Biochar is charcoal used as a soil amendment. Biochar is a stable solid, rich in carbon, can endure in soil for thousands of years. Like most charcoal, biochar is made from biomass via pyrolysis. Biochar is under investigation as an approach to carbon sequestration, as it has the potential to help mitigate climate change, it results in processes related to storage. Independently, biochar can increase soil fertility of acidic soils, increase agricultural productivity, provide protection against some foliar and soil-borne diseases. Regarding the definition from the production part, biochar is defined by the International Biochar Initiative as "The solid material obtained from the thermochemical conversion of biomass in an oxygen-limited environment"; the word "biochar" is a combination of "bio-" and "char". A search of the scientific literature for the term on databases such as SciFinder shows the first appearance of "biochar" in the scientific literature was in a paper at a national meeting of the American Chemical Society presented by Ph.
D. candidate at the University of Missouri Dr. Harshavardhan D. Bapat and his thesis advisor Professor Stanley E. Manahan, “Chemchar Gasification of Hazardous Wastes and Mixed Wastes on a Biochar Matrix,” 215th American Chemical Society National Meeting, March 29-April 2, 1998; the biochar described in this paper was prepared from milo grain seed by the "ChemChar triple-reverse-burn" gasification process ” developed in Prof. Manahan’s laboratory and patented in 1992: “Process for the regeneration of activated carbon product by reverse burn gasification,” Patent number: 5124292 Pre-Columbian Amazonians are believed to have used biochar to enhance soil productivity, they seem to have produced it by smoldering agricultural waste in trenches. European settlers called. Following observations and experiments, a research team working in French Guiana hypothesized that the Amazonian earthworm Pontoscolex corethrurus was the main agent of fine powdering and incorporation of charcoal debris to the mineral soil.
Biochar is a high-carbon, fine-grained residue that today is produced through modern pyrolysis processes. The specific yield from the pyrolysis is dependent on process condition, such as temperature, residence time and heating rate; these parameters can be optimized to produce either biochar. Temperatures of 400–500 °C produce more char, while temperatures above 700 °C favor the yield of liquid and gas fuel components. Pyrolysis occurs more at the higher temperatures requiring seconds instead of hours; the increasing heating rate will lead to a decrease of pyrolysis biochar yield, while the temperature is in the range of 350–600 °C. Typical yields are 60% bio-oil, 20% biochar, 20% syngas. By comparison, slow pyrolysis can produce more char. Once initialized, both processes produce net energy. For typical inputs, the energy required to run a “fast” pyrolyzer is 15% of the energy that it outputs. Modern pyrolysis plants can use the syngas created by the pyrolysis process and output 3–9 times the amount of energy required to run.
Besides pyrolysis and hydrothermal carbonization process can thermally decompose biomass to the solid material. However, these products cannot be defined as biochar; the carbon product from the torrefaction process still remains some volatile organic components, thus its properties are between that of biomass feedstock and biochar. Furthermore the hydrothermal carbonization could produce a carbon-rich solid product, the hydrothermal carbonization is evidently different from the conventional thermal conversion process. Therefore, the solid product from hydrothermal carbonization is defined as "hydrochar" rather than "biochar"; the Amazonian pit/trench method harvests neither bio-oil nor syngas, releases a large amount of CO2, black carbon, other greenhouse gases into the air, though less greenhouse gasses than captured during the growth of the biomass. Commercial-scale systems process agricultural waste, paper byproducts, municipal waste and eliminate these side effects by capturing and using the liquid and gas products.
The production of biochar as an output is not a priority in most cases. In a centralized system, all biomass in a region is brought to a central plant for processing. Alternatively, each farmer or group of farmers can operate a lower-tech kiln. A truck equipped with a pyrolyzer can move from place to place to pyrolyze biomass. Vehicle power comes from the syngas stream; the biofuel is sent to a storage site. Factors that influence the choice of system type include the cost of transportation of the liquid and solid byproducts, the amount of material to be processed, the ability to feed directly into the power grid. For crops that are not for biochar production, the Residue-to-Product Ratio and the collection factor the percent of the residue not used for other things, measure the approximate amount of feedstock that can be obtained for pyrolysis after harvesting the primary product. For instance, Brazil harvests 460 million tons of sugarcane annually, with an RPR of 0.30, a CF of 0.70 for the sugarcane tops, which are burned in the field.
