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Patel Dipak H.5th Sem. M. Sc.
Soil science and Agricultural chemistryN. M. C. A., N. A. U., Navsari
Major AdvisorDr. H. M. PATEL
Assistant Professor Department of soil science
N. M. College of Agriculture N. A. U., Navsari - 396 450
Minor AdvisorDr. D. D. PATEL
Associate Professor Department AgronomyCollege of Agriculture,
Bharuch N. A. U., Navsari- 396 450
“POTASSIUM DYNAMICS IN SOIL AND ITS IMPACT ON CROP
PRODUCTION”
2
3
Introduction Potassium The role of potassium in increasing the yield of crops and
improving the quality of produces has been in
the agenda of soil scientists.
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
and the rest occurs in either fixed or non-exchangeable form or exchangeable (adsorbed)
form or in soil solution.
Role of Potassium to increase crop yield
4
Increases growth and improves drought resistance
for crop.
Activates many enzyme systems.
Maintains turgor; reduces water loss and wilting.
In photosynthesis and food formation.
Reduces respiration, preventing energy losses.
Enhances translocation of sugars and starch.
Produces grain rich in starch.
Builds cellulose and reduces lodging.
To helps for crop diseases resistance.
Das (2004) 5
FORMS OF SOIL K
6
There are four forms of K in soil:
1. Solution K
2. Exchangeable K
3. Fixed or non exchangeable K
4. Structural or mineral K
1. Soil Solution K
7
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 form 1 to 10 ppm in
soil.
Solution K concentration is important for successful
crop production specially maturity condition for crop.
2. Exchangeable K
8
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.
3. Fixed or non exchangeable K
9
Nonexchangeable 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.
K changes from a non-exchangeable from to an exchangeable
form.
Nonexchangeable K in soil is generally measured by extracting
the soil with 1 N boiling nitric acid and is reported as HNO3
extractable.
Nonexchangeable K, fixed K in soil varies from 50 to 750 ppm
in soil.
10 Indian society of soil Science (2010)
4. Structural or mineral K
11
The potassium bearing minerals 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].
Potassium in mineral from in soils may vary
generally from 5000 to 25000 ppm in soil.
BECKETT - Q/I RELATIONSHIPS
Exchange reaction and exchange capacity in soils are sources of
plant nutrient such as K, Ca and Mg. However, it is difficult to visualize
how the complex interaction between ions, exchange capacity and
extraction of nutrients by plant affect nutrient supplies. Beckett developed a technique and theory to examine the buffer
capacity of soils with respect to potassium. The theory is based on exchange reactions between Ca, Mg, and K.
Beckett called the buffering capacity of the soil with respect to
potassium quantity-intensity relations. In this concept Q stands for quantity, I stands for intensity. Although
the following from Beckett was derived for assessing potassium status
in soils, it can be generalized to a large number of other systems. 12
The following graph illustrates the concept of Q/I for soil solution ions and soil buffering capacity as derived from the changes in Q in relation to changes in solution ion levels.
Soil A = clay soil Soil B = Sandy soil 13
Ads
sorb
ed Q
ualit
y (Q
)
Solution Intensity (I)
Potassium Fixation
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
1. Clay minerals
15
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.
2. Soil pH
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.
3. Wetting and Drying
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.
This has been attributed to the ex-folilation of edge-
weathered micas and exposure of inter layer K.
4. Potassium Fertilization
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.
5. Freezing and Thawing
Freezing and thawing may result in increased
exchangeable K in some soil; however, the reverse may
also happen in illite soil.
Loss of Potassium
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.
20
On the older leaves, the edges will look
burned.
Plants will easily lodge and be sensitive to
disease infestation.
Fruit and seed production will be impaired
and quality is poor.
Potassium Deficiency
21
K deficiency symptom in Banana and maize plant
22
Fertilizers containing potassium must be
applied wherever soil potassium reserves are
inadequate for targeted crop or pasture
production.
Potassium can be applied as a straight
fertilizer, or as part of a blended or compound
fertilizer with nitrogen and phosphorous.
