Nitrogen Fertilizer

January 6

2016In this project we will talk about the nitrogen fertilizers. It includes that how to make nitrogen fertilizers, its various steps, the history of nitrogen fertilizer Haber process advantages and disadvantages of N. fertilizer, types of nitrogen fertilizer a small article about it etc…

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Nitrogen Fertilizer

Nitrogen fertilizer is a compound that is added to plants or lawns to stimulate growth. The nitrogen stimulates chloroplasts in plants, which are responsible for the process of photosynthesis. Plants that do not have enough nitrogen will turn yellow and eventually perish from a lack of food.

The development of nitrogen fertilizer began in 1905 with the German chemist Fritz Haber. Haber discovered a way to fixate nitrogen from the air. Fixation is the process by which a gas, such as nitrogen, is converted into a usable compound. In this case, Haber was able to convert gaseous hydrogen and nitrogen into ammonia. He received a Nobel Prize for his work in 1918.

Originally, Haber's process was used to synthesize nitrates for Germany during the First World War, to aid in the production of explosives. A refinement of his method led to the ability to create ammonium sulphate for use in soil. Once this process was adapted to work on a large scale, nitrogen fertilizer was born.

There are two common forms of nitrogen used for plant growth. The first is natural nitrogen, which is found in decaying plant or animal matter. This is why compost is used on lawns or gardens — the manure and other material in it release nitrogen into the soil.

The second form of nitrogen fertilizer available is commercially synthesized. In this case, the nitrogen is present in the form of

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ammonium or nitrate. Ammonium-based fertilizers bond securely with soil, but release their nitrogen slowly into a plant. Those based around nitrates are quickly absorbed by a plant, but can be easily washed away by water in a process known as leaching.

Natural nitrogen takes longer to be used by a plant than either commercial form, but does not come with the same risks. Improper application of commercial fertilizer can lead to groundwater contamination. The widespread use of commercial nitrogen fertilizer is now a serious environmental concern as contaminated runoff water has begun to adversely affect sea plants around the world. Extra nitrogen present in the water has caused unrestrained algae growth in some bodies of water, which then results in massive algae death and decay. This happens because, as water in the immediate area is depleted of oxygen, the algae die. Subsequently, this kills large amounts of animal life that need it for food.

Nitrogen lawn fertilizer also contains phosphorous and potassium, since phosphorus assists in root growth and potassium is needed for water movement. A bag of fertilizer will list the percentage of each compound present in the fertilizer. One marked 10-10-10 means that each compound accounts for 10% of the bag by weight, and the other 70% of the bag is simply an inert chemical.

Properly applying nitrogen fertilizer is important. Too much will kill a lawn as surely as too little. Bags will list suggested amounts to use, based on the size of lawn being fertilized. Ideally, apply the material when the lawn is wet and likely to stay that way for a while. This can prevent the nitrogen from burning the grass, or making it yellow and brittle.

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How to Make Nitrogen Fertilizer

Nitrogen is an essential component of plant growth and plays a vital role in the development of healthy foliage. While you can find a chemical fertilizer that contains high nitrogen levels, those interested in an organic approach can also make nitrogen fertilizer by understanding which natural products have high levels of usable nitrogen and can be mixed in or applied to the soil.

Steps

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1. Use compost.

Compost is nothing more than decomposed organic matter. The average compost pile contains a plethora of beneficial nutrients, including potassium, phosphorus, and nitrogen. Regarding nitrogen, the bacteria in compost break matter down into ammonium, which is then naturally converted by other bacteria into nitrates that plants can absorb through their roots. Compost high in nitrogen materials, including moist greens, fruits, and vegetables, tends to provide the highest content of nitrogen to the soil bed it is applied to.

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2. Add in some composted coffee grounds. Coffee grounds can be mixed directly into the soil or added to a pre-established compost pile. The grounds contain about two percent nitrogen by volume, which is considered fairly high as far as nitrogen-containing materials are concerned. Additionally, while some worry about the acidic properties of coffee, it is the coffee beans rather than the grounds that contain high levels of acid. Coffee grounds that remain after brewing are usually between a pH of 6.5 and 6.8, which is near neutral.

