10. lime requirement soil science prese

Soil science

1. Reclamation of acid soilReclamation of acid soil

2. Lime requirementLime requirement
Liming materialsLiming materials
Reclamation & Reclamation &
management of acid soilmanagement of acid soil

3. Lime RequirementLime Requirement
Lime requirement of an acid soil is Lime requirement of an acid soil is
defined as the defined as the amount of liming amount of liming
material that must be added material that must be added
to raise the soil pto raise the soil pH H to some to some
prescribed value prescribed value ((Shoemaker Shoemaker et alet al.,1961.,1961))

4. Lime Requirement depends on;Lime Requirement depends on;
1.1.Change in pH Change in pH requiredrequired
2.2.Buffering capacity Buffering capacity of soilsof soils
3.3.Chemical composition Chemical composition of of
liming materialsliming materials
4.4.FinenessFineness of liming material of liming material
5.5.TextureTexture of soils of soils
6.6.Organic matter Organic matter content of content of
soilssoils

5. Principles of Liming ReactionsPrinciples of Liming Reactions
NatureNature & & finenessfineness of liming of liming
materialsmaterials
CalciteCalcite ( (CaCOCaCO
33), ), dolomitedolomite ( (CaMg CaMg
(CO(CO
33))
22) or a ) or a mixturemixture of two of two
Both are Both are sparingly soluble sparingly soluble in pure in pure
waterwater
Highly soluble in water Highly soluble in water
containing containing carbon di oxidecarbon di oxide

6. ReactionsReactions
AnyAny liming materials when liming materials when
added to soil, convert in to added to soil, convert in to
calcium bicarbonate in the calcium bicarbonate in the
presence of COpresence of CO
22 due to due to high high
partial pressurepartial pressure of CO of CO
22
(hundred times more than (hundred times more than
atmosphere)atmosphere)

7. Involve in Involve in exchangeexchange reaction reaction  Replaces Replaces HH
++
from collo from colloidsids
CaOCaO + H + H
22O + 2COO + 2CO
22  CaCa((HHCOCO
33))
22
Ca(OH)Ca(OH)
22 + 2CO + 2CO
22  CaCa((HHCOCO
33))
22
CaCOCaCO
33 + H+ H
22O + COO + CO
22  CaCa((HHCOCO
33))
22
micelle micelle
HH
+ Ca(OH)+ Ca(OH)
22 micelle
⇌
micelle
⇌
CaCa
+ + 2H2H
22OO
micelle micelle
HH
+ Ca(HCO) + Ca(HCO)
33 micelle
⇌
micelle
⇌
CaCa
+ + 2H2H
22OO + 2CO + 2CO
22
micellemicelle
HH
+ CaCO + CaCO
33 micelle
⇌
micelle
⇌
CaCa
+ + HH
22OO + CO + CO
22

8. CaCOCaCO
33 + H + H
22O + COO + CO
22 Ca (HCO Ca (HCO
33))
22
Ca (HCOCa (HCO
33))
2 2 CaCa
2+2+
+ 2HCO + 2HCO
33
--
HH
++
+ HCO+ HCO
33
- -
HH
22COCO
33 + + HH
22O +COO +CO
22
((soil solutionsoil solution) ) ((from limefrom lime))
In this way, hydrogen ions (In this way, hydrogen ions (HH
++
) in soil solution ) in soil solution
formed from formed from limestonelimestone react to form react to form weakly weakly
dissociated water & calcium dissociated water & calcium (Ca(Ca
2+2+
) ion to ) ion to
undergo cation exchange reactionsundergo cation exchange reactions
Soil acidity is thus neutralized & Soil acidity is thus neutralized & per cent base per cent base
saturation of colloidal material is saturation of colloidal material is increasedincreased

9. HH
++
HH
++
HH
++
HH
++
HH
++
MgMg
++++
KK
++
Acidic clayAcidic clay
++ Ca (OH)Ca (OH)
22
CaCa
++++
KK
++
MgMg
++++
+ 6H+ 6H
22OO
HH
++
CaCa
++++
LimeLimeNeutral clayNeutral claywaterwater
Liming ReactionsLiming Reactions

10. Factors affecting liming Factors affecting liming
reactionsreactions
1.1.MoistureMoisture
2.2.TemperatureTemperature
3.3.Amount of exchange acidityAmount of exchange acidity
4.4.Liming materialsLiming materials

