

Aqua ammonia

 20% N



 Dissolved ammonia in water



 Low pressure solution



 Use declining

Nitrogen Carriers

Ammonium nitrate

 33% N



 ½ ammonium N, ½ nitrate N



 Good general purpose fertilizer



 Absorbs moisture and cakes



 Keep in enclosed containers/ bags

Nitrogen Carriers

 Ammonium sulfate

 21% N

 Acid forming since it contains S

 Good for acid loving plants

 Not good starter fertilizer

 Ammonium fertilizers must be mixed

into soil by volatilization

Nitrogen carriers

Nitrate of soda

 16% N



 Used on tobacco



 Raises pH because of Na



 Ca works similar but less salty

Nitrogen Carriers

Urea

 46% N



 Synthetic organic



 Rapidly breaks down



 Cheapest to produce



 Most popular



 “Hot”: don’t over apply

Nitrogen Carriers

Urea-ammonium nitrate (UAN)

 Made by mixing liquid urea with

ammonium nitrate

 Can make either 28% or 32% N

Nitrogen Carriers

Urea-formaldehyde (UF)

 (IBDU)



 Sulfur coated (SCU)



 Slow release synthetic organic



 Used for turf and greenhouse

Nitrogen Carriers

 Carrier %N %NH4 %NO3 pH

 Anhydrous 82.0 82.0 0 very A

 NH4NO3 33.0 16.7 16.6 acid

 NH4SO3 21.0 21.0 0 very A

 H2ONH4 24.0 24.0 0 acid

 NaNO3 16.0 0 16.0 basic

 CaNO3 15.5 0 15.5 basic

Nitrogen Carriers

 Carrier %N %NH4 %NO3 pH

 Urea 46.0 46.0 0 acid

 UAN 32.0 22.0 10.0 acid

 Urea Form. 37.0 37.0 0 acid

 Sulfur ctd 39.0 39.0 0 acid

 IBDU 30.0 -- - -

The Haber process

Carbon

dioxide Urea

Ammonia

Ammonium UAN

Oxygen

Sodium Nitrate

Carbonate Sodium

calcium Nitrate

Natural carbonate Calcium

gasN2NH3 Nitrate

Sulfuric

acid Ammonium

Phosphoric Sulfate

Acid Ammonium

Phosphates

Anhydrous

ammonia

The Haber Process

Organic Fertilizers

 Material N P2O5 K2O

 Guano 10 4 2

 Blood meal 12 2 1

 Fish meal 10 6 -

 Cttn sd ml 6 3 1.5

 Soy bn ml 7 1.2 1.5

 Bone meal 3 22 -

 Wood ashes - 1 4

Phosphate Carriers

 Obtained by mining rock phosphate in

Florida

 From apatite or calcium phosphate

 Usually treated with acid to release P

Phosphate Fertilizer

Phosphate Carriers

 Rock phosphate 25-35% P

 Slow release

 Works best when finely ground and

applied to acid soil

 Acid soils break down apatite

Phosphate Carriers

 Superphosphate 20% P

 Made from rock phosphate and sulfuric

acid

 ½ gypsum (calcium sulfate) and ½

calcium phosphate

 Not used much

Superphosphate Fertilizer

Phosphate Carriers

 P Carrier %> P2O5 P% N%

 Rock phosphate 25-35 11-15 -

 Superphosphate 20 8.7 -

 Triple phosphate 46 20 -

 Monoammonium 46-53 21-24 11-13

 Diammonium 46-53 20-23 18-21

 Ammonium phos 36-62 16-27 10-15

 Phosphoric acid 53 23 -

Phosphate Fertilizers



70%

Sulfuric

Acid

90% Superphosphate

Sulfuric

rock Acid

phosphate

Phosphoric Phosphoric acid

acid

Treble superphosphate



Rock phosphate

Phosphate fertilizers

Superphosphate

 46% P



 No sulfur or calcium



 Popular fertilizer



 Contains Fluorine, not good for many



potted foliage plants

Phosphate Fertilizers

Phosphoric acid

 53% P



 Highly corrosive



 Used to prepare fluid fertilizers

Phosphate Fertilizers:

Ammonium Phosphates

Mix phosphoric acid and ammonia

 Makes monoammonium phosphate 53%



 And diammonium phosphate 46%



 Referred to as MAP and DAP



 Used as dry or fluid



 Ammonium polyphosphate similar



 Ammonium ions improves P uptake

Phosphate Fertilizers

Bone meal

 Contain phosphates and calcium



 By-product of meat packing



 Widely used by homeowners

Bone Meal

Potassium Carriers

 Mines are in New Mexico, Utah,

California, and Canada

 A mixture of P, Na, an Mg salts

 Producers separate and purify

Potassium Carriers:

Muriate of Potash KCl

 60% P accounts for 97% of all K fert.

