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Hydric Soil
Hydric soil is soil which is permanently or seasonally saturated by water, resulting in anaerobic conditions, as found in wetlands. Overview Most soils are aerobic. This is important because plant roots respire (that is, they consume oxygen and carbohydrates while releasing carbon dioxide) and there must be sufficient air—especially oxygen—in the soil to support most forms of soil life. Air normally moves through interconnected pores by forces such as changes in atmospheric pressure, the flushing action of rainwater, and by simple diffusion. In addition to plant roots, most forms of soil microorganisms need oxygen to survive. This is true of the more well-known soil animals as well, such as ants, earthworms and moles. But soils can often become saturated with water due to rainfall and flooding. Gas diffusion in soil slows (some 10,000 times slower) when soil becomes saturated with water because there are no open passageways for air to travel. When oxygen levels becom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil
Soil, also commonly referred to as earth or dirt Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty. Common types of dirt include: * Debris: scattered pieces of waste or remains * Dust: a gener ..., is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former term specifically to displaced soil. Soil consists of a solid phase of minerals and organic matter (the soil matrix), as well as a Porosity, porous phase that holds Soil gas, gases (the soil atmosphere) and water (the soil solution). Accordingly, soil is a three-state of matter, state system of solids, liquids, and gases. Soil is a product of several factors: the influence of climate, terrain, relief (elevation, orientation, and slope of terrain), organisms, and the soil's parent materials (ori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Gas
Soil gases (soil atmosphere) are the gases found in the air space between soil components. The spaces between the solid soil particles, if they do not contain water, are filled with air. The primary soil gases are nitrogen, carbon dioxide and oxygen. Oxygen is critical because it allows for respiration of both plant roots and soil organisms. Other natural soil gases include nitric oxide, nitrous oxide, methane, and ammonia. Some environmental contaminants below ground produce gas which diffuses through the soil such as from landfill wastes, mining activities, and contamination by petroleum hydrocarbons which produce volatile organic compounds. Gases fill soil pores in the soil structure as water drains or is removed from a soil pore by evaporation or root absorption. The network of pores within the soil aerates, or ventilates, the soil. This aeration network becomes blocked when water enters soil pores. Not only are both soil air and soil water very dynamic parts of soil, but both ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xeric
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this habitat type vary greatly in the amount of annual rainfall they receive, usually less than annually except in the margins. Generally evaporation exceeds rainfall in these ecoregions. Temperature variability is also diverse in these lands. Many deserts, such as the Sahara, are hot year-round, but others, such as East Asia's Gobi, become quite cold in winter. Temperature extremes are a characteristic of most deserts. High daytime temperatures give way to cold nights because there is no insulation provided by humidity and cloud cover. The diversity of climatic conditions, though quite harsh, supports a rich array of habitats. Many of these habitats are ephemeral in nature, reflecting the paucity and seasonality of available water. Woody-stemm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wade Hurt
G. Wade Hurt is a soil scientist in the United States and an authority on hydric soils. As of 2007, he has a position with the University of Florida's Soil and Water Science Department in Gainesville. Hurt retired from the Natural Resources Conservation Service (NRCS) in 2007. He served as NRCS National Leader for Hydric Soils. Wade received his bachelor's degree from Mississippi State University. Editor Wade Hurt served as editor for several editions of ''Field Indicators of Hydric Soils'', a technical reference used to identify wetland areas that fall under USA jurisdiction as defined by the Clean Water Act. Educator Wade Hurt teaches hydric soils classes for soil science undergraduate and graduate students as well as environmental professionals. Classes teach theoretical, morphologic, and regulatory criteria used for delineating wetlands, siting septic drain fields and identifying seasonal high water table The water table is the upper surface of the zone of saturation. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bonds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesic Habitat
In ecology, a mesic habitat is a type of habitat with a moderate or well-balanced supply of moisture, e.g., a mesic forest, a temperate hardwood forest, or dry-mesic prairie. Mesic habitats transition to xeric shrublands Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (ancient Greek xērós, “dry") shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this ... in a non-linear fashion, which is evidence of a threshold. Mesic is one of a triad of terms used to describe the amount of water in a habitat. The others are xeric and hydric. Further examples of mesic habitats include streamsides, wet meadows, springs, seeps, irrigated fields, and high elevation habitats. These habitats effectively provide drought insurance as land at higher elevations warms due to seasonal or other change. Healthy mesic habitats act like sponges in that they store water in such a way that it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gley Soil