Fat is one of the three main macronutrients, along with carbohydrate and protein. Fats molecules consist of carbon and hydrogen atoms, thus they are all hydrocarbon molecules. Examples include cholesterol and triglycerides; the terms "lipid", "oil" and "fat" are confused. "Lipid" is the general term, though a lipid is not a triglyceride. "Oil" refers to a lipid with short or unsaturated fatty acid chains, liquid at room temperature, while "fat" refers to lipids that are solids at room temperature – however, "fat" may be used in food science as a synonym for lipid. Fats, like other lipids, are hydrophobic, are soluble in organic solvents and insoluble in water. Fat is an important foodstuff for many forms of life, fats serve both structural and metabolic functions, they are a necessary part of the diet of most heterotrophs and are the most energy dense, thus the most efficient form of energy storage. Some fatty acids that are set free by the digestion of fats are called essential because they cannot be synthesized in the body from simpler constituents.
There are two essential fatty acids in human nutrition: linoleic acid. Other lipids needed by the body can be synthesized from other fats. Fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas. Fats and oils are categorized according to the number and bonding of the carbon atoms in the aliphatic chain. Fats that are saturated fats have no double bonds between the carbons in the chain. Unsaturated fats have one or more double bonded carbons in the chain; the nomenclature is based on the non-acid end of the chain. This end is called the n-end, thus alpha-linolenic acid is called an omega-3 fatty acid because the 3rd carbon from that end is the first double bonded carbon in the chain counting from that end. Some oils and fats are therefore called polyunsaturated fats. Unsaturated fats can be further divided into cis fats, which are the most common in nature, trans fats, which are rare in nature. Unsaturated fats can be altered by reaction with hydrogen effected by a catalyst.
This action, called hydrogenation, tends to break all the double bonds and makes a saturated fat. To make vegetable shortening liquid cis-unsaturated fats such as vegetable oils are hydrogenated to produce saturated fats, which have more desirable physical properties e.g. they melt at a desirable temperature, store well, whereas polyunsaturated oils go rancid when they react with oxygen in the air. However, trans fats are generated during hydrogenation as contaminants created by an unwanted side reaction on the catalyst during partial hydrogenation. Saturated fats can stack themselves in a packed arrangement, so they can solidify and are solid at room temperature. For example, animal fats tallow and lard are solids. Olive and linseed oils on the other hand are liquid. Fats serve both as energy sources for the body, as stores for energy in excess of what the body needs immediately; each gram of fat when burned or metabolized releases about 9 food calories. Fats are broken down in the healthy body to release their constituents and fatty acids.
Glycerol itself can be converted to glucose by the liver and so become a source of energy. There are many different kinds of fats. All fats are derivatives of fatty acids and glycerol. Most fats are glycerides triglycerides. One chain of fatty acid is bonded to each of the three -OH groups of the glycerol by the reaction of the carboxyl end of the fatty acid with the alcohol. Water is eliminated and the carbons are linked by an -O- bond through dehydration synthesis; this process is called esterification and fats are therefore esters. As a simple visual illustration, if the kinks and angles of these chains were straightened out, the molecule would have the shape of a capital letter E; the fatty acids would each be a horizontal line. Fats therefore have "ester" bonds; the properties of any specific fat molecule depend on the particular fatty acids. Fatty acids form a family of compounds that are composed of increasing numbers of carbon atoms linked into a zig-zag chain; the more carbon atoms there are in any fatty acid, the longer its chain will be.
