Resource recovery

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Resource_recovery 

 

Resource recovery is using wastes as an input material to create valuable products as new outputs. The aim is to reduce the amount of waste generated, thereby reducing the need for landfill space, and optimising the values created from waste. Resource recovery delays the need to use raw materials in the manufacturing process. Materials found in municipal solid waste, construction and demolition waste, commercial waste and industrial wastes can be used to recover resources for the manufacturing of new materials and products. Plastic, paper, aluminium, glass and metal are examples of where value can be found in waste.

Resource recovery goes further than just the management of waste. Resource recovery is part of a circular economy, in which the extraction of natural resources and generation of wastes are minimised, and in which materials and products are designed more sustainably for durability, reuse, repairability, remanufacturing and recycling. Life-cycle analysis (LCA) can be used to compare the resource recovery potential of different treatment technologies. Resource recovery can be enabled by changes in government policy and regulation, circular economy infrastructure such as improved 'binfrastructure' to promote source separation and waste collection, reuse and recycling, innovative circular business models, and valuing materials and products in terms of their economic but also their social and environmental costs and benefits. For example, organic materials can be treated by composting and anaerobic digestion and turned into energy, compost or fertilizer. Similarly, wastes currently stored in industrial landfills and around old mines can be treated with bioleaching and engineered nanoparticles to recover metals such as Lithium, Cobalt and Vanadium for use in low-carbon technologies such as electric vehicles and wind turbines.

Resource recovery can also be an aim in the context of sanitation. Here, the term refers to approaches to recover the resources that are contained in wastewater and human excreta (urine and feces). The term "toilet resources" has come into use recently. Those resources include: nutrients (nitrogen and phosphorus), organic matter, energy and water. This concept is also referred to as ecological sanitation. Separation of waste flows can help make resource recovery simpler. Examples include keeping urine separate from feces (as in urine diversion toilets) and keeping greywater and blackwater separate in municipal wastewater systems.

Materials used as a source

Solid waste

Steel crushed and baled for recycling

 

Recycling is a resource recovery practice that refers to the collection and reuse of disposed materials such as empty beverage containers. The materials from which the items are made can be reprocessed into new products. Material for recycling may be collected separately from general waste using dedicated bins and collection vehicles, or sorted directly from mixed waste streams. 

The most common consumer products recycled include aluminium such as beverage cans, copper such as wire, steel food and aerosol cans, old steel furnishings or equipment, polyethylene and PET bottles, glass bottles and jars, paperboard cartons, newspapers, magazines and light paper, and corrugated fiberboard boxes. 

PVC, LDPE, PP, and PS (see resin identification code) are also recyclable. These items are usually composed of a single type of material, making them relatively easy to recycle into new products. The recycling of complex products (such as computers and electronic equipment) is more difficult, due to the additional dismantling and separation required. 

The type of recycling material accepted varies by city and country. Each city and country have different recycling programs in place that can handle the various types of recyclable materials.

Wastewater and excreta

Valuable resources can be recovered from wastewater, sewage sludge, fecal sludge and human excreta. These include water, energy, and fertilizing nutrients nitrogen, phosphorus, potassium, as well as micro-nutrients such as sulphur and organic matter. There is also increasing interest for recovering other raw materials from wastewater, such as bioplastics and metals such as silver. Originally, wastewater systems were designed only to remove excreta and wastewater from urban areas. Water was used to flush away the waste, often discharging into nearby waterbodies. Since the 1970s, there has been increasing interest in treating the wastewater to protect the environment, and efforts focused primarily on cleaning the water at the end of the pipe. Since around the year 2003, the concepts of ecological sanitation and sustainable sanitation have emerged with the focus on recovering resources from wastewater. As of 2016, the term "toilet resources" came into use, and encouraged more attention to the potential for resource recovery from toilets.