11. ReclamationReclamation
Liming materials :(Agrl.liming materials)Liming materials :(Agrl.liming materials)
1.1.Quick lime / Burnt lime / Oxide of lime ( CaO )Quick lime / Burnt lime / Oxide of lime ( CaO )
2.2.Hydrated lime Hydrated lime  Ca(OH) Ca(OH)
2 2

3.3.Lime / Calcite ( CaCOLime / Calcite ( CaCO
3 3 ))
4.4.Dolomite Dolomite  CaMg(Co CaMg(Co
33))
22 
5.5.Marl / Oyster shells / Basic slag etc.,Marl / Oyster shells / Basic slag etc.,

12. Kinds of Liming MaterialsKinds of Liming Materials
1. Oxides of lime 1. Oxides of lime
Burned lime is produced by heating limestoneBurned lime is produced by heating limestone
CaCOCaCO
33 + + HeatHeat CaOCaO + CO + CO
22
LimestoneLimestone
CaMg(COCaMg(CO
33))
22 + + HeatHeat CaOCaO + MgO + 2CO + MgO + 2CO
22
2. Hydroxides of lime 2. Hydroxides of lime
Produced by adding water to burned lime & is called Produced by adding water to burned lime & is called slaked limeslaked lime
CaO + CaO + HH
22OO Ca (OH) Ca (OH)
22 + CO + CO
22
(Burned lime)(Burned lime) (Slaked lime)(Slaked lime)
3. Carbonates of lime 3. Carbonates of lime
By products of certain industries & so has By products of certain industries & so has ccalcium & magnesiumalcium & magnesium
eg., eg., calcitecalcite (CaCO (CaCO
33) & ) & dolomitedolomite (CaMg(CO (CaMg(CO
33))
22) )

13. SlagsSlags
1.1. Blast furnace slag Blast furnace slag
By- product of By- product of Pig iron Pig iron manufacture manufacture
Behaves as Behaves as calcium silicatecalcium silicate

NV- NV- 75-90%75-90%
2. 2. Basic slag Basic slag
By-product of basic By-product of basic open hearth method open hearth method of making steel of making steel
from pig iron, (from pig iron, (high phosophorus iron oreshigh phosophorus iron ores))
Impurities in iron, including Impurities in iron, including silica & phosphorus are silica & phosphorus are
fluxed with lime & basic slags fluxed with lime & basic slags are producedare produced
NV ranges from NV ranges from 60-70%60-70%
3. 3. Electric furnace slag Electric furnace slag
•This is produced from This is produced from electric furnace reduction of electric furnace reduction of
phosphate rock during preparation of elemental phosphate rock during preparation of elemental
phosphorusphosphorus ((calcium silicatecalcium silicate))

14. Management practicesManagement practices

Use of Use of basicbasic fertilizers fertilizers

Reducing Reducing leachingleaching of basic cationsof basic cations
Acid tolerant Acid tolerant crops (crops (rice, potato, tea, wheat, sweet potato, rice, potato, tea, wheat, sweet potato,
maize, brinjal etcmaize, brinjal etc))
Liming FactorLiming Factor
Factor by which the Factor by which the actual amount of lime actual amount of lime can be can be
calculated from the estimated theoretical amount of lime calculated from the estimated theoretical amount of lime
This factor varies from This factor varies from 1 to 31 to 3, depending on , depending on raterate of of
limestone, limestone, plant uptake plant uptake & & leachingleaching during reaction period during reaction period

15. Efficiency of liming Efficiency of liming
materialsmaterials
ii) Neutralizing value (NV) or Calcium Carbonate Equivalent (CCE)) Neutralizing value (NV) or Calcium Carbonate Equivalent (CCE)
Defined as the Defined as the acid neutralizing capacity of an agricultural liming acid neutralizing capacity of an agricultural liming
material expressed as a weight percentage of material expressed as a weight percentage of calcium carbonatecalcium carbonate

Molecular weight of CaCOMolecular weight of CaCO
3 3 X X 100 100
CCE of a liming material CCE of a liming material == Mol.Wt of a liming material, whose Mol.Wt of a liming material, whose
CCE is to be determinedCCE is to be determined

16. Liming materialsLiming materials
Neutralizing Neutralizing
value of CCE (value of CCE (%%))
1. Calcite (CaCO1. Calcite (CaCO
33)) 100100
2. Calcium oxide (2. Calcium oxide (CaOCaO)) 179179
3. Calcium hydroxide 3. Calcium hydroxide (Ca (OH)(Ca (OH)
22)) 136136
4. Dolomite (4. Dolomite (Ca Mg(COCa Mg(CO
33))
22)) 108.7108.7
5. Basic slag (5. Basic slag (CaSiOCaSiO
33)) 8686

