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nitrogen used for plant nutrition
|Nitrogen plant food -- commercial, industrially-produced "fertilizer" containing nitrogen -- where on earth does it come from? Does it contain animal products, or is it obtained from animal products? Is animal husbandry involved in producing it?|
by Theodore Zuckerman
article last updated 2003 Apr 14
Industrially-produced so-called fertilizer, really single or combination-of-ingredient green-plant nutrients for adding to the soil, are widely available in "lawn and garden centers" and from "agricultural supply centers." Frequently found are bags of fertilizer that contain usable nitrogen (N), available phosphorous (P), and available potassium (K). In gardening literature they are often described as NPK fertilizers. In addition, sometimes a small amount of ground limestone is added, and sometimes other nutrients are added, such as sources of iron, sulfur, magnesium, and boron. But the main ingredients are N, or P, or K, or some combination of these. N, P, and K are often present in different percentages, and these bags of nutrients always have a 3-number "code" on them describing the percentage of N, P, and K, in any handful of the stuff. 10-10-10 means 10 percent N, 10 percent P, and 10 percent K. 5-3-3 would be 5 percent N, 3 percent P, and 3 percent K. 0-0-60 would be 0 percent N, 0 percent P, and 60 percent K.
I will soon be updating this article to include information on the P and K in N-P-K "fertilizer." As I just said, P is the abbreviation for phosphorous.
K is the abbreviation for potassium. This article so far contains information on the N -- nitrogen.. However I can tell you that I have found that the P and the K compounds in industrially-produced "fertilizer" are substantially mineral products -- mined minerals -- that have been chemically altered with substances whose origin can also be traced to mined minerals.
|Potassium got its name from the substance that chemists identified as being a good source of it -- potash. Potash got its name from one of its sources -- the ashes left on the bottom of a pot after wood was burned, somewhere. Potassium has also been called kalium, but I'm not sure where. Potassium's official abbreviation, used in chemistry, is K. Is this short for Kalium? I don't know. But most of the chemists who use P for Phosphorous and K for potassium don't seem to know either. Instead they are, inexplicably, sometimes able to remember these names and abbreviations, without the comforting historic connections that most people find to be indespensible mnemonic aids.|
The nitrogen-containing compounds used in commercially-available, industrially-produced plant food (the N in N-P-K "fertilizer") come from (1) the molecular nitrogen of the air and (2) a source of hydrogen. The source of hydrogen is often natural gas. Therefore it is correct to say that the earthly origin of industrially-produced nitrogen-containing plant food, is air, and often natural gas. An industrial process called the Haber Process is used to combine the nitrogen and hydrogen together, into ammonia, or in the language of chemists, to synthesize ammonia from nitrogen and hydrogen.
The word synthesize here, means simply combine together chemically, to form a chemical compound. Ammonia produced by such synthesis is termed synthetic ammonia. The word synthetic here doesn't mean unnatural, nor is it used to mean the opposite of natural. It simply means the ammonia was produced when people combined nitrogen and hydrogen together, rather than that the ammonia was already in the form of ammonia, when people found it, and rather than that the ammonia was separated from a more complex chemical compound, consisting of ammonia combined with something else. Various natural, living organisms also synthesize substances. The substances they synthesize would thus be correctly called both synthetic and natural. In the case of industrially produced ammonia, however, it is both synthetic, and unnatural. The word unnatural here, as it applies to ammonia, means that the ammonia in question was not ammonia that was found by people, already in the form of ammonia when people found it, but rather that people used art to create it. A natural substance is a substance that is the way it was when it was found by people, and that has not been intentionally altered by people. An unnatural, or artificial, substance, is a substance that resulted when one or more natural substances was altered by the artistry and industry of people.
A correct term for a substance that is imitative or the same as a natural substance, but is produced by human industry, or artistry, rather than naturally, is artificial. Thus, industrially-produced vanillin, though it is chemically identical to the vanillin produced by vanilla plants, is correctly termed an artificial vanilla flavor. A correct term for a substance that is imitative of a natural substance, and is produced by human industry, or artistry, rather than naturally, and is also not identical to the natural substance, is imitation. Thus vinyl that looks like leather is imitation leather. Artificial leather, imitation leather, is certainly not synthetic leather -- it is not leather at all.
