With intentionally wet hay (or similar) I would start worrying about spontaneous combustion. https://news.okstate.edu/articles/agriculture/2020/stotts_braums-f

With intentionally wet hay (or similar) I would start worrying about spontaneous combustion. https://news.okstate.edu/articles/agriculture/2020/stotts_braums-fire.html https://news.okstate.edu/articles/agriculture/2020/stotts_br... https://www.beefmagazine.com/livestock-management/-what-are-your-options-with-wet-hay- https://www.beefmagazine.com/livestock-management/-what-are-... Perhaps worthwhile to annually top with a cover membrane (possibly bioplastic) to control moisture? Maybe even two layers (bottom airtight and top vapor permeable), sandwiching the dry "insulation" to avoid moisture ingress from both sides. If the area-to-volume ratio is so favorable the cost might be managed. Thank you, very interesting proposal and discussion. I'm all for it!