Potassium Fertilizer
Material N (%) P2O5 (%) K2O (%) S (%) Mg (%)Potassium chloride - - 58-60 - -
Potassium sulfate - - 48-50 17 -Potassium magnesium sulfate - - 22 22 11
Potassium nitrate 13 - 44 - -Potassium and sodium nitrate 15 - 14 - -
Manure salts - - 22-27 - -
Potassium hydroxide - - 83 - -
Potassium carbonate - - < 68 - -
Potassium orthophosphate - 30-60 30-50 - -
Potassium polyphosphates - 40-60 22-48 - -
Potassium meta phosphate - 55-57 38 - -Potassium calcium pyrophosphate - 39-54 25-26 - -
Table 1: Plant Nutrient Content of Common Potassium Fertilizers.
23
24
Potassium is applied to majority of crops as
potassium chloride or muriate of potash.
The recognition that the Cl- ion, quite apart from
its role in plant nutrient.
Potassium sulphate is commonly applied to
tobacco and potatoes.
Choice of Potassium Fertilizer
Table 2: Effect of different treatments on different forms of K (kg ha-1) in surface soil.
Treatment(K2O kg ha-1) Ws-K Exch-K Fixed K Mineral K
0 35.0 90.1 250.0 1291.615 38.3 137.6 245.9 1244.930 55.0 165.9 266.7 1579.245 43.3 166.7 250.1 2206.660 65.0 262.5 270.9 1741.675 58.3 254.2 241.7 2179.190 58.3 254.3 254.3 2133.2
CD (0.05) NS 95.7 NS 264.1
Ws-water soluble K, Exch.K-exchangeable K25
Kerala Joseph and Punnose(2000)Red and lateritic soil
Table 3: Effect of different treatment on different forms of K (kg ha-1) in subsurface soil.
Treatments(K2O kg ha-1) Ws-K Exch-K Fixed K Mineral K
0 36.7 67.5 225.1 937.115 31.7 108.3 245.9 1014.130 36.7 131.7 255.0 1509.945 30.0 129.2 237.6 2003.260 43.3 157.5 245.9 1677.375 35.0 122.5 233.4 1809.190 48.3 134.2 230.0 1454.1
CD(0.05) NS NS NS NS
Kerala Joseph and Punnose (2000)Red and lateritic soil
26
Table 4 : Effect of Added K and moisture regimes on dynamics of K under different soil series
Moisture andFertilizer regimes
Available K Water Soluble K Exchangeable K Fixed K
KCl K2SO4 KCl K2SO4 KCl K2SO4 KCl K2SO4
CHALKOT SOILS : Fine loamy, occurring on hill topsM1K50 63.80 63.30 8.00 9.00 55.80 54.30 18.50 19.00M1K100 112.40 111.80 18.00 17.00 96.40 94.80 19.90 20.50M1K150 161.60 160.90 28.00 29.30 133.60 131.60 20.70 21.40M2K50 64.95 64.20 10.20 10.50 54.75 53.70 17.35 18.10M2K100 114.60 113.35 18.40 19.10 96.20 94.25 17.70 18.95M2K150 164.20 161.70 29.40 30.50 133.80 131.20 19.10 20.60
ZUKHESHESEMA SOILS: Fine loamy, occurring on upper hill slopesM1K50 120.20 120.00 17.00 17.00 103.20 102.00 17.20 18.00M1K100 170.06 169.75 25.00 25.00 145.06 143.50 17.34 18.20M1K150 218.86 218.10 38.00 38.00 180.86 178.40 18.54 19.00M2K50 121.14 121.10 18.00 18.00 103.14 101.50 16.26 16.70M2K100 170.50 170.20 27.00 27.90 143.50 142.30 16.90 17.60M2K150 220.33 220.05 42.00 42.13 178.33 177.95 17.07 18.15