17. ii) ii) Purity of liming materials Purity of liming materials
Higher the purity higher is the efficiencyHigher the purity higher is the efficiency
iiiiii) ) Degree of fineness of liming materials Degree of fineness of liming materials
Finer materials, Finer materials, >>surface contact, surface contact, >> rate of rate of
reactionreaction
Less amount requiredLess amount required
Fineness is measured using Fineness is measured using 60 mesh60 mesh sieve sieve

18. Per cent Effective Calcium Carbonate (ECC) or (Per cent Effective Calcium Carbonate (ECC) or (Neutralizing Index)Neutralizing Index)
ECCECC of a limestone or liming material is the of a limestone or liming material is the
product of calcium carbonate equivalent (product of calcium carbonate equivalent (CCECCE) & ) &
fineness factorfineness factor
The The fineness factor fineness factor is the is the sum of product of sum of product of
percentage of materialpercentage of material in each of in each of three size three size
fractions fractions ((6060 mesh sieve, mesh sieve, 20 20 mesh sieve & mesh sieve & 88
mesh sieve) multiplied by appropriate mesh sieve) multiplied by appropriate
effectiveness factoreffectiveness factor
Per cent ECC or NI Per cent ECC or NI = CCE x Fineness factor= CCE x Fineness factor

19. Chemical reactions during the process of ameliorationChemical reactions during the process of amelioration
HH
++
AlAl
++
HH
++
HH
++
HH
++
AlAl
++
KK
++
HH
++
AlAl
++
HH
++
CaCa
++
CaCa
++
KK
++
1.1.Oxides of lime (CaOOxides of lime (CaO))
When oxides of lime like When oxides of lime like CaOCaO is applied to an acid soil is applied to an acid soil
+ H+ H
22O + 2CaOO + 2CaO
2. 2. Hydroxides of lime (Ca(OH)Hydroxides of lime (Ca(OH)
22) )

When hydroxides of lime like When hydroxides of lime like Ca(OH)Ca(OH)
22 is applied to an acid soil is applied to an acid soil
HH
++
AA
ll
++
HH
++
HH
++
HH
++
AlAl
++
KK
++
HH
++
AlAl
++
HH
++
CaCa
++
CaCa
++
KK
++
+ 2Ca(OH)+ 2Ca(OH)
22 + + AlAl (OH) (OH)
33 +H +H
22OO

20. 3. 3. Carbonates of lime (CaCOCarbonates of lime (CaCO
33) )
When carbonates of lime (calcite) is applied to an acid soil, a part of CaCOWhen carbonates of lime (calcite) is applied to an acid soil, a part of CaCO
3 3
undergoes solution & combines with Hundergoes solution & combines with H
22COCO
33 to form to form soluble Ca(HCOsoluble Ca(HCO
33))
22
The calcium bicarbonate (Ca(HCOThe calcium bicarbonate (Ca(HCO
33))
22 reacts with soil colloids with evolution of reacts with soil colloids with evolution of
COCO
22CaCOCaCO
33 + H + H
22COCO
33 Ca (HCOCa (HCO
33))
22
Ca(HCOCa(HCO
33))
22 + soil + soil Ca(Soil) Ca(Soil) + H+ H
22O + O + 2CO2CO
22
HH
HH
4. Basic Slag 4. Basic Slag : : When basic slag is used as a liming in acid soilWhen basic slag is used as a liming in acid soil
HH
++
AlAl
++
HH
++
HH
++
HH
++
AlAl
++
KK
++
+ 2+ 2CaSiOCaSiO
33 + 3H + 3H
22OO + H+ H
22SiOSiO
33 + + Al(OH)Al(OH)
33
CaCa
++
AlAl
++
KK
++
HH
++

21. CropsCrops Optimum pH Optimum pH
rangerange
CerealsCereals
Maize, sorghum, wheat, barleyMaize, sorghum, wheat, barley 6.0-7.56.0-7.5
MilletsMillets 5.0-6.55.0-6.5
RiceRice 4.0-6.04.0-6.0
OatsOats 5.0-7.75.0-7.7
LegumesLegumes
Field beans, soybean, pea, lentil Field beans, soybean, pea, lentil
etc.etc.
5.5-7.05.5-7.0
GroundnutGroundnut 5.3-6.65.3-6.6
OthersOthers
SugarcaneSugarcane 6.0-7.56.0-7.5
CottonCotton 5.0-6.55.0-6.5
PotatoPotato 5.0-5.55.0-5.5
TeaTea 4.0-6.04.0-6.0
Relative tolerance of crops to Relative tolerance of crops to soil aciditysoil acidity