 Costs less

 Dissolves easily in water

 Sold primarily as dry fertilizer

 Not good for chlorine sensitive crops

Potassium Carriers:

Sulfate of Potash KSO4

 49% K

 Used in dry fertilizer

 Primarily used for tobacco because

tobacco is sensitive to chlorine

 Also adds sulfur to the soil

Potassium Carriers:

Nitrate of Potash KNO3

 13% N and 44%K

 Common for container plants

 Used dry

 Or weak solution

Potassium Carriers:

Sulfate of Potash-Magnesia

 Also used in chlorine sensitive crops

 22% K, 11%Mg, 22%S

 Used in soils lacking Mg and S

 Wood ashes and manure are also good

potash sources

Potassium Carriers:

Granite Meal

 Dust by product of monument and

building stone industry

 Used by organic growers

 Not readily soluble but slow reserve

Potassium Carriers

 K carrier %K2O %N

 Muriate of potash 60 -

 Sulfate of potash 49 -

 Potassium nitrate 44 13

 Sulfate of K Mg 22 -

Potassium Carriers:

Secondary Elements

 Mineral fertilizers supply most of

Ca,Mg,S

 Most important fertilizers are lime,

gypsum, and sulfur

Common Sources of

Secondary Elements

 Material Ca Mg S effect pH

 Calcitic lime 31.7 - - basic

 Dolomite 21.5 11.4 - basic

 Gypsum 22.5 - 12 neutral

 Hydrated Lm 46.1 - - basic

 Burned Lime 60.3 - - basic

 Magnesia - 55 - basic

Common Sources of

Secondary Elements

 Material Ca Mg S effect pH

 Mg sulfate - 11 14.5 neutral

 K Mg So4 - 11 22 neutral

 Flowers of S - - 30-100 acidic

Trace Elements

 Each trace element is available in a

number of different forms

 Sulfate salts are inexpensive and

dissolve easily in water

 Or can be used dry

 FTE fritted trace elements

 Salts added to molten glass

 Glass ground to fine powder

Trace Elements

 Chelates- special form of trace element

that guards elements from being fixed

in the soil

 Chelates are water soluble

 Mixing fertilizers is more convenient

than applying each element separately

Trace Elements

El FTE SO4 chel other treatment

B X borax BC borax

Cu X X X oxide BC or BSO

Fe X X X F chelate

Mn X X X oxide BC or BSO4

Zn X X X B chelate

Mo X NaMo mx w/NPK,lime

Iron Chelate

Fertilizer Analysis and Grade

 Fertilizer analysis tells fertilizer elements

and percent content

 Grade lists contents as three numbers

 NPK

 0-0-60 means 60%K in bag

100

 Potash= 2000 # x60%=1200#

Fertilizer Analysis and Grade

 20-10-20 means

 20% N

 10% P

 20% K

 Grade may also indicate secondary

elements

 Fertilizer grade never totals 100%

Fertilizer Analysis and Grade

 The bag may also contain fillers such as

 Sand

 Clay granules

 Limestone

 Corncobs

 Used to bring weight up to one ton

Fertilizer Ratio

 Grade ratio

 10-10-10 1-1-1

 20-20-20 1-1-1

 6-12-12 1-2-2

 5-15-30 1-3-6

 Applying one ton of 10-10-10 is the

same as ½ ton of 20-20-20-

Elements and Oxides

 Most people think of fertilizer grade as

N-P-K

 Nitrogen is listed as the element but P

and K are listed as oxides

 N-P2O5-K2O

 In a 20-10-10 it appears that there is

200# of P per ton…no! 88#P per ton

Elements and Oxides

 Oxide Element

 N 400 400

 P 200 88

 K 200 166

Elements and Oxides:

Converting Between

 (a) P X 2.29 = P2O5

 (b) P2O5 X ).44 =P

 (C) K X 1.2 = K2O

 (d) K2O X 0.83 =K

 How much K in 0-0-60/ton

 K= 2000 X 60% X 0.83 = 996#

100

Calculations for Blending

 Z = AxB

C

 Z = # of carrier for each element

 A = # of mixed fertilizer needed

 B = % of element needed

 C = % of element in the carrier

Blending

 Blend a 10-10-20 using;

 Ammonium nitrate 33-0-0

 Triple superphosphate 0-46-0

 Muriate of potash 0-0-60

Blending

 Ammonium nitrate=2000 x 10 =606#

33



 Triple super P =2000 x 10 = 435#

46



 Muriate of K = 2000 x 20 = 667

60



 Total carriers = 1708# + 292# fillers

Choosing Fertilizers

 Nitrates are preferred for early spring

 Nitrate produce a better tobacco leaf

 Ammonia is better for fall application

because less will leach out by spring

 Ammonia is better for rice paddy

because nitrate N converts to gas and is

lost

Choosing Fertilizers (cont’d)

 Container plants prefer nitrate because

ammonia are easily damaged by

ammonia

 Many acid loving plants prefer

ammonium N

 Price per # is another factor

Pricing Fertilizer

 Price/lb N= Price per ton x 100

2000 x % N



 A ton of ammonium nitrate @ $200/T

 Price/lbN = 200 x 100 = $.30 per lb N

2000 x 33



 The price can also be figured per bag

Applying fertilizer

 Can be applied before, during or after

planting

 In a fine soil with little leaching and

high CEC one application may do, but

 P is not placed correctly for best results

 N may leach out before used

Applying Fertilizer:

Irrigated Corn, Sandy Soil

 Crop stage fertilization

 Preplant 1/6

 8 leaves 1/6

 12-15 leaves ½

 Early tassel 1/6

Applying Fertilizer

 The best pre-plant is by broadcast

 Soil injection (liquids)



 Banding applied 2”below and 1” to the

side of seed

Pop-up applied with seed, small amounts

Should be water soluble, high P, low salt

not produce free ammonia

Applying Fertilizer

 Dilute fertilizer in water at transplant

 Topdressing, applied over growing crop

such as grains, range, and turf.

 Side dressing is a fertilizer application

along the plant row part way through

the growing season

Applying Fertilizer

 Fertigation is fertilizer injected into the

water system

 Foliar feeding, applying fertilizer directly

to leaves, usually a trace element such

as iron

Applying Fertilizer:

Fluids

 Knifed

 Foliar

 Fertigation

 Broadcast

 Banded

 Pop-up

 top-dress

Applying fertilizer

solids

 Broadcast

 Banded

 Pop-up

 Top-dress

Applying Fertilizer:

Slow-Release

 Top dress applications recommended

Effects of Fertilizer on pH

 A fertilizer may be chosen to change pH

 P fertilizers do not cause lasting pH

change

 Superphosphate do not cause change

but phosphoric acid and ammonium

phosphates are acidic

 Ammonium and urea lower pH

 Ca and Na nitrates raise pH

Effects of Fert. on Soluble Salts

 Most fertilizers are salts

 High salts prevent germination

 A concentration of salts may “burn”

 Low watering can cause salt build up

 Intensive growing such as a

greenhouse must have constant salt

monitoring

Effects of Fert. on Soluble Salts

 Fertilizer salt rel.sal anal. CCE

 Na NO3 100 100 16.5-0-0 +36

 NH4NO3 105 49 35-0-0 -36

 NH4SO4 69 54 21-0-0 -107

 ANYHNH4 47 9 82-0-0 -36

 Urea 75 2 46-0-0 -36

Effects of Fert. on Soluble Salts

 Fertilizer salt rel.sal anal. CCE

 Mono NH4P 30 13 12-55-0 -107

 Spr phos 8 17 0-20-0 0

 3 x phos 10 9 0-46-0 0

 KNO3 74 24 13-0-46 +36

 KCl 116 39 0-0-60 0

Fertilizer Summary

 Fertilizer is a substance used to supply

elements to plants

 The Haber process fixes N from the air

into usable forms

 Fertilizers come in many forms

 Cost and effect are factors in deciding

what to use