Insulating wooden floor panel with straw

At the moment, the idea is to fill or assemble the insulation like an insulation between rafters with straw bales (which, after all, have a high density). What seems easier for me on the roof is still somewhat uncertain for me regarding the floor slab.

What would the plan be? Is the straw simply "filled in," or are there any preparatory processes it goes through? Filling it untreated would be too risky for me (gut feeling). I think it needs some kind of flame protection and compaction.

Of course, such preparatory processes are necessary, and that brings us back to the problem of chasing our own tail. Meeting today's required building standards plus — and this is the even bigger part — fulfilling our own demands is often hardly possible with simple building materials, unless they are properly prepared, which then usually is un-ecological again. Therefore, the question of ecology and sustainability can only be answered in a very complex way. In the past, many things were built that way and still are in some countries. But there, people live Spartan or even poor out of necessity, and ecology is a foreign word. They simply use whatever is freely available, and if they are cold, they put on their coat or throw a piece of wood into the stove. I basically find the approach exciting, but I would not like the result.

I'll throw in seagrass as insulation.
Of course, it must be insulated to an appropriate thickness.

if the straw bales are to be used as they come from the field, an idea is needed on how to fill the gaps that "remain". (as far as I know, "gaps" in insulation make the entire insulation significantly weaker) ... and these bales are not fire-retardant treated.

In the roof, straw might be blown in, similar to wood fibers in the cavity insulation. Exterior walls would only work with solid wood if panels are glued onto the wood. Concrete slab, I really have serious concerns. Moisture, animals, etc. Then there's the structural stability; the reinforcement probably cannot be placed and connected in straw.

The base plate would be constructed in the same way as the ceiling structure. So no load on the straw.