Long chains are more susceptible to intermolecular forces of attraction, so the longer ones melt at a higher temperature. Fatty acid chains may differ by length categorized as short to long. Short-chain fatty acids are fatty acids with aliphatic tails of fewer than six carbons. Medium-chain fatty acids are fatty acids with aliphatic tails of 6–12 carbons, which can form medium-chain triglycerides. Long-chain fatty acids are fatty acids with aliphatic tails of 13 to 21 carbons. Long chain fatty acids are fatty acids with aliphatic tails of 22 or more carbons. Any of these aliphatic fatty acid chains may be glycerated and the resultant fats may have tails of different lengths from short triformin to long, e.g. cerotic acid, or hexacosanoic acid, a 26-carbon long-chain saturated fatty acid. Long chain fats are exemplified by tallow. Most fats found in foo
A microorganism, or microbe, is a microscopic organism, which may exist in its single-celled form or in a colony of cells. The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from 6th century BC India and the 1st century BC book On Agriculture by Marcus Terentius Varro. Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis and anthrax. Microorganisms include all unicellular organisms and so are diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms; these were grouped together in the two domain system as Prokaryotes, the other being the eukaryotes. The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans.
Some protists are related to some to green plants. Many of the multicellular organisms are microscopic, namely micro-animals, some fungi and some algae, but these are not discussed here, they live in every habitat from the poles to the equator, geysers and the deep sea. Some are adapted to extremes such as hot or cold conditions, others to high pressure and a few such as Deinococcus radiodurans to high radiation environments. Microorganisms make up the microbiota found in and on all multicellular organisms. A December 2017 report stated that 3.45-billion-year-old Australian rocks once contained microorganisms, the earliest direct evidence of life on Earth. Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel and other bioactive compounds, they are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. They are a vital component of fertile soils. In the human body microorganisms make up the human microbiota including the essential gut flora.
They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures. The possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century. By the fifth century BC, the Jains of present-day India postulated the existence of tiny organisms called nigodas; these nigodas are said to be born in clusters. According to the Jain leader Mahavira, the humans destroy these nigodas on a massive scale, when they eat, breathe and move. Many modern Jains assert that Mahavira's teachings presage the existence of microorganisms as discovered by modern science; the earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a 1st-century BC book titled On Agriculture in which he called the unseen creatures animalcules, warns against locating a homestead near a swamp: … and because there are bred certain minute creatures that cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and they cause serious diseases.
In The Canon of Medicine, Avicenna suggested that tuberculosis and other diseases might be contagious. Akshamsaddin mentioned the microbe in his work Maddat ul-Hayat about two centuries prior to Antonie Van Leeuwenhoek's discovery through experimentation: It is incorrect to assume that diseases appear one by one in humans. Disease infects by spreading from one person to another; this infection occurs through seeds that are so small they are alive. In 1546, Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or without contact over long distances. Antonie Van Leeuwenhoek is considered to be the father of microbiology, he was the first in 1673 to discover, describe and conduct scientific experiments with microoorganisms, using simple single-lensed microscopes of his own design. Robert Hooke, a contemporary of Leeuwenhoek used microscopy to observe microbial life in the form of the fruiting bodies of moulds.
In his 1665 book Micrographia, he made drawings of studies, he coined the term cell. Louis Pasteur exposed boiled broths to the air, in vessels that contained a filter to prevent particles from passing through to the growth medium, in vessels without a filter, but with air allowed in via a curved tube so dust particles would settle and not come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment; this meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur supported the germ theory of disease. In 1876, Robert Koch established, he found that the blood of cattle which were infected with anthrax always had large numbers of Bacillus anthracis. Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, this caused the healthy animal to become sick.
He found that he could grow the bacteria in a nutrient broth inject it into a heal
Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids with melting points above about 40 °C, melting to give low viscosity liquids. Waxes are soluble in organic, nonpolar solvents. Natural waxes of different types occur in petroleum. Waxes are organic compounds. Natural waxes may contain unsaturated bonds and include various functional groups such as fatty acids and secondary alcohols, ketones and fatty acid esters, aromatic compounds may be present. Synthetic waxes consist of homologous series of long-chain aliphatic hydrocarbons that lack functional groups. Waxes are synthesized by many animals; those of animal origin consist of wax esters derived from a variety of carboxylic acids and fatty alcohols. In waxes of plant origin, characteristic mixtures of unesterified hydrocarbons may predominate over esters; the composition depends not only on species, but on geographic location of the organism. The best known animal wax is beeswax used in constructing the honeycombs of honeybees, but other insects secrete waxes.