KANGAN SOILS: Fine loamy, on middle hill slopesM1K50 230.35 229.00 15.00 15.05 215.35 213.95 15.65 16.80M1K100 279.56 278.70 19.00 20.24 260.56 258.46 16.44 17.94M1K150 329.00 327.09 23.00 23.89 306.00 303.20 17.00 19.10M2K50 230.86 230.00 15.70 16.80 215.16 213.20 15.14 16.10M2K100 280.70 279.20 21.00 21.30 259.70 257.90 15.30 16.50M2K150 330.01 329.08 26.00 27.28 304.01 301.01 15.99 17.90Con…
27
BHAGITTY SOILS: Fine loamy, occurring on foot hill slopes
M1K50 155.70 154.00 19.00 19.00 136.70 135.00 15.50 16.70
M1K100 204.90 203.40 36.00 36.50 168.90 166.90 16.30 17.80
M1K150 254.29 253.50 54.00 56.45 200.29 197.05 16.91 18.25
M2K50 159.35 158.00 23.00 24.00 136.35 134.00 11.85 12.25
M2K100 206.90 206.00 41.00 42.30 165.90 163.70 14.30 15.10
M2K150 255.78 255.17 60.00 62.32 195.78 192.85 15.42 16.80ZUSUMA SOILS: Coarse loamy, occurring in valleys
M1K50 340.98 340.50 80.00 81.85 260.98 258.65 2.52 3.05
M1K100 390.86 389.88 100.00 101.63 290.86 288.25 2.64 3.75
M1K150 440.23 439.60 115.00 117.50 325.23 322.10 3.27 4.80
M2K50 341.00 340.80 84.00 84.82 257.00 255.00 2.50 3.00
M2K100 391.00 390.98 106.08 106.08 285.00 284.00 2.50 3.21M2K150 440.72 440.20 124.00 124.55 318.72 315.65 2.78 3.65
M= Moisture regimes, M1=50% WHC, M2=1:2 soil solution ratio (submerged)New Delhi Singh et. al., (1999) 28
Table 5: Forms of potassium in surface soil under different land use systemsName of the
land use system
Water soluble K(mg kg-1)
Exchangeable K(mg kg-1)
No-exch K (mg kg-1)
Total K (%)
Agri-system- RiceS-1 12.2 152.6 230.5 1.49S-2 11.6 132.0 220.6 1.35S-3 12.0 126.8 228.0 1.40S-4 12.6 135.1 232.8 1.22S-5 12.1 140.9 232.1 1.31
Mean 12.1 137.5 228.8 1.35Agri-system- Tobacco
S-1 10.2 64.8 210.8 1.62S-2 12.6 72.0 206.1 1.38S-3 16.0 60.8 209.0 1.40S-4 16.4 70.1 198.8 1.26S-5 13.1 59.4 204.2 1.30
Mean 13.6 65.4 205.8 1.39Horti-system – Arecanut
S-1 12.8 120.5 308.7 0.82S-2 15.3 124.1 302.0 1.24S-3 16.6 112.8 290.0 0.98S-4 16.0 120.0 302.4 1.10S-5 13.4 126.1 314.0 1.06
Mean 14.8 120.7 303.4 1.04 Con…
29
Silvi-system- EucalyptusS-1 12.5 98.3 290.7 1.17 2.95S-2 15.0 110.0 306.0 1.26 2.78S-3 12.5 102.8 298.0 1.02 2.89S-4 10.7 112.6 302.2 1.23 2.68S-5 13.6 98.7 318.7 1.32 3.22
Mean 12.9 104.5 303.1 1.20 2.90Current fallow land – Control
S-1 11.9 64.3 168.2 1.20 2.61S-2 13.3 79.4 186.4 1.38 2.34S-3 10.0 50.1 150.0 1.17 2.98S-4 11.0 62.8 161.3 1.25 2.58S-5 13.2 65.3 174.5 1.30 2.67
Mean 11.9 64.4 168.1 1.26 2.63
Karnataka Gurumurthy and Prakasha (2011)
loamy sandy to sandy loam soil
30
Table 6: Potassium fixation capacity of surface soil samples under different land use systems.
