In fact, modern agriculture has become completely dependent on using phosphate rock as a basis for fertilisers, says Cordell. “We have essentially become addicted.”
The trouble is that the global supply of that rock is running out. According to Cordell, “current global reserves will be depleted in 50 to 100 years.”
That’s a figure broadly echoed by Dr Richard Simpson, a senior scientist with the CSIRO’s Sustainable Agriculture Flagship.
“We know the high quality phosphorus reserves in the world are pretty finite,” Simpson says. “It may be 70 years, 90 years, maybe 150 years away before they are exhausted, leaving us with sources of phosphorus that will be more expensive to use.”
This is yet another reason for adopting land-saving New Urbanism across the western world. Our cities could shrink to 10% or 20% of their size, and the 80% that was abandoned could be reclaimed and REPLENISHED as agricultural land. Cities and suburbs are always changing, and houses are always aging and being torn down. If the right REZONING laws were adopted, natural attrition (aging and demolition) of old homes would do the job in 50 years. When a home is torn down, just don’t replace it. The government can and should subsidise people moving into the new population dense CBD’s and New Urbanist townships. It’s not impossible. Portland has already pretty much done it.
Consider that Berlin uses 20% of the land of Sydney while having roughly the same population. Imagine Sydney freeing up the other 80% of our land for local agriculture! Sydney gets so much more rain than over the mountains in our traditional farming regions. But the focus here of course is that phosphorus could more efficiently be returned to agricultural land if agriculture was right next to our living quarters.
With the rise of Seawater Greenhouse technology which makes mass desalination possible, maybe one day we will see real eco-cities out in deserts, gradually reclaiming human caused deserts like the ever growing Sahara. Maybe with water, biochar, and some clever ecocity architecture and biofarming we’ll bring even deserts back to life. But that’s a future project. Right now, when so much has to be done so fast just to wean off oil and coal and gas in time to adapt to both climate change and peak fossil fuels, surely clever city design should be part of the picture to also help prepare for peak phosphorus?