Ultisol | |
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Red Clay Soil | |
![]() A Ultisol profile | |
Used in | USDA soil taxonomy |
Key process | weathering |
Climate | tropical, humid subtropical, oceanic |
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 (calcium carbonate containing) 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 the World Reference Base for Soil Resources (WRB), most Ultisols are known as Acrisols and Alisols. Some belong to the Retisols or to the Nitisols. Aquults are typically Stagnosols or Planosols. Humults may be Umbrisols. [1]
Ultisols vary in color from purplish-red, to a bright reddish-orange, to pale yellowish-orange and (in cooler areas such as Pennsylvania) even some subdued yellowish-brown or grayish-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 and potassium, are typically deficient in Ultisols, [2] 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.
The lack of organic matter in Ultisol makes it difficult for plants to grow without proper care and considerations. Soil amendments are generally required each year in order to sustain plant life in regions with primarily Ultisol soil. [3] The use of soil tests, coupled with the corresponding provisions, can alleviate issues of nutrition and irrigation that can result from non porous Ultisol. [4] Soil tests help indicate the pH, and red clay soil typically has a low pH. [5] The addition of lime is used to help to increase the pH in soil and can help increase the pH in Ultisol as well. [6]
Clay soil is known to retain nutrients very well because its negative charge helps to attract cations. As a result, Ultisol does not often require the high amounts of fertilizer additions other types of soils often do. [7] However, this retention of nutrients coincides with a lack of water filtration that may subject plants to highly saturated soil.[ citation needed ]
Generally, gardeners aim to have 45% mineral, 5% organic matter and 50% pore space in their soil. [8] The composition of Ultisol in North Carolina, for reference, is approximately 16% pore space, 2% organic matter and 82% mineral. [9] The use of mulch is widespread in the Piedmont region of the United States as a solution to the high temperatures and saturation of the soil. [10] The addition of mulch helps to make the soil more porous. [11]
Adding manure and/or compost can help to boost the amount of organic material present in the soil which in turn helps to add essential nutrients. Specifically, the addition of a 2- to 3-inch layer of compost and/or manure should be mixed into the soil to approximately match the depth of a shovel. [12] The addition of organic material also helps to improve the drainage, while decreasing the overall weight of the soil. [13]
However, microorganisms in the soil consume the same nutrients that plants use to grow so certain nutrients will remain unavailable to plants until the microorganisms completely break down the organic material and release nutrients. [14] Living organisms within the soil use, and subsequently convert, organic material into usable humus. [15] To avoid the delay presented by this process, adding manure in the fall is advisable. [16]
Some gardeners who live in areas with large amounts of red clay soil use raised beds or Hügelkultur to avoid having to amend the soil. [17] By using raised beds, gardeners avoid having to deal with Ultisols altogether.
Plants found native to regions with high amounts of Ultisol are able to thrive. Generally these are species adapted to poorly drained, damp soils. [18] The Missouri Botanical Garden recommends tickweed, spotted jewelweed, mealycup sage, Camassia , spring starflower, ostrich fern, sideoats grama, Bouteloua curtipendula , and prairie dropseed. [19]
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by decomposing plant and food waste, recycling organic materials, and manure. The resulting mixture is rich in plant nutrients and beneficial organisms, such as bacteria, protozoa, nematodes, and fungi. Compost improves soil fertility in gardens, landscaping, horticulture, urban agriculture, and organic farming, reducing dependency on commercial chemical fertilizers. The benefits of compost include providing nutrients to crops as fertilizer, acting as a soil conditioner, increasing the humus or humic acid contents of the soil, and introducing beneficial microbes that help to suppress pathogens in the soil and reduce soil-borne diseases.
Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions in an artificial environment. Terrestrial or aquatic plants may grow freely with their roots exposed to the nutritious liquid or the roots may be mechanically supported by an inert medium such as perlite, gravel, or other substrates.
No-dig gardening is a non-cultivation method used by some organic gardeners. The origins of no-dig gardening are unclear, and may be based on pre-industrial or nineteenth-century farming techniques. Masanobu Fukuoka started his pioneering research work in this domain in 1938, and began publishing in the 1970s his Fukuokan philosophy of "do-nothing farming" or natural farming, which is now acknowledged by some as the tap root of the permaculture movement. Two pioneers of the method in the twentieth century included F. C. King, Head Gardener at Levens Hall, South Westmorland, in the Lake District of England, who wrote the book "Is Digging Necessary?" in 1946, and a gardener from Middlecliffe in the UK, A. Guest, who in 1948 published the book "Gardening Without Digging". The work of these gardeners was supported by the Good Gardeners Association in the UK. No-dig gardening was also promoted by Australian Esther Deans in the 1970s, and American gardener Ruth Stout advocated a "permanent" garden mulching technique in Gardening Without Work and no-dig methods in the 1950s and 1960s.