Sample Amount of K fixed [cmol(p+)kg-1] Per cent K fixed (%)
Agri-system- RiceS-1 0.25 10.0S-2 0.31 12.5S-3 0.22 8.7S-4 0.36 14.0S-5 0.22 8.6
Mean 0.27 10.7Agri-system- Tobacco
S-1 0.32 12.5S-2 0.38 15.1S-3 0.39 15.5S-4 0.48 18.7S-5 0.39 15.2
Mean 0.39 15.4Horti-system – Arecanut
S-1 0.44 17.1S-2 0.51 20.0S-3 0.57 22.2S-4 0.41 16.0S-5 0.48 18.7
Mean 0.48 18.8 Con…..31
Silvi-system- EucalyptusS-1 0.59 23.1S-2 0.76 29.6S-3 0.61 24.1S-4 0.57 22.5S-5 0.59 23.0
Mean 0.62 24.5Current fallow land – Control
S-1 0.65 25.3S-2 0.46 17.9S-3 0.63 24.5S-4 0.64 25.1S-5 0.49 19.1
Mean 0.57 22.4
Karnataka Gurumurthy and Prakasha (2011)
loamy sandy to sandy loam soil
32
Table 7: Correlation coefficients among Various forms of potassium
Sr. No Forms of K Total K Fixed K Exchangeable K
Water Soluble K
1 Total K - 0.48** 0.44** 0.37**
2 Fixed K - - 0.72** 0.53**
3 Exchangeable K - - - 0.63**
Uttar Pradesh Singh et. al., (2007) 33
Table 8: Correlation coefficients between chemical properties among Various forms of potassium(n=200)
Soil Characteristics
Potassium fraction
Total K Fixed K Exchangeable K
Water Soluble K
pH 0.06 0.02 0.07 -0.05
EC 0.05 0.11 0.17* 0.09
CaCO3 0.06 0.02 0.09 0.08
Organic carbon 0.04 0.42** 0.10 0.02
Mean pH 7.3-9.4 EC (dsm-1) = 0.35 CaCO3= 20.2 Organic Carbon (g kg-1) = 4.27
Uttar Pradesh Singh et. al., (2007) 34
Table 9: Fraction of various forms of the Potassium in different soil Series of Navsari
Series nameWater soluble K Exchangeable
K
NonExchangeable
KTotal K Mineral K
0-15cm 15-30cm
0-15cm
15-30cm
0-15cm
15-30cm
0-15cm
15-30cm
0-15cm
15-30cm
Eru Series 0.028 0.025 0.59 0.53 0.86 0.69 20.15 23.88 18.67 22.63Jalalpur Series 0.027 0.023 0.71 0.62 1.09 1.01 29.54 29.82 27.70 28.17
Amalsad Series 0.026 0.020 1.06 0.75 1.19 1.34 23.76 25.48 21.48 23.37
Mandir Series 0.034 0.030 0.69 0.57 1.08 1.07 21.14 23.36 19.34 21.69
Bodali Series 0.029 0.025 0.59 0.40 1.09 0.88 18.96 20.33 17.25 19.02Sisodra Series 0.057 0.048 1.11 0.78 1.22 1.16 27.43 27.95 25.05 25.96
Onjal Series 0.039 0.035 0.39 0.21 1.33 1.27 28.28 31.30 26.52 29.78Aat Series 0.041 0.033 0.47 0.26 1.19 1.29 24.20 26.97 22.51 25.38
Dandi Series 0.041 0.034 0.54 0.34 0.74 0.65 19.42 22.04 18.10 21.02Bilimora Series 0.037 0.029 0.48 0.31 0.69 0.68 24.19 27.60 22.98 26.58
Gadat Series 0.064 0.055 0.82 0.69 1.13 0.65 22.28 24.07 20.26 22.67Kabilpor Series 0.049 0.039 0.58 0.53 1.30 1.12 23.69 24.75 21.76 23.06
Mean 0.039 0.033 0.67 0.50 1.08 0.98 23.58 25.63 21.80 24.11 Navsari Singh(2012) 35
Table 10: Q/I parameters of potassium for different soil series in Navsari District.
