PLSC 101 - Fertilizers

Exam 3

Questions one must answer before applying fertilizer:

a.      Which fertilizer should be used?

b.      How much fertilizer should be used?

c.      When should fertilizer be applied?

organic fertilizer

waste and residue from plant and animal material

examples of organic fertilizer:

manures, bone meal, blood meal

how far in advance of planting must you incorporate the fertilizer into the soil?

weeks to months

various ___ content per the source of organic fertilizer

nitrogen (N)

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

inorganic fertilizer

manufactured with various levels of nutrient combinations and concentrations

inorganic fertilizers are a _______ ______ form

liquid soluble

(mixed with water and applied)

inorganic fertilizers are available to plants __________ after application

immediately

two slow release types of inorganic fertilizers

granular and coated

granular

granules; non-coated; evenly spread around plants Water aids breakdown of some; medium vs coarse grade and longevity

coated

coated with a plastic or sulfur

moisture or temp activated

Ex: Osmocote – uses a porous plastic resin

what’s an example of an inorganic fertilizer?

Miracle-Gro

chelation

compound formed when a metallic ion (micronutrient) bonds to a molecule (organic matter)

chelation increases the solubility of:

Fe, Zn, Cu, Mn

filler

carrier of fertilizer; ensures even distribution of nutrients; helps prevent fertilizer “burn” of plants

types of filler:

bio-solids (sewage sludge), clay materials, vermiculite (type of volcanic rock)

typically have a neutral pH

ammonium nitrate (34-0-0)

most common source derived from NH4+ and NO3-

34% Nitrogen, 0% Phosphorous, 0% Potassium, 66% filler

ammonium sulfate (21-0-0)

lower N content than NH4+NO3-; used for N and lowering pH in one application

Sulfur reduces soil pH

Urea (46-0-0)

drawback is volatilization of N into atmosphere; Nitrogen not always readily available

calcium nitrate (15-0-0)

lowest N content of common N sources; used for N and raising pH in one application

name the nitrogen sources in order of nitrogen availability

1. ammonium nitrate

2. ammonium sulfate

3. urea

4. calcium nitrate

triple super phosphate: (0-45-0)

soluble P for plant uptake; contains 15% calcium

Ca raises pH

di-ammonium phosphate: (18-46-0)

contains 18% N; used for N and lowering pH in one application

ammonium can lower pH

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; used for K and lowering pH in one application; lower solubility than KCl

sulfur lowers pH, calcium raises pH

calcitic lime

supplies Ca to soil

dolomitic lime

supplies Ca and Mg to soil

finer grades of lime

raise pH quicker but also leach out quicker

coarser grades of lime

raise pH slower but remain active longer

fertilizer concentrations

based mainly on amount of N-P-K

EX: A 20(N)-20(P)-20(K) fertilizer has:

Nitrogen = 20%

Phosphorous = 20% P2O5 (not straight P)

Potassium = 20% K20 (not straight K)