A gleysol is a wetland soil ( hydric soil) that, unless drained, is saturated with groundwater for long enough to develop a characteristic colour pattern. The pattern is essentially made up of reddish, brownish, or yellowish colours at surfaces of soil particles and/or in the upper soil horizons mixed with greyish/blueish colours inside the peds and/or deeper in the soil. Gleysols are also known as ''Gleyzems'', ''meadow soils'', ''Aqu''-suborders of Entisols, Inceptisols and Mollisols ( USDA soil taxonomy), or as ''groundwater soils'' and ''hydro-morphic soils''. Gleysols occur within a wide range of unconsolidated materials, mainly fluvial, marine and lacustrine sediments of Pleistocene or Holocene age, having basic to acidic mineralogy. They are found in depression areas and low landscape positions with shallow groundwater. Wetness is the main limitation on agriculture of virgin gleysols; these are covered with natural swamp vegetation and lie idle or are used f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Goo
Blue goo is a sticky, plasticky, blueish-grey, clay-textured soil derived from a highly weathered serpentinite mélange. The name derives from the soil's color; a result of undergoing anaerobic conditions and becoming gleyed. A greyer variation is called "grey goo". Blue goo is primarily found along the Northern California coast. Parent material The Franciscan Complex is the bedrock from which blue goo is derived. It stretches along the coastline from Central California up to Southern Oregon and contains sheared materials from both the Pacific and North American Plates that have accumulated in the accretionary wedge. The rock types that produce blue goo include: greenstones, cherts, basalts, shales, sandstones, schists, and serpenitites. These materials mixed together forming a "plum pudding" or a mélange. This mélange decomposed through weathering to form blue goo. Common features Clay soils like blue goo have the highest water-holding capacity when compared with other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acid Sulfate Soil
Acid sulfate soils are naturally occurring soils, sediments or organic substrates (e.g. peat) that are formed under waterlogged conditions. These soils contain iron sulfide minerals (predominantly as the mineral pyrite) and/or their oxidation products. In an undisturbed state below the water table, acid sulfate soils are benign. However, if the soils are drained, excavated or otherwise exposed to air, the sulfides react with oxygen to form sulfuric acid.Identification & Investigation of Acid Sulfate Soils (2006), Department of Environment, Western Australia. Retrieved froportal Release of this sulfuric acid from the soil can in turn release iron, aluminium, and other heavy metals and metalloids (particularly arsenic) within the soil. Once mobilized in this way, the acid and metals can create a variety of adverse impacts: killing vegetation, seeping into and acidifying groundwaterMosley LM, Palmer D, Leyden E, Fitzpatrick R, and Shand P (2014). Changes in acidity and metal geochemi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ponding
Ponding is the (typically) unwanted pooling of water, typically on a flat roof or roadway. Ponding water accelerates the deterioration of many materials, including seam adhesives in single-ply roof systems, steel equipment supports, and particularly roofing asphalt. On low-slope asphalt roofs, ponding water allows the oil solvent components of the asphalt to leach out and evaporate, leaving the roof membrane brittle and susceptible to cracking and leaking in the ponding location. The time taken for water to saturate a zone, usually from rainfall, causing a pond to form, is referred to as the "ponding time" or "time of ponding". Cause Most flat roof systems (properly called "low-slope roof systems") are designed with a slight pitch to shed water off the sides, usually into gutters, scuppers, internal drains, or a combination of these. When a scupper or drain is clogged or fails for other reasons, storm water tends to pool around that low area. Over time, with each passing storm, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Security Act Of 1985
The Food Security Act of 1985 (P.L. 99–198, also known as the 1985 U.S. Farm Bill), a 5-year omnibus farm bill, allowed lower commodity price and income supports and established a dairy herd buyout program. This 1985 farm bill made changes in a variety of other USDA programs. Several enduring conservation programs were created, including sodbuster, swampbuster, and the Conservation Reserve Program. Summary The Food Security Act of 1985 was passed by the United States Congress on December 18, 1985, and signed by the President Ronald Reagan on December 23, 1985. This was the first farm bill with a specific title devoted to conservation programs and policies. The 1985 Farm Bill included the Conservation Reserve Program (CRP) in its current form and operation, but most notably it included conservation compliance requirements: to be eligible for commodity subsidies farmers had to comply with provisions known as swampbuster (addressing the draining of wetlands), sodbuster (addressi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territories, nine Minor Outlying Islands, and 326 Indian reservations. The United States is also in free association with three Pacific Island sovereign states: the Federated States of Micronesia, the Marshall Islands, and the Republic of Palau. It is the world's third-largest country by both land and total area. It shares land borders with Canada to its north and with Mexico to its south and has maritime borders with the Bahamas, Cuba, Russia, and other nations. With a population of over 333 million, it is the most populous country in the Americas and the third most populous in the world. The national capital of the United States is Washington, D.C. and its most populous city and principal financial center is New York City. Paleo-Americ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
