Management of problematic soils

INSTITUTE OF AGRICULTURAL SCIENCE

BHU VARANASI

Problem soilSoils which set a limit to crop production due to mineral stress, drought, acidity, sodicity, water logging etc.

could be considered as problem soil.Abiotic environmental factors( abiotic stresses ) are considered to be the main source (71%) of yield reduction

(Boyer, 1982).Estimation of potential yields losses by individual abiotic stresses are;

Ashraf and Harris(2005)

Abiotic stresses Potential yield reduction(%)

Drought 17

Salinity 20

Low temperature 15

High temperature 40

Others 8

Status of soil degradation in India

Classification of Problem soil Area (Mha)

1. Water and soil Erosion 162.4

2. Area degraded through special problem

a. Waterlogged 11.6

b. Alkali soil 4.50

c. Saline soil 4.50

d. Acid soil (pH < 5.5) 25.00

e. Riverine and gullies 3.97

f. Shifting cultivation 4.91

g. Riverine and torrents 2.73

3. Flood affected 40.00

4. Total drought prone 60.00

5. Annual loss of nutrient(in 106 t) 5.37-8.4 Swarup and Abrol (1994)

Problem area in major statesStates Area (lakh ha)

Andhra pradesh 123.23

Bihar 65.52

Gujarat 125.86

Haryana 41.62

Karnataka 114.03

Maharashtra 198.46

North-east states 97.00

Orissa 78.02

Punjab 32.30

Rajasthan 342.22

Tamil nadu 38.22

Uttar pradesh 131.15

West bengal 43.03

Saxena and Pofali (2007)

India: Soil degradation

Degradation of soils, due to….

•Soil erosion•Water logging•Saoil compaction

• Salinization• Alkalinization• Acidification• Gleization etc.

• Drought• Sand dunes• Floods• Natural calamities

etc.

• Deforestation• Pesticides• Acid rains• Inorganic fertilizers

etc.

Physical Chemical

Atmosphere

Anthropological

Soil Salinity

Electrical

http://www.bgr.de/b425/images/Salz-Thailand-1.jpg

Types of salt affected soils in India

Type of soil Comprising states Area(mha)

1. Coastal salt affected soil

a. Coastal salt affected soils of arid region

Gujarat 0.72

b. Deltaic coastal salt affected soils of the humid region

W.B., Orissa, A.P., and T.N.

1.40

C. Acid salt affected soils Kerala o.o16

2. Salt affected soils of the medium and deep black soil regions

Karnatka, M.P., A.P. and Mah.

1.42

3. Salt affected soils of the arid and semi arid regions

Gujarat, Raj., Punjab, Haryana and U.P.

1.00

4. Sodic soils of the Indo-Gangetic plains

Haryana, Punjab, U.P., Bihar, Raj. And M.P.

2.50

Total 7.04 CSSRI,Karnal, 2006

Causes of formation of salt affected soils

Salt affected

soil

Primary minerals

Irrigation water and

lack of drainage

Salts blown by

windSubsidies on Irrigation and

Fertilizers

use of basic

fertilizers

Ground and sea water

Arid and semi arid climate

Water logging

Transpiration

Salinization

Mechanical method

Scrapping of salts

Flooding

Leaching

Ditching/Trenching

Drainage

Thermopriming ( Brassica,

p.millet)

Hydropriming(Rice , maize, p.pea)

Halopriming(MnSO4, ZnSO4 eg.

Wheat,bean)

Osmoprimin(sugar,PEG, sorbitol,eg.

tomato,asparagus)

Hormone priming

(Sorghum, p.pea)

Management of salt affected soils for crop production

Application of amendments

Gypsum

Calcium chloride

Sulphuric acid : Na2CO3 + H2SO4 CO2 + H2O + Na2SO4 (leachable)

CaCO3 + H2SO4 CaSO4 + H2O + CO2

Iron and aluminium sulphate : FeSO4 + 2H2O H2SO4 + Fe (OH)2

H2SO4 + CaCO3 CaSO4 + H2O + CO2

: Na2CO3 + CaCl2 CaCO3 + 2 NaCl (leachable)

: Na2CO3 + CaSO4 CaCO3 + Na2SO4 (leachable)

Others. Press mud; carbonation, sulphitation process.

