11. Soil orders.pptx ........soil resource inventory

Soil orders

1. Soil Order Characteristics & Distribution Lecture: 11 1 10 April 2024 SAC 201 Soil Resource Inventory (1+1)

2. 2 USDA Soil Taxonomy Order 12 orders Name of order Formative element Entisol ent Inceptisol ept Alfisol alf Ultisol ult Oxisol ox Vertisol ert Mollisol oll Aridisol id Spodosol od Histosol ist Andisol and Gelisol el USA VIA HOME AG MAAGAVI HOUSE USA VIA AG HOME AVAGAMI HOUSE

3. 3 Entisols ( Soils of initial origin / immature ) Very recently developed mineral soils with no diagnostic horizon (other than ochric or anthropic epipedon) Slight degree of soil formation ( either limiting time or exceeding unfavorable condition ) Parent material: Resistant to weathering (parent material quartz ) Not altered much by soil forming process Characteristics Distribution Associated with steep slopes, flood plains, coastal lands and sand dune areas World: Sahara (Africa), Asia, Australia, middle-east countries, South America, USA, South Africa and Russia (C onstitute 18% of soils worldwide ) India: Flood plains, sand dunes, rocky humid regions and coastal land forms distributed in all the states

4. 4 Entisols ( Soils of initial origin / immature ) Susceptible to erosion Poor physical condition Lesser depth in case of eroded soils Psamments : Lesser clay content, Low water holding capacity, low nutrient status Constraints Utility Recent alluvium : Productive & suitable for agriculture Barren sands & eroded soils : Infertile; grazing & forestry use Sand dune areas : Raising single crop by conserved moisture Classification Aquents 2. Arrents (fragments of diagnostic horizon) 3. Psamments 4. Fluvents (recent flood plains) 5. Orthents (Non- fluviatile )

5. 5 Inceptisols – Recently developed soil Early stage of soil formation ( beyond Entisols but < Alfisols ) Poor soil profile development Presence of diagnostic horizons viz., cambic , umbric or mollic Limited leaching Less accumulation of material in subsoil Soils developed owing to the alteration of parent material to develop soil structure Characteristics Distribution Throughout the world are commonly found forming in alluvium on floodplains and delta deposits. Varied climatic conditions : Semi-arid to humid) All vegetation conditions : Grassland to tundra forest They constitute 15% of soils worldwide

6. 6 Inceptisols – Recently developed soil Aquepts Udepts Ustepts Xerepts Cryepts Anthrepts : Plaggen /anthropic epipedon Classification Utility Many Inceptisols agriculturally very productive and provide excellent natural grazing In past most of this soils were Brown Forest, Andisol and Soil Brun Acide

7. 7 Alfisols Light coloured surface horizon ( Ochric epipedon ) Presence of Argillic sub horizon (accumulation of clays) Base saturation : > 35% Surface horizon: Grey to brown Strongly weathered soils than Inceptisol but less weathered than Ultisol Having a favorable moisture balance and good fertility , they are very productive soils for agriculture. Characteristics Distribution Sub-humid and humid regions World: USA, South America, Northern Europe, Africa, Brazil, southeast Asia, eastern Australia and Russia ( constitute 10% of soils worldwide ) In India, Red soils ( Rhod -, Pale-, Hapl - ustalfs ) predominantly observed in TN, AP, Karnataka, MH, Orissa, MP, Assam, Arunachal Pradesh, Bihar and HP

8. 8 Alfisols Productive and suitable for agriculture In India, these soils growing crops like, wheat, maize, sorghum, rice, and horticultural crops (mango. Cashew, jackfriuts and litchi) Utility Classification Aqualfs Ustalfs Udalfs Xeralfs Cryalfs In past most of this soils were Gray Brown Podzols , Planosols and some half Bog soils

