Is Humanity Really Going to Starve to Death in Twenty Years Because We Will Have Run Out of Potash and Phosphorus Fertilizers?

Don’t believe everything you read. Even if it’s published by the respected journal “Nature”.

A week ago, my eyes about popped out of my head as I read the “World View” column in “Nature” featuring Jeremy Grantham:

Then there is the impending shortage of two fertilizers: phosphorus (phosphate) and potassium (potash). These two elements cannot be made, cannot be substituted, are necessary to grow all life forms, and are mined and depleted. It’s a scary set of statements. Former Soviet states and Canada have more than 70% of the potash. Morocco has 85% of all high-grade phosphates. It is the most important quasi-monopoly in economic history. What happens when these fertilizers run out is a question I can’t get satisfactorily answered and, believe me, I have tried. There seems to be only one conclusion: their use must be drastically reduced in the next 20–40 years or we will begin to starve.

If you don’t know who Jeremy Grantham is, he’s a British investor who is co-founder and chief strategist of GMO, a Boston-based asset management firm managing more than $97 billion. Recently, he’s taken on the subject of the future challenges of global agricultural production, and takes a rather dismal view. Readers love doom in agriculture, and his latest quarterly letters have gained him a devoted following. I’ve begged to differ with a few of his takes on issues as I’ve read these reports, but have kept silent, as I’m not paid to do what he does.

But, after I read the above quoted paragraph, I aborted everything I was doing that day to begin my rebuttal to this outrageous statement. My article was about half-done and that is the way it will stay, because I discovered that Tim Worstall over at Forbes had already written a superb response titled, “What Jeremy Grantham Gets Horribly, Horribly, Wrong About Resource Availability.” What he writes does not only apply to these two fertilizers, it applies to most element mining. He explains to us the difference between reserves and resources. If this is a subject that interests you, you must read Worstall’s writing.

The subject of phosphate and potash fertilizers is frequently mentioned in limits to growth circles as being a defining limit for our future survival. Like every issue when one digs deeper, this is not a simple subject. A current study which you might read about fertilizer reserves is “NPK – will there be enough plant nutrients to feed a world of 9 billions? Supply of and access to key nutrients NPK for fertilizers for feeding the world in 2050″, by Maria Blanco. She mentions the failure to see that the nature of reserves is dynamic.

The USGS publishes official updates on potash and phosphate rock reserves. Blanco, like Worstall, conclude that though there may be official stated reserves of these fertilizers of 300-400 years, they will last far beyond that.

Certainly, however, in the never-ending quest for the best farming methods, those which use less phosphate fertilizer, or reuse it, should be encouraged. That applies to all farming inputs.

To demonstrate the variability of this subject, the farm that I grew up on, and much of the soil in Nebraska doesn’t require potash fertilizer. Before farmers fertilize, they need to know what they lack by doing soil studies, and many fertilizers are overused today. A very interesting soils study which I covered previously also demonstrates the dynamic demand side by showing that some U.S. soils showed increased potassium levels after growing nutrient-hungry corn on them for many years, something that couldn’t be explained by the researchers. There is a reason that PhD’s are awarded to those serious about the study of soil chemistry and science.

We must remember the dynamic nature of soils due to their live inhabitants, too. Mycorrhizal fungus greatly amplifies the ability of plant roots to uptake and reuse phosphorus, for example. There are many other living micro-organisms in healthy soils which are also affecting the supply, balance, and uptake of nutrients by plants.

Farming practices and crop choices also affect which soil nutrients are required. Animal and human wastes and urines contain nitrogen, potassium, and phosphorus and have the potential for recycling. The basic crop and livestock rotation practices of yester-year feed the soils naturally. Agroforestry is all about tree roots fixing nitrogen and potassium to better grow crops in the poor, depleted soils of Africa and elsewhere. Genetic technology holds hope for decreasing specific nutrients required for growing specific crops. And in industrial agriculture, precision agricultural methods are being used so that only the amount of nutrients needed are used, specific down to small areas within fields.

It’s not simple. As the Indigo Girls would say, “There’s more than one answer to these questions,” Jeremy.

9 thoughts on “Is Humanity Really Going to Starve to Death in Twenty Years Because We Will Have Run Out of Potash and Phosphorus Fertilizers?

  1. mikeb

    I read the Forbes article.

    I don’t know Grantham and have no idea if he’s right or wrong. But in the article rebutting him, the writer says something I cannot take seriously:

    “Ore is an economic concept, not a natural world one.”

    So if we just think hard enough–or throw enough money around–ore will show up?

    1. Regulus

      The concept is simple. Whether a mineral can be considered a refinable ore depends upon multiple economic and technological (ultimately economic) factors. Foremost among those factors is the price of the finished material on global markets.

      One dimensional thinking will not solve many problems in an increasingly complex world. But one dimensional thinking is all that doomers have got.