22. Methods of applying limeMethods of applying lime
Application of small amounts of lime Application of small amounts of lime
every year or twice a yearevery year or twice a year
Applied Applied well ahead of crop cultivation well ahead of crop cultivation by by
broadcasting broadcasting
 Mixed with Mixed with whole plough layerwhole plough layer
Ultisols-Ultisols- incorporation upto a depth of incorporation upto a depth of
about 30 cm (12 inches)about 30 cm (12 inches)

23. Effects of over limingEffects of over liming
GrowthGrowth of plants is affected of plants is affected
Deficiency of Deficiency of iron, copper & zinciron, copper & zinc
Phosphorus & potassium Phosphorus & potassium availability availability
will be reducedwill be reduced
Root developmentRoot development affected -affected -Tip Tip
swellingswelling
BoronBoron deficiency deficiency occursoccurs
Incidence of diseases like Incidence of diseases like scab in scab in
root crops root crops

24. Liming on Plant NutritiLiming on Plant Nutritionon
Direct BenefitsDirect Benefits
1.1.ReductionReduction in in toxicity of aluminium & toxicity of aluminium &
manganesemanganese
2.2.IncreasedIncreased uptake of uptake of calcium (Cacalcium (Ca
2+2+
) & ) &
magnesium (Mgmagnesium (Mg
2+2+
))
3.3.RemovalRemoval / amelioration of / amelioration of hydrogen (Hhydrogen (H
++
) )
ion toxicityion toxicity

25. Indirect BenefitsIndirect Benefits
PhosphorusPhosphorus availability: availability: pH between 5.5 -7.0 pH between 5.5 -7.0
to derive maximum benefit from applied P to derive maximum benefit from applied P
fertilizerfertilizer
MicronutrientMicronutrient availability: toxic effect of availability: toxic effect of
most micronutrients like most micronutrients like Fe,Mn,Cu,Zn,BFe,Mn,Cu,Zn,B (except (except
Mo) can be preventedMo) can be prevented
NitrificationNitrification: : Nitrification is enhanced at a Nitrification is enhanced at a pH pH
5.5 to 6.55.5 to 6.5
Nitrogen fixation Nitrogen fixation : : both symbiotic & non-both symbiotic & non-
symbiotic is favouredsymbiotic is favoured

26. Soil Physical ConditionSoil Physical Condition
The structure of The structure of fine textured soil fine textured soil may be improvedmay be improved
This is the result of an increase in This is the result of an increase in organic matter content organic matter content & &
to the to the flocculationflocculation of calcium-saturated soilsof calcium-saturated soils
Decreases the Decreases the bulk density, increases infiltration & bulk density, increases infiltration &
percolation ratespercolation rates
Liming Liming checks soil erosionchecks soil erosion
Diseases- Diseases- control certain control certain plant pathogensplant pathogens
Eg., Eg., Club root Club root disease of cole cropsdisease of cole crops
Efficiency of fertilizersEfficiency of fertilizers
Increases the Increases the efficiency of different fertilizers especially efficiency of different fertilizers especially
nitrogenous & phosphatic fertilizersnitrogenous & phosphatic fertilizers

27. Gypsum Gypsum is not considered as a liming material is not considered as a liming material inin acid soil, it acid soil, it
dissociates into dissociates into calcium (Cacalcium (Ca
2+2+
) & sulphate (SO) & sulphate (SO
44
2-2-
) ) ionsions
CaSOCaSO
4 4 CaCa
2+2+
+ SO + SO
44
2-2-
The accompanying anion is The accompanying anion is sulphatesulphate & it reacts with soil moisture & it reacts with soil moisture
produces produces mineral acid (Hmineral acid (H
22SOSO
44), ), which increases soil acidity which increases soil acidity
instead of reducing soil acidityinstead of reducing soil acidity
SOSO
44
2-2-
+ H + H
22O O HH
22SOSO
44
In addition, calcium (CaIn addition, calcium (Ca
2+2+
) in gypsum after dissociation will ) in gypsum after dissociation will result result
in replacement of adsorbed aluminium (in replacement of adsorbed aluminium (AlAl
3+3+
) in localized soil zone) in localized soil zone
with a significant with a significant lowering of soil pHlowering of soil pH
Hence, gypsum does not qualify as a liming materialHence, gypsum does not qualify as a liming material

28. thanksthanks