The following resources can be recovered:

• Water: In many water-scarce areas there are increasing pressures to recover water from wastewater. In 2006, the World Health Organization, in collaboration with the Food and Agriculture Organization of the United Nations (FAO) and the United Nations Environment Program (UNEP), developed guidelines for safe use of wastewater. In addition, many national governments have their own regulations regarding the use of recovered water. Singapore for example aims to recover enough water from its wastewater systems to meet the water needs of half the city. They call this NEWater. Another related concept for wastewater reuse is sewer mining.
• Energy: The production of biogas from wastewater sludge is now common practice at wastewater treatment plants. In addition, a number for methods have been researched regarding use of wastewater sludge and excreta as fuel sources.
• Fertilizing nutrients: Human excreta contains nitrogen, phosphorus, potassium and other micronutrients that are needed for agricultural production. These can be recovered through chemical precipitation or stripping processes, or simply by use of the wastewater or sewage sludge. However, reuse of sewage sludge poses risks due to high concentrations of undesirable compounds, such as heavy metals, environmental persistent pharmaceutical pollutants and other chemicals. Since the majority of fertilizing nutrients are found in excreta, it can be useful to separate the excreta fractions of wastewater (e.g. toilet waste) from the rest of the wastewater flows. This reduces the risk for undesirable compounds and reduces the volume that needs to be treated before applying recovered nutrients in agricultural production.

Other methods are also being developed for transforming wastewater into valuable products. Growing Black Soldier Flies in excreta or organic waste can produce fly larvae as a protein feed. Other researchers are harvesting fatty acids from wastewater to make bioplastics.

Organic matter

An active compost heap.

 

Disposed materials that are organic in nature, such as plant material, food scraps, and paper products, can be recycled using biological composting and digestion processes to decompose the organic matter. The resulting organic material is then recycled as mulch or compost for agricultural or landscaping purposes. In addition, waste gas from the process (such as methane) can be captured and used for generating electricity and heat (CHP/cogeneration) maximising efficiencies. The intention of biological processing is to control and accelerate the natural process of decomposition of organic matter. 

There is a large variety of composting and digestion methods and technologies varying in complexity from simple home compost heaps, to small town scale batch digesters, industrial-scale enclosed-vessel digestion of mixed domestic waste (see mechanical biological treatment). Methods of biological decomposition are differentiated as being aerobic or anaerobic methods, though hybrids of the two methods also exist.

Anaerobic digestion of the organic fraction of municipal solid waste (MSW) has been found to be more environmentally effective, than landfill, incineration or pyrolysis. Life cycle analysis (LCA) was used to compare different technologies. The resulting biogas (methane) though must be used for cogeneration (electricity and heat preferably on or close to the site of production) and can be used with a little upgrading in gas combustion engines or turbines. With further upgrading to synthetic natural gas it can be injected into the natural gas network or further refined to hydrogen for use in stationary cogeneration fuel cells. Its use in fuel cells eliminates the pollution from products of combustion. There is a large variety of composting and digestion methods and technologies varying in complexity from simple home compost heaps, to small town scale batch digesters, industrial-scale, enclosed-vessel digestion of mixed domestic waste (see mechanical biological treatment). Methods of biological decomposition are differentiated as being aerobic or anaerobic methods, though hybrids of the two methods also exist.

Recovery methods

In many countries, source-separated curbside collection is one method of resource recovery.

Australia

In Australia, households are provided with several bins: one for recycling (yellow lid), another for general waste (usually a red lid) and another for garden materials (green lid). The garden recycling bin is provided by the municipality if requested. Some localities have dual-stream recycling, with paper collected in bags or boxes and all other materials in a recycling bin. In either case, the recovered materials are trucked to a materials recovery facility for further processing. 

Municipal, commercial and industrial, construction and demolition debris is dumped at landfills and some is recycled. Household disposal materials are segregated: recyclables sorted and made into new products, and unusable material is dumped in landfill areas. According to the Australian Bureau of Statistics (ABS), the recycling rate is high and is "increasing, with 99% of households reporting that they had recycled or reused within the past year (2003 survey), up from 85% in 1992". In 2002–03 "30% of materials from municipalities, 45% from commercial and industrial generators and 57% from construction and demolition debris" was recycled. Energy is produced is part of resource recovery as well: some landfill gas is captured for fuel or electricity generation, although this is considered the last resort, as the point of resource recovery is avoidance of landfill disposal altogether.

