Phosphate – Nature’s biological clifftop

by Bruce Jackson, Senior Engagement Manager at GES

As a former science teacher when we studied plants, the focus was often photosynthesis and the nitrogen cycle. However, as a chemist I would always mention the holy trinity of nutrients: PNK as being vital for life. PNK? Phosphorous, nitrogen and potassium. They are available in the soil as nitrates, phosphates and as potassium ions.

Egyptian Permaculture – a possible brake? Photo credit: Wikipedia

Plant life has obviously survived many millions of years with the natural occurrence of these three nutrients in the environment. So, what is the problem? Why the alarmist title?

Well, it is quite simple; with the industrialisation of agriculture and an increase in vast areas of monocultural crop development, we have been using these naturally occurring nutrients at an unsustainable rate.  This isn’t really a problem as we can just add fertilisers to maintain yields, can’t we?

Well, yes, we can and we do. But, there is a problem with the use of fertilisers. If we compare nitrogen-containing fertilisers with phosphorous-containing fertilisers, the problem becomes clearer:

  • Nitrogen is plentiful, it makes up 78 per cent of the atmosphere, and thanks to Herr Faber nitrates can be produced on an industrial scale. Nitrogen can also be fixed in the soil naturally, through the planting of legumes, which is why farmers would traditionally leave fields fallow and plant them with clover.
  • Phosphorous is also naturally occurring in the soil but is not always in a form conducive to being readily available to plants. So, we add phosphate-containing fertilisers, but the phosphates for these fertilisers need to be mined and, like any other mineral, there is only a finite supply. However, unlike many minerals, such as metals, phosphates cannot be truly recycled and once applied are often lost through run-off into the oceans and in the plants themselves.

Using a similar methodology as that used to develop Hubbert’s peak for oil[1], we can estimate that at the current rate of extraction, we will reach a peak of extraction sometime between 2034 and 2048[2]. The implications are many, based upon the estimate that 40 percent of the world’s arable land is limited by phosphorous availability[3], we can envisage: a decrease in food availability, an increase in starvation rates, and drop in population, all with the resultant potential political unrest that this could cause.

There are certain actions which could be taken to slow the decline and shift the peak further into the future:

  1. We could apply fertilisers in a far more efficient manner.
  2. We could develop methods of promoting mycorrhizal fungus growth, allowing plants to access currently unavailable phosphorous.
  3. We could change our farming practices, adopting the use of “no-till” and “permaculture” methodologies.
  4. We could add both human and animal manure to the soil; a natural form of phosphorous recirculation.

Until we put a brake on our current agricultural practices, we are accelerating toward a clifftop and a potential disaster which is, in my opinion, far graver than the potential impacts of climate change.

[1] K.S. Deffryes, “Hubbert’s Peak: The Impending World Oil Shortage,” 2008.

[2] S. White and D. Cordell, “Peak Phosphorous: the Sequel to Peak Oil,” Global Phosphorous Research Initiative, 2008.

[3] G.M Turner, “A Comparison of the Limits to Growth with Thirty Years of Reality,” Socio-Economics and the Environment in Discussion (SEED) working paper 19, Canberra, Australia: CSIRO Sustainable Ecosystems) June 2008; cited in U. Bardi, “Extracted – How the Quest for Mineral Wealth is Plundering the Planet. A report to the Club of Rome”, 2014.

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