A major component of the beeswax is myricyl palmitate, an ester of triacontanol and palmitic acid. Its melting point is 62-65 °C. Spermaceti occurs in large amounts in the head oil of the sperm whale. One of its main constituents is another ester of a fatty acid and a fatty alcohol. Lanolin is a wax obtained from wool. Plants secrete waxes into and on the surface of their cuticles as a way to control evaporation and hydration; the epicuticular waxes of plants are mixtures of substituted long-chain aliphatic hydrocarbons, containing alkanes, alkyl esters, fatty acids and secondary alcohols, ketones, aldehydes. From the commercial perspective, the most important plant wax is carnauba wax, a hard wax obtained from the Brazilian palm Copernicia prunifera. Containing the ester myricyl cerotate, it has many applications, such as confectionery and other food coatings and furniture polish, floss coating, surfboard wax. Other more specialized vegetable waxes include ouricury wax. Plant and animal based waxes or oils can undergo selective chemical modifications to produce waxes with more desirable properties than are available in the unmodified starting material.
This approach has relied on green chemistry approaches including olefin metathesis and enzymatic reactions and can be used to produce waxes from inexpensive starting materials like vegetable oils. Although many natural waxes contain esters, paraffin waxes are hydrocarbons, mixtures of alkanes in a homologous series of chain lengths; these materials represent a significant fraction of petroleum. They are refined by vacuum distillation. Paraffin waxes are mixtures of saturated n- and iso- alkanes and alkyl- and naphthene-substituted aromatic compounds. A typical alkane paraffin wax chemical composition comprises hydrocarbons with the general formula CnH2n+2, such as hentriacontane, C31H64; the degree of branching has an important influence on the properties. Microcrystalline wax is a lesser produced petroleum based wax that contains higher percentage of isoparaffinic hydrocarbons and naphthenic hydrocarbons. Millions of tons of paraffin waxes are produced annually, they are used in foods, in candles and cosmetics, as non-stick and waterproofing coatings and in polishes.
Montan wax is a fossilized wax extracted from lignite. It is hard, reflecting the high concentration of saturated fatty acids and alcohols. Although dark brown and odorous, they can be purified and bleached to give commercially useful products; as of 1995, about 200 million kilograms/y were consumed. Polyethylene waxes are manufactured by one of three methods: 1- direct polymerization of ethylene; each production technique generates products with different properties. Key properties of low molecular weight polyethylene waxes are viscosity and melt point. Polyethylene waxes produced by means of degradation or recovery from polyethylene resin streams contain low molecular weight materials that must be removed to prevent volatilization and potential fire hazards during use. Polyethylene waxes manufactured by this method are stripped of low molecular weight fractions to yield a flash point > 500°F. Many polyethylene resin plants produce a low molecular weight stream referred to as Low Polymer Wax. LPW is unrefined and contains volatile oligomers, corrosive catalyst and may contain other foreign material and water.
Refining of LPW to produce a polyethylene wax involves removal of hazardous catalyst. Proper refining of LPW to produce polyethylene wax is important when being used in applications requiring FDA or other regulatory certification. Waxes are consumed industrially as components of complex formulations for coatings; the main use of polyethylene and polypropylene waxes is in the formulation of colourants for plastics. Waxes confer matting effects and wear resistance to paints. Polyethylene waxes are incorporated into inks in the form of dispersions to decrease friction, they are employed as release agents, find use as slip agents in furniture, confer corrosion resistance. Waxes such as paraffin wax or beeswax, hard fats such as tallow are used to make can
Agriculture is the science and art of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to live in cities; the history of agriculture began thousands of years ago. After gathering wild grains beginning at least 105,000 years ago, nascent farmers began to plant them around 11,500 years ago. Pigs and cattle were domesticated over 10,000 years ago. Plants were independently cultivated in at least 11 regions of the world. Industrial agriculture based on large-scale monoculture in the twentieth century came to dominate agricultural output, though about 2 billion people still depended on subsistence agriculture into the twenty-first. Modern agronomy, plant breeding, agrochemicals such as pesticides and fertilizers, technological developments have increased yields, while causing widespread ecological and environmental damage. Selective breeding and modern practices in animal husbandry have increased the output of meat, but have raised concerns about animal welfare and environmental damage.
