Potassium cycle

History of Potassium Cycle• Potassium comes from the word

"potash"• Potassium metal was first isolated in

1807 in England by Sir Humphry Davy, who derived it from caustic potash (KOH, potassium hydroxide)

Properties of Potassium • symbol K (from Neo-Latin kalium)

and is an alkali metal• 　 　 Potassium makes up about 2.6%

of the weight of the Earth's crust and is the seventh most abundant element.

• Potassium accumulates in plant cells, and thus fresh fruits and vegetables are a good dietary source of it

• .

Biological Role• is the eigth or ninth most common

element by mass (0.2%) in the human body

• Potassium is necessary to many plant functions, including carbohydrate metabolism, enzyme activation, osmotic regulation, and protein synthesis.

• Potassium is essential for photosynthesis, for N-fixation in legumes, starch formation, and translocation of sugars.

• A good supply of K promotes production of plump grains and large tubers. plump grains and large tubers pictures

Potassium sources•Primary Minerals, the original sources

of potassium are the primary minerals, such as:

Feldspars - Orthoclase and microcline - KAlSi3O8

Mica - Biotite - KAl(AlSi3O10)(OH)2Mica - Muscovite - K(Mg, Fe)(AlSiO10)

(OH)2

• Potassium in the crystalline structure of primary minerals is not available to plants and it accounts for 90-98% of the total soil K.

Potassium FertilizersThey consist essentially of potassium in

combination with chloride, sulfate, nitrate or polyphosphate, and include the following:

Potassium chloride (KCl)Potassium sulfate (K2SO4)Potassium nitrate (KNO3)Potassium phosphates (KPO3, K4P2O7,

KH2PO4, K2HPO4)

Potassium losses• Erosion-erosion is one of the main pathways

through which K is lost from the soil.

• Runoff-runoff is one of the main pathways through which K is lost from the soil.

• Leaching-annual leaching loss of K from the soils in a humid region under agricultural production (receiving only a moderate rate of K fertilizer) is usually about 25 to 50 kg K/ha.

• Harvesting-plants take up very large amounts of K.

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