Role of potassium in increasing the yield of crops and improving the quality of produces has been in the agenda of soil scientists.

2. Department of soil science and Agricultural
chemistry, College of Agriculture, SKRAU Bikaner
334006
Seminar Incharge
Dr. Yogesh Sharma
Speakar
Chetan Kumar Dotaniya
Credit Seminar

3.  Potassium is one of the essential major plant
nutrients after nitrogen and phosphorus.
 Its management is more important since large
amount of native K is mined by the crops if it is
not supplied externally.
 Role of potassium in increasing the yield of
crops and improving the quality of produces has
been in the agenda of soil scientists.

4.  Potassium is the most abundant macronutrient in
soils. It is also the seventh most common element in
the lithosphere which contains on average 2.6%
potassium.
 The total potassium content of Indian soils varies
from 0.5 to 3.0%.
 Total potassium present in soils, more than 98%
occurs in primary and secondary minerals.

5.  It has important role in pH stabilization, enzyme
activation, protein synthesis, stomata movement, cell
extension, and photosynthesis.
 Essential in the formation and transfer of starch and
sugars especially in potato, sweet potato, Banana.
 It increases plumpiness of grains and seeds.
 Straw of cereals become strong and stiff and thus it
reduces lodging.
 It is considered as quality element for many crops.
 Imparting resistance against environmental stresses
such as drought old and frost.

6.  Plants will easily lodge and be sensitive to disease
infestation.
 Fruit and seed production will be impaired and quality
is poor.
 Scorching of leaves and burning appearance of leaves
mergence and tip.

7.  Reduced ability to adapt to environmental stress, e.g.,
drought, lodging, etc
 Tips and edges of leaves become yellow (chlorosis)
and then die (necrosis).
 In some crops, K deficiency produces white necrotic
spots that looks like insect damage.
 Older leaves turn yellow initially around margins and
die; irregular fruit development.

8. Healthy leaf
Kdeficient
leaves

9. Banana Maize

10.  Progressively greater removal of soil K due to increase in
agricultural production by increasing fertilizer use,
intensifying cropping systems, promoting high-yield crop
varieties and improving irrigation.
 Due to use of high-analysis, K-free fertilizers, such as urea
and DAP.
 Decreasing use of traditional organic manures and K-
containing fertilizers.
 Leaching losses of soil K with the spread of flood irrigation to
large areas.

11. Availability of Potassium FormsAvailability of Potassium Forms

12. Mica- Muscovite and Biotite
Feldspars- Orthoclase and Microcline constitute the
major K bearing minerals which on weathering slowly
release K to the soil.

14.  This is the potassium present in soil solution and
measured by extracting the soil with distilled water.
 Amount of water-soluble K generally comparable to
those determined by electro-ultrifilitration a technique
proposed by Nemeth (1979).
 Water-soluble K in soil may vary from 1 to 10 ppm in
soil.
 Solution K concentration is important for successful
crop production specially maturity condition for crop.

15.  This is potassium held in the exchange complex of 2:1 layer
silicates.
 Soil containing mica group (<10% K) having more
exchangeable K than those containing illite (6-8%) and
vermiculite contains (<2%), which in turn have more than
the soil containing kaolinite.
 The amount of exchangeable K in soil may vary from 40 to
600 ppm in soil.
 For the precise determination of exchangeable K, water-
soluble K should be determine by extracting soil with
distilled water separately and the value obtain should be
substrated from the 1N ammonium acetate extractable K
value to obtain exchangeable K.

16.  K changes from a non-exchangeable form to an
exchangeable form.
 Non-exchangeable K in soil is generally measured by
extracting the soil with 1 N boiling nitric acid and is
reported as HNO3 extractable.
 Non-exchangeable K, fixed K in soil varies from 50 to 750
ppm in soil.
 Non-exchangeable K is distinct from mineral K in that is
not bonded covalently within the crystal structure of soil
mineral particles; instead, it is held between adjacent
tetrahedral such as micas, vermiculites, and intergraded
minerals.

17. A. The potassium minerals forms in soil:
Orthoclase [(K,Na)AlSi3O8]
Microcline [(Na,K) AlSiO4],
Muscovite-mica [KAl3Si3O10(OH)2],
Biotite [K(Mg,Fe)3AlSi3O10(OH)2],
Phlogopite [KMg3AlSi3O10(OH)2].
B. Potassium in mineral form in soils may vary generally from
5000 to 25000 ppm in soil.