Sustainability

Resource recovery is a key component in a business' ability to maintaining ISO14001 accreditation. Companies are encouraged to improve their environmental efficiencies each year. One way to do this is by changing a company from a system of managing wastes to a resource recovery system (such as recycling: glass, food waste, paper and cardboard, plastic bottles etc.)

Education and awareness in the area of resource recovery is increasingly important from a global perspective of resource management. The Talloires Declaration is a declaration for sustainability concerned about the unprecedented scale and speed of environmental pollution and degradation, and the depletion of natural resources. Local, regional, and global air pollution; accumulation and distribution of toxic wastes; destruction and depletion of forests, soil, and water; depletion of the ozone layer and emission of "green house" gases threaten the survival of humans and thousands of other living species, the integrity of the earth and its biodiversity, the security of nations, and the heritage of future generations. Several universities have implemented the Talloires Declaration by establishing environmental management and resource recovery programs. University and vocational education are promoted by various organizations, e.g., WAMITAB and Chartered Institution of Wastes Management. Many supermarkets encourage customers to use their reverse vending machines to deposit used purchased containers and receive a refund from the recycling fees. Brands that manufacture such machines include Tomra and Envipco. 

In 2010, CNBC aired the documentary Trash Inc: The Secret Life of Garbage about waste, what happens to it when it's "thrown away", and its impact on the world.

Extended producer responsibility

Extended producer responsibility (EPR) is a pricing strategy that promotes integrating all costs associated with a given product throughout its life cycle. Having the market price also reflect the "end-of-life disposal costs" encourages more accuracy in pricing. Extended producer responsibility is meant to impose accountability over the entire lifecycle of products, from production, to packaging, to transport and disposal or reuse. EPR requires firms that manufacture, import and/or sell products to be responsible for those products throughout the life and disposal or reuse of products.

Ammonium nitrate

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Ammonium_nitrate 

 

Ammonium nitrate

Names
IUPAC name Ammonium nitrate
Identifiers
CAS Number	6484-52-2
3D model (JSmol)	Interactive image
ChEBI	CHEBI:63038
ChEMBL	ChEMBL1500032
ChemSpider	21511
ECHA InfoCard	100.026.680
EC Number	229-347-8
PubChem CID	22985
RTECS number	BR9050000
UNII	T8YA51M7Y6
UN number	0222 – with > 0.2% combustible substances 1942 – with ≤ 0.2% combustible substances 2067 – fertilizers 2426 – liquid
CompTox Dashboard (EPA)	DTXSID2029668
InChI[show]
SMILES[show]
Properties
Chemical formula	NH4NO3
Molar mass	80.043 g/mol
Appearance	colorless
Density	1.725 g/cm3 (20 °C)
Melting point	169.6 °C (337.3 °F; 442.8 K)
Boiling point	approx. 210 °C (410 °F; 483 K) decomposes
Solubility in water	Endothermic 118 g/100 ml (0 °C) 150 g/100 ml (20 °C) 297 g/100 ml (40 °C) 410 g/100 ml (60 °C) 576 g/100 ml (80 °C) 1024 g/100 ml (100 °C)[1]
Magnetic susceptibility (χ)	-33.6·10−6 cm3/mol
Structure
Crystal structure	trigonal
Explosive data
Shock sensitivity	very low
Friction sensitivity	very low
Detonation velocity	2500 m/s
Hazards
Main hazards	Explosive, Oxidizer
GHS pictograms
GHS Signal word	Danger
GHS hazard statements	H201, H271, H319
GHS precautionary statements	P220, P221, P271, P280, P264, P372
NFPA 704 (fire diamond)	0 1 3 OX
Lethal dose or concentration (LD, LC):
LD50 (median dose)	2085–5300 mg/kg (oral in rats, mice)
Related compounds
Other anions	Ammonium nitrite
Other cations	Sodium nitrate Potassium nitrate Hydroxylammonium nitrate
Related compounds	Ammonium perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Ammonium nitrate is a chemical compound with the chemical formula NH₄NO₃. It is a white crystalline solid consisting of ions of ammonium and nitrate. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer. Global production was estimated at 21.6 million tonnes in 2017.

