Role of Potassium in Plant Growth

Potassium is an essential plant nutrient and is required in large amounts for proper growth and reproduction of plants. It affects the plant shape, size, color, taste and other measurements attributed to healthy produce.

2. ROLE OF POTASSIUM IN
PLANT GROWTH
Presenter
Ayesha Iftikhar
DEPARTMENT OF SOIL SCIENCE

3. History of Potassium
PotassiumsymbolKcomesfrom“Kalium”the
nameoftheelementinGermanyand
Scandinavia.
Potassiummetalwasfirstisolatedin1807by
SirHumphryDavywhoderiveditfromcaustic
potashbytheuseofelectrolysisofthemolten
saltwiththenewlydiscoveredvoltaicpile.
Potassiumwasthefirstmetalthatwasisolated
byelectrolysis.

4. Introduction
▪Potassiumisanessentialplant
nutrientandisrequiredinlarge
amountsforpropergrowthand
reproductionofplants.
▪Itaffectstheplantshape,size,
color, taste and other
measurementsattributedtohealthy
produce.
▪Plantsabsorbpotassiuminits
ionicform,K+.

5. Percentage of potassium in soil
Portion of total K Form of K
90 to 98 percent
Potassiumcontainingminerals(Micas,
Feldspars,etc.)
1 to 10 percent
Clayminerals(Illitictypes)
0.1 to 2 percent
ExchangeableK
+
andSoilsolutionK
+

6. Roles of Potassium in Plants
InPhotosynthesis,potassiumregulates
theopeningandclosingofstomata,
andthereforeregulatesCO2uptake.
Potassiumtriggersactivationof
enzymesandisessentialforproduction
ofATP.
Potassiumplaysamajorroleinthe
regulationofwaterinplants(osmo-
regulation).

7. (Cont.)
Knowntoimprovedroughtresistance.
Potassiumisessentialatalmosteverystepofthe
proteinsynthesis.
Instarchsynthesis,theenzymeresponsibleforthe
processisactivatedbypotassium.

8. Deficiency Symptoms of Potassium
▪Chlorosis
▪Slow or Stunted growth
▪Poor resistance to temperature changes
▪Poor resistance todrought
▪Defoliation
▪Other symptoms
▪Poor resistance to pests
▪Weak and unhealthy roots
▪Uneven ripening of fruits

9. K Deficiency Symptoms in Field Crops

10. Potassium in soils
The total K content of soils frequently exceeds 20,000 ppm (parts per million).

11. 1) Unavailable Potassium
90-98%oftotalsoilKisfoundinthisform.
FeldsparsandmicasaremineralsthatcontainmostoftheK.
PlantscannotusetheKinthiscrystalline-insolubleform.
Overlongperiodsoftime,thesemineralsweather(breakdown)andK
isreleased.
Asthesemineralsweather,someKmovestotheslowlyavailable
pool.Somealsomovestothereadilyavailablepool.

12. 2) Slowly Available Potassium
ThisformofKisthoughttobetrappedbetweenlayersofclaymineralsand
isfrequentlyreferredtoasbeingfixed.
GrowingplantscannotusemuchoftheslowlyavailableKduringasingle
growingseason.
ThisslowlyavailableKisnotmeasuredbytheroutinesoiltesting
procedures.
SlowlyavailableKcanalsoserveasareservoirforreadilyavailableK.
WhilesomeslowlyavailableKcanbereleasedforplantuseduringagrowing
season,someofthereadilyavailableKcanalsobefixedbetweenclaylayers
andthusconvertedintoslowlyavailableK

13. 3) Readily Available Potassium
Potassiumthatisdissolvedinsoilwater(watersoluble)plusthatheldonthe
exchangesitesonclayparticles(exchangeableK)isconsideredreadilyavailable
forplantgrowth.
Theexchangesitesarefoundonthesurfaceofclayparticles.
ThisistheformofKmeasuredbytheroutinesoiltestingprocedure.
PlantsreadilyabsorbtheKdissolvedinthesoilwater.
AssoonastheKconcentrationinsoilwaterdrops,moreisreleasedintothis
solutionfromtheKattachedtotheclayminerals.
TheKattachedtotheexchangesitesontheclaymineralsismorereadily
availableforplantgrowththantheKtrappedbetweenthelayersoftheclay
minerals.

