Fertilizer, Energy and Liebig's Law of the Minimum

The loss of fertilizer shipments coming from the Persian Gulf as a result of the Iran war got me thinking about the chemist Justus von Liebig, a prominent 19th century proponent of the mineral theory of plant nutrition. Liebig is the popularizer of what is now known as Liebig's Law of the Minimum. The law states that the least available essential nutrient limits the growth of plants. This means once a grower runs out of one essential nutrient, adding extra of others will not make up for the lack of the one that is limited.

Liebig's eponymous law is about to assert itself in a big and distressing way in the coming growing season. That's because the Persian Gulf region supplies 36 percent of the world's urea (a form of nitrogen fertilizer), 29 percent of its anhydrous ammonia (another form of nitrogen fertilizer), 26 percent of diammonium phosphate and 13 percent of monoammonium phosphate.

Just to review a little high school biology, nitrogen, phosphorus and potassium are primary nutrients that cannot be obtained from the air or water and must come from the soil. (With regard to nitrogen, legumes such as soybeans are an exception in that they can fix nitrogen from the air for use in the plant.) Adding these primary nutrients to the soil improves the quality and quantity of plant growth. Huge of amounts of two of the three primary nutrients mentioned above are no longer flowing out of the Persian Gulf.

In addition, 20 percent of the world's liquefied natural gas (LNG) is no longer flowing from the gulf. In places such as India, imported LNG is the feedstock for making nitrogen fertilizers in domestic factories. And, there are probably other complications that are impacting fertilizer supplies that I'm not aware of.

The rising price of fertilizer is causing wheat farmers in Argentina to consider using less urea fertilizer which would limit the availability of nitrogen, an essential nutrient. It's either that or plant another crop that won't require so much fertilizer and thus limit wheat production. In Egypt one farmer decided not to grow wheat (which requires a lot of fertilizer) in favor of other crops while cutting the area used for growing to just half of what he normally sows—all because he cannot afford any help this year due to high prices for fertilizer, seeds and other farm chemicals (presumably herbicides and pesticides that often consist of petrochemicals). The American Farm Bureau Federation recently released a survey showing that 70 percent of American farmers cannot afford all the fertilizer they need.

Now, as you may already have surmised, Liebig's law can be applied beyond fertilizer input for crops. Farm equipment runs almost exclusively on diesel. The high cost of diesel came on mostly after farmers in the United States made their planting decisions and so this year will simply eat into profits rather reduce output. But persistent high prices for diesel could lead to decisions to reduce planting or at least shift to other crops farmers believe will be less costly to grow. Clearly, diesel must be considered an essential input just like fertilizers.

But we can also take Liebig further afield and apply his law to essential inputs to the broader society. Energy expert Vaclav Smil has posited four essential inputs required for the modern world: cement, steel, plastics, and ammonia. Ammonia, of course, is essential for the production of nitrogen fertilizers which we've already covered. The other three are ubiquitous enough that their importance to the modern world ought to be self-evident.

Smil notes a connection that is particularly relevant just now because of the cutoff of oil and natural gas from the Persian Gulf: All four essential inputs require copious use of fossil fuels to produce. Beyond these, we are about to find out that the loss of significant amounts of oil and natural gas will limit the production of a very wide array of products for which these fossil fuels and their derivatives are essential inputs—just as Liebig's law predicts.

The danger such limits posed for the global economy were always there for people to see. But there has been a belief that such limits would never arise or if they did, they would only be temporary. That belief is now being tested. If, as petroleum consultant Art Berman says, we are unlikely ever again to reach world oil production levels experienced before the Iran war, then the belief that we face no limits will have to make way for a new reality of constrained production of many of globe's most essential materials.

Kurt Cobb is a freelance writer and communications consultant who writes frequently about energy and environment. His work has appeared in The Christian Science Monitor, Resilience, Common Dreams, Naked Capitalism, Le Monde Diplomatique, Oilprice.com, OilVoice, TalkMarkets, Investing.com, Business Insider and many other places. He is the author of an oil-themed novel entitled Prelude and has a widely followed blog called Resource Insights. He can be contacted at kurtcobb2001@yahoo.com.