Environmental issues include contributions to global warming, depletion of aquifers, antibiotic resistance, growth hormones in industrial meat production. Genetically modified organisms are used, although some are banned in certain countries; the major agricultural products can be broadly grouped into foods, fibers and raw materials. Food classes include cereals, fruits, meat, milk and eggs. Over one-third of the world's workers are employed in agriculture, second only to the service sector, although the number of agricultural workers in developed countries has decreased over the centuries; the word agriculture is a late Middle English adaptation of Latin agricultūra, from ager, "field", which in its turn came from Greek αγρός, cultūra, "cultivation" or "growing". While agriculture refers to human activities, certain species of ant and ambrosia beetle cultivate crops. Agriculture is defined with varying scopes, in its broadest sense using natural resources to "produce commodities which maintain life, including food, forest products, horticultural crops, their related services".
Thus defined, it includes arable farming, animal husbandry and forestry, but horticulture and forestry are in practice excluded. The development of agriculture enabled the human population to grow many times larger than could be sustained by hunting and gathering. Agriculture began independently in different parts of the globe, included a diverse range of taxa, in at least 11 separate centres of origin. Wild grains were eaten from at least 105,000 years ago. From around 11,500 years ago, the eight Neolithic founder crops and einkorn wheat, hulled barley, lentils, bitter vetch, chick peas and flax were cultivated in the Levant. Rice was domesticated in China between 11,500 and 6,200 BC with the earliest known cultivation from 5,700 BC, followed by mung and azuki beans. Sheep were domesticated in Mesopotamia between 11,000 years ago. Cattle were domesticated from the wild aurochs in the areas of modern Turkey and Pakistan some 10,500 years ago. Pig production emerged in Eurasia, including Europe, East Asia and Southwest Asia, where wild boar were first domesticated about 10,500 years ago.
In the Andes of South America, the potato was domesticated between 10,000 and 7,000 years ago, along with beans, llamas and guinea pigs. Sugarcane and some root vegetables were domesticated in New Guinea around 9,000 years ago. Sorghum was domesticated in the Sahel region of Africa by 7,000 years ago. Cotton was domesticated in Peru by 5,600 years ago, was independently domesticated in Eurasia. In Mesoamerica, wild teosinte was bred into maize by 6,000 years ago. Scholars have offered multiple hypotheses to explain the historical origins of agriculture. Studies of the transition from hunter-gatherer to agricultural societies indicate an initial period of intensification and increasing sedentism. Wild stands, harvested started to be planted, came to be domesticated. In Eurasia, the Sumerians started to live in villages from about 8,000 BC, relying on the Tigris and Euphrates rivers and a canal system for irrigation. Ploughs appear in pictographs around 3,000 BC. Farmers grew wheat, vegetables such as lentils and onions, fruits including dates and figs.
Ancient Egyptian agriculture relied on its seasonal flooding. Farming started in the predynastic period at the end of the Paleolithic, after 10,000 BC. Staple food crops were grains such as wheat and barley, alongside industrial crops such as flax and papyrus. In India, wheat and jujube were domesticated by 9,000 BC, soon followed by sheep and goats. Cattle and goats were domesticated in Mehrgarh culture by 8,000–6,000 BC. Cotton was cultivated by the 5th-4th millennium BC. Archeological evidence indicates an animal-drawn plough from 2,500 BC in the Indus Valley Civilisation. In China, from the 5th century BC there was a nationwide granary system and widespread silk farming. Water-powered grain mills were in use followed by irrigation. By the late 2nd century, heavy ploughs had been developed with iron mouldboards; these spread westwards across Eurasia. Asian rice was domesticated 8,200–13,500 years ago – depending on the molecular clock estimate, used – on the Pearl River in southern China with a single genetic origin from the wild rice Oryza rufipogon
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere and marine ecosystems. The conversion of nitrogen can be carried out through both physical processes. Important processes in the nitrogen cycle include fixation, ammonification and denitrification; the majority of Earth's atmosphere is atmosphere nitrogen. However, atmospheric nitrogen has limited availability for biological use, leading to a scarcity of usable nitrogen in many types of ecosystems; the nitrogen cycle is of particular interest to ecologists because nitrogen availability can affect the rate of key ecosystem processes, including primary production and decomposition. Human activities such as fossil fuel combustion, use of artificial nitrogen fertilizers, release of nitrogen in wastewater have altered the global nitrogen cycle. Human modification of global nitrogen cycle can negatively affect the natural environment system and human health. Nitrogen is present in the environment in a wide variety of chemical forms including organic nitrogen, nitrite, nitrous oxide, nitric oxide or inorganic nitrogen gas.
