Green Gardens: What are ‘petroleum-based fertilizers’?
I keep hearing the term “petroleum based fertilizer” in the context of peak oil doom or other claims that we, as humans, are so dependent on oil that we can’t even eat without it because we grow our food with “petroleum based fertilizer.” I guess “We’re just too reliant on petroleum based fertilizer.” right?
No, not exactly. In general, fertilizer is not made from petroleum, period. The only exception to this might be the occasions where some very heavily contaminated oil comes out of the ground, and after a lot of purification, there’s a little bit of phosphorus left over as a byproduct. Occasionally such chemicals are derived from the stuff that’s extracted from crude, but this is not a major source. Other than that, oil is just plain not used to make fertilizer. It might be used to mine some of the minerals or transport the fertilizer, but this is pretty minor in the grand scheme of things.
For some further explanation, lets look at the primary types of fertilizer used in agriculture.
Potassium - Potassium comes from a variety of natural sources. One of the most common is potash, which can be found in large deposits in Canada, Russia, Europe and elsewhere. It can also be produced from seaweed or wood ash. Potassium can also be extracted from potassium salts which are commonly found in ancient lakebeds as well as in salt lakes such as the Dead Sea. Several other minerals also contain easily extractable potassium Significant amounts of potassium also can be found in seawater.
Phosphorus – Phosphorus is commonly produced from a number of phosphate minerals. phosphorus may also be extracted from processed biomass or from other sources including sea water, but the concentrations are too low to make it competitive with mineral-based phosphorus.
Nitrogen – Nitrogen fertalizers are created from the atmosphere through nitrogen fixation. This requires the use of hydrogen which is used in the Haber-Bosch process. Natural gas (methane) is by far the most common source of the hydrogen used in modern nitrogen fertalizer production, but it can be made from hydrogen derived from water and historically this has been done in a few instances when natural gas was not avalibale or because it was not feisable to purify the natural gas to remove sulfur, which can damage the catalyst used in the process.
Trace Mineral – A much less common fertalizer type, but in some cases areas may lack trace minerals such as iron or calcium, making this the limiting factor in the growth of plants. In such cases, mixtures of minerals may be added to suppliment the soil.
Now… where did you see oil in that list???
This entry was posted on Sunday, January 18th, 2009 at 11:37 pm and is filed under Agriculture, Bad Science, Culture, Good Science, Misc, Obfuscation. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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