Backyard Aquaponics
A place to discuss aquaponics

Time for something serious...

Whilst climate change appears to have fallen off the radar for a lot of folks in light of the global credit crisis, especially for Kevin Rudd given his recent woefully inadequate emissions reduction targets , there is another big issue on the horizon that we need to start thinking about...peak phosphorus.

The story goes that phosphate rock, from which phosphate fertilisers are derived, the cornerstone of modern agriculture, is actually a finite resource. Unlike nitrogen, phosphorus cannot be fixed by plants and there is no substitute for phosphorus in food production.

It has been estimated that production of phosphorus will peak around 2034 and that known reserves are likely to be depleted within the next century or so.

Some quotes from http://phosphorusfutures.net

"Phosphorus is essential for all living matter, including bacteria, plants and animals..P fertilizer is essential for modern food production and is the limiting factor in crop yields. P is a critical global resource, along side water and energy resources"

"All modern agricultural systems are dependent on continual inputs of phosphate fertilizers derived from phosphate rock. Yet this is relying on a finite resource and current reserves could be depleted this century"

"Phosphate rock is a non-renewable resource that takes 10-15 million years to form from seabed to uplift and weathering"

"P cannot be produced or synthesized in a laboratory. Quite simply, without phosphorus, we cannot produce food"

Fortunately there is some good news. Human excreta, particularly urine, is a readily available renewable source of phosphorus. Treatment and reuse is possible and recovery rates can be quite high. It is possible that the recovery of phosphorus from human excreta, combined with other organic sources, could replace the demand for phosphate rock.

It is important that the community becomes aware of this issue now so that the appropriate policy and technology can be put in place in a timely fashion.

Time to take peeponics a bit more seriously?...

Phosphate rock is not the only source of phosphorus. All living stuff has some amount of phosphorus to add to soil. Bone meal is a standard phosphorus supplement. Manure and urine are both good sources of all the big three. I generally have a far harder time supplementing potassium in my garden since many sources of that also contain high amounts of phosphorus and around here, one rarely needs to supplement phosphorus in dirt gardens.

You're right in that incorporating organic matter into soil adds phosphorus to it, but what was the original source of the phosphorus?

For example, the livestock from which bone meal is derived are raised on grain / pasture that is grown using phosphate fertilisers...

As for having to add phosphate to gardens, we aren't blessed with fertile soils here in the South West, more aptly dubbed 'gutless grey sands' or 'glass beads', and so fertiliser application is required...Also, our soils typically have a low capacity for binding nutrients and tend to shed any that is applied to them..

Another benefit of reclaiming phosphorus from human excreta is that it lessens the nutrient loads to aquatic receiving environments such as rivers, wetlands and estuaries. Given the seriousness of eutrophication in such environments, this is an important point in favour of human effluent reuse.

We need to simply close the nutrient circle. For ages now we have been running an open cycle where we put limited synthetic fertilizers on the ground and keep taking all the ogranic material away and placing it in landfills or septic tanks.

I've regularly been using liquid gold as fertilizer. When I ran tests side by side with miracle grow on container plants with 10% urine, I could see no difference between the miracle grow plants and the urine fertilized plants.

However, about half the urine we produce must be used for the proper composting of the humanure to make sure we get good hot compost that will be safe for use on the garden after it has been allowed to cure for a year.

Some of the urine goes to the pee ponic system and as far as hydroponics goes, pee ponics is pretty darn easy. I still find I need to supplement the pee ponic system with iron and potassium same as the aquaponic system.

Sounds like we are saying a similar thing, just in a different way.

Yep, I think we are!

There are huge phosphate reserves in the USA. I know of one you can see from outerspace near Aurora North Carolina. No way will we be running out as soon as that. Phosphate rock is all over the place.

The free market place controls these things if allowed to do so. If someone sees we are running out, the price goes way up and we look for alternatives. In this case there are plenty of them.

Gibson, TCL is our forum's resident expert on recycling human waste, and it is not just internet research, She has succesful experiments that can really help change the way people think about human waste.

I read the Humanure Handbook by Joseph Jenkens several years back and just had to try it to see if it really did work. We managed to humanure compost in bins on our 9 foot by 9 foot patio when we lived in an apartment. Now it is easy to compost in more normal on the ground post and fencing compost bins.

I got the Humanure Handbook for xmas and am almost finished reading it. TClynx is right, it is worth using as a guide. Some years ago my main toilet pipe (made of asphalt) collapsed and rather than jack hammer it out & remove tub and walls I purchased a Biolet composting toilet. It does not compost the stuff. So I have been storing ithe results in closed top plastic drums. I was planning to set up an anarobic digester to make cooking gas and fertilizer with it. The problem is the 95 deg. F required. Even in summer when 95 in daytime the nightime temp maydrop to 75. The process is reportedly unforgiving.
I had tried conventional composting here with no success. It is very dry here and turning the pile as commonly directed would make the pile dry out even faster than with out turning. The key insight in the book is that with proper layering and humanure no turning should be done. the pile stays hot ,moist, and oxygenated. Yesterday I had to dump my Biolet toilet and did so in a pile of bermuda grass hay from the rabbits, then covered with more hay. It is below freezing every night now so I put an old glass door to loosly cover the pile. Both ends are open. We will see if it heats up and works as per the book. If so, and as time permits I will mix in the stored excreta and hay in the pile.
Another revelation in the book is that oil will readily comnpost if all else is right. I have water contaminated with veggie oil from settling and washing in the process of making biodiesel. I have been storing this and taking to hazardose waste collection annually. I will try it in compost. This low teck process is as exciting and hopefully as rewarding as AP or biodiesel.
If it all works as reported I will take out the remaining flush toilet and install a sawdust bucket, Then I can reclaim all the greywater for irrigation. Remember I live in a desert and have to pump my water from a deep well.
I have had to buy sacks of steer manure and compost for my raised beds. I have also been mulching with bedding and spilled hay from the animals. My soil is still barely able to produce a garden and will only support earth worms in the raised beds. Good homemade compost should be a great boon. The bonus is no load on septic tank or trips to waste recyclers.

The solution for any sustainable future requires we close the loop. Our current society just strip mines everything, uses it for one short pass and moves it a man made mountain of trash. Garden>Food > poo > septic, needs to be Garden>Food>poo>Garden.