Coping without rock phosphate

Rob Haward - 10 February 2011

Rob Haward: Rock phosphate supplies globally will be exhausted inside the next 70 years according to Professor Carlo Leifert from Newcastle University. The application of rock phosphate in organic and non organic farming is needed for plant growth – encouraging root development and helping plants make DNA. Organic farmers try to recycle as much phosphate through returning crop residues to the land and making use of compost and manures – but there is a missing link in the chain when food (containing phosphate) leaves the farm. The organic standards do not allow the use of sewage sludge on organic land – one potential way of completing the circle. While this remains the case, organic farmers will continue to need to apply rock phosphate when their soils become depleted of phosphorous.

But this reliance cannot continue. Professor Carlo Leifert from Newcastle University, presented more pessimistic  predictions showing  phosphate supplies could run out in the next 30 years.  The problem is exacerbated by the location of the global sources of phosphate. Europe imports all its phosphate from outside of the continent. The Chinese have a fair bit – but they understandably want to keep it for themselves. Supplies from North Africa look increasingly precarious. Even if political access doesn’t become restricted the energy required to keep digging it up could soon become prohibitive.

Waiting for fifty years until the problem is upon us doesn’t seem to be a wise solution. One solution appears to be rethinking the use of sewage sludge, which is not allowed in organic farming across Europe. There have, in the past, been lots of good reasons for organic farmers and growers to avoid sewage sludge. The treatment processes haven’t historically given adequate reassurances that contaminants like heavy metals are completely removed before being used on the land. But technology in the treatment of sewage sludge has developed – so contaminant concerns should no longer be a barrier.  The real obstacle seems to be consumer perception – organic carrots fertilised with human excrement is not an easy story to portray to even the least sensitive consumers. But perhaps it is time for us to engage with consumers across Europe on this subject – rather than shy away from it. We might find that it is an absolute ‘no go’ area – in which case we will need to quickly respond to opinion and look for other solutions. But we also might find that the with more education and engagement the barriers aren’t quite as solid as we perhaps think.
 

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Comments



Debal Deb
08 April 2011 11:12

One of the best source of P is the night soil - if decomposed by aerobic bacteria, for instance in a dry toilet. Most of the P input to my organic farm is the EcoSan system. Because our farm food is bereft of any heavy metals and antibiotics, the inputs from the EcoSan is safe for the soil organisms and the food that grow on the compost.

Debal Deb
08 April 2011 11:09

A great source of P is the night soil, decomposed by aerobic bacteria - as in dry toilets. Most of the P input into my organic farm is from the EcoSan system on my farm, and because there is no heavy metals nor antibiotics in the food from our farm, there is no risk of contamination. EcoSan seems to be the best solution for repleting nutrients of the farm soil.

Barrie Bain
16 February 2011 18:09

Carlo Liefert's numbers on phosphate reserves are way out of date - latest estimates are 300 years - but that is not a reason to be complacent and we need to cut phosphate losses in the food chain. Exagerating the problem doesn't help the case for better use of phosphate resources. Most phosphate that goes into animal feed is already recycled in the form of animal manure. Recycling of sewage is the obvious way to reduce losses to the system from the human food chain. Products like struvite, produced from sewage waste, could provide a socially acceptable and safe way to recycle phosphate. A lot could also be done by reducing and recyling food waste.

Samuel Gamester
14 February 2011 18:12

Is it possible to extract phosphate from the sewage treatment process for long-term storage either chemically or biologically? Can we efficiently use sewage to grow green manures which are harvested 'clean' and composted as an intermediary stage for use as fertiliser on crops? Whatever we do our hand will be forced by nature at some point, so it makes good sense to begin the educational work now.

mark houghton brown
11 February 2011 19:05

Well said Rob. One problem is that organic is a consumer led movement and consumers dont seem to be ready for this; i have observed a number of large scale discussions on the topic and the public response is overwhelmingly -"YUK" and organic leaders dont seem to be very brave about the issue either, claiming that he time is not right.

Michael Dimock
11 February 2011 15:07

So important to increase focus on this looming reality. It is so basic and yet so few understand realities of producing food. People need to awaken to the fragility of the food & ag system so that we can make decisions and act to solve challenges. Peak rock phosphate will force rethink about sewage. Peak oil will force rethink about industrial ag model. Obesity is forcing rethink of processed foods & eating habits. Thanks for your blog from an American fan of SA!

Michael Dimock
11 February 2011 15:06

So important to increase focus on this looming reality. It is so basic and yet so few understand realities of producing food. People need to awaken to the fragility of the food & ag system so that we can make decisions and act to solve challenges. Peak rock phosphate will force rethink about sewage. Peak oil will force rethink about industrial ag model. Obesity is forcing rethink of processed foods & eating habits. Thanks for your blog from an American fan of SA!

Rob
11 February 2011 12:14

Not sure that it is fully on the agenda at a European level - as far as I am aware some European countries are much more anti than us so could bequite a struggle.

Ed Dowding
11 February 2011 10:17

Really good summary, Rob - thank you! It seems this is a glitch in contemporary organic policy. Did I hear Peter Melchett say it was being readdressed?

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