Navsari Singh (2012)
Sr. No. Soil series
ARK k Potential PBCNon Specific
K (cmol/kg) (mol L-1)1/2 cmolkg-1/(mol L-1)-1/2 (cmol/kg)
1 Eru Series 0.0025 1.41 23.60 0.06
2 Jalalpur Series 0.0039 3.11 28.30 0.11
3 Amalsad Series 0.0025 0.99 19.80 0.05
4 Mandir Series 0.0048 3.54 27.30 0.13
5 Bodali Series 0.0022 3.71 41.30 0.09
6 Sisodara Series 0.0057 3.44 24.60 0.14
7 Onjal Series 0.0032 1.11 18.50 0.06
8 Aat Series 0.0047 3.61 27.80 0.13
9 Dandi Series 0.0084 4.27 22.50 0.19
10 Bilimora Series 0.0028 1.30 21.70 0.06
11 Gadat Series 0.0023 2.81 35.20 0.08
12 Kabilpor Series 0.0039 4.38 33.70 0.1336
Table 11: Long-term effect of organic materials addition on the distribution of available K (mg kg-1) in soil ( 5 year data)
Treatment Depth (cm)
0-7.5 7.5- 15 15-30 30-60 Mean Experiment-I
N150 35.0 30.0 28.0 31.0 31.0GM 28.5 25.5 27.5 32.0 28.4WS 34.5 27.0 26.5 33.0 30.3
WS+GM+RS 36.5 30.0 29.0 30.0 31.4FYM 35.0 32.5 28.0 36.0 32.9
FYM+GM 36.0 30.5 27.0 31.5 31.3Mean 34.5 30.0 28.0 32.2
LSD (p=0.05) Treatment=2.5, Depth=1.8, Treatment×Depth=NS
Experiment-IIRS Removed 33.0 20.5 21.0 22.5 24.3
RS Incorporated 38.0 36.5 34.5 34.0 35.8 N150 = 150 kg N ha-1 GM = Green Manure WS = Wheat Straw RS= Rice Straw
Ludhiana (Punjab) Pannu et. al. (2002) Sandy loam37
Treatment
Grade wise Tuber yield (q/ha)Average tuber
weight (g)>75g 50-75g 25-50g <25g Total
K0 95.42 108.18 58.07 15.54 277.21 52.53
K50 140.68 131.09 46.36 15.89 334.02 61.52
K100 158.73 145.34 43.88 13.90 361.85 65.52
K150 169.54 152.42 42.12 13.64 377.71 69.88
SEm ± 5.84 3.98 3.65 3.12 8.49 2.15
CD (0.05) 16.83 11.45 10.51 NS 24.43 6.20
Table 12: Grade wise potato yield of Kufri Pukhraj as influenced by potassium.
Patna Singh (2010) 38
Levels of potassium
Diameter of flower (cm)
Weight of individual flower
(g)
Yield of flowers(kg/plot)
K0 4.60 4.43 13.64
K50 5.49 4.91 17.96
K100 5.62 5.22 21.25
K150 5.74 5.43 22.72
K200 5.84 5.56 23.94
SEm ± 0.09 0.07 0.53
C.D. at 5% 0.27 0.22 1.59
Table 13: Effect of different levels of potassium on flowering attributes and yield of American marigold cv. ‘Siracole’
Mohanpur (West Bengal) sandy loam soil Pal and Ghosh (2010)
39
Table 14 : Effect different levels of potassium on yield (kg ha-1) and nutrient uptake (kg ha-1) by coriander.
Level of potash N P K Seed
yieldStraw yield
K0 57.65 6.78 36.26 1517.62 2239.95
K15 67.53 7.91 42.88 1526.95 2283.08
K30 73.01 8.54 46.57 1615.75 2408.66
S.Em ± 2.06 0.23 1.43 41.52 60.90
C.D. at 5% 5.85 0.67 4.06 NS NS
Navasari Bhoya(2009) 40
Comprehensive knowledge about the forms of potassium
and their relationship among themselves help in assessing
the status of potassium and its availability in soil. The surface soils contained normally more amount of all
forms of K than sub-surface soils except mineral and total
K.Q/I isotherm provides a better overview of K dynamics in
soils. It is useful method to assess the K supplying power of
soils to plant.K fertilization increased crop production and quality of
produce under deficient K soil.41
Conclusion