9. 9 Aridisols ( Soils of arid region) Soils remain dry for most part of the year A negative moisture balance in these soils inhibits eluviation [ Salts accumulation: Surface and/or in solum ] Presence of calcic, gypsic or salic horizons [ Calcification and salinization are important soil forming processes acting in these soils ] Presence of ochric epipedon They are light in color - little vegetation to add organic matter to the soil profile Soil horizons are weakly developed and Na ion is often high in concentration Characteristics Distribution Mineral soils of dry places [arid and semiarid] where moisture is scarce; high ground water table World: Africa, Australia, South America, USA, South Asia and Russia India: Rajasthan, Punjab & Haryana (non- gypsiferous ) and Gujarat ( constitute 12% of soils worldwide )

10. 10 Aridisols ( Soils of arid region) Limited soil moisture ( Aridic climate) or Xerophytic climatic conditions and brackish water comes to surface Higher salt content Constraints Utility Productive if water is available with reclamation Suitable for grazing and tree crops tolerant to salinity Classification Cryids Salids Durids Gypsids Argids Calcids Cambids : common type of Aridisols

11. 11 Ultisols - similar to Alfisols except low base saturation More weathered soils than Alfisols Presence of argillic or kandic horizon More acidic than Alfisols but not as acidic as Spodosols Highly weathered soils, they are often red / yellow in color reflecting the oxidation of iron and aluminum. Accumulation of clay at subsoil which distinguishes them from Oxisols which do not. Characteristics Distribution Warm, humid and subtropical regions High rainfall and forested vegetation Mid to low altitudes regions World: USA, South America, south-east Asia and central Africa India: Kerala, Tamil Nadu, Orissa and north eastern states ( constitute 8% of soils worldwide )

12. 12 Ultisols - similar to Alfisols except low base saturation 1) Aquults 2) Udults 3) Ustults 4) Xerults 5) Humults : high OC (12 kg/m 2 ) within 1m soil Classification Utility Suitable for agriculture after liming and fertilization Suitable for pineapple, sugarcane, coffee, cocoa, coconut and rubber Suitable for natural vegetation Fertility: Low Base saturation: low (<35%) Constraints

13. 13 Oxisols ( Strongly weathered mineral soils of Tropics) Surface: Oxic horizon High Fe & Al oxides Silica leached out Low in weatherable minerals, bases and exchange capacity Low water and nutrient holding capacity Clay content: High but non sticky (1:1 type; Kaolinite) Poor in fertility Low cation exchange capacity Characteristics Distribution Found in warm, rainy climates under broadleaf, evergreen vegetation World: Central Africa, South America and South-east Asia India: In tropical India Not yet reported ( constitute 8% of soils worldwide )

14. 14 Oxisols ( Strongly weathered mineral soils of Tropics) Aquox 2) Torrox 3) Ustox 4) Udox 5) Perox Classification Utility Grazing, forestry Plantation crops: Coffee, rubber, cocoa, sugarcane Tropical fruit crops : Pineapple, coconut, cashew nuts, jackfruit Shifting agriculture (>20 years) common practice adopted in such areas Low in fertility Phosphate fixation (High Fe and Al) Liable to crusting (hard surface layer) Chemically-degraded soils Constraints

15. 15 Mollisols ( dark coloured, organic, grassland soils) Mollisols are among the most fertile soils (best agricultural soils) on the Earth Thick and organic matter rich ( Mollic epipedon ) Well-structured (granular or crumb) top soil; soft consistency when dry. Soil colour: Dark brown to black organic rich surface layers. High WHC; High base saturation with abundant calcium Subsurface horizons either rich in illuviated clay ( Argillic ) or calcareous ( Calcic ) or gypsiferous ( Gyspic ) nature Characteristics Distribution Grassland soils of Sub-humid (semiarid) to humid environment World: USA, South America and Russia India: Tarai region of UP, Uttarkhand , HP, Bihar, MH and MP

