Add a little P, get a load more Poo! Part 5: P reserves and productivity!!

More on the reserves of P!

Van Vuuren et al.’s (2010) highlights predicted use of P from 1970 to 2100. Clearly they think that P reserves are going to last a while; they come to the conclusion that:

• There are no signs of short-term to medium-term depletion
• In the longer term, the depletion of low-cost and high-grade resources will have consequences for future production trends
• Given the impact of resource uncertainty on the assessment of risks associated with P depletion, it is important to pay more attention to data on P resources. Uncertainty was found to play a role in data on P production,
• Phosphate rock depletion may lead to concentrating production to a few countries, thus increasing production costs.
• Major reductions in the use of fertiliser P can be achieved by improving plant nutrition management, better integrating of animal manure and recycling P content in human and/or animal excreta

What is most interesting about the article is that it highlights the different scenarios of P depletion; the figures show their findings:

Cordell et al. (2009) also look at the geopolitics; inequality; economics and relative irony of it all – peak oil has received a lot of attention and it is only necessary for energy and cars (I know hear me out!) whilst P is integral to crop growing, and that ever vital necessity that is food.

The figures below (taken from Cordell et al. 2009) include a pretty graph showing Phosphorous sources over time; it just shows how dependant, or as Cordell et al. puts it ‘addicted’ (2009, 292). 

With high grade P reserves being depleted (Cisse and Mrabet, 2004), and our addiction (Cordell et al. 2009), the debate as to where the next lot of P will come from, which just adds to increased food insecurity and environmental degradation due to a potential in greater mining; this leads to:

• Greater energy use – fossil fuels and GHG emissions.
• Greater waters usage and wastage – particularly in countries where safe water supplies are already an issue.
• Rising prices – of P, fertilisers, agriculture and fundamentally the cost of food).

Inorganic fertiliser alone is not sufficient in restoring soil organic carbon (SOC) that forms through decomposition in situ of organic materials , and attaining the highest yields in crop production  (Su et al, 2006; Liu et al., 2010). SOC is an integral part to the soil and provides plants with capacity to grow due to its properties or absorbing water and nutrients. Fertilisers cannot provide that level of SOC; just another benefit of using manure and other waste material to fertilise the soil.

Turnerand Leytem (2004) looked into phosphorous compound sequestration from, of all things, urine. Their success in fractionating the compounds in two steps furthers the research in attaining P from readily available resources, excrement. Admittedly, this is a much more energy intensive way as well as poorly cost-effective; but it opens the doors to greater utilisation and indeed valuation of what we all poop and pee out.

So a variety of sources point to manure and other forms of excreta as a sustainable and beneficial source of P; not to mention an eventual necessary source!

Happy New Year!!! Lets hope there are a lot less cows farting this year!

Add a little P, get a load more Poo! Part 4: P reserves and losses!

Cordell et al. (2009)’s paper on the story of phosphorous is a MUST READ! 

It is packed full of information on the subject… but I will try my best to extract the useful information. Being half Moroccan (half Italian), I can’t help but rub my hands with glee… the largest stores of P are locating in the country (regardless of what anyone says, Western Sahara does not exist in Morocco; we call the southern provinces… moving swiftly on…!) as shown in the figure below from Elser and Bennet (2011). 

This is however a big problem in terms of global securities and power balances. With turmoil in north Africa and the apparent ‘revolutions’ reaching their 1^st birthday, it is more important than ever that food and the fertiliser used, does not fall into the same fate as it did 3-4 years back with the large prices rises in grains (Elser and Bennet, 2011). 700% price rise in P coupled with the price rise signalled a warning light to governments worldwide. However, as Cordell et al. (2009) and Elser and Bennet (2011) note, the world still is not reacting to this train wreck; they can’t even pull their act together on gas emissions and the Kyoto agreement (COP Durban 2011 round of talks).

One thing is for sure is that if we use less, costs will go down and we are less dependent on another out-sourced commodity that everyone needs. If we all became vegetarian, then we would require significantly less P than a meat based diet, and most of the crop can easily be returned to the soil as residue, recycling most of the P used as a fertiliser. Even so; the largest wastage of P originates in the poor application of fertilisers to soils (8 million tonnes, MT). Leeching of the synthetically produced nutrients results in massive inefficiencies in P management; contaminating ground, surface and coastal waters with high levels of nutrients had led to vast amounts of eutrophication.

Eutrophication is when nutrients (either via leeching direct from fertilisers or poor waste management) added to water bodies causes the growth of organisms; algal blooms are a common example of added nutrients altering the natural ecology of a body of water (lake, sea, estuary, etc.). (Smithand Schindler, 2009) The blooms photosynthesis at high rates, starving most other organisms of oxygen (increased when the blooms die and decompose); creating a hypoxic environment.

Please read more on eutrophication in these sites:

• http://rtseablog.blogspot.com/2011/03/eutrophication-mapping-first-steps-that.html
• http://feastingonnaturalresources.blogspot.com/ This blog, by Megan Smith is great! She also talks about agriculture and environmental issues surrounding the wider debate. I highly recommend her post on Coastal Eutrophication – The impact of Agriculture in Chesapeake Bay

Back to wastes of P and as the figure above (Cordell et al. 2009) suggests, 14/17.5 MT of P go to agriculture; of that only 3 MT make it to our forks. 8 MT is wasted through poor application, and of the 3 MT we consume as food, 1 MT is wasted as spoiled food. By just eating within our means we save 1 MT. through better fertiliser management techniques with save an extra 8 MT. It is easier said than done, but through accurate monitoring of soil nutrient levels, we can guage whether or not the land needs to be fertilised, saving energy, money and effort as well as P. Using more natural fertiliser we can solve some of the problems, by no means is sh… poo a panacea for eutrophication/power insecurities/commodity prices/waste management/agricultural productivity and the like, but it is a step in the right direction!

Reserves of P aren't well documented globally, in fact many researches, scientists, geologists and mad hatters disagree as to how much P there is under ground. Cordell et al. (2009) explores this using a number of different scenarios showing just how long it would take, depending on how much P we need, to finally hit the last nail on the head of the coffin that would be global inorganic P reserves. 

Next part coming soon!

Add a little P, get a load more Poo! Part 3: Video time...AGIAN!

This video is from an Australian Broadcasting Corporation (ABC) did a special on... you guessed it, peak P!


It is a really interesting video investigating the potential for utilising urine for nutrient extraction. I love the toilet! However, the man said that men will have to sit down... errr has anyone ever told him men can aim where they pee? This is very disturbing....


There is also a related article on the website. Please read!