Joe Wolf via Flickr // CC BY-ND 2.0
Joe Wolf via Flickr // CC BY-ND 2.0

What’s Actually Used as Dirt on Rooftop Farms

Joe Wolf via Flickr // CC BY-ND 2.0
Joe Wolf via Flickr // CC BY-ND 2.0

With more people moving to cities than ever before, many are looking to urban farming as the future of sustainable agriculture. But growing crops in the city isn’t as simple as dumping soil on a rooftop and planting some seeds. If farmers were to use real dirt in their rooftop gardens, they’d likely end up with dead plants, leaks, soil compaction, and in extreme cases, ceiling collapse. 

That’s why instead of dirt, rooftop farmers cultivate their crops in something called “growing media.” This futuristic-sounding soil substitute is carefully engineered to mimic the properties of natural dirt and improve them as well. It’s made from a blend of minerals and organic matter, which could include rice hulls, ground coconut husks, pumice, or sand. 

Annie Novak, co-founder and farmer of Brooklyn’s Eagle Street Rooftop Farm, tell Atlas Obscura that compost blends can vary greatly. The growing media she uses at her rooftop farm is made from mushrooms, peat moss, and additional components like perlite (a mineral made by air-puffing volcanic glass) and vermiculite (a mineral particulate).

In order for growing media to be suitable for rooftop gardening, it must first pass a strict set of regulations. In addition to not containing any organic soil, all growing media must be sterile, stable, and capable of properly retaining and draining water while providing enough air for the plants to breath. Nutrients, salt content, and pH levels must all fit specific criteria, and most importantly, the growing media needs to be heavy enough to resist wind and water while not so heavy that it compromises the structure of the roof. 

Today there are only six rooftop farms in New York City, but there's plenty of potential for the city's future. In just New York City alone, there are approximately 1 million buildings with a total of 38,256 acres of roof space. That's a lot of rooftops waiting to be filled with fake dirt. 

[h/t: Atlas Obscura]

The Secret World War II History Hidden in London's Fences

In South London, the remains of the UK’s World War II history are visible in an unlikely place—one that you might pass by regularly and never take a second look at. In a significant number of housing estates, the fences around the perimeter are actually upcycled medical stretchers from the war, as the design podcast 99% Invisible reports.

During the Blitz of 1940 and 1941, the UK’s Air Raid Precautions department worked to protect civilians from the bombings. The organization built 60,000 steel stretchers to carry injured people during attacks. The metal structures were designed to be easy to disinfect in case of a gas attack, but that design ended up making them perfect for reuse after the war.

Many London housing developments at the time had to remove their fences so that the metal could be used in the war effort, and once the war was over, they were looking to replace them. The London County Council came up with a solution that would benefit everyone: They repurposed the excess stretchers that the city no longer needed into residential railings.

You can tell a stretcher railing from a regular fence because of the curves in the poles at the top and bottom of the fence. They’re hand-holds, designed to make it easier to carry it.

Unfortunately, decades of being exposed to the elements have left some of these historic artifacts in poor shape, and some housing estates have removed them due to high levels of degradation. The Stretcher Railing Society is currently working to preserve these heritage pieces of London infrastructure.

As of right now, though, there are plenty of stretchers you can still find on the streets. If you're in the London area, this handy Google map shows where you can find the historic fencing.

[h/t 99% Invisible]

This Just In
What Do You Get the Person Who Has Everything? Perhaps a German Village for Less Than $150,000

Looking for a gift for the world traveler who has everything? If cost isn't an issue and they're longing for a quiet country home, Fortune reports that an entire village in East Germany is up for sale. The tiny hamlet of Alwine, in Germany's Brandenburg region, is going up for auction on Saturday, December 9. Opening bids begin at $147,230.

Alwine has around one dozen buildings and 20 full-time residents, most of them elderly. It was once owned by a neighboring coal plant, which shut down in 1991, soon after East Germany reunited with West Germany. Many residents left after that. Between 1990 and 2015, the regional population fell by 15 percent, according to The Local.


In 2000, a private investor purchased the decaying hamlet for just one Deutsche Mark (the currency used before the euro). But its decline continued, and now it's up for grabs once more—this time around, for a much-higher price.

Andreas Claus, the mayor of the district surrounding Alwine, wasn't informed of the village's sale until he heard about it in the news, according to The Local. While no local residents plan to purchase their hometown, Claus says he's open to fostering dialogue with the buyer, with hopes of eventually revitalizing the local community.

[h/t Fortune]


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