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Soil Fertility
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.Bodenfruchtbarkeit Retrieved on 2015-11-09. 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: * The ability to supply essential plant nutrients and water in adequate amounts and proportions for plant growth and reproduction; and * The absence of toxic substances which may inhibit plant growth e.g Fe^2+ which leads to nutrient toxicity. The following properties contribute to soil fertili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Horizons
A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These may be described both in absolute terms (particle size distribution for texture, for instance) and in terms relative to the surrounding material, i.e. 'coarser' or 'sandier' than the horizons above and below. The identified horizons are indicated with symbols, which are mostly used in a hierarchical way. Master horizons (main horizons) are indicated by capital letters. Suffixes, in form of lowercase letters and figures, further differentiate the master horizons. There are many different systems of horizon symbols in the world. No one system is more correct—as artificial constructs, their utility lies in their ability to accurately describe local conditions in a consistent manner. Due to the different definitions of the horizon symb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. However, when a medication is administered via routes other than intravenous, its bioavailability is generally lower than that of intravenous due to intestinal endothelium absorption and first-pass metabolism. Thereby, mathematically, bioavailability equals the ratio of comparing the area under the plasma drug concentration curve versus time (AUC) for the extravascular formulation to the AUC for the intravascular formulation. AUC is used because AUC is proportional to the dose that has entered the systemic circulation. Bioavailability of a drug is an average value; to take population variability into account, deviation range is shown as ±. To ensure that the drug taker who has poor absorption is dosed appropriately, the bottom value ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slash-and-burn
Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed vegetation, or "slash", is then left to dry, usually right before the rainiest part of the year. Then, the biomass is burned, resulting in a nutrient-rich layer of ash which makes the soil fertile, as well as temporarily eliminating weed and pest species. After about three to five years, the plot's productivity decreases due to depletion of nutrients along with weed and pest invasion, causing the farmers to abandon the field and move to a new area. The time it takes for a swidden to recover depends on the location and can be as little as five years to more than twenty years, after which the plot can be slashed and burned again, repeating the cycle. In Bangladesh and India, the practice is known as jhum or jhoom. Slash-and-burn is a type of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Cronon
William Cronon (born September 11, 1954 in New Haven, Connecticut) is an environmental historian and the Frederick Jackson Turner and Vilas Research Professor of History, Geography, and Environmental Studies at the University of Wisconsin–Madison. He was president of the American Historical Association (AHA) in 2012. Education and recognition Cronon was born in Connecticut. Cronon received a Bachelor of Arts with double major in history and English from the University of Wisconsin–Madison in 1976. He received a Master of Arts in 1979 and a Master of Philosophy in 1980 both in American history from Yale University. He received a Doctor of Philosophy in British urban and economic history from the Jesus College of the University of Oxford as a Rhodes Scholar in 1981. He received a Doctor of Philosophy in American history from Yale University in 1990. In July 1985 Cronon was awarded a MacArthur Fellowship. Cronon serves on the board of directors for The Trust for Public L ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Colonial New England
The New England Colonies of British America included Connecticut Colony, the Colony of Rhode Island and Providence Plantations, Massachusetts Bay Colony, Plymouth Colony, and the Province of New Hampshire, as well as a few smaller short-lived colonies. The New England colonies were part of the Thirteen Colonies and eventually became five of the six states in New England, with Plymouth Colony absorbed into Massachusetts and Maine separating from it. Captain John Smith's 1616 work ''A Description of New England'' first applied the term "New England" to the coastal lands from Long Island Sound to Newfoundland. Arriving in America England, France, and the Netherlands made several attempts to colonize New England early in the 17th century, and those nations were often in contention over lands in the New World. French nobleman Pierre Dugua Sieur de Monts established a settlement on Saint Croix Island, Maine in June 1604 under the authority of the King of France. Nearly half the settlers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Management
