Pigeon Towers: A Low-tech Alternative to Synthetic Fertilizers

pigeon-towers-iranPhoto credit: Bekleyen, A. (2009). The dovecotes of Diyarbakır: the surviving examples of a fading tradition. The Journal of Architecture, 14(4), 451-464..

Many societies, ancient and contemporary, have innovated ways of supplying their fields with fixed nitrogen and phosphorus—two crucial ingredients for crop productivity. One is crop rotation, which alternates nitrogen-fixing and nitrogen-exhausting crops. Farmers around the world make use of chickens, ducks, and geese to add “fresh” guano to their fields. Cattle manure is another useful alternative—although it often lacks in phosphorus. Much more labor intensive than simply adding fossil-fuel derived synthetic fertilizer, these practices tend to build up soil, limit greenhouse gas emissions, and lead to less run-off into rivers, lakes, and oceans.

Persian pigeon towers are one of the more elegant solutions to the nitrogen-phosphorus problem. These are essentially castles built for thousands of wild pigeons, strategically placed in the middle of the fields. Their droppings were shoveled up once a year and sold to nearby farmers. While most pigeon towers existing today are in disrepair, the oldest still standing are dated to the 16th century (but they are assumed to have existed over 1,000 years ago) and helped fuel the cultivation of Persia’s legendary orchards, melons, and wheat production.[1] [Read more…]

The Flying Men of Yungas Valley

Wire cables “In Bolivia’s jungles and steep cliffs the Yungas people do not walk. They fly. On ropes. Like birds. Faster than astronauts. These ‘birds’ are known as cocaleros, or coca harvesters. They use ropes to swing across the narrow valleys, suspended from ancient rusting pulleys.” Watch the video. Jerry, thanks for the link. Previously: Aerial ropeways: automatic cargo transport for a bargain.

Drug Catapult Found at US-Mexico Border

Trebuchet “Drug smugglers trying to get marijuana across the Arizona-Mexico border apparently are trying a new approach – a catapult. National Guard troops operating a remote video surveillance system at the Naco Border Patrol Station say they observed several people preparing a catapult and launching packages over the International Border fence last Friday evening.” Read & watch.

Obsolete Technology Prints and Photograph Collections

Tissandier collection

Three wonderful collections from the Library of Congress, showing obsolete technologies.

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Airships Past and Present, by A.Hildebrandt (1908)

airships past and present

Airships past and present – together with chapters on the use of balloons in connection with meteorology, photography and the carrier pigeon” by A. Hildebrandt, captain and instructor in the Prussian Balloon Corps (1908). Pictures, table of contents and list of illustrations below. Related: Camping in the clouds – the zeppelin that never lands / Green slow air cargo / Kite aerial photography.

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The History of Helicopters and Autogyros

Yakovlev helicopter

Entry page. Full list of 787 flying machines. Picture: the Yakovlev VVP-6.