Soils of Mizoram for Mizoram PSC

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Soils of Mizoram

  • Mizoram is a mountainous region which became the 23rd State of the Indian Union in February, 1987.
  • It was one of the districts of Assam till 1973 when it became a Union Territory.
  • Sandwiched between Myanmar in the east and south and Bangladesh in the west, Mizoram occupies an area of great strategic importance in the north-eastern corner of India. It has a total of 722 Km. boundary with Myanmar and Bangladesh.
  • Mizoram has the most variegated hilly terrain in the eastern part of India.
  • The hills are steep and are separated by rivers which flow whether to the north or south creating deep gorges between the hill ranges.
  • The average height of the hill is about 1000 meters.
  • The highest peak in Mizoram is the Blue Mountain (Phawngpui) with a height of 2210 meters.

Common/General Features of Soils of Mizoram

  • Mizoram has a varied blend of climatic conditions ranging from tropical, sub-tropical to temperate conditions.
  • State has high mean annual rainfall of 2500 mm and high relative humidity upto 90%.
  • There is plenty of rainfall in a concentrated period of six months, leaving rest of the months relatively dry and water scarce.
  • Mizoram has primarily sand-loamy and clay-loamy soil rich in organic carbon and moderately rich in available potash.
  • Due to high rainfall during May to September, soil is acidic ranging from 4.5-5.6 pH.
  • The fertility of Soils of Mizoram is affected by the cultivation practices employed by the people, soil erosion, landslides associated with high intensity rainfall and hailstorm.
  • The temperature during summer season varies from 20°C to 34°C and during the winter season varies from 8°C to 17°C.

 

Some Facts about Soils of Mizoram –Entisols/Inceptisols/Ultisols

  • All the Soils of Mizoram were acidic and about 57 per cent of Entisols, 42 per cent of Inceptisols and 77 per cent of Ultisols were high in available N.
  • About 71 per cent of Entisols, 100 per cent of Inceptisols and 77 per cent of Ultisols was high in available K, rest being medium in K.
  • All the soils were low to very low in available P and fixed on an average 82.6 to 96 per cent of added P (1000 ppm).
  • Phosphate fixation was positively related with clay, organic carbon and Fe and Al oxide’contents of soil and negatively with pH.
  • Phosphorus appears to be the most limiting nutrient for plant growth.
  • These Soils of Mizoram have adequate supply of plant available Mn, Cu and Fe but, 71 per cent of Entisols, 33 per cent of Inceptisols and 20 per cent of Ultisols were deficient in zinc 0.8 ppm DTPA extractable Zn.
  • Total Soils of Mizoram acidity varied from 8.6 to 16.3 c mol (p+) kg-l .
  • The mean contribution of pH-dependent and exchange acidity to total acidity was 88 per cent and 12 per cent, respectively and exchangeable Al3t constituted 81 per cent of exchange acidity fraction.
  • The Al saturation of soil based on effective CEC was 43.0 per cent at pH 4.5 and was essentially zero at pH 5.6. These soils have low permanent.

 Type of Soils of Mizoram

  • The Soils of Mizoram are classified by Sanker and Nandy into three orders of soil taxonomy :
  • Entisols,
  • Inceptisols
  • Ultisols
  • The Soils of Mizoram also fall under the above three orders.
  • They were generally young, immature and sandy.
  • The surface soils are dark, highly leached and poor in bases, rich in iron and have low pH values ranging from 4.5 – 5.5. (Highly Acidic).
  • They are well drained, rich in organic carbon, low in phosphate content and high inSoils of Mizoram available potash.
  • The surface soil textures are loam to clay loam with clay content increasing in depth.
  • The pH and organic carbon content decreases with the increase in depth.
  • They are capable of providing substantial oxygen supply for plant growth and retaining moisture for sufficient supply of oxygen throughout the year.
  • The percentages of clay silt and sand within 50cms.of the surface is 15-30%, 35-45% and 25 – 45% respectively.

Entisols

  • They are recently developed, mineral soils with no diagnostic horizon.
  • This is because either of limiting time available for development or because of exceedingly unfavorable conditions.
  • In USDA soil taxonomy, entisols are defined as soils that do not show any profile development other than an A horizon.
  • An entisol has no diagnostic horizons, and most are basically unaltered from their parent material, which can be unconsolidated sediment or rock.
  • They are moderately to deep, well drained, fine to fine loamy textured soils.
  • Families which have been identified under this orders are :-
  1. Fine-loamy typic Udifluvents
  2. Fine-loamy typic Udorthents
  3. Coarse-loamy typic Udorthents
  4. Fine-loamy Lithic Udorthents
  5. Coarse loamy Lithic Udorthents

Inceptisols

  • This soil order represents beginning stage of soil formation which belong to that of Entisols but still short of the degree of development found in Alfisols.
  • They may have some accumulation of clay in the sub-surface horizon, limiting in depth, organic matter content, and base saturation.
  • Although not found under aridic climate regimes, Inceptisols nevertheless are widely distributed and occur across a wide range of ecological settings
  • This soil dominates the entire State having fine loamy, fine clay, clay loam etc.
  • The identified families under this order are:
  1. Fine- loamy Umbric Dystrochrepts
  2. Fine loamy typic Dystrochrepts
  3. Fine Umbric Dystrochrepts
  4. Loamy , skeletal Umbric Dystrochrepts
  5. Fine typic Dystrochrepts
  6. Loamy-skeletal typic Dystrochrepts
  7. Clayey-skeletal Umbric Dystrochrepts
  8. Loamy-skeletal Pachic Haplumbrepts
  9. Fine Pachic Haplumbrepts
  10. Fine-loamy typic Haplumbrepts
  11. Clayey-skeletal Pachic Haplumbrepts
  12. Fine loamy Pachic Haplumbrepts
  13. Fine-loamy Dystric Eutrochrepts
  14. Coarse loamy typic Dystrocrepts
  15. Loamy skeletal typic Dystrocrepts
  16. Loamy skeletal Dystric Eutrocrepts

ULTISOLS

  • The Ultisols are similar with Alfisols, except for having low base saturation on the exchange complex due to advance stage at weathering.
  • These are base-poor mineral soils of humid region developed under high rainfall and forest vegetation.
  • The high acidity and relatively low quantities of plant-available Ca, Mg, and K associated with most Ultisols make them poorly suited for continuous agriculture without the use of fertilizer and lime
  • They are characterized by low, less than 35% base saturation and clay enriched sub-surface horizon.
  • This soil is sparely scattered in all parts of the State having fine loam, clay loam and clayey texture.
  • Well to excessively drained with moderate to deep soils. The families under this order which have been identified so far are :
    1. Fine Humic Hapludults
    2. Fine Typic Paleudults
    3. Fine Typic Haplohumults
    4. Fine Loamy Typic Hapludults

 

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