• You can add coffee grounds directly to the soil by mixing damp grounds into the soil or by spreading the grounds over the surface of the soil and covering them with organic mulch

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3. Try composted manure.

Sheep, beef cattle, and swine manure contain the largest concentrations of nitrogen, with poultry and dairy cattle manure following closely behind. Horse manure also contains some nitrogen, but the concentration is significantly less than it is in other forms of manure. Composted manure, or manure that has had the chance to decompose, is better to use because bacteria has already begun to break down the nitrogen into a form that plants can absorb. • Note that there are downsides to using animal manure. Manure tends to increase the salt content of soil, and using manure may lead to an increased yield of weeds.

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4. Mix in a good dose of blood meal for a quick-release

fertilizer.

Blood meal is an organic product made from dried blood, and it contains 13 percent total nitrogen. This is a notably high percentage for fertilizer components. You can use blood meal as a nitrogen fertilizer by sprinkling it over the top surface of the soil and pouring water over it to help the soil soak it in, or you could mix the blood meal directly with water and apply it as a liquid fertilizer.

• Blood meal is an especially good source of nitrogen for heavy feeders, like lettuce and corn, because of how fast-acting it is.

• Blood meal can also be used as a component in compost or as an accelerant for other organic materials, since it promotes the decomposition process.

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5. Apply cotton seed meal cautiously.

This fertilizer component is made of ground seeds from the cotton plant. Some consider it to be the second best natural source of nitrogen, following blood meal. Unlike blood meal, however, cotton seed meal breaks down slowly, distributing nitrogen to plants over an extended length of time.

• The major disadvantage of cotton seed meal is that it has a negative impact on soil pH. It greatly acidifies soil, so if you plan to make an organic fertilizer out of cotton seed meal, you should also carefully monitor the pH of your soil.

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6. Use crab meal, feather meal, or leather meal for slow-

release fertilizers.

These products are made from ground crab, feathers, and cowhide leather, respectively, and each contains a decent amount of nitrogen. These components all break down at a slow pace, however, and will not provide adequate amounts of usable nitrates to plants in need of a quick dose. These components are good to use in fertilizer mixes and composts, though, since they can maintain a steady content of nitrogen throughout the growing season.

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7. Try biosolids and wood.

Treated biosolids and wood materials Sawdust, wood chips, and sewage sludge (which are pre-treated before using as fertilizer) all contain nitrogen and can all be used in nitrogen fertilizers, just make sure that the biosolid you will be using are treated and monitored properly, if not, the associated risks of such products may not be worth the potential benefit. Moreover, because these materials all decompose slowly and contribute small amounts of nitrogen, they are not even the most beneficial nitrogen components available. While they might not be the best choice for nitrogen fertilizers, biosolid fertilizers add much needed nutrients. Wood chips also add anchorage for the plants.

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8. Plant nitrogen-fixing cover crops.

Certain plants, like legumes and clover, store nitrogen in nodules at their roots. These nodules release nitrogen into the soil gradually while the plant lives, and when the plant dies, the remaining nitrogen enhances the overall quality of the soil.

• Just toss some legumes on the soil. Mung beans are suggested since they don't grow too big but they grow fast.

• To replenish Nitrogen on the soil. Try fallowing. When resting your plot on the 7th year, sow some mung beans. Don't harvest the mung beans, instead, let the seeds fall into the ground for more nitrogen-fixers. Do this, especially if you will be planting heavy feeders like corn on the next growing year.

