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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]

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Animals
Why Tiny 'Hedgehog Highways' Are Popping Up Around London
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iStock

Hedgehogs as pets have gained popularity in recent years, but in many parts of the world, they're still wild animals. That includes London, where close to a million of the creatures roam streets, parks, and gardens, seeking out wood and vegetation to take refuge in. Now, Atlas Obscura reports that animal activists are transforming the city into a more hospitable environment for hedgehogs.

Barnes Hedgehogs, a group founded by Michel Birkenwald in the London neighborhood of Barnes four years ago, is responsible for drilling tiny "hedgehog highways" through walls around London. The passages are just wide enough for the animals to climb through, making it easier for them to travel from one green space to the next.

London's wild hedgehog population has seen a sharp decline in recent decades. Though it's hard to pin down accurate numbers for the elusive animals, surveys have shown that the British population has dwindled by tens of millions since the 1950s. This is due to factors like human development and habitat destruction by farmers who aren't fond of the unattractive shrubs, hedges, and dead wood that hedgehogs use as their homes.

When such environments are left to grow, they can still be hard for hedgehogs to access. Carving hedgehog highways through the stone partitions and wooden fences bordering parks and gardens is one way Barnes Hedgehogs is making life in the big city a little easier for its most prickly residents.

[h/t Atlas Obscura]

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environment
Germany Wants to Fight Air Pollution With Free Public Transit
Michael Gottschalk, AFP/Getty Images
Michael Gottschalk, AFP/Getty Images

Getting people out of their cars is an essential part of combating climate change. By one estimate, getting people to ditch their two-car household for just one car and a public transit commute could save up to 30 percent in carbon dioxide emissions [PDF]. But how do you convince commuters to take the train or the bus? In Germany, the answer may be making all public transit free, according to The Local.

According to a letter from three of Germany's government ministers to the European Union Environment Commissioner, in 2018, Germany will test free public transit in five western German cities, including Bonn. Germany has failed to meet EU air pollution limits for several years, and has been warned that it could face heavy fines if the country doesn't clean up its air. In a report from 2017, the European Environment Agency estimated that 80,767 premature deaths in Germany in 2014 were due to air pollution.

City officials in the regions where free transport will be tested say there may be some difficulty getting ahold of enough electric buses to support the increase in ridership, though, and their systems will likely need more trains and bus lines to make the plan work.

Germany isn't the first to test out free public transportation, though it may be the first to do it on a nation-wide level. The Estonian capital of Tallinn tried in 2013, with less-than-stellar results. Ridership didn't surge as high as expected—one study found that the elimination of fares only resulted in a 1.2 percent increase in demand for service. And that doesn't necessarily mean that those new riders were jumping out of their cars, since those who would otherwise bike or walk might take the opportunity to hop on the bus more often if they don't have to load a transit card.

Transportation isn't prohibitively expensive in Germany, and Germans already ride public transit at much higher rates than people do in the U.S. In Berlin, it costs about $4 a ride—more expensive than a ride in Paris or Madrid but about what you'd pay in Geneva, and cheaper than the lowest fare in London. And there are already discounts for kids, students, and the elderly. While that doesn't necessarily mean making public transit free isn't worth it, it does mean that eliminating fares might not make the huge dent in car emissions that the government hopes it will.

What could bring in more riders? Improving existing service. According to research on transportation ridership, doing things like improving waits and transfer times bring in far more new riders than reducing fares. As one study puts it, "This seldom happens, however, since transport managers often cannot resist the idea of reducing passenger fares even though the practice is known to have less impact on ridership."

The same study notes that increasing the prices of other modes of transit (say, making road tolls and parking fees higher to make driving the more expensive choice) is a more effective way of forcing people out of their cars and onto trains and buses. But that tends to be more unpopular than just giving people free bus passes.

[h/t The Local]

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