Imagine the Central Valley of California not as a patchwork of drought-vulnerable crops but as a network of farms that use almost no water. Not only that, these farms can also filter existing water while providing acres of food for Californians. Imagine that thirsty alfalfa no longer reigns: Cactus is king.
This is one potential future scenario for California according to a winner of Dry Futures, a competition sponsored by Archinect to unearth design solutions to the state's drought. There are plenty of intriguing solutions but this one in particular caught my eye as it's one we've talked about here: The power of the prickly pear cactus.
"Grassroots Cactivism" is the name of the concept by Ali Chen, which taps the prickly pear (commonly called nopales when humans are eating the paddles, but you can also eat the bright pink fruit) as a renewable centrepiece of a water purifying system, something it's been used for informally for centuries:
Locals in Mexico have often dumped the water used to cook cactus into polluted rivers and streams. The 'mucilage' or inner cactus pulp has also been tested and used in oil spills. Cactus pulp was found to disperse crude oil efficiently at much lower concentrations than synthetic dispersants.
In this concept, farms of prickly pear cactus would replace traditional "treatment plants," helping to recycle wastewater without using additional energy, while producing a water-efficient crop that can feed local residents. Assuming the cactus can effectively act as a cleaning agent as described, this seems like a brilliant idea.
Curiously, this concept won the speculative category but it's clearly not that far-fetched. We reported earlier this summer on a study by Oxford scientists which highlighted the prickly pear as an important water-efficient source of bioenergy. And of course the part where you can eat both the energy source itself if necessary as well as its highly nutritious fruit as a byproduct is a huge bonus. Can't say that about coal.
With all this talk about what food makes sense to grow where, and which plants are simply converting tons of water into empty calories, cactus appears to be a clear winner as far as agriculture goes. The fact that it can also clean water makes it seem like a super-crop. Who can help make cactus the next kale?