18.  Time of potassium uptake and its translocation to
reproductive part varies with different plants.
 The plants generally absorb most of their potassium
requirement during an earlier growth stage.
 Maize absorbs 70-80% K by silking time, and 100% is
absorbed three to four weeks after silking.
 The potassium in normal healthy leaves varies between
1-4%.
 Potassium uptake is often equal to or more than that of
nitrogen.

19.  Total soil K content ranges between 0.5 to 2.5%.
 Listed in order of increasing availability, soil K exists
in four forms:
Mineral 0.5 to 2.5%
Non-exchangeable 50-750 ppm
Exchangeable 40-600 ppm
Solution 1-10 ppm

20. Crop Yield(t/ha) Total K-uptake
(kg/ha)
Wheat 3.90 137
Rice 5.14 180
Chickpea 1.50 49
Musttard 2.60 133
Alfalfa 91.90 669
Banana 38.00 1053
Source I.S.S.S. Edi.- 2012

21. Sr. No Forms of
K
Total K Fixed K
Exchang
eable
K
Water
Soluble
K
1 Total K - 0.48** 0.44** 0.37**
2 Fixed K - - 0.72** 0.53**
3 Exchang
eable K
- - - 0.63**
Madhya Pradesh - Singh et. al., (2007)

22.  The main problem with managing soil K is that of converting the
unavailable forms of the element to available forms.
 Available K is usually supplemented by fertilization.
 Another problem is removing a lot of crops from the soil without
returning the crop residues.
 Attempts should be made to return as much residue as possible
for the natural plant-soil cycling of K to continue.

23.  Growing high K content plants places demand on the soil
supply of potassium.
 To have high yields of such crops, e.g., Alfalfa, it needs to
planned in advance to supply soil with enough K to last the
cropping season –fertilization.
 Treating soils with lime have been found to increase K
retention in soils.

24. 14
 Potassium fixation : It is define as the conversion of soil solution or
exchangeable K into nonexchangeable forms and was once
considered a negative soil property causing a drastic reduction of
plant available K.
A number of factor affect potassium fixation in soil.
1. Clay minerals
2. Soil pH
3. Wetting and Drying
4. Potassium Fertilization
5. Freezing and thawing

25.  The amount of K fixed by soil depends much upon its clay
content.
 The greater the clay content, the greater the K fixation.
 Regarding the kind of clay minerals like illite, weathered
mica, vermiculite, smectite, and interstratified minerals fix
more K, while kaolinite fixes very little.
15

26. 16
 In acid soil the presence of Al+3 and aluminum hydroxide
cations and their polymer occupy the K-selective binding
sites on clay minerals.
 Raising soil pH above neutrality increase the negative
charge on oxide and hydroxyoxides of iron and
aluminum, which result in increased adsorption of K ions
and consequent reduction in soil solution K.

27. 17
 K-fixation despite great differences between temperate and
tropical soil, K fixation was 2 to 3 times grater than after
wetting.
 Arid - Semiarid soil high in exchangeable K.
 Drying of field-moist soils, particularly subsoil, with low
to medium levels of K is reported to increase exchangeable
K.

28. 18
 Adding large amounts of fertilizer K generally result in
increased K fixation.
 Because solution K concentration is generally increased, disturbed
the equilibrium between soluble and fixed K.
Freezing and Thawing
 Freezing and thawing may result in increased exchangeable K in
some soil; however, the reverse may also happen in illite soil.

29. 19
Potassium leaching from a soil fluctuates in
accordance with the quantity, and intensity of
rainfall.
Despite low K content in tropical soils, considerable
K may be lost by leaching due to heavy rains.

30. Comprehensive knowledge about the forms of potassium and
their relationship among themselves help in assessing the
status of potassium and its availability in soil. Use of potassic
fertilizer and management practices increased crop production
and quality of produce under K deficient soil. In management
practices apply of potassic fertilizer on the basis of soil test and
crop requirement. To enhance availability potasic fertilizer
applied through split application and foliar application ( if
needed ).

31. Name – CK Dotaniya
Ph.D. Research Scholar, Soil Science and
Agricultural Chemistry,
College of Agriculture, SKRAU Bikaner
Email-ckdotaniya1991@gmail.com
Mob.- 9571362926