Its other major use is as a component of explosive mixtures used in mining, quarrying, and civil construction. It is the major constituent of ANFO, a popular industrial explosive which accounts for 80% of explosives used in North America; similar formulations have been used in improvised explosive devices.

Many countries are phasing out its use in consumer applications due to concerns over its potential for misuse. Accidental ammonium nitrate explosions have killed thousands of people since the early 20th century.

Occurrence

Ammonium nitrate is found as the natural mineral gwihabaite – the ammonium analogue of saltpetre – in the driest regions of the Atacama Desert in Chile, often as a crust on the ground or in conjunction with other nitrate, iodate, and halide minerals. Ammonium nitrate was mined there in the past, but virtually 100% of the chemical now used is synthetic.

Production, reactions and crystalline phases

The industrial production of ammonium nitrate entails the acid-base reaction of ammonia with nitric acid:

HNO₃ + NH₃ → NH₄NO₃

Ammonia is used in its anhydrous form (a gas) and the nitric acid is concentrated. The reaction is violent owing to its highly exothermic nature. After the solution is formed, typically at about 83% concentration, the excess water is evaporated off to leave an ammonium nitrate (AN) content of 95% to 99.9% concentration (AN melt), depending on grade. The AN melt is then made into "prills" or small beads in a spray tower, or into granules by spraying and tumbling in a rotating drum. The prills or granules may be further dried, cooled, and then coated to prevent caking. These prills or granules are the typical AN products in commerce.

The ammonia required for this process is obtained by the Haber process from nitrogen and hydrogen. Ammonia produced by the Haber process can be oxidized to nitric acid by the Ostwald process. Another production method is a variant of the nitrophosphate process:

Ca(NO₃)₂ + 2 NH₃ + CO₂ + H₂O → 2 NH₄NO₃ + CaCO₃

The products, calcium carbonate and ammonium nitrate, may be separately purified or sold combined as calcium ammonium nitrate. 

Ammonium nitrate can also be made via metathesis reactions:

(NH₄)₂SO₄ + Ba(NO₃)₂ → 2 NH₄NO₃ + BaSO₄

NH₄Cl + AgNO₃ → NH₄NO₃ + AgCl

Reactions

As ammonium nitrate is a salt, both the cation, NH₄⁺, and the anion, NO₃⁻, may take part in chemical reactions. 

Solid ammonium nitrate decomposes on heating. At temperatures below around 300 °C, the decomposition mainly produces nitrous oxide and water:

NH₄NO₃ → N₂O + 2H₂O

At higher temperatures, the following reaction predominates.

2NH₄NO₃ → 2N₂ + O₂ + 4H₂O

Both decomposition reactions are exothermic and their products are gas. Under certain conditions, this can lead to a runaway reaction, with the decomposition process becoming explosive. See § disasters for details. Many ammonium nitrate disasters, with loss of lives, have occurred.

The red–orange colour in an explosion cloud is due to nitrogen dioxide, a secondary reaction product.

Crystalline phases

A number of crystalline phases of ammonium nitrate have been observed. The following occur under atmospheric pressure.

Phase	Temperature (°C)	Symmetry
(liquid)	(above 169.6)
I	169.6 to 125.2	cubic
II	125.2 to 84.2	tetragonal
III	84.2 to 32.3	α-rhombic
IV	32.3 to −16.8	β-rhombic
V	below −16.8	tetragonal

Both the β-rhombic to α-rhombic forms are potentially present at ambient temperature in many parts of the world but have a 3.6% difference in density. As a result, this phase transition and attending change of volume, with the practical consequence that ammonium nitrate formed as solid rocket motor propellant develops cracks. For this reason, phase stabilized ammonium nitrate (PSAN) which incorporates metal halides as stabilisers has been investigated.

