Adam means from the Red Earth, which indicates that they could have had reddish skin.
Red soil is any of a group of soils that develop in a warm, temperate, moist climate under deciduous or mixed forests and that have thin organic and organic-mineral layers overlying a yellowish-brown leached layer resting on an illuvial (see illuviation) red layer. Red soils generally derived from igneous (Lava from Volcano) rock. They are usually poor growing soils, low in nutrients and humus and difficult to cultivate. Red soils denote the second largest soil group of India covering an area of about 6.1 lakhs sq. km (18.6% of India's area) over the Peninsula from Tamil Nadu in the south to Bundelkhand in the north and Rajmahal hills in the east to Kachchh in the west. They surround the black soils on their south, east and north.
Red soil is any of a group of soils that develop in a warm, temperate, moist climate under deciduous or mixed forests and that have thin organic and organic-mineral layers overlying a yellowish-brown leached layer resting on an illuvial (see illuviation) red layer. Red soils generally derived from igneous (Lava from Volcano) rock. They are usually poor growing soils, low in nutrients and humus and difficult to cultivate. Red soils denote the second largest soil group of India covering an area of about 6.1 lakhs sq. km (18.6% of India's area) over the Peninsula from Tamil Nadu in the south to Bundelkhand in the north and Rajmahal hills in the east to Kachchh in the west. They surround the black soils on their south, east and north.
Red soil, Any of a group of soils that develop in a warm, temperate, moist climate under deciduous or mixed forests and that have thin organic and organic-mineral layers overlying a yellowish-brown leached layer resting on an illuvial (see illuviation) red layer. Red soils generally form from iron-rich sedimentary rock. They are usually poor growing soils, low in nutrients and humus and difficult to cultivate.
Distribution[edit]
These soils are found in large tracts of western Tamil Nadu, Karnataka, southern Maharashtra, Chhattisgarh, Andhra Pradesh, Orissa and Chotanagpur plateau of Jharkhand. Scattered patches are also seen in Birbhum (West Bengal), Mirzapur, Jhansi, Banda, Hamirpur (Uttar Pradesh), Udaipur, Chittaurgarh, Dungarpur, Banswara and Bhilwara districts (Rajasthan).
Content[edit]
This soil, also known as the omnibus group, have been developed over Archaean granite, gneiss and other crystalline rocks, the sedimentaries of the Cuddapah and Vindhayan basins and mixed Dharwarian group of rocks. Their colour is mainly due to ferric oxides occurring as thin coatings on the soil particles while the iron oxide occurs as haematite or as hydrous ferric oxide, the colour is red and when it occurs in the hydrate form as limonite the soil gets a yellow colour. Ordinarily the surface soils are red while the horizon below gets yellowish colour.
Characteristics[edit]
The texture of red soils varies from sand to clay, the majority being loam. Their other characteristics include porous and friable structure, absence of lime, kankar and free carbonates, and small quantity of soluble salts. Their chemical composition include non-soluble material 90.47%, iron 3.61%, aluminium 2.92%, organic matter 1.01%, magnesium 0.70%, lime 0.56%, carbon-Di-oxide 0.30%, potash 0.24%, soda 0.12%, phosphorus 0.09% and nitrogen 0.08%. However significant regional differences are observed in the chemical composition.
In general these soils are deficient in lime, magnesia, phosphates, nitrogen, humus and potash. Intense leaching is a menace to these soils. On the uplands, they are thin, poor and gravelly, sandy, or stony and porous, light-colored soils on which food crops like bajra can be grown. But on the lower plains and valleys they are rich, deep, dark colored fertile loam on which, under irrigation, can produce excellent crops like cotton, wheat, pulses, tobacco, jowar, linseed, millet, potatoes and fruits. These are also characterized by stunted forest growth and are suited to dry farming.
Morphology[edit]
Ray Chaudhary (1941) has morphologically grouped red soils into following two categories:
(a) Red Loam Soil-these soils have been formed by the decomposition of granite, gneiss charnocite and diorite rocks. It is cloddy porous and deficient in concretionary materials. It is poorer in nitrogen, phosphorus and organic materials but rich in potash. Leaching is dominant.