The Haber process of synthesizing ammonia from nitrogen and hydrogen involves submitting nitrogen and hydrogen to at least 3,000 pounds per square inch of pressure, in the pressence of osmium as a catalyst.
This industrially-produced synthetic ammonia is the principal source of the commercially-available, industrially-produced nitrogen that is contained in plant food -- synthetic ammonia is the principal starting point from which all of the different kinds of industrially-produced, so-called nitrogen "fertilizer," are made from. Or synthetic ammonia may itself be injected into the soil.
|Artistry and industry
This industrially produced ammonia is correctly called synthetic ammonia. It is also not natural ammonia, because it is not something that is the way it was when it was found by humans; rather, it was created by human artistry and industry, from other substances found by humans. In this case, the substance is synthetic and is not natural. But other substances are both synthetic and natural.
Removing the nitrogen from air
The major gas of ordinary air is nitrogen, and the pure nitrogen needed for the Haber process can be fairly easily extracted from it. Oxygen can be removed from air by a simple combustion process, or by liquefaction. Carbon dioxide, and other gasses, can be separated from aerial nitrogen by liquefation.
Obtaining the hydrogen needed
The pure hydrogen needed for the Haber process is, in the United States, often made by the "catalytic re-forming" of methane. Methane is the main constituent of natural gas, and natural gas is abundant in the United States. Chemically, methane is a compound in which each molecule consists of 1 carbon atom and 3 hydrogen atoms. Hydrogen is also obtained, industrially, by catalytic re-forming of light petroleum fractions.
The industrially-produced synthetic ammonia that is the principal source of industrially-produced commercial nitrogen contained in plant food (so called by the misnomer "fertilizer"), is a gas at normal temperatures, and can be injected into soil as a gas, or injected into soil after first being dissolved in water. Some agriculturalists inject ammonia, or ammonia dissolved in water, into their soil, but most industrially-produced ammonia is converted into solid compounds that can be spread in granular form over the soil and then mixed in. Such solid compounds include ammonium nitrate, potassium nitrate, urea, ammonium sulfate, and ammonium chloride. I believe all of them do not require any animal substances, in significant amounts, to be produced. Ammonium chloride, for example, is created by reacting ammonia with hydrochloric acid, hydrogen chloride.
|Ammonia is chemically transformed into ammonium hydroxide when dissolved in water, and is therefore ammonium hydroxide, in the language of chemistry; however in the language of commerce this substance is sometimes called ammonia, or ammonia-water. Yes, the cleaning product available on supermarket shelves, called ammonia is, chemicaly, really a very dilute solution of ammonium hydroxide in water.|
Ammonia is about 82 percent nitrogen. Ammonium nitrate is about 33 percent nitrogen. Urea is about 45 percent. These are very concentrated sources of nitrogen. Compost, on the other hand, is typically less than 1 percent nitrogen. So adequate amounts are more difficult (and expensive) to transport. It takes weeks or months to form. However compost has other things that benefit plants, other than the nitrogen. This is a bit of an understatement.
Also, while concentrated industrially-produced nitrogen products need large factories for efficient production, compost can be created easily anywhere (saying that compost can be created easily is a bit of an understatement). Thus industrially-produced nitrogen is generally produced in large quantities in one place, and transported long distances to many agriculatural areas, while compost is readily produced only a few feet from where it is needed, and transportation requires only a hand-drawn cart, or hand-carried baskets or buckets.
Here is a link to fantastic article called "Global Population and the Nitrogen Cycle," by Vaclav Smil,
that was originally published in Scientific American (1997 Jul, pg 76). The article discusses
the importance of nitrogen to life, and the impact that industrial production
of ammonia and industrial production of nitrogen fertilizers has
had - on the global distribution of nitrogen, and on humanity. From the article: "The advent of large-scale fertilizer production modifies natural flows of this element enormously, unbalancing the nitrogen cycle in sometimes troubling ways."
Valclav Smil's web site is here.
Reference: "Chemical Fertilizers," by Christopher J. Pratt, Scientific
1965 June, pg 62.
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