Applications

Fertilizer

Ammonium nitrate is an important fertilizer with NPK rating 34-0-0 (34% nitrogen). It is less concentrated than urea (46-0-0), giving ammonium nitrate a slight transportation disadvantage. Ammonium nitrate's advantage over urea is that it is more stable and does not rapidly lose nitrogen to the atmosphere.

Explosives

Ammonium nitrate is an ingredient in certain explosives. Examples of explosives containing ammonium nitrate include:

• Astrolite (ammonium nitrate and hydrazine rocket fuel)
• Amatol (ammonium nitrate and TNT)
• Ammonal (ammonium nitrate and aluminum powder)
• Amatex (ammonium nitrate, TNT and RDX)
• ANFO (ammonium nitrate and fuel oil)
• DBX (ammonium nitrate, RDX, TNT and aluminum powder)
• Tovex (ammonium nitrate and methylammonium nitrate)
• Minol (explosive) (ammonium nitrate, TNT and aluminum powder)
• Goma-2 (ammonium nitrate, nitroglycol, Nitrocellulose, Dibutyl phthalate and fuel)

Mixture with fuel oil

ANFO is a mixture of 94% ammonium nitrate ("AN") and 6% fuel oil ("FO") widely used as a bulk industrial explosive. It is used in coal mining, quarrying, metal mining, and civil construction in undemanding applications where the advantages of ANFO's low cost and ease of use matter more than the benefits offered by conventional industrial explosives, such as water resistance, oxygen balance, high detonation velocity, and performance in small diameters.

Terrorism

Ammonium nitrate-based explosives were used in the Sterling Hall bombing in Madison, Wisconsin, 1970, the Oklahoma City bombing in 1995, the 2011 Delhi bombings, the 2011 bombing in Oslo, and the 2013 Hyderabad blasts. 

In November 2009, the government of the North West Frontier Province (NWFP) of Pakistan imposed a ban on ammonium sulfate, ammonium nitrate, and calcium ammonium nitrate fertilizers in the former Malakand Division – comprising the Upper Dir, Lower Dir, Swat, Chitral, and Malakand districts of the NWFP – following reports that those chemicals were used by militants to make explosives. Due to these bans, "Potassium chlorate – the stuff that makes safety matches catch fire – has surpassed fertilizer as the explosive of choice for insurgents."

Niche uses

Ammonium nitrate is used in some instant cold packs, as its dissolution in water is highly endothermic. It also was used, in combination with independently explosive "fuels" such as guanidine nitrate, as a cheaper (but less stable) alternative to 5-aminotetrazole in the inflators of airbags manufactured by Takata Corporation, which were recalled as unsafe after killing 14 people.

A solution of ammonium nitrate with nitric acid called Cavea-b showed promise for use in spacecraft as a more energetic alternative to the common monopropellant hydrazine. A number of trials were carried out in the 1960s but the substance was not adopted by NASA.

Safety, handling, and storage

Numerous safety guidelines are available for storing and handling ammonium nitrate. Health and safety data are shown on the safety data sheets available from suppliers and from various governments.

Pure ammonium nitrate does not burn, but as a strong oxidizer, it supports and accelerates the combustion of organic (and some inorganic) material. It should not be stored near combustible substances. 

While ammonium nitrate is stable at ambient temperature and pressure under many conditions, it may detonate from a strong initiation charge. It should not be stored near high explosives or blasting agents. 

Molten ammonium nitrate is very sensitive to shock and detonation, particularly if it becomes contaminated with incompatible materials such as combustibles, flammable liquids, acids, chlorates, chlorides, sulfur, metals, charcoal and sawdust.

Contact with certain substances such as chlorates, mineral acids and metal sulfides, can lead to vigorous or even violent decomposition capable of igniting nearby combustible material or detonating.

Ammonium nitrate begins decomposition after melting, releasing NO
x , HNO₃, NH
₃ and H₂O. It should not be heated in a confined space. The resulting heat and pressure from decomposition increases the sensitivity to detonation and increases the speed of decomposition. Detonation may occur at 80 atmospheres. Contamination can reduce this to 20 atmospheres.