Organic nitrogen may be in the form of a living organism, humus or in the intermediate products of organic matter decomposition. The processes in the nitrogen cycle is to transform nitrogen from one form to another. Many of those processes are carried out by microbes, either in their effort to harvest energy or to accumulate nitrogen in a form needed for their growth. For example, the nitrogenous wastes in animal urine are broken down by nitrifying bacteria in the soil to be used by plants; the diagram alongside shows. The conversion of nitrogen gas into nitrates and nitrites through atmospheric and biological processes is called nitrogen fixation. Atmospheric nitrogen must be "fixed", into a usable form to be taken up by plants. Between 5 and 10 billion kg per year are fixed by lightning strikes, but most fixation is done by free-living or symbiotic bacteria known as diazotrophs; these bacteria have the nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, converted by the bacteria into other organic compounds.
Most biological nitrogen fixation occurs by the activity of Mo-nitrogenase, found in a wide variety of bacteria and some Archaea. Mo-nitrogenase is a complex two-component enzyme that has multiple metal-containing prosthetic groups. An example of free-living bacteria is Azotobacter. Symbiotic nitrogen-fixing bacteria such as Rhizobium live in the root nodules of legumes. Here they form a mutualistic relationship with the plant, producing ammonia in exchange for carbohydrates; because of this relationship, legumes will increase the nitrogen content of nitrogen-poor soils. A few non-legumes can form such symbioses. Today, about 30% of the total fixed nitrogen is produced industrially using the Haber-Bosch process, which uses high temperatures and pressures to convert nitrogen gas and a hydrogen source into ammonia. Plants can absorb ammonium from the soil by their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and ammonium ions for incorporation into amino acids, nucleic acids, chlorophyll.
In plants that have a symbiotic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. It is now known that there is a more complex cycling of amino acids between Rhizobia bacteroids and plants; the plant provides amino acids to the bacteroids so ammonia assimilation is not required and the bacteroids pass amino acids back to the plant, thus forming an interdependent relationship. While many animals and other heterotrophic organisms obtain nitrogen by ingestion of amino acids and other small organic molecules, other heterotrophs are able to utilize inorganic compounds, such as ammonium as sole N sources. Utilization of various N sources is regulated in all organisms; when a plant or animal dies or an animal expels waste, the initial form of nitrogen is organic. Bacteria or fungi convert the organic nitrogen within the remains back into ammonium, a process called ammonification or mineralization. Enzymes involved are: GS: Gln Synthetase GOGAT: Glu 2-oxoglutarate aminotransferase GDH: Glu Dehydrogenase: Minor Role in ammonium assimilation.
Important in amino acid catabolism. The conversion of ammonium to nitrate is performed by soil-living bacteria and other nitrifying bacteria. In the primary stage of nitrification, the oxidation of ammonium is performed by bacteria such as the Nitrosomonas species, which converts ammonia to nitrites. Other bacterial species such as Nitrobacter, are responsible for the oxidation of the nitrites into nitrates, it is important for the ammonia to be converted to nitrates or nitrites because ammonia gas is toxic to plants. Due to their high solubility and because soils are unable to retain anions, nitrates can enter groundwater. Elevated nitrate in groundwater is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome. Where groundwater recharges stream flow, nitrate-enriched groundwater can contribute to eutrophication, a process that leads to high algal population and growth blue-green algal populations.