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Haber process The Haber process, also called the Haber–Bosch process, is an artificial nitrogen fixation process and is the main industrial procedure for the production of ammonia today.[1] It is named after its inventors, the German chemists Fritz Haber and Carl Bosch, who developed it in the

first half of the twentieth century. The process converts atmospheric

Nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using a metal catalyst under high temperatures and pressures:

N2 + 3 H2 → 2 NH3 (ΔH = −92.4 kJ•mol−1)

Before the development of the Haber process, ammonia had been difficult to produce on an industrial scale[2][3][4] with

Fritz Haber, 1918

early methods such as the Birkeland–Eyde process and Frank–Caro process all being highly inefficient.

Although the Haber process is mainly used to produce fertilizer today, during World War I, it provided Germany with a source of ammonia for the production of explosives, compensating for the Allied trade blockade on Chilean saltpeter.

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History

Throughout the nineteenth century the demand for nitrates and ammonia for use as fertilizers and industrial feedstock’s had been steadily increasing; however, the main source remained the mining of niter deposits. By the start of the twentieth century it was being predicted that these reserves would be unable to satisfy future demand and research into new potential sources of ammonia became ever-more important. The most obvious source was atmospheric nitrogen (N2), which makes up nearly 80% of the air; however N2 is exceptionally stable and will not readily react with other chemicals. Converting N2 into ammonia therefore posed a chemical challenge which occupied the efforts of chemists across the world.

Haber together with his assistant Robert Le Rossignol developed the high-pressure devices and catalysts used to demonstrate the Haber process at laboratory scale. They demonstrated their process in the summer of 1909 by producing ammonia from air drop by drop, at the rate of about 125 ml (4 US FL oz.) per hour. The process was purchased by the German chemical company BASF, which assigned Carl Bosch the task of scaling up Haber's tabletop machine to industrial-level production. He succeeded in this process in 1910. Haber and Bosch were later awarded Nobel prizes, in 1918 and 1931 respectively, for their work in overcoming the chemical and engineering problems posed by the use of large-scale, continuous-flow, high-pressure technology.

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Ammonia was first manufactured using the Haber process on an industrial scale in 1913 in BASF's Oppau plant in Germany, production reaching 20 tons per day the following year. During World War I, the synthetic ammonia was used for the production of nitric acid, a precursor to munitions. The Allies had access to large amounts of sodium nitrate deposits in Chile (so called "Chile saltpetre") that belonged almost totally to British industries. As Germany lacked access to such readily available natural resources, the Haber process proved essential to the continued German war effort.

The Process

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An historical (1921) high-pressure steel reactor for production of ammonia via the Haber process is displayed at the Karlsruhe Institute of Technology, Germany.

This conversion is typically conducted at 15–25 MPa (2,200–3,600 psi) or 150–250 bar and between 400–500 °C (752–932 °F), as the gases are passed over four beds of catalyst, with cooling between each pass so as to maintain a reasonable equilibrium constant. On each pass only about 15% conversion occurs, but any unreacted gases are recycled, and eventually an overall conversion of 97% is achieved.

The steam reforming, shift conversion, carbon dioxide removal, and methanation steps each operate at pressures of about 2.5–3.5 MPa (360–510 psi) or 25–35 bar, and the ammonia synthesis loop operates at pressures ranging from 6–18 MPa (870–2,610 psi) or 60–180 bar, depending upon which proprietary process is used.

Sources of hydrogen

The major source of hydrogen is methane from natural gas. The conversion, steam reforming, is conducted with air, which is deoxygenated by the combustion of natural gas. Originally Bosch obtained hydrogen by the electrolysis of water

Reaction rate and equilibrium

Nitrogen (N2) is very unreactive because the molecules are held together by strong triple bonds. The Haber process relies on catalysts that accelerate the scission of this triple bond.

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Two opposing considerations are relevant to this synthesis: the position of the equilibrium and the rate of reaction. At room temperature, the equilibrium is strongly in favor of ammonia, but the reaction doesn't proceed at a detectable rate. The obvious solution is to raise the temperature, but because the reaction is exothermic, the equilibrium constant (using atm units) becomes 1 around 150° or 200 °C. (See Le Chatelier's principle.)