Ammonium nitrate has a critical relative humidity of 59.4%, above which it will absorb moisture from the atmosphere. Therefore, it is important to store ammonium nitrate in a tightly sealed container. Otherwise, it can coalesce into a large, solid mass. Ammonium nitrate can absorb enough moisture to liquefy. Blending ammonium nitrate with certain other fertilizers can lower the critical relative humidity.

The potential for use of the material as an explosive has prompted regulatory measures. For example, in Australia, the Dangerous Goods Regulations came into effect in August 2005 to enforce licensing in dealing with such substances. Licenses are granted only to applicants (industry) with appropriate security measures in place to prevent any misuse. Additional uses such as education and research purposes may also be considered, but individual use will not. Employees of those with licenses to deal with the substance are still required to be supervised by authorized personnel and are required to pass a security and national police check before a license may be granted.

Health hazards

Health and safety data are shown on the material safety data sheets, which are available from suppliers and can be found on the internet.

Ammonium nitrate is not hazardous to health and is usually used in fertilizer products.

Ammonium nitrate has an LD₅₀ of 2217 mg/kg, which for comparison is about two-thirds that of table salt.

Disasters

Ammonium nitrate decomposes, non-explosively, into the gases nitrous oxide and water vapor when heated. However, it can be induced to decompose explosively by detonation. Large stockpiles of the material can also be a major fire risk due to their supporting oxidation, a situation which can easily escalate to detonation. Explosions are not uncommon: relatively minor incidents occur most years, and several large and devastating explosions have also occurred. Examples include the Oppau explosion of 1921 (one of the largest artificial non-nuclear explosions), the Texas City disaster of 1947, the 2015 Tianjin explosions in China, and the 2020 Beirut explosion.  Ammonium nitrate can explode through two mechanisms:

• Shock-to-detonation transition. An explosive charge within or in contact with a mass of ammonium nitrate causes the ammonium nitrate to detonate. Examples of such disasters are Kriewald, Morgan (present-day Sayreville, New Jersey), Oppau, and Tessenderlo.
• Deflagration to detonation transition. The ammonium nitrate explosion results from a fire that spreads into the ammonium nitrate (Texas City, TX; Brest; West, TX; Tianjin; Beirut), or from ammonium nitrate mixing with a combustible material during the fire (Repauno, Cherokee, Nadadores). The fire must be confined at least to a degree for successful transition from a fire to an explosion.

History of organic farming

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/History_of_organic_farming 

 

Traditional farming (of many particular kinds in different eras and places) was the original type of agriculture, and has been practiced for thousands of years. All traditional farming is now considered to be "organic farming" although at the time there were no known inorganic methods. For example, forest gardening, a fully organic food production system which dates from prehistoric times, is thought to be the world's oldest and most resilient agroecosystem.  After the industrial revolution had introduced inorganic methods, most of which were not well developed and had serious side effects. An organic movement began in the 1940s as a reaction to agriculture's growing reliance on synthetic fertilizers and pesticides. The history of this modern revival of organic farming dates back to the first half of the 20th century at a time when there was a growing reliance on these new synthetic, non-organic methods.

Pre-World War II

The first 40 years of the 20th century saw simultaneous advances in biochemistry and engineering that rapidly and profoundly changed farming. The introduction of the gasoline-powered internal combustion engine ushered in the era of the tractor and made possible hundreds of mechanized farm implements. Research in plant breeding led to the commercialization of hybrid seed. And a new manufacturing process made nitrogen fertilizer — first synthesized in the mid-19th century — affordably abundant. These factors changed the labour equation: there were almost no tractors in the US around 1910, but over 3,000,000 by 1950; in 1900, it took one farmer to feed 2.5 people, but currently the ratio is 1 to well over 100. Fields grew bigger and cropping more specialized to make more efficient use of machinery. The reduced need for manual labour and animal labour that machinery, herbicides, and fertilizers made possible created an era in which the mechanization of agriculture evolved rapidly. 

