Fertilizers

Questions a person must answer before applying fertilizer:

1. Which fertilizer should be used?

2. How much fertilizer should be used?

3. When should fertilizer be applied?

Fertilizer types

Organic and Inorganic

Organic fertilizer

Waste 7 residue from plant and animal material

Ex: Manures, bone meal, blood meal

Organic fertilizers incorporate

into soil weeks/months in advance of planting

Organic fertilizer have various

N content per source

Usually large amounts needed if relied on as sole source for N as a fertilizer

Inorganic fertilizer

Manufactures with various levels of nutrient combinations and concentrations

Inorganic fertilizers: liquid soluble form

mixed with water & applied

Available to plants immediately after app.

Two slow release types:

• Coated- coated with a plastic or sulfur

  • Moisture or temp activated

  • Ex: Osmocote- uses a porous plastic resin

Granular

granules; non-coated; evenly spread around plants

Water aids breakdown of some

Medium vs.coarse grade & longevity

Coated

coated with a plastic or sulfur

Moisture or temp activated

Coated Ex :Osmocote

uses a porous plastic resin

Nutrient Mobility: Chelation

compound formed when a metallic ion (micronutrient) binds to a molecule (organic matter) (associated with the taking up of metals)

Chelation increases solubility of

Fe, Zn, Cu, & Mn

Fertilizer filler

Carrier of fertilizer

Ensures even distribution of nutrients

Helps prevent fertilizer “burn” of plants

Types of filler

Bio solids (sewer sludge)

Clay materials

Vermiculite

Nitrogen Sources in order of Nitrogen availability

Ammonium Nitrate, Ammonium Sulfate, Urea, Calcium Nitrate

Ammonium Nitrate

(34-0-0)

Most common source derived from NH4+ and NO3-

Ammonium Sulfate

(21-0-0)(sulfur helps lower the pH)

Lower N content than NH4+NO3-

Used for N & lowering pH in one application

Urea

(46-0-0)

Drawback is volatilization of N into atmosphere

Calcium Nitrate

(15-0-0) (used to raise pH)

Lowest N content of common N sources

Used for N & raising pH in one application

Phosphorous Sources

Triple super phosphate, Di-ammonium phosphate

Triple super phosphate

(0-45-0)

Soluble P for plant uptake

Contains 15% calcium (Ca)

Di-ammonium phosphate

(18-46-0)

Contains 18% N 

Used for N & lowering pH in one app.

Know the difference between ammonium(make it more acidic lower pH)

and nitrate (raises the Ph)

Potassium Sources

Potassium chloride, Potassium Sulfate

Potassium Chloride

(0-0-60)

Muriate of potash

Soluble K for plant uptake

Muriate

name for any chloride containing salt

Potassium Sulfate

(0-0-53)

Contains 18% sulfur (S)

Used for K & lowering pH in one app.

Lower solubility than KCI

Lime

• Finger grades of lime:

  • Raise pH quicker but also leach out quicker

• Coarser grade of lime:

  • Raise pH slower but remain active longer

Calcitic lime, Dolomitic lime

Calcitic lime

supplies Ca to soil

Dolomitic Lime

supplies Ca and Mg to soil

Finger grades of lime:

Raise pH quicker but also leach out quicker

Coarser grade of lime:

Raise pH slower but remain active longer

Fertilizer Concentrations

For Ex: a 20(N)-20(P)-20(K) fertilizer:

Based mainly on amount of N-P-K

Nitrogen=20%

Phosphorus = 20% P2O5 (Not straight P)

Potassium = 20% K20 (Not straight K)

How to Calculate 5 of N, P , & K

N-P-K=20-20-20

Nitrogen=20%N

Phosphorus= 20 x 0.44+8.8%P

So, of the 2-5 P2O5,8.8% is straight P

Potassium= 20 x 0.83=16.6%K

So, of the 20% K2O,16.6% is straight K