Kp(T) for N 2 + 3 H 2 ⇌ 2 NH 3[12]

Temperature (°C)

Kp

300 4.34 x 10−3

400 1.64 x 10−4

450 4.51 x 10−5

500 1.45 x 10−5

550 5.38 x 10−6

600 2.25 x 10−6

Above this temperature, the equilibrium quickly becomes quite unfavourable at atmospheric pressure, according to the Van 't Hoff equation. Thus one might suppose that a low temperature is to be used and some other means to increase rate. However, the catalyst itself requires a temperature of at least 400 °C to be efficient.

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Pressure is the obvious choice to favor the forward reaction because there are 4 moles of reactant for every 2 moles of product (see entropy), and the pressure used (around 200 atm) alters the equilibrium concentrations to give a profitable yield. [Citation needed]

Economically, though, pressure is an expensive commodity. Pipes and reaction vessels need to be strengthened, valves more rigorous, and there are safety considerations of working at 200 atm. In addition, running pumps and compressors takes considerable energy. Thus the compromise used gives a single pass yield of around 15%. [Citation needed]

Another way to increase the yield of the reaction would be to remove the product (i.e. ammonia gas) from the system. In practice, gaseous ammonia is not removed from the reactor itself, since the temperature is too high; but it is removed from the equilibrium mixture of gases leaving the reaction vessel. The hot gases are cooled enough, whilst maintaining a high pressure, for the ammonia to condense and be removed as liquid. Unreacted hydrogen and nitrogen gases are then returned to the reaction vessel to undergo further reaction. [Citation needed]

Catalysts

The most popular catalysts are based on iron promoted with K2O, CaO, SiO2, and Al2O3. The original Haber–Bosch reaction chambers used osmium as the catalyst, but it was available in extremely small quantities. Haber noted uranium was almost as effective as and easier to obtain than osmium. Under Bosch's direction in 1909, the BASF researcher Alwin Mittasch discovered a much less expensive iron-based

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catalyst, which is still used today. Some ammonia production utilizes ruthenium-based catalysts (the KAAP process). Ruthenium forms more active catalysts that allow milder operating pressures. Such catalysts are prepared by decomposition of triruthenium dodecacarbonyl on

graphite.

In industrial practice, the iron catalyst is obtained from finely ground iron powder, which in turn is usually obtained by reduction of high purity magnetite (Fe3O4).

The pulverized iron metal is burnt (oxidized) to give magnetite of a defined particle size. The magnetite particles are then partially reduced, removing some of the oxygen in the process. The resulting catalyst particles consist of a core of magnetite, encased in a shell of wüstite (FeO), which in turn is surrounded by an outer shell of iron metal. The catalyst maintains most of its bulk volume during the reduction, resulting in a highly porous high surface area material, which enhances its effectiveness as a catalyst. Other minor components of the catalyst include calcium and aluminium oxides, which support the iron catalyst and help it, maintain its surface area. These oxides of Ca, Al, K, and Si are immune to reduction by the hydrogen.

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The reaction mechanism, involving the heterogeneous catalyst, is believed to involve the following steps: [13]

1. N2 (g) → N2 (adsorbed)

2. N2 (adsorbed) → 2 N (adsorbed)

3. H2 (g) → H2 (adsorbed)

4. H2 (adsorbed) → 2 H (adsorbed)

5. N (adsorbed) + 3 H (adsorbed) → NH3 (adsorbed)

6. NH3 (adsorbed) → NH3 (g)

Reaction 5 occurs in three steps, forming NH, NH2, and then NH3. Experimental evidence points to reaction 2 as being the slow, rate-determining step. This is not unexpected since the bond broken, the nitrogen triple bond, is the strongest of the bonds that must be broken.

A major contributor to the elucidation of this mechanism is Gerhard Ertl.

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Advantages and disadvantages of nitrogen fertilizers:

The following are the advantages and disadvantages of nitrogen fertilizers.

