Calcareous soil , Origin, Properties and Distribution in India (IGKV RAIPUR , C.G.)

Calcareous soil , Origin, Properties and Distribution in India (IGKV RAIPUR , C.G.)

1. CALCAREOUS SOIL ORIGIN, PROPERTIES AND DISTRIUTION

2. INTRODUCTION C alcareous is an adjective meaning “mostly or partly composed of calcium carbonate “ in other words ,containing lime or being chalky. Calcareous soil are soils in which a high amount of calcium carbonate dominates the problems related to agricultural land use.

3. CONTINUE.... They are characterised by the presence of calcium carbonate in the parent material and by a calcic horizon ,a layer of secondary accumulation of carbonates ( usually calcium or magnesium) in excess of 15% calcium carbonate equivalent and at –least 5% more carbonate than an underlying layer.

4. ORIGIN AND FORMATION OF CALCAREOUS SOIL:- Calcareous soil is formed in arid as well as humid region. It is more common in arid areas . In dry regions ,calcareous soil is formed in-situ whereas, it has secondary origin in water logged area.

5. CONTINUE..... (A) Formation of calcareous soil in situ by weathering of parent rock materials:- There is formation of calcium carbonate due to weathering of rocks. The low rainfall in arid and semi- arid regions , is not sufficient to leach out the soluble products of weathering to ground water. In dry weather, the salt moves up with the water by capillary movement to the surface where they are deposited. (B) Development of calcareous soil by secondary origin :- Calcareous soil of secondary origin is developed in low-lying areas or in basin shaped areas .Generally drainage is impeded in these lowlying areas . During the rainy season , soluble calcium bicarbonate of nearby areas accumulate in the lowlying areas. During dry season, calcium bicarbonate converted into calcium carbonate and deposited on the soil surface by capillary movement.

6. CONTINUE....... The source of primary carbonate minerals in most soils is marine limestone or dolomite limestone deposits. Carbonate parent materials are mineralogical quite uniform ,varying only in the presence and quantity of cation other than Ca and in clay content. Soil development on calcareous parent material is controlled by the dissolution , re-precipitation , and leaching of carbonates and their products .

7. PROPERTIES OF CALCAREOUS SOIL Calcareous soils mainly contains calcium carbonate in free form and magnesium carbonate may remain present in small quantity. There is effervescence when calcareous soils come in contact with the acid ( Hcl ). Soil colloids contain about 90% calcium and magnesium carbonate as absorbed bases. Calcareous soils are sometimes referred to as alkaline ( high ph) soils, but they are distinguishable from other soils with high ph.

8. CONTINUE..... Calcite and aragonite ,dolomite and magnesite are the calcium and magnesium carbonate minerals found in calacareous soil. They are mainly present as calcite , and to lesser extent as dolomite. The ph range of calcareous soils( determined in water) is from 7.0 to 8.5. (A) Physical properties of soil:- Calcareous soils remain in a flocculated condition(granulated). Soil is permeable to water and air due to large number of pore spaces.

9. CONTINUE..... Flocculation in heavy (clay) soil increases pore spaces and consequently drainage but in light (sandy) soil it decreases water holding capacity. (B)Availability of nutrients:- 1. Phosphorous- In calacareous soil , the solubility of phosphorous is depressed which results in the decrease of P availability. 2. Potassium- Availability of potassium is decreased due to presence of excess calcium carbonate. 3. Zinc- Availability of zinc is reduced.

10. (C) Activity of microorganism:- Moisture is essential o microorganism activity . Microorganism activity in wet calcareous soil is normal but it is affected in dry calcareous soil. DISTRIBUTION The calcareous soils in I ndia are located in eastern Uttarpradesh and north B ihar . In Bihar ,calcareous soils are found in Muzaffarpur , Darbhanga , Saran , Champaran and Munger district of north bihar.