14. Potassium Releasing From Mica
Itsbehaviorinsoilisinfluencedmostlybycation
exchangereactionsthanbymicrobialactivity.

16. Factors affecting Potassium Uptake
1)Soil Moisture
2)Soil Aeration and Oxygen Level
3)Soil Temperature
4)Soil pH
5)Leaching

17. Inorganic sources of K
Material ChemicalFormula K2OContent%
potassium chloride KCl 60 %
potassium-magnesiumsulfate K2SO4-2MgSO4 20 %
potassium nitrate KNO3 44 %
potassium sulfate K2SO4 50 %
Common fertilizer sources of K.

18. Organic sources of K
Break down of crop residues
Manures
A.Majority of K is soluble
a.80% of total K in manure available the year of application
b.10% of total K is available 2
nd
year after application
c.5% of total K is available 3
rd
year after application
B.Book values
a.Dairy solids-9 lbK2O/ton
b.Dairy liquids-20 lbK20/1000gal
C.Book solids

19. Potassium losses from Soil
Erosion:Erosionisoneofthemainpathways
throughwhichKislostfromthesoil.
Runoff:Runoffisoneofthemainpathways
throughwhichKislostfromthesoil.
Leaching:AnnualleachinglossofKfromthe
soilsinahumidregionunderagricultural
production(receivingonlyamoderaterateofK
fertilizer)isusuallyabout25to50kgK/ha.
Harvesting:Plantstakeupverylargeamounts
ofK.

20. Influence of Potassium on Crop Quality
TheeconomicreturnfromtheinvestmentinKcanoriginate
from:
(1)Improvement in total yield;
(2)A greater percentage of total yield which is marketable;
(3)Better crop quality;
(4)Lower cost per unit of production;
(5)Disease resistance;
(6)Stress tolerance;
(7)More effective use of other inputs such as nitrogen (N).

21. Corn
Earliersilkingandlongergrainfill
Uniformmaturityandgrainmoisture
Improvedstalkqualityandreduced
lodging
Morekernelsperearandbettertest
weight
ImprovedNuseeffectiveness

22. Wheat
Improved grain protein
Better milling and baking qualities
More efficient use of N
Improved disease resistance

23. Soybeans
Improvedseedsize
Fewershriveledandmoldybeans
Improvedoilandproteincontent
MoreandlargernodulesforNfixation
Bettertolerancetopestsand
improvedresistancetodisease

24. Application of Potassium Fertilizer
Incorporate for most of crops
Top-dressing effective on perennial basis
Broadcast__when large amounts of K requiredunless soil has
high fixing capacity
Banding___Ridgestill or no till soil with low subsoil K
Starter care must be taken when applied near seed

25. Management Practices for Potassium
SuggestedmanagementpracticesforKvarywithcrop.
Thebeststrategywouldbetoapplypotashfertilizersbeforeseeding
followedbyannualtop-dressapplications.
Theannualapplicationsshouldbebasedontheresultsofroutinesoiltests
forK.
Anypotashneededforsmallgrainproductioncanbeappliedinabandnear
theseedatplantingorbroadcastandincorporatedbeforeplanting.
Whenappliedinaband,therecommendedbroadcastrateofpotashcanbe
reducedbyone-halfwithoutcausingareductioninyield.

26. Environmental effects of Potassium
Potassiumhasnoknowndeleteriouseffectonthequalityof
naturalanddrinkingwatersanditdoesnotinduceeutrophication
inriversandlakes.
Underregularagriculturalpractices,smallamountsofpotassium
ionsisleachedintodeepersoillayersandfinallyreachingthe
aquifers,whichpresentsnoecologicalthreat;Kindrinkingwater
and/orfoodisnohazardforhumanhealthprovidedrenalfunction
isnormal.
adequatesupplyofpotassiumandbetternitrogenmanagement,
nitrogenuseefficiencysignificantlyincreases,andconsequently
thedisposedNtotheenvironmentisreduced.

27. Thank you !
Any Question ..?