Advantages:

• Nitrogen fertilizers are able to make up the deficiency when the soil has become depleted of its natural nitrogen stores.

• The use of nitrogen fertilizers helps to keep nutrient levels at an optimum level, protect against disease and control weeds, resulting in healthier crops and consistent quality and quantity of yields.

Disadvantages:

• Excess nitrogen not absorbed by the plants has been shown to leach into the groundwater and nearby rivers.

• High levels of nitrogen in the water can create algal blooms, large growths of algae that imbalance the delicate ecosystem to the detriment of other aquatic species.

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Organic and inorganic chemical nitrogen fertilizers types: This type of fertilizer is divided into different groups according to the manner in which the nitrogen combines with other elements.

1. Sodium Nitrate: Sodium nitrates are also known as Chilean Nitrate. The nitrogen contained in sodium nitrate is refined to 16%. This means that the nitrogen is immediately available to plants and is a valuable source of nitrogen in this type of fertilizer. When one makes a soil amendment using sodium nitrates as a type of fertilizer in the garden, it is usually as a top- and side-dressing. Particularly when nursing young plants and garden vegetables. Sodium nitrate is quite useful as atype of fertilizer in an acidic soil. However, the excess use of sodium nitrate may causes de-flocculation.

2. Ammonium Sulfate: This fertilizer type comes in a white crystalline salt form. It is easy to handle and it stored well under dry conditions. However, during the rainy season, it sometimes forms lumps. Though this fertilizer type is soluble in water, its nitrogen is not readily lost in drainage, because the ammonium ion is retained by the soil particles. Ammonium sulfate may have an acidic effect on garden soil. Over time, the long-continued use of this type of fertilizer will increase soil acidity and thus lower the yield. The application of ammonium sulfate fertilizer can be done

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before sowing, at sowing time, or even as a top-dressing to the growing crop.

3. Ammonium Nitrate: This fertilizer type also comes in white crystalline salts. Ammonium nitrate salts contain 33 to 35% nitrogen, of which half is nitrate nitrogen and the other half is in the ammonium form. As part of the ammonium form, this type of fertilizer cannot be easily leached from the soil. This fertilizer is quick-acting, but highly hygroscopic thus making it unfit for storage. Ammonium nitrate also has an acidic effect on the soil, in addition this type of fertilizer can be explosive under certain conditions.

4. Ammonium Sulfate Nitrate: This fertilizer type is available as a mixture of ammonium nitrate and ammonium sulfate. It is recognizable as a white crystal or as dirty-white granules. This fertilizer contains 26% nitrogen, three-fourths of it in the ammonium form and the remainder (i.e. 6.5%) as nitrate nitrogen. Ammonium sulfate nitrate is non-explosive, readily soluble in water and is very quick-acting. Because this type of fertilizer keeps well, it is very useful for all crops. Though it can also render garden soil acidic, the acidifying effect is only one-half of that of ammonium sulfate on garden soil. Application of this fertilizer type can be done before sowing, at sowing time or as a top-dressing, but it should not be applied along the seed.

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5. Ammonium Chloride: This fertilizer type comes in a white crystalline compound, which has a good physical condition and 26% ammoniac nitrogen. It is not recommended to use this type of fertilizer on crops such as tomatoes because the chlorine may harm the crop.

6. Urea: This type of fertilizer usually is available to the public in a white, crystalline, organic form. It is a highly concentrated nitrogen fertilizer and fairly hygroscopic. This also means that this fertilizer can be quite difficult to apply. Urea is also produced in granular or pellet forms and is coated with a non-hygroscopic inert material. It is highly soluble in water and therefore, subject to rapid leaching. It produces quick results. When applied to the soil, its nitrogen is rapidly changed into ammonia. Urea supplies nothing but nitrogen and the application of urea as fertilizer can be done at sowing time or as a top-dressing, but should not be allowed to come into contact with the seed.

