Features of Soils in Agro-Ecological Sub-Regions of West Bengal

After reading this article you will learn about the features of soil found in agro-ecological sub-regions of West Bengal.

1. The Warm Humid Agro-Ecological Sub-Region:

The warm humid agro-ecological sub-region covers the mountainous region of Darjeeling District. It occupies an area of 0.26 m ha, representing 2.9 per cent of the total geographical area of the state. Soils of this sub-region are heterogeneous in nature. The soils developed on steep hill slopes are shallow, excessively drained with severe erosion hazard potential.

The soils of the foothill slopes and valleys are moderately deep, well-drained, and loamy in texture with moderate erosion hazards. Soil acidity, high run-off rate and limiting soil depth (on steep hill slopes) are the most important problems of this region.

2. The Warm to Hot Humid Agro-Ecological Sub-Region:

The warm to hot humid agro-ecological sub-region comprising of foothills of Bhutan Himalayas constitutes the northern fringe of Jalpaiguri district with Tarai soils. The sub- region covers an area of 0.17 m ha, representing 1.9 per cent of total area of the state of West Bengal. The soils are partly developed and are mainly formed of young alluvium on alluvial fans of the foothills.

These are shallow to moderately deep and at places deep with medium to fine texture. Mostly tea and horticultural plantation are supported by these soils. Severe flood hazards coupled with abrupt break in gradient and severe run-off poses serious water management problems.

3. The Hot Humid Agro-Ecological Sub-Region:

The hot humid agro-ecological sub-region comprising of the level Teesta Plain (Duars) below the Bhutan Himalayas, covers the districts of Kooch Behar, Jalpaiguri (southern part) and northern parts of West Dinajpur. This sub-region occupies an area of 0.85 m ha representing 9.6 per cent of the total geographical area of the state.

The soils of this region have developed from the alluvium deposited by the rivers Teesta, Mahananda and Jaldhaka. These are moderately deep to deep, coarse to fine loamy in texture. At places these soils are moderately well drained but mostly they are imperfectly and/or poorly drained. The area is intensively cultivated for rice and jute. The major problems are waterlogging, severe flood hazards etc.

4. The Hot Moist Sub-Humid Agro-Ecological Sub-Region:

The hot moist sub-humid agro-ecological sub-region comprises of the Ganga Plain (an eastward continuation of Indo Gangetic Plain covering the districts of Maldah, Dinajpur (southern part), Murshidabad, Nadia, Howrah, Hooghly, 24 Parganas (Northern Part), Bardhaman (eastern part), Birbhum, Bankura and Medinipur (eastern part).

It covers an area of 4.39 m ha representing 55.7 per cent of the total geographical area of the state. The soils have been formed from the alluvium deposited by Ganga and its tributaries and sub-tributaries viz. Ajoy, Damodar, Kansabati, Bhagirathi, Haldi, Rupnarayan etc.

These soils are greatly variable in their morphological, physical properties depending upon the geomorphic situations, moisture regime and degree of profile development.

The soils are intensively cultivated for rice, wheat, potato and oilseed crops. Frequent inundation of low lying areas result in stagnation of water for certain times of the year. Besides flood hazards also affect the normal dry land crop yields. The soils of this sub-region have high nutrient content and mineral resource with a high potential for a large variety of agricultural and horticultural crops.

5. The Moist Sub-Humid Agro-Ecological Sub-Region:

The moist sub-humid agro-ecological sub-region encompasses the coastal parts of the districts of 24 Parganas comprising mostly Sundarban areas of south 24 Parganas and coastal Medinipur. It covers an area or 0.68 m ha, representing 7.6 per cent of the total geographical area of the state.

The alluvium deposited by Matla, Haldi, Rupnarayan Rivers have gradually developed into deep, tine loamy to fine textured soils, by and large salt impregnated due to tidal flow of sea water through creeks and sub-tributaries.

These soils are imperfectly to poorly drain with moderate to very high salinity hazards. The soils remain wet and saline for considerable period of the year and are suitable particularly for salt resistant crops.

6. The Hot Dry Sub-Humid Agro-Ecological Sub-Region:

The hot dry sub-humid agro-ecological sub-region comprising the outlines of Chotonagpur Plateau includes the district of Puruliya and western parts of Bardhaman, Bankura, Birbhum and Medinipur. It covers an area of 1.98 m ha representing 22.3 per cent of the total area of the state. The soils have developed on parent materials of sedentary nature.

They vary from shallow to deep reddish to yellowish red, loamy to clayey and are imperfectly to well drain. Relatively less aggregated red and laterite soils are prone to frequent development of surface encrustation. Poor capacity for retention of rainwater leads to severe run-off and soil loss. Soil infertility and limiting soil depth also pose problems.