H2SO4 + CaCO3 CaSO4 + H2O + CO2

Sulphur (S) : 2 S + 3 O2 2 SO3 (microbiological oxidation)

SO3 + H2O H2SO4

Pyrite : 2 FeS2 + 2 H2O + 7 O2 2 FeSO4 + 2 H2SO4 (T.ferrooxidans)

4 FeSO4 + O2 +2 H2SO4 2 Fe2 (SO4)3 + 2 H2O

Fe2 (SO4)3 + FeS2 3 FeSO4 +2 S (T. thiooxidans)

4 FeS2 + 2 H2O + 15 O2 2 Fe2 (SO4)3 + 2 H2SO4

What is soil acidity?Soil acidity may be defined as

the soil system’s proton (H+ions) donating capacity during its transition from a given state to a reference state

Low per cent base saturation ,i.e below 50%, and a pH below 7, indicates acidity.

IntroductionAcid soils occupy about 90 million

hectares , constituting over one fourth of total geographical area of the country.

Occurs primarily in high rainfall,

hilly/mountainous and coastal region. Found in the Himalayan regions, the

eastern and north eastern plains, peninsular India and coastal plains under varying agro climatic situations.

Acid soils of West Bengal, Jharkhand, Assam and parts of Orissa.

.

Development of acidic Soils

• Potential acidity• Active acidity• Hydrolic acidity

• Formation of acidity in soil

Soil pH range

http://www.spectrumanalytic.com/support/library/ff/Soil_Aluminum_and_test_interpretation.htm

Causes of acid soil

Acid soil

Sources of hydrogen ions （ 1 ） Water dissociation

（ 2 ） Carbon dioxide

（ 3 ） Organic acid

（ 4 ） Inorganic acid (inorganic fertilizer)

（ 5 ） Acid rain

Union Carbide Chemical Plant, Bhopal India

Formation of acid sulfate soil

Constraints in crop production PHYSICAL

NUTRITIONAL

MICROBIAL

CHEMICAL

PHYSICALcrop production constraint

High infiltration rate, Low WHC, High permeability, High bulk density Soil crusting Soil compaction

NUTRITIONAL CROP PRODUCTION CONSTRAINT

•Availability of cationic •micronutrients such as •Zinc, Copper, Iron is quite •high may lead to toxicity •in plants.

•In acid soils availability of Calcium, Magnesium, Phosphorus, Sulphur, Molybdenum Boron, is low.

MICROBIAL CROP PRODUCTION CONSTRAINT

Fungi grow well in acidic pH range.

Bacteria and actinomycetes perform better in near neutral to slightly alkaline pH respectively.

Ammonifiers and nitrifiers are advesely affectd in acid soils.

CHEMICALCROP PRODUCTION CONSTRAINT

Low pH and CEC.Low base saturation %Low in NitrogenHigh P fixing capacityAluminium toxicityManganese toxicityIron toxicity

Acid sulphate soil Potential acid sulphate soil(anaerobic soil) - Sulfidization process

(coastal areas).

SO4-2 + 10 H+ + 8e- H2S + 4H2O

Fe+2 + S2- FeS(loss of e-) FeS2

Active acid sulphate soil-

2S + 3O2 + 2H2O H2SO4(by microbial process)

2FeS2 + 2H2O + 7O2 2FeSO4 + 2H2SO4

2FeSO4 + O2 + 2H2SO4 2Fe2(SO4)3 + 2H2O

FeS2+ 7Fe2(SO4)3 + 8H2O 15 FeSO4 + 8 H2SO4

Methods for ameliorating soil acidity

Liming to ameliorate soil acidity

Integrated nutrient management.

Growing acid tolerant crops

Use of gypsum for reclaiming subsurface acidity.

Liming of SoilCaO

CaSiO3

CaMg(CO3)2CaCO3

Ca(OH)2

LIMING MATERIALS

Liming materials Neutralizing value of CCE(%)

Calcium oxide(CaO) 179

Calcium hydroxide[Ca(OH)2]

136

Dolomite[CaMg(CO3)2] 108.7

Calcite(CaCO3) 100

Basic Slag(CaSiO3) 86

Lime application by the farmers

Furrow application of lime in red acidic soils of Jharkhand

AFTER RECLAIMNATION OF SOIL

Thank you

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