7. Ammonia: This fertilizer type is a gas that is made up of about 80% of nitrogen and comes in a liquid form as well because under the right conditions of temperature and pressure, ammonia becomes liquid (anhydrous ammonia).Another form, aqueous ammonia, results from the absorption of ammonia gas into water, in which it is soluble. Ammonia is used as a fertilizer in both forms. The anhydrous liquid form of

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ammonia can be applied by introducing it into irrigation water, or directly into the soil from special containers.

8. Organic Nitrogen Fertilizers: Organic nitrogen fertilizer is the type of fertilizer that includes plant and animal by-products. These by-products can be anything from oil cakes, to fish manure and even to dried blood. The nitrogen available in organic nitrogen fertilizer types first has to be converted before the plants can use it. This conversion occurs through bacterial action which is a slow process. The upside of this situation is that the supply of available nitrogen lasts so much longer. This type of fertilizer may contain small amounts of organic stimulants that contain other minor elements that might also be needed by the plants that are being fertilized. Furthermore, they may also contain small amounts of organic stimulants, or some of the minor elements needed by plant. Oil-cakes contain not only nitrogen but also some phosphoric and potash, besides a large quantity of organic matter. This type of fertilizer is used in conjunction with quicker-acting chemical fertilizers.

9. Future of fertilizers: Fertilizer research is currently focusing on reducing the harmful environmental impacts of fertilizer use and finding new, less expensive sources of fertilizers. Such things that are being investigated to make fertilizers more environmentally friendly are improved methods of application, supplying fertilizer in a form which is less susceptible to runoff, and making more concentrated mixtures. New sources of fertilizers are also being investigated. It has been found that sewage

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sludge contains many of the nutrients that are needed for a good fertilizer. Unfortunately, it also contains certain substances such as lead, cadmium, and mercury in concentrations which would be harmful to plants. Efforts are underway to remove the unwanted elements, making this material a viable fertilizer. Another source that is being developed is manures. The first fertilizers were manures; however, they are not utilized on a large scale because their handling has proven to be too expensive. When technology improves and costs are reduced, this material will be a viable new fertilizer.

A Brief History of Our Deadly Addiction to Nitrogen Fertilizer

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As investigators and rescuers move through a destroyed fertilizer factory in West, Texas, it makes me think about just what nitrogen fertilizer is, and why we use so much of it.

Nitrogen is one of the nutrient elements plants need to grow. Every apple or ear of corn plucked represents nutrients pulled from soil, and for land to remain productive, those nutrients must be replenished. Nitrogen is extremely plentiful—it makes up nearly 80 percent of the air we breathe. But atmospheric nitrogen (N2) is joined together in an extremely tight bond that makes it unusable by plants. Plant-available nitrogen, known as nitrate, is actually scarce, and for most of agriculture's 10,000-year-old history, the main challenge was figuring out how to cycle usable nitrogen back into the soil. Farmers of yore might not have known the chemistry, but they knew that composting crop waste, animal manure, and even human waste led to better harvests.

But then, to make a long and complicated story short, in the 19th century European scientists figured out the science behind nitrogen's central role in plant growth, just as the industrial revolution was pushing more people off of farms and into cities. European elites realized that feeding a growing urban population from a shrinking rural labor base would be a problem—and that cheap and easy nitrate would be part of the solution. So the "fixation" of nitrogen—the ability pull it from the air and transform it into something that plants could use—became, well, a fixation. In 1909, a German chemist named Fritz Haber developed a high-temperature, energy-intensive process to synthesize plant-available nitrate from air. And so agriculture's millennia-old nitrogen-cycling problem was solved. Today's industrial-scale farms would not be possible without it.

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Of course, agriculture wasn't the only reason Germany and other European countries wanted to generate tons of nitrate. As we just tragically saw in Texas, the stuff can also make a massive explosion. Before it made it onto farm fields in a big way, Haber's breakthrough fueled the US and European munitions industry, particularly in World

War II. In that way, the industrialization of farming shares roots with the industrialization of killing represented by modern war.