    2. Landbeyond

      I have not read the Forbes article, but have attempted to debate Tim Worstall in the past, and that quote sounds typical of his smug, closed-minded approach to topics he doesn’t understand.

      He also refuses to believe that peak oil is a valid concept because there is a lot of oil in the ground. He refuses to address arguments to the contrary, preferring a childish insistence that he is correct, and likes to retreat to what he claims is his area of expertise – rare earths.

      Okay; after writing the above I thought it only fair to actually read what Worstall wrote. It’s still the snide, simple-minded tosh I recall from a year or two ago. Get this: in his whole article about reserves/resources, the word “energy” does not appear once. For Worstall, technology and “cost” are all that stand in the way of extracting from the earth’s crust every last molecule of any useful substance.

      Worstall is a fool.

      K.M. should complete his rebuttal of Grantham, but since his own article doesn’t refer to energy either I’m not sure it will be any more valid.

      1. K.M. Post author

        1. I’m not a he.
        2. I’ve written more about energy and agriculture than any other site out there.
        3. I am well aware of the concept of energy depletion and it concerns me a great deal.
        4. I figure that if Canadian tar sands mining is going on a hundred years from now, that fertilizer mining surely will be.
        5. You need to look at the slack in the system that we are living today. Removing that slack gives us a lot of leeway for mining fertilizers in the future.
        6. I agree that Worstall “might” be on the cornucopian side of the issue. But I also think his perspective is a very valuable one.
        7. Technology is a wildcard that can’t be predicted. Keep an open mind.

        1. Landbeyond


          The concept of energy depletion bothers Mr Worstall not one whit.

          Given diminishing energy returns overall and in tar sands in particular, I rather doubt such mining will be going on a hundred years from now; and diminishing available energy and diminishing returns for energy expended on fertilizer mining put rather a large question mark over that.

          If I understand what you mean by “the slack in the system that we are living today” it seems likely that slack will disappear rather quickly as we descend the energy curve with little preparation, thanks partly to the likes of Worstall being given a platform from which to regularly mislead the uninformed.

          I keep an open mind; I don’t even dismiss the possible realization of the singularity. But I also try to stay within the bounds of logic and rational argument.

          Worstall isn’t as much a cornucopian as he is a self-satisfied, stubborn know-it-all who thinks economics trumps physics. This is someone who can write, as he did in response to me last year:

          “Here are my two basic contentions again:
          1) There’s plenty of oil around.
          2) Even if there isn’t, even if “peak oil” really is here, it doesn’t mean very much. For we can and will adapt to other energy sources, can and will adapt to the higher prices for oil.
          Now I know you disagree with me on both these points. But that isn’t the same as you having convinced me that I’m wrong on these two points. So, yes, I do dismiss, as I have done, peak oil as nonsense.”

          This is a perspective in which I see only negative value.

          The study you cite, in contrast, takes energy very much into account. Whether it fully recognizes the potential future effects of energy depletion on the obtaining of plant nutrients is another matter.

          If you still believe you can provide a valid rebuttal of Grantham, since Worstall’s attempt was a dismal failure, perhaps you should go for it.

  2. Hal

    The problem with the whole “reserves vs resources” argument is that it assumes an unending supply of energy and technological innovation to make those heretofore uneconomical and forever decreasing quality resources into reserves. While there may be some validity with respect to innovation (I certainly hope so), the same cannot be said for energy. No matter what you do, it is going, on balance, to take more energy to mine and process into commercial products ores that are 0.1% mineral than it did to do the same when the content was 10%. Not necessarily a 1:1 increase, but there are hard physical limits to what you can get energy to do.

    Now energy is, in the forms we use, especially in agriculture, primarily also a mineral resource. It is simultaneously going through the same process.

    The other problem is that as more energy and labor (technology at some stage of the process) is diverted into mining and processing, that leaves less for other uses. I could make a complicated case about that, but to cut to the chase, it means those resources will be more expensive in real terms compared with other goods. When you’re talking about food, this is a problem, if not in developed countries where we pay a small portion of our incomes on food, then definitely in the rest of the world.

    The rest of KM’s thesis is that the whole use of fertilizers and agriculture should be done a lot more efficiently. Well, of course, I think that is what anyone worried about a shortage of those minerals would be driving at.

  3. Brian

    Thanks for this article. As and Indiana corn and soybean farmer N, P, and K are certainly vital parts of my profession. I’ve never been concerned about running out of inputs in my lifetime, but I have wondered how long they will last.

    If for no more selfish reason than my own monetary well being I would love to use less inputs and raise a better crop each year. This is why we have been soil testing and using variable rate technology to apply potash and lime for quite a few years now.

    I’m not informed enough to speak on how finite some of these resources may be, but I can tell you that farmers are always looking for a way to reduce costs and/or pad the bottom line. Here’s to more corn and beans on less fertilizer in the future!

    1. Landbeyond

      Well put. Cheap energy has been such a constant in the lives of everyone now living in the developed world that getting across the importance of the availability of energy to doing anything is uphill work.


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