Consciously organic agriculture (as opposed to traditional agricultural methods from before the inorganic options existed, which always employed only organic means) began more or less simultaneously in Central Europe and India. The British botanist Sir Albert Howard is often referred to as the father of modern organic agriculture, because he was the first to apply modern scientific knowledge and methods to traditional agriculture. From 1905 to 1924, he and his wife Gabrielle, herself a plant physiologist, worked as agricultural advisers in Pusa, Bengal, where they documented traditional Indian farming practices and came to regard them as superior to their conventional agriculture science. Their research and further development of these methods is recorded in his writings, notably, his 1940 book, An Agricultural Testament, which influenced many scientists and farmers of the day. 

In Germany, Rudolf Steiner's development, biodynamic agriculture, was probably the first comprehensive system of what we now call organic farming. This began with a lecture series Steiner presented at a farm in Koberwitz (Kobierzyce now in Poland) in 1924. Steiner emphasized the farmer's role in guiding and balancing the interaction of the animals, plants and soil. Healthy animals depended upon healthy plants (for their food), healthy plants upon healthy soil, healthy soil upon healthy animals (for the manure). His system was based on his philosophy of anthroposophy rather than a good understanding of science. To develop his system of farming, Steiner established an international research group called the Agricultural Experimental Circle of Anthroposophical Farmers and Gardeners of the General Anthroposophical Society.

In 1909, American agronomist F.H. King toured China, Korea, and Japan, studying traditional fertilization, tillage, and general farming practices. He published his findings in Farmers of Forty Centuries (1911, Courier Dover Publications, ISBN 0-486-43609-8). King foresaw a "world movement for the introduction of new and improved methods" of agriculture and in later years his book became an important organic reference. 

The term "organic farming" was coined by Walter James (Lord Northbourne), a student of Biodynamic Agriculture, in his book Look to the Land (written in 1939, published 1940). In this text, James described a holistic, ecologically balanced approach to farming, "the farm as organism," basing this on Steiner's agricultural principles and methods. One year previously to his book's publication, James had hosted the first Biodynamic Agriculture conference in England, the Betteshanger Summer School and Conference, at which Ehrenfried Pfeiffer was the key presenter.

In 1939 James, Albert Howard, Ehrenfried Pfeiffer and George Stapleton joined at Farleigh to implement an experiment comparing Biodynamic, organic and chemical fertilization methods. "The Farleigh Experiment", had been planned since initial meetings in 1936 including ten participants. The experiment was cut short due to the fact that Biodynamic compost was not available until after the Betteshanger Summer School event, the disruption of the impending war, and lack of funding. Though inconclusive, this experiment was seen as providing impetus for the similar "Haughley Experiment" described below. 

In 1939 Lady Eve Balfour, who had been farming since 1920 in Haughley Green, Suffolk, England, launched the Haughley Experiment. Lady Balfour believed that mankind's health and future depended on how the soil was used, and that non-intensive farming could produce more wholesome food. The experiment was run to generate data to test these beliefs. Four years later, she published The Living Soil, based on the initial findings of the Haughley Experiment. Widely read, it led to the formation of a key international organic advocacy group, the Soil Association.

In Japan, Masanobu Fukuoka, a microbiologist working in soil science and plant pathology, began to doubt the modern agricultural movement. In 1937, he quit his job as a research scientist, returned to his family's farm in 1938, and devoted the next 60 years to developing a radical no-till organic method for growing grain and many other crops, now known as natural farming (自然農法, shizen nōhō), nature farming, 'do–nothing' farming or Fukuoka farming.

Post-World War II

Technological advances during World War II accelerated post-war innovation in all aspects of agriculture, resulting in large advances in mechanization (including large-scale irrigation), fertilization, and pesticides. In particular, two chemicals that had been produced in quantity for warfare, were repurposed for peacetime agricultural uses. Ammonium nitrate, used in munitions, became an abundantly cheap source of nitrogen. And a range of new pesticides appeared: DDT, which had been used to control disease-carrying insects around troops, became a general insecticide, launching the era of widespread pesticide use.

At the same time, increasingly powerful and sophisticated farm machinery allowed a single farmer to work larger areas of land and fields grew bigger.