These soils have thin layers and are less fertile. These soils are mainly found in Karnataka (Shimoga, Chikmaglur and Hassan districts), Andhra Pradesh (Telangana), estern Tamil Nadu, Orissa, Jharkhand (Chotanagpur), Uttar Pradesh (Bundelkhand), Madhya Pradesh (Balaghat and Chhindwara), Rajasthan (Banswara, Bhilwara, Bundi, Chittaurgarh, Kota and Ajmer districts), Meghalaya, Mizoram, Manipur and Nagaland.
(b) Sandy Red Soil-these soils have formed by the disintegration of granite, grani gneiss, quartzite and sandstone. These are 1 friable soil with high content of secondary conc tions of sesquioxide clays.
Due to presence of haematite and limonite its colour ranges from red to yellow These soils have been rightly leached occupyi parts of former eastern Madhya Pradesh (exce Chhattisgarh region), neighbouring hills of Oriss Andhra Pradesh, and Tamil Nadu (Eastern Ghats and Sahyadris.
The Indian Council of Agricultural Research (ICAR) has divided red soils into four categories-(a) red soils, (b) red gravelly soils, (c) red and yellow soils, and (d) mixed red and black soil
other uses, see Red clay (disambiguation).
| Ultisols | |
|---|---|
| Red Clay Soil | |
 | |
| an Ultisol profile | |
| Used in: | USDA soil taxonomy |
| Key process: | weathering |
| Climate: | tropical, humid subtropical,oceanic |
Ultisols, commonly known as red clay soils, are one of twelve soil orders in the United States Department of Agriculture soil taxonomy. They are defined as mineral soils which contain no calcareous material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer of soil, and have less than 35% base saturation throughout the soil. Ultisols occur in humid temperate or tropical regions. While the term is usually applied to the red clay soils of the Southern United States, ultisols are also found in regions of Africa, Asia, and South America. In the World Reference Base for Soil Resources system, most ultisols are known as acrisols. Others with higher-activity clays are classed as alisols ornitisols.
The word "ultisol" is derived from "ultimate", because ultisols were seen as the ultimate product of continuous weathering of minerals in a humid, temperate climate without new soil formation via glaciation.
Ultisols vary in color from purplish-red, to a bright reddish-orange, to pale yellowish-orange and even some subdued yellowish-brown tones. They are typically quite acidic, often having a pH of less than 5. The red and yellow colors result from the accumulation of iron oxide (rust) which is highly insoluble in water. Major nutrients, such as calcium andpotassium, are typically deficient in ultisols, which means they generally cannot be used for sedentary agriculture without the aid of lime and other fertilizers, such as superphosphate. They can be easily exhausted, and require more careful management than alfisols or mollisols. However, they can be cultivated over a relatively wide range of moisture conditions.
Ultisols can have a variety of clay minerals, but in many cases the dominant mineral is kaolinite. This clay has good bearing capacity and no shrink–swell property. Consequently, well-drained kaolinitic ultisols such as the Cecil series are suitable for urban development.
Ultisols are the dominant soils in the Southern United States (where the Cecil series is most famous), southeastern China, Southeast Asia and some other subtropical and tropical areas. Their northern limit (except fossil soils) is very sharply defined in North America by the limits of maximum glaciation during the Pleistocene, because ultisols typically take hundreds of thousands of years to form - far longer than the length of an interglacial period today.
The oldest fossil ultisols are known from the Carboniferous period when forests first developed. Though known from far north of their present range as recently as the Miocene, Ultisols are surprisingly rare as fossils overall, since they would have been expected to be very common in the warm Mesozoic and Tertiary paleoclimates.
Suborders[edit]
- Aquults - Ultisols with a water table at or near the surface for much of the year
- Humults - well-drained ultisols that have high organic matter content
- Udults - Ultisols of humid climates
- Ustults - Ultisols of semiarid and subhumid climates
- Xerults - temperate ultisols with very dry summers and moist winters