Red soil is a type of soil that typically develops in warm, temperate, and humid climates and comprises approximately 13% of Earth's soils. [1] It contains thin organic and organic-mineral layers of highly leached soil resting on a red layer of alluvium. Red soils contain large amounts of clay and are generally derived from the weathering of ancient crystalline and metamorphic rock. They are named after their rich red color, varying from reddish brown to reddish yellow due to their high iron content. [2] Red soil can be good or poor growing soil depending on how it is managed. It is usually low in nutrients and humus and can be difficult to cultivate due to its low water holding capacity; however, the fertility of these soils can be optimized with liming and other farming techniques. [1]
Red soils are an important resource because they make up such a large portion of farmland on the earth. In countries such as China, India, and Greece, where there are large amounts of red soil, understanding the soil's properties is crucial to successful agriculture. Red soil properties vary across regions and may require different management practices to achieve the best results. [3]
Red soils include multiple soil types (e.g. ultisols, alfisols, oxisols) that are classified as red soil when they develop a distinct reddish color, which can vary from reddish brown to reddish yellow due to their high iron content. [1] In general, red soils possess some characteristics of a good growing soil. They are generally acidic soils, which can be positive for agriculture but, in this case, often cause a lack of sufficient nutrients. These soils are also prone to frequent drought in drier regions. [1]
Red soils are generally derived from the weathering of crystalline and metamorphic rock in areas of high rainfall. Red soil contains large amounts of clay and thin organic and organic-mineral layers of highly leached soil resting on an alluvium red layer. [2] The composition and agricultural properties of red soil vary across regions. One type of red soil may be considered infertile in one region but nutrient-rich in another. [1] There is not a singular composition that classifies all red soils.
Red soils are typically difficult for crop cultivation because high leaching leads to low water holding capacity, low nutrients, low organic matter (humus), and acidification. [1] Fluctuations in the concentration of iron within red soil are found to have significant implications on its fertility and growth properties. The fertility of red soils can be improved with various farming techniques. [1]
The soil liming process helps raise the pH of acidic soils. Because red soils are generally acidic, liming is a valuable farming technique that allows crops intolerant of acidic environments to thrive in red soil. However, modern research suggests that liming may have long-term environmental consequences on the soil. The systematic overflow of water through the soil gets into the organic matter of relevant sophgate of the soil. [1]
Red soils are often deficient in nitrogen, which limits the growth properties of most red soil. Phosphorus and potassium can also become limited after the land has been harvested repeatedly. Nutrient application techniques introduce more of these lacking nutrients to the soil and allow them to restore chemicals that have diminished over time. [1]
Another management practice that can be used to improve the fertility of red soil is incorporating organic matter into the soil. Some strategies employed to practice this include the use of organic manure and establishing proper tillage systems for the land. [1]
The rotation of crops grown in red soil can significantly help to limit some of the compositional issues mentioned previously. Crop rotation helps to increase the content of organic matter, minimize nitrogen deficiency, and help avoid pests that damage the crops. [1]
Red soil resources are estimated to cover 102 million hectare (1,020,000 square kilometers) of land in tropical and subtropical regions of China. The primary areas of distribution are Hainan, Guangdong, and Yunnan among other agricultural regions. [4]
Red soils have a significant role in agriculture in Greece as well. They fall into two groups: residual soil forming in place from parent rock and soil forming in deep sedimentary deposits. The residual red soils in Greece tend to be less than a meter in depth and form on sloping hillsides. Like other red soils in the Mediterranean, they tend to form in limestone. The red soils that form in deep sediments are widespread in the lowlands of Greece, occurring on gently sloping terrain. Taxonomically, the Greek red soils belong to Rhodoxeralfs (red alfisol), Palexeralfs (well-aged alfisols), Xerochrepts (xeric inceptisol), and Orthents. [5]
Red soils denote the most extensive soil group of India, covering an area of about 350,000 km2 (10.6% of India's area) across the peninsula. India is rich with red soils in their southern, eastern, and northern regions. There, the soil appears yellow in its hydrated form. [6] 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. In the uplands of India, the red soils are thin, poor and gravelly, sandy, or stony and porous, light-colored soils on which food crops like bajra can be grown. In contrast, on the lower plains and valleys, they are rich, deep, dark-colored fertile loam which, under irrigation, can produce excellent crops like cotton, wheat, pulses, tobacco, jowar, linseed, millet, potatoes and fruits.
Prince Edward Island is famous for its iron-rich red soil. [7]
Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from soil by restricting the former term specifically to displaced soil.