While not directly tox
Manure is organic matter derived from animal feces except in the case of green manure, which can be used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are utilised by bacteria and other organisms in the soil. Higher organisms feed on the fungi and bacteria in a chain of life that comprises the soil food web. In the past, the term "manure" included inorganic fertilizers, but this usage is now rare. There are three main classes of manures used in soil management: Most animal manure consists of feces. Common forms of animal manure include farmyard farm slurry. FYM contains plant material, used as bedding for animals and has absorbed the feces and urine. Agricultural manure in liquid form, known as slurry, is produced by more intensive livestock rearing systems where concrete or slats are used, instead of straw bedding. Manure from different animals has different qualities and requires different application rates when used as fertilizer.
For example horses, pigs, chickens, turkeys and guano from seabirds and bats all have different properties. For instance, sheep manure is high in nitrogen and potash, while pig manure is low in both. Horses eat grass and a few weeds so horse manure can contain grass and weed seeds, as horses do not digest seeds the way that cattle do. Cattle manure is a good source of nitrogen as well as organic carbon. Chicken litter, coming from a bird, is concentrated in nitrogen and phosphate and is prized for both properties. Animal manures may be adulterated or contaminated with other animal products, such as wool, feathers and bone. Livestock feed can be mixed with the manure due to spillage. For example, chickens are fed meat and bone meal, an animal product, which can end up becoming mixed with chicken litter; some people refer to human excreta as human manure, the word "humanure" has been used. Just like animal manure, it can be applied as a soil conditioner. Sewage sludge is a material that contains human excreta, as it is generated after mixing excreta with water and treatment of the wastewater in a sewage treatment plant.
Compost is the decomposed remnants of organic materials. It is of plant origin, but includes some animal dung or bedding. Green manures are crops grown for the express purpose of plowing them in, thus increasing fertility through the incorporation of nutrients and organic matter into the soil. Leguminous plants such as clover are used for this, as they fix nitrogen using Rhizobia bacteria in specialized nodes in the root structure. Other types of plant matter used as manure include the contents of the rumens of slaughtered ruminants, spent grain and seaweed. Animal manure, such as chicken manure and cow dung, has been used for centuries as a fertilizer for farming, it can improve the soil structure so that the soil holds more nutrients and water, therefore becomes more fertile. Animal manure encourages soil microbial activity which promotes the soil's trace mineral supply, improving plant nutrition, it contains some nitrogen and other nutrients that assist the growth of plants. Manures with a unpleasant odor are knifed directly into the soil to reduce release of the odor.
Manure from pigs and cattle is spread on fields using a manure spreader. Due to the lower level of proteins in vegetable matter, herbivore manure has a milder smell than the dung of carnivores or omnivores. However, herbivore slurry that has undergone anaerobic fermentation may develop more unpleasant odors, this can be a problem in some agricultural regions. Poultry droppings are harmful to plants when fresh, but after a period of composting are valuable fertilizers. Manure is commercially composted and bagged and sold as a soil amendment. In 2018, Austrian scientists offered a method of paper production from cow manure. Any quantity of manure may be a source of pathogens or food spoilage organisms which may be carried by flies, rodents or a range of other vector organisms and cause disease or put food safety at risk. In 2007, a University of Minnesota study indicated that foods such as corn and potatoes have been found to accumulate antibiotics from soils spread with animal manure that contains these drugs.
Organic foods may be much more or much less to contain antibiotics, depending on their sources and treatment of manure. For instance, by Soil Association Standard 4.7.38, most organic arable farmers either have their own supply of manure or else rely on green manure crops for the extra fertility. On the other hand, as found in the University of Minnesota study, the non-usage of artificial fertilizers, resulting exclusive use of manure as fertilizer, by organic farmers can result in greater accumulations of antibiotics in organic foods. Application and environmental risks of livestock manure North American Manure Expo Cornell Manure Program County-Level Estimates of Nitrogen and Phosphorus from Animal Manure for the Conterminous United States, 2002 United States Geological Survey Manure Management, Water Quality Information Center, U. S. Department of Agriculture Livestock and Poultry Environmental Learning Center, an eXtension community