In 1944, an international campaign called the Green Revolution was launched in Mexico with private funding from the US. It encouraged the development of hybrid plants, chemical controls, large-scale irrigation, and heavy mechanization in agriculture around the world.

During the 1950s, sustainable agriculture was a topic of scientific interest, but research tended to concentrate on developing the new chemical approaches. One of the reasons for this, which informed and guided the ongoing Green Revolution, was the widespread belief that high global population growth, which was demonstrably occurring, would soon create worldwide food shortages unless humankind could rescue itself through ever higher agricultural technology. At the same time, however, the adverse effects of "modern" farming continued to kindle a small but growing organic movement. For example, in the US, J.I. Rodale began to popularize the term and methods of organic growing, particularly to consumers through promotion of organic gardening. 

In 1962, Rachel Carson, a prominent scientist and naturalist, published Silent Spring, chronicling the effects of DDT and other pesticides on the environment. A bestseller in many countries, including the US, and widely read around the world, Silent Spring is widely considered as being a key factor in the US government's 1972 banning of DDT. The book and its author are often credited with launching the worldwide environmental movement.

In the 1970s, global movements concerned with pollution and the environment increased their focus on organic farming. As the distinction between organic and conventional food became clearer, one goal of the organic movement was to encourage consumption of locally grown food, which was promoted through slogans like "Know Your Farmer, Know Your Food".

In 1972, the International Federation of Organic Agriculture Movements (IFOAM) was founded in Versailles, France and dedicated to the diffusion and exchange of information on the principles and practices of organic agriculture of all schools and across national and linguistic boundaries.

In 1975, Fukuoka released his book, The One-Straw Revolution, with a strong impact in certain areas of the agricultural world. His approach to small-scale grain production emphasized a meticulous balance of the local farming ecosystem, and a minimum of human interference and labour.

In the U.S. during the 1970s and 1980s, J.I. Rodale and his Rodale Press (now Rodale, Inc.) led the way in getting Americans to think about the side effects of nonorganic methods, and the advantages of organic ones. The press's books offered how-to information and advice to Americans interested in trying organic gardening and farming.

In 1984, Oregon Tilth established an early organic certification service in the United States.

In the 1980s, around the world, farming and consumer groups began seriously pressuring for government regulation of organic production. This led to legislation and certification standards being enacted through the 1990s and to date. In the United States, the Organic Foods Production Act of 1990 tasked the USDA with developing national standards for organic products, and the final rule establishing the National Organic Program was first published in the Federal Register in 2000.

In Havana, Cuba, the loss of Soviet economic support following the collapse of the Soviet Union in 1991 led to a focus on local agricultural production and the development of a unique state-supported urban organic agriculture program called organopónicos. 

Since the early 1990s, the retail market for organic farming in developed economies has been growing by about 20% annually due to increasing consumer demand. Concern for the quality and safety of food, and the potential for environmental damage from conventional agriculture, are apparently responsible for this trend.

Twenty-first century

Throughout this history, the focus of agricultural research and the majority of publicized scientific findings has been on chemical, not organic, farming. This emphasis has continued to biotechnologies like genetic engineering. One recent survey of the UK's leading government funding agency for bioscience research and training indicated 26 GM crop projects, and only one related to organic agriculture. This imbalance is largely driven by agribusiness in general, which, through research funding and government lobbying, continues to have a predominating effect on agriculture-related science and policy. 

Agribusiness is also changing the rules of the organic market. The rise of organic farming was driven by small, independent producers and by consumers. In recent years, explosive organic market growth has encouraged the participation of agribusiness interests. As the volume and variety of "organic" products increases, the viability of the small-scale organic farm is at risk, and the meaning of organic farming as an agricultural method is ever more easily confused with the related but separate areas of organic food and organic certification. 

As efforts to protect our environment increase, so does the popularity of sustainable produce. Agricultural chemicals, pesticides, and fertilizers can contaminate our environment though run-off into watercourses. In the US, Certified organic standards from the EPA do not allow for the use of toxic chemicals or artificial fertilizers in organic farming.