Today's fertilizer plants, reports Vaclav Smil in his seminal book on nitrogen fertilizer, enriching the Earth, rely on a scaled-up, refined

version of the same process developed by Haber.

By the end of World War II, the United States had built 10 large-scale nitrate factories to make bombs. With Europe's and Japan's production facilities in ruins, the US entered the postwar period as the undisputed global champion of nitrogen production. The industry quickly shifted from munitions to fertilizer and domestic consumption began to skyrocket, driven, Smil writes, by the rise of new hybrid strains of corn, "the first kind of high-yielding grain cultivar dependent on higher fertilizer applications."

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Today, the United States remains a massive nitrogen-fertilizer user; with just 5 percent of the world's population, we consume about 12 percent of global nitrogen-fertilizer production. And corn—which according to the USDA "requires the most nitrogen per acre" of any crop—remains at the center of our agriculture, covering 30 percent of farmland each year.

While our reliance on cheap nitrogen fertilizer occasionally (though quite rarely) results in attention-grabbing explosions, the real problems are more subtle and long-term. In a recent article, I laid them out:

Industrial agriculture's reliance on plentiful synthetic nitrogen brings with it a whole bevy of environmental liabilities: excess nitrogen that seeps into streams and eventually into the Mississippi River, feeding a massive annual algae bloom that blots out sea life; emissions of nitrous oxide, a greenhouse gas 300 times more potent than carbon; and the destruction of organic matter in soil.

As I also noted in that article, the US fertilizer industry increasingly relies on cheap natural gas extracted by hydro fracturing, or fracking—the controversial process of extracting gas from rock formations by bombarding them with water spiked with toxic chemicals. "If Big Ag becomes hooked on cheap fracked gas to meet its fertilizer needs," I warned, "then the fossil fuel industry will have gained a powerful ally in its effort to steamroll regulation and fight back opposition to fracking projects."

Our future doesn't have to be drenched in vast quantities of synthetic nitrogen, with all its liabilities both subtle and spectacular. A 2012 Iowa State University study found that by simply shifting to more diverse crop rotations, Midwestern farmers could radically reduce their

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reliance on added nitrogen while maintaining current levels of overall food production. Another recent study by Cornell researchers found similar crop rotations also reduced nitrogen runoff.

Yet instead of weaning us from our huge reliance on nitrogen, federal and state agencies are underwriting the construction of new plants and the expansion of old ones. Meanwhile, federal farm and "renewable fuel" policies continue to prop up corn—in 2013, the USDA expects farmers to plant the most since 1936: 97.3 million acres, covering an area nearly the size of California. We won't be kicking our nitrogen habit anytime soon.

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Nitrogen fertilizer component • 1 Ammonia is one nitrogen fertilizer component that can be synthesized from in-expensive raw materials. Since nitrogen makes up a significant portion of the earth's atmosphere, a process was developed to produce ammonia from air. In this process, natural gas and steam are pumped into a large vessel. Next, air is pumped into the system, and oxygen is removed by the burning of natural gas and steam. This leaves primarily nitrogen, hydrogen, and carbon dioxide. The carbon dioxide is

removed and ammonia is produced by introducing an electric current

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into the system. Catalysts such as magnetite (Fe304) have been used to improve the speed and efficiency of ammonia synthesis. Any impurities are removed from the ammonia, and it is stored in tanks until it is further processed.

• 2 While ammonia itself is sometimes used as a fertilizer, it is often converted to other substances for ease of handling. Nitric acid is produced by first mixing ammonia and air in a tank. In the presence of a catalyst, a reaction occurs which converts the ammonia to nitric oxide. The nitric oxide is further reacted in the presence of water to produce nitric acid.

• 3 Nitric acid and ammonia are used to make ammonium nitrate. This material is a good fertilizer component because it has a high concentration of nitrogen. The two materials are mixed together in a tank and a neutralization reaction occurs, producing ammonium nitrate. This material can then be stored until it is ready to be granulated and blended with the other fertilizer components.