Physiological plant disorders are caused by non-pathological conditions such as poor light, adverse weather, water-logging, phytotoxic compounds or a lack of nutrients, and affect the functioning of the plant system. Physiological disorders are distinguished from plant diseases caused by pathogens, such as a virus or fungus. While the symptoms of physiological disorders may appear disease-like, they can usually be prevented by altering environmental conditions. However, once a plant shows symptoms of a physiological disorder, it is likely that that season's growth or yield will be reduced.
Vermicompost (vermi-compost) is the product of the decomposition process using various species of worms, usually red wigglers, white worms, and other earthworms, to create a mixture of decomposing vegetable or food waste, bedding materials, and vermicast. This process is called vermicomposting, with the rearing of worms for this purpose is called vermiculture.
The following outline is provided as an overview of and topical guide to organic gardening and farming:
Vegan organicagriculture is the organic production of food and other crops with minimal animal inputs. Vegan organic agriculture is the organic form of animal-free agriculture.
In agriculture, a green manure is a crop specifically cultivated to be incorporated into the soil while still green. Typically, the green manure's biomass is incorporated with a plow or disk, as is often done with (brown) manure. The primary goal is to add organic matter to the soil for its benefits. Green manuring is often used with legume crops to add nitrogen to the soil for following crops, especially in organic farming, but is also used in conventional farming.
Soil test may refer to one or more of a wide variety of soil analysis conducted for one of several possible reasons. Possibly the most widely conducted soil tests are those done to estimate the plant-available concentrations of plant nutrients, in order to determine fertilizer recommendations in agriculture. Other soil tests may be done for engineering (geotechnical), geochemical or ecological investigations.
Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come from the feces and remains of organisms such as plants and animals. Organic molecules can also be made by chemical reactions that do not involve life. Basic structures are created from cellulose, tannin, cutin, and lignin, along with other various proteins, lipids, and carbohydrates. Organic matter is very important in the movement of nutrients in the environment and plays a role in water retention on the surface of the planet.
In soil science, agriculture and gardening, hardpan or soil pan is a dense layer of soil, usually found below the uppermost topsoil layer. There are different types of hardpan, all sharing the general characteristic of being a distinct soil layer that is largely impervious to water. Some hardpans are formed by deposits in the soil that fuse and bind the soil particles. These deposits can range from dissolved silica to matrices formed from iron oxides and calcium carbonate. Others are man-made, such as hardpan formed by compaction from repeated plowing, particularly with moldboard plows, or by heavy traffic or pollution.
Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture in soil building and conservation, pest management, and heirloom variety preservation.
A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility and sometimes its mechanics. In general usage, the term "soil conditioner" is often thought of as a subset of the category soil amendments, which more often is understood to include a wide range of fertilizers and non-organic materials. In the context of construction soil conditioning is also called soil stabilization.
Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. The organic-mess refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.
Potting soil or growing media, also known as potting mix or potting compost (UK), is a substrate used to grow plants in containers. The first recorded use of the term is from an 1861 issue of the American Agriculturist. Despite its name, little or no soil is usually used in potting soil.
Red soil is a type of soil that typically develops in warm, temperate, and humid climates and comprise approximately 13% of Earth's soils. 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, which can vary from reddish brown to reddish yellow as a result of their high iron content. 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.
Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nutrients, such as nitrogen, that are utilised by bacteria, fungi and other organisms in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web.
French intensive gardening also known as raised bed, wide bed, or French market gardening is a method of gardening in which plants are grown within a smaller space and with higher yields than other traditional gardening methods. The main principles for success are often listed as soil improvement, raised beds, close spacing, companion planting, succession planting and crop rotation. Originating in France, the practice is very popular among urban gardeners and small for profit farming operations.
A Retisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). Retisols are characterized by clay migration and an additional specific feature: The clay-poorer and lighter coloured eluvial horizon intercalates netlike into the clay-richer more intensely coloured illuvial horizon. The illuvial horizon is the diagnostic argic horizon, and the intercalation is called retic properties.