Low-tech Magazine covered pigeon towers, as previously mentioned on HN: https://solar.lowtechmagazine.com/2016/10/pigeon-towers-a-low-tech-alternative-to-synth

Low-tech Magazine covered pigeon towers, as previously mentioned on HN: https://solar.lowtechmagazine.com/2016/10/pigeon-towers-a-low-tech-alternative-to-synthetic-fertilizers/ https://solar.lowtechmagazine.com/2016/10/pigeon-towers-a-lo... https://news.ycombinator.com/item?id=31885525 https://news.ycombinator.com/item?id=31885525