Synthetic fertilizer is shunned by organic gardeners and one reason is the fact that they are made from petroleum, or so it is claimed. Who wants to put petroleum chemicals into their garden and then eat vegetables from them? Nobody.
Terms like oil-based fertilizer, petroleum fertilizer and petrochemical fertilizer have been used to describe synthetic fertilizers, as in this quote from a popular gardening blog, “Petrochemical fertilizers are another name for the synthetic products because they are produced using large quantities of petroleum.”
I am not going to argue for or against synthetic fertilizer in this post. I just want to examine the claim that fertilizer is made from petroleum.
What is Petroleum?
Petroleum is the same as crude oil, the material that is refined to make things like gasoline.
Unfortunately, the term is also used in a more general way to include other forms of hydrocarbon, such as natural gas and this misuse of the term leads to confusion in our discussion.
Nitrogen Fertilizer
Nitrogen is a key component of most synthetic fertilizers. It is made by combining the nitrogen in the air with hydrogen in methane to produce ammonia (NH3). The ammonia is then used to create other forms of nitrogen including ammonium nitrate and urea (ammonia + CO2).
72% of the global nitrogen fertilizer is produced using natural gas which provides the methane and a heat source for the process. 22% of the global nitrogen is produced using coal and most of this is done in China.
Petroleum, as properly defined, is not used in the majority process.
Phosphorus Fertilizer
Most of the phosphorus fertilizer is made from rock phosphate, a mineral that is mined from the ground.
Petroleum is not used in this process.
Potassium Fertilizer
Potassium fertilizer is made from mined potash, a mineral that contains potassium chloride.
Petroleum is not used in this process.
Sulfur Fertilizer
Sulfur is an important ingredient in fertilizer that is not discussed very much. Historically, there were enough impurities in fertilizer that soil received enough sulfur. Sulfur was also a component in acid rain. The manufactured fertilizer of today is purer and we have less acid rain, which is leading to sulfur deficiencies in soil.
Sulfur can be mined, but today most of it comes from refining petroleum. Sulfur is an unwanted waste product of the petroleum industry. The oil from the Canadian oil sands has high levels of sulfur and Alberta now has huge piles of it that nobody wants.
I guess you could say that sulfur is made from petroleum but we don’t use petroleum to make the sulfur. Sulfur is a waste product of other manufacturing processes, like making gasoline.
Petroleum as an Energy Source
In the above I have said several times that petroleum is not used. That is not strictly correct. Petroleum is refined to make gasoline and that is used for running all kinds of equipment. Petroleum products may also be used as a heating source.
However, every manufacturing process uses petroleum for this purpose, including all of our processed food. Even though petroleum is used to harvest and move corn to factories, and is used to heat the manufacturing process, we don’t consider cornflakes to be made from petroleum. If we did, then everything we consume would be petroleum-based, even those organic fertilizers.
You can’t make blood meal or alfalfa meal without petroleum.
Is Synthetic Fertilizer Petroleum Based?
Using the correct definition of petroleum, synthetic fertilizer containing the macronutrients N, P and K is not petroleum based.
It can be argued that sulfur is petroleum based, but the sulfur produced from petroleum or a mine is identical.
Why Does It Matter?
From a chemical perspective, it doesn’t matter. The nutrients in synthetic fertilizer are identical to those found in compost and organic fertilizer. Even if they are petroleum based, they are still identical.
Using petroleum products may not be good for the environment, but the resulting fertilizer is perfectly safe for plants, microbes and humans, provided it is used in reasonable amounts.
So why do terms like oil-based fertilizer and petroleum fertilizer exist? Proponents of organic methods need to find some way to convince people that organic fertilizer is better and labeling synthetic fertilizer as “petroleum based” easily convinces the general public that these products are BAD.
That is unfortunate, because there are very good arguments for using organic products instead of synthetic products, in some gardening situations. But trying to explain the concept of building soil structure and increasing levels of organic matter are more complex and require more knowledge of both the writer and the audience. It is so much easier to use name calling. The term, petroleum-based fertilizer, is easier to understand and more convincing.
But it’s a myth – synthetic fertilizer is NOT petroleum based.
Could the amount of fertilizer the world needs/uses be made without any oil or it’s byproducts?
As the post says ammonia is not made from oil
Fixing nitrogen requires a lot of energy which has to come from somewhere – gas, coal. Without it, the amount of food would drop significantly.