16. 16 Mollisols ( dark coloured, organic, grassland soils) Aquolls Albolls : Albic (bleached) horizon over an argillic or natric horizon and which has chroma 2 or less Udolls Ustolls Xerolls Cryolls Rendolls : 40% or more of CaCO 3 content either within or below mollic epipedon Classification Utility Suitable for farming (wheat, maize, sorghum) In drier regions used for grazing

17. 17 Vertisols - Clay rich, dark coloured soils Clay content: > 30 % Swells on wetting & Shrinks on drying Colour: Black or dark Sticky and plastic in consistency Surface deep cracks under dried condition Sub surface horizon Gilgai micro-relief or slickensides Characteristics Distribution Parent materials containing basaltic composition Sub-humid to semi-arid climates (RF: 500 to 1500 mm/year) with pronounced dry season World: Africa, Australia, and USA India: Maharashtra, TN, AP, MP and Rajasthan ( constitute 2 % of soils worldwide )

18. 18 Vertisols - Clay rich, dark coloured soils 1) Xererts 2) Torrerts 3) Uderts 4) Usterts 5) Aquerts 6) Cryerts Classification Utility Very productive if managed Suitable for agriculture with management measures Suitable for dryland and rainfed farming Swell shrink properties High clay content Poor infiltration rate or hydraulic conductivity Susceptible to water erosion Constraints

19. 19 Histosols ( Soils rich in organic matter) Originated from organic materials (peat, muck, bog soils) with thick peaty horizon ( Histic epipedon ) Organic matter is 12 - 30 % The minimum amount of OM required is 20%, if no clay content Thumb rule, a soil without permafrost and have half or more of upper 80 cm is organic matter High quantities of plant and animal residues in various stages of decomposition (lower in swamps than herbaceous) Moderate accumulation of iron and aluminium sulphates , iron pyrite ( tidal swamp areas ) Rate of accumulation of peat is 0.5 to 1 mm per year They are often " mined" for peat which is dried and burned as fuel. Characteristics

20. 20 Histosols ( Soils rich in organic matter) Need for drainage : reducing anaerobic condition Sulphate accumulated soils: No drainage (formation of H 2 SO 4 ) Toxicity of Fe and Al and Deficiency of phosphorus Constraints Utility Hemists and Fibrists : Suitable for natural vegetation (growing vegetables) Folist : Suitable for farming Classification 1. Folists : free drained areas 2. Fibrists : depression areas 3. Hemists : Moderately decomposed OM 4. Saprists : Highly decomposed Distribution Water saturated environment Temperate regions (slow decomposition) World : Europe, USA, Canada and north-west Asia India : pockets of Kerala, Tripura and Andaman & Nicobar islands ( constitute 1 % of soils worldwide )

21. 21 Spodosols - Strongly weathered mineral soils Surface horizon: Bleached, wood ash coloured, mineral soil Subsurface: Accumulation of humus ( Bh ) and sesquioxides ( Bs ) Surface litter composed of pine needles breaks down in the presence of water to form a weak organic acid . Coarse textured siliceous parent material favours free leaching conditions Characteristics Distribution Under coniferous vegetation Cool, humid climate conditions World: Europe, Canada and USA India: Not reported ( constitute 4 % of soils worldwide )

22. 22 Spodosols - Strongly weathered mineral soils 1. Aquods 2. Orthods 3. Cryods 4. Humods : High OC (> 6%) within spodic horizon Classification Utility Grazing, forestry Agriculture: Need management and fertilization Fertility: Low Constraints Podzol , Brown podzolic and Hydromorphic soils (Groundwater podzols )

23. 23 Andisol ( Soils of volcanic origin) Colour : Dark Bulk density : < 0.9 Mg m -3 Don’t have albic horizon but have andic properties Parent material: 60% Volcanic ash with in 60 cm depth Mineral composition: High allophane Porosity: High and Surface area: High Water holding capacity: High Very fertile Fixes Phosphorous Characteristics Distribution World: Japan, Indonesia, New Zealand, Phillipines , Rift valley of Africa, west coast of USA and south America volcanic islands and mountains of "The Ring of Fire", that encircles the Pacific Ocean from North America through Japan India: Andaman and Nicobar ( constitute 1 % of soils worldwide )