A soil test is a laboratory or in-situ analysis to determine the chemical, physical or biological characteristics of a soil. Possibly the most widely conducted soil tests are those performed to estimate the plant-available concentrations of nutrients in order to provide fertilizer recommendations in agriculture. In geotechnical engineering, soil tests can be used to determine the current physical state of the soil, the seepage properties, the shear strength and the deformation properties of the soil. Other soil tests may be used in geochemical or ecological investigations.
Oxisols are a soil order in USDA soil taxonomy, best known for their occurrence in tropical rain forest within 25 degrees north and south of the Equator. In the World Reference Base for Soil Resources (WRB), they belong mainly to the ferralsols, but some are plinthosols or nitisols. Some oxisols have been previously classified as laterite soils.
Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.
Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes. Tropical rainforests are a type of tropical moist broadleaf forest, that includes the more extensive seasonal tropical forests. True rainforests usually occur in tropical rainforest climates where no dry season occurs; all months have an average precipitation of at least 60 mm (2.4 in). Seasonal tropical forests with tropical monsoon or savanna climates are sometimes included in the broader definition.
USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series. The classification was originally developed by Guy Donald Smith, former director of the U.S. Department of Agriculture's soil survey investigations.
Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality. It also refers to the soil's ability to supply plant/crop nutrients in the right quantities and qualities over a sustained period of time. A fertile soil has the following properties:
In soil science, podzols, also known as podosols, spodosols, or espodossolos, are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of human interference through grazing and burning. In some British moorlands with podzolic soils, cambisols are preserved under Bronze Age barrows.
Ultisol, commonly known as red clay soil, is one of twelve soil orders in the United States Department of Agriculture soil taxonomy. 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. 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, Australia and South America.
In geoscience, paleosol is an ancient soil that formed in the past. The definition of the term in geology and paleontology is slightly different from its use in soil science.
The paleopedological record is, essentially, the fossil record of soils. The paleopedological record consists chiefly of paleosols buried by flood sediments, or preserved at geological unconformities, especially plateau escarpments or sides of river valleys. Other fossil soils occur in areas where volcanic activity has covered the ancient soils.
This is an index of articles relating to soil.
Hydrophobic soil is a soil whose particles repel water. The layer of hydrophobicity is commonly found at or a few centimeters below the surface, parallel to the soil profile. This layer can vary in thickness and abundance and is typically covered by a layer of ash or burned soil.
Soil acidification is the buildup of hydrogen cations, which reduces the soil pH. Chemically, this happens when a proton donor gets added to the soil. The donor can be an acid, such as nitric acid, sulfuric acid, or carbonic acid. It can also be a compound such as aluminium sulfate, which reacts in the soil to release protons. Acidification also occurs when base cations such as calcium, magnesium, potassium and sodium are leached from the soil.
Nitisol, in the World Reference Base for Soil Resources (WRB), is a deep, red, well-drained soil with a clay content of at least 30% and a polyhedral structure or a blocky structure, breaking into a polyhedral or a flat-edged structure. The soil aggregates show pressure faces. Nitisols correlate with the kandic alfisols, ultisols and inceptisols of the USDA soil taxonomy.
There are seven soil deposits in India. They are alluvial soil, black soil, red soil, laterite soil, or arid soil, and forest and mountainous soil, marsh soil. These soils are formed by various geographical factors. They also have varied chemical properties. Sundarbans mangrove swamps are rich in marsh soil.
The Indian Institute of Soil Science is an autonomous institute for higher learning, established under the umbrella of Indian Council of Agricultural Research (ICAR) by the Ministry of Agriculture, Government of India for advanced research in the field of soil sciences.
Seventeen elements or nutrients are essential for plant growth and reproduction. They are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), nickel (Ni) and chlorine (Cl). Nutrients required for plants to complete their life cycle are considered essential nutrients. Nutrients that enhance the growth of plants but are not necessary to complete the plant's life cycle are considered non-essential, although some of them, such as silicon (Si), have been shown to improve nutrent availability, hence the use of stinging nettle and horsetail macerations in Biodynamic agriculture. With the exception of carbon, hydrogen and oxygen, which are supplied by carbon dioxide and water, and nitrogen, provided through nitrogen fixation, the nutrients derive originally from the mineral component of the soil. The Law of the Minimum expresses that when the available form of a nutrient is not in enough proportion in the soil solution, then other nutrients cannot be taken up at an optimum rate by a plant. A particular nutrient ratio of the soil solution is thus mandatory for optimizing plant growth, a value which might differ from nutrient ratios calculated from plant composition.