If you update this piece, you might include a distinction made at Wikipedia:
“The natural gas produced from oil wells is generally classified as associated-dissolved gas meaning that the gas had been associated with or dissolved in crude oil. Natural gas production not associated with crude oil is classified as “non-associated.”
Thanks, Robert. As the (long-retired) National Speaker for Greenpeace in the U.S., and subsequently a volunteer leader for the Sierra Club and my state’s (MN) Renewable Energy Society, I have long been preoccupied with the fact that in using natural gas as a massive feedstock for combustion, we ignore the fact that – in a world now hosting eight billion people – we are robbing future generations of something that will be critical to the production of the food needed for their survival. I appreciate your clear distinction between the role of natural gas, and the role of petroleum, in fertilizer production.
I love organic farming, and I have great appreciation for those exploring the use of renewable energy to produce ammonia, for fertilizer production, from water (itself now a scarce commodity in much of the U.S.), but I cannot yet see a way for these approaches, in the near- or mid-term, to supplant natural-gas-based fertilizer in food production sufficient to nourish eight-billion-plus human beings. However… I’d love to be proven wrong.
“Ammonia is manufactured using atmospheric nitrogen and hydrogen derived from natural gas or petroleum refinery byproducts.” – https://www.epa.gov/eg/fertilizer-manufacturing-effluent-guidelines
Ammonia is usually made using natural gas, which is what the post says.
“petroleum refinery byproducts” China is the largest ammonia producer and consumer, generating 47.35 million tons of ammonia in 2019. This value accounts for approximately one-third of the world’s total output (National Bureau of Statistics of China, 2020). Currently, the global ammonia production is obtained mostly through the Haber-Bosch process (Makhlouf et al., 2015) and depends on fossil fuels as a major source (Kool et al., 2012). (…) However, given the abundant coal resources and the scarcity of oil and natural gas in China, coal is the primary energy substance for China’s synthetic ammonia industry (Zhou et al., 2016), accounting for 79% of the total ammonia production. https://www.sciencedirect.com/science/article/abs/pii/S0959652621038361
Thank you for this – I added the information to the post.
Very informative! Thanks! Ignore the headline commenters, or more specifically, low-information arguers.
when did you publish it? coz im gonna use it on my rrl with ur name and publication date
no sure – the data has not changed.
Synthetic fertiliser gets washed away if soil absorbers, soil stabilisers aren’t used. Then all those elements gets washed away into the ocean. This is one of the reasons for bleaching of corals and does damage the environment. Farmers must use a combination so those fertiliser stay where they are needed to nourish plant not end up in rivers and ocean. Common sense strategies will help everyone.
“Synthetic fertiliser gets washed away if soil absorbers, soil stabilisers aren’t used. ”
Your understanding of fertilizer is poor.
1) First of all, it is nutrients that move through soil, and it does not matter if they come from synthetic or organic sources, since they are the same.
2) You do NOT need to add soil absorbers or stabilizers – whatever those are. Clay and organic matter work very well to hold most nutrients.
3) Not all nutrients move quickly through soil. Phosphate for example only moves a few mm a year.
synthetic fertilizer will harden the soil with time and also kills the microbes in the soil. For long term it harms the soil and in turn, the fruit will not taste as good.
None of that is true.
Where are your references?
It’s a cop-out to say that fertilizer is not made from petroleum when millions or billions of it is used in the process of creating it. And, from an environmental standpoint, there is no difference between petroleum and methane and you darned well know it.
If we agree with your first point, then you will also have to agree that organic fertilizer like fish emulsion or seaweed extract is also made from petroleum. They too use a lot of petroleum to manufacture and ship around the country. Most people would not agree with this.
There is a big difference between petroleum and methane when it comes to the pollution they cause.
To be clear, I never said petroleum was not used. In fact what I said was “Petroleum is refined to make gasoline and that is used for running all kinds of equipment. Petroleum products may also be used as a heating source.”
But when people say fertilizers are made from petroleum – they are wrong.
Most synthetic fertilizers have chelators like EDTA. I’m pretty sure EDTA is derived from petroleum.
1) “Most synthetic fertilizers have chelators like EDTA” – I doubt that. EDTA is not cheap and would not be found in cheaper products. Chelates are also used to solublize the micronutrients – not the macro-nutrients.
2) “I’m pretty sure EDTA is derived from petroleum” – why don’t you look it up instead of trying to start a new myth. From wiki: EDTA is mainly synthesised from ethylenediamine (1,2-diaminoethane), formaldehyde, and sodium cyanide.
I’m beginning my own gardening and starting a blog about the same topics. I found these really helpful. Thanks for sharing!