24. 24 Andisol ( Soils of volcanic origin) Utility Productive, suitable for less P demanding crops/agriculture eg . Sweet Potato P fixation is the main constraint Civil construction: Not suitable Liable for wind erosion Management : Low bulk density, poor compactability , fluffiness Constraints Classification Aquands Cryands Torrands Udands Ustands Xerands Vitrands : Andisols that have a duripan or petro calcic ( 60% vitric volcanic ash )

25. 25 Gelisol ( Soils of permafrost regions) Contains gelic materials Presence of permafrost within 2m depth Cryoturbation (Frost churning): predominant Soil forming process is limited ( may or may not present diagnostic horizon ) Freezing and thawing: Major factor No downward movement of soil solution Characteristics Distribution Tundra region (Northern and southern hemisphere) World: Northern USA, Canada, Green land, Russia, Mangolia and Russia. India: not yet reported (higher Himalayas) ( constitute 9 % of soils worldwide )

26. 26 Gelisol ( Soils of permafrost regions) Very low soil temperature Low organic matter Poor soil development Constraints Utility Not cultivable (cold climate) Suitable for natural vegetation Classification Histels : Organic soil materials or saturated with water for 30 or more days in a year Turbels : Shows cryoturbation in the form of irregular, broken or distorted horizon boundaries Orthels Cryoturbation

27. Salient characteristics of soil orders Based on Diagnostic property Order Nature of soil material Very high content of organic matter Histosols Cracking or swell-shrink clay Vertisols Andic material > 35 cm soil Andisols Dark organic surface layer underlain by permafrost Gelisols Presence or absence of diagnostic horizons Spodic horizon Spodosol Oxic horizon Oxisols Argillic horizon but High base status Alfisols Argillic horizon but with low base saturation Ultisols Mollic epipedon and high base saturation Mollisols Cambic horizon (or) umbric, plaggen epipedon Inceptisols No distinct horizons Entisols Soil moisture regimes Aridic or dry or saline Aridisols 29

28. 30 Order Typical Character Alfisol Argilic subsoil horizon, BS >35 % (red soil), suitable to agriculture Andisol Volcanic soils, BD: < 1 Mg m -3 ; Fixes phosphorous, more porous, WHC – high, Suitable for less P demanding crops Aridisol Dry soil conditions, accumulation of salt, calcic, gypsic or salic horizons, organic matter – Low, Productive if water available Entisol Soil formation - i nitial stage; No profile development, PM – Not altered; poor physical conditions; alluvial soil – Fertile, sand dunes – infertile Histosol Rich OM (12-30 %), Dark colour, peat, muck soils, suitable for farming and natural vegetation Gelisol Permafrost layers, cryoturbation, freezing and thawing, low OM; Suitable for natural farming Inceptisol Recently developed soil; soil formation – early stage, poor profile development, cambic , umbric , mollic horizons, suitable for farming Mollisol Grass land soils; dark, high OM, structured, WHC – High, BS – High, suitable for farming Oxisol Strongly weathered, High Fe &Al, Low fertility, High 1:1 clay, low CEC, fixation of P, Suitable for natural farming, tree crops Spodosol Strongly weathered mineral soil, Surface: humus accumulation and Fe&Al oxides Accumulation, fertility – Low, suitable for grazing, forestry Ultisol Similar to Alfisol ; BS: < 35%; Argilic , kandic horizon, acidic, Fertility – Low; Suitable to agriculture after amendments Vertisol Clay > 30 %; dark, presence of surface cracks in summer, shrink and swell properties, slicken sides at subsurface, suitable for dry land and rainfed farming Ease Recall