Soil management is the application of operations, practices, and treatments to protect soil and enhance its performance (such as soil fertility or soil mechanics). It includes soil conservation, soil amendment, and optimal soil health. In agriculture, some amount of soil management is needed both in nonorganic and organic types to prevent agricultural land from becoming poorly productive over decades. Organic farming in particular emphasizes optimal soil management, because it uses soil health as the exclusive or nearly exclusive source of its fertilization and pest control. Soil management is an important tool for addressing climate change by increasing soil carbon and as well as addressing other major environmental issues associated with modern industrial agriculture practices. Project Drawdown highlights three major soil management practices as actionable steps for climate change mitigation: improved nutrient management, conservation agriculture (including No-till agricul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name ''photosynthesis'', from the Greek ''phōs'' (), "light", and ''synthesis'' (), "putting together". Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Health
Soil health is a state of a soil meeting its range of ecosystem functions as appropriate to its environment. In more colloquial terms, the health of soil arises from favorable interactions of all soil components (living and non-living) that belong together, as in microbiota, plants and animals. It is possible that a soil can be healthy in terms of eco-system functioning but not necessarily serve crop production or human nutrition directly, hence the scientific debate on terms and measurements. Soil health testing is pursued as an assessment of this status but tends to be confined largely to agronomic objectives, for obvious reasons. Soil health depends on soil biodiversity (with a robust soil biota), and it can be improved via soil management, especially by care to keep protective living covers on the soil and by natural (carbon-containing) soil amendments. Inorganic fertilizers do not necessarily damage soil health if 1) used at appropriate and not excessive rates and 2) if they ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochar
Biochar is the lightweight black residue, made of carbon and ashes, remaining after the pyrolysis of biomass. Biochar is defined by the International Biochar Initiative as "the solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment". Biochar is a stable solid that is rich in pyrogenic carbon and can endure in soil for thousands of years. The refractory stability of biochar leads to the concept of pyrogenic carbon capture and storage (PyCCS), i.e. carbon sequestration in the form of biochar. It may be a means to mitigate climate change. Biochar may increase the soil fertility of acidic soils and increase agricultural productivity. History The word "biochar" is a late 20th century English neologism derived from the Greek word , ''bios'', "life" and "char" (charcoal produced by carbonisation of biomass). It is recognised as charcoal that participates in biological processes found in soil, aquatic habitats and in animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Conditioner
A soil conditioner is a product which is added to soil to improve the soil’s physical qualities, usually its fertility (ability to provide nutrition for plants) and sometimes its mechanics. In general usage, the term "soil conditioner" is often thought of as a subset of the category soil amendments (or soil improvement, soil condition), which more often is understood to include a wide range of fertilizers and non-organic materials. Soil conditioners can be used to improve poor soils, or to rebuild soils which have been damaged by improper soil management. They can make poor soils more usable, and can be used to maintain soils in peak condition. Composition A wide variety of materials have been described as soil conditioners due to their ability to improve soil quality. Some examples include biochar, bone meal, blood meal, coffee grounds, compost, compost tea, coir, manure, straw, peat, sphagnum moss, vermiculite, sulfur, lime, hydroabsorbant polymers, and biosolids. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Phosphorus
Peak phosphorus is a concept to describe the point in time when humanity reaches the maximum global production rate of phosphorus as an industrial and commercial raw material. The term is used in an equivalent way to the better-known term peak oil. The issue was raised as a debate on whether phosphorus shortages might be imminent around 2010, which was largely dismissed after USGS and other organizations increased world estimates on available phosphorus resources, mostly in the form of additional resources in Morocco. However, exact reserve quantities remain uncertain, as do the possible impacts of increased phosphate use on future generations. This is important because rock phosphate is a key ingredient in many inorganic fertilizers. Hence, a shortage in rock phosphate (or just significant price increases) might negatively affect the world's food security. Phosphorus is a finite (limited) resource that is widespread in the Earth's crust and in living organisms but is relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cation-exchange Capacity
Cation-exchange capacity (CEC) is a measure of how many cations can be retained on soil particle surfaces. Negative charges on the surfaces of soil particles bind positively-charged atoms or molecules (cations), but allow these to exchange with other positively charged particles in the surrounding soil water. This is one of the ways that solid materials in soil alter the chemistry of the soil. CEC affects many aspects of soil chemistry, and is used as a measure of soil fertility, as it indicates the capacity of the soil to retain several nutrients (e.g. K+, NH4+, Ca2+) in plant-available form. It also indicates the capacity to retain pollutant cations (e.g. Pb2+). Definition and principles Cation-exchange capacity is defined as the amount of positive charge that can be exchanged per mass of soil, usually measured in cmolc/kg. Some texts use the older, equivalent units me/100g or meq/100g. CEC is measured in moles of electric charge, so a cation-exchange capacity of 10 cmolc/kg cou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
