ASSOCIATION OF AMERICAN PLANT FOOD CONTROL OFFICIALS (AAPFCO) OFFICIAL FERTILIZER DEFINITIONS
POTASH PRODUCTS (K₂O)

 

K-9 — Double Sulfate of Potash and Magnesia (Langbeinite)

Is a commercial product containing not less than twenty-one percent (21%) soluble potash (K₂O) nor less than fifty-three percent (53%) sulfate of magnesia and not more than two and one-half percent (2.5%) chlorine (Cl) may be expressed as chloride (Cl).
(Official 2016, WA)

K-16 — Greensand

The naturally occurring mineral glauconite, which is a hydrated silicate of iron and potassium.
(Official 1997)

K-3 — Kainit

Is a potash salt containing potassium and sodium chlorides and sometimes sulfate of magnesia with not less than twelve percent (12%) soluble potash (K₂O).
(Official 1975)

K-11 — Kelp

Marine algae belonging to the orders Laminariales in the class Phaeophyceae. Kelp is classified as a seaweed.
(Tentative WA 2020, Official SA 2021)

K-18 — Manure Salts

Are soluble salts from manure, chiefly potassium chloride (KCl). It shall contain not less than twenty percent (20%) soluble potash (K₂O).
(Official 2013)

K-4 — Mine Run Potash Salts

Are potash salts containing a high percentage of chloride and from twenty percent (20%) to thirty percent (30%) soluble potash (K₂O).
(Official 1951)

K-5 — Muriate of Potash (commercial potassium chloride)

Is a potash salt containing forty-eight percent (48%) to sixty-two percent (62%) soluble potash (K₂O) chiefly as chloride.
(Official 1951)

K-6 — Nitrate of Potash (potassium nitrate)

Is chiefly the potassium salt of nitric acid. It shall contain not less than twelve percent (12%) nitrogen and forty-four percent (44%) soluble potash.
(Official 1951)

K-7 — Nitrate of Soda and Potash (sodium and potassium nitrate)

Is chiefly the sodium and potassium salts of nitric acid. It shall contain not less than fifteen percent (15%) nitrate nitrogen, ten percent (10%) soluble potash and eighteen percent (18%) sodium.
(Official 1952)

K-1 — Potash

Moved. See T-127.
(SA 2020)

K-17 — Potassium Acetate (fertilizer quality)

Is the potassium salt of acetic acid having the formula KC₂H₃O₂.
(Official 2005)

K-19 — Potassium Carbonate

(K₂CO₃) is the salt of carbonic acid and potassium. It shall contain not less than sixty-four percent (64%) soluble potash (K₂O).
(Official 2013)

K-15 — Potassium Citrate (monopotassium citrate) (KH₂C₆H₅O₇) (fertilizer quality)

Is a potassium salt of citric acid, principally monopotassium citrate.
(Official 2002)

K-25 — Potassium Formate

The water-soluble potassium salt of formic acid (KCHO₂).
(Tentative WA 2022, Official SA 2022)

K-23 — Potassium Hydrogen Phosphate Dihydrate

Inorganic water-soluble fertilizer, double salt of monopotassium phosphate and dipotassium phosphate. It shall contain forty-two percent (42%) to forty-five percent (45%) available phosphate and forty-two percent (42%) to forty-five percent (45%) soluble potash. (CAS Number 66922-99-4)
(Tentative WA 2019, Official SA 2019)

K-13 — Potassium Hydroxide (KOH, caustic potash)

Is a solid, strong base containing sixty-six percent (66%) soluble potash (K₂O).
(Official 1999)

K-14 — Potassium Phosphite

Is a product obtained when phosphorous acid is neutralized with potassium hydroxide (aqueous) and consists primarily of dipotassium phosphite (K₂HPO₃) in a stable aqueous solution. The phosphorus atom is in the oxidation state of III. It does not contain any significant amount of available phosphate.
(Official 2002)

K-26 — Potassium Propionate (potassium propanoate)

Is a potassium salt of propionic acid (propanoic acid) with the formula of KC₃H₅O₂.
(Tentative WA 24, Official SA 2024)

K-12 — Potassium Thiosulfate (fertilizer quality)

Is a product composed principally of K₂S₂O₃. It is most commonly available in aqueous solution.
(Official 1999)

K-20 — Potassium Metaphosphate

(KPO₃) is chiefly the potassium salt of metaphosphoric acid (HPO₃). It shall contain not less than fifty-five percent (55%) available phosphate (P₂O₅) and thirty-seven percent (37%) soluble potash (K₂O).
(Official 2013)

K-24 — Seaweed

Macroscopic multicellular marine algae.
(Tentative WA 2020, Official SA 2021)

K-2 — Soluble Potash

Moved. See T-128.
(SA 2020)

K-10 — Sulfate of Potash (commercial potassium sulfate)

Is a potash salt containing not less than forty-eight percent (48%) soluble potash (K₂O), chiefly as sulfate, and not more than two and one-half percent (2.5%) chlorine.
(Official 1950)

K-8 — Sulfate of Potash-Magnesia

Is a potash salt containing not less than twenty percent (20%) soluble potash (K₂O) nor less than ten percent (10%) magnesium (Mg) and not more than two and one-half percent (2.5%) chlorine (Cl) may be expressed as chloride (Cl).
(Official 2016, WA)

K-21 — Tobacco Stems

Are whole or ground waste tobacco products, principally stems. It shall contain not less than two percent (2%) total nitrogen and six percent (6%) soluble potash (K₂O).
(Official 2013)