Cypripedium?

[Vinny 123]

I have never heard that moss has some kind of symbiote to convert molecular nitrogen to a compound usefull to the moss - my experience/learning goes no further than legumes and clovers. Nitrogen compounds in the air were significant in the past, but not today in most of the world.

https://www.sciencedirect.com/science/article/pii/S2351989421003413#:~:text=The%20nutrient%20source%20of%20Sphagnum%20is%20limited%2C%20and,as%20phosphorus%29%20and%20result%20in%20a%20nutrient%20imbalance.

Sorry, any logic about oxygen transport and aerobic v. anaerobic conditions is well beyond my knowledge, although, from a very great deal of personal experience, most soils/detritus that forms the beds and banks of water courses are anaerobic - if they are pierced or disturbed they very commony produce hydrogen sulphide and are routinely black.

[partisangardener]

I read through your link and it says that there is a critical load of nitrogen for sphagnum. But it uses nitrogen too. (I observed several fungi present in Sphagnum. Found never life one without these)
The critical load of nitrogen in Sphagnum is certainly lower than for our crop plants. They do have a critical load too as every farmer knows.

The detritus banks you mention are the habitat for many plants which are able to transport oxygen from the air into this "dead zones" to keep their roots alive, which are the habitat for microbes avoiding free oxygen. Higher plants should have means to respire or they will die.
Most peat bog plants cant do this. Many plants which are able to do this, need more fertile substrates to thrive than peat bogs mostly offer.
These banks you mention are often quite fertile.

The problem these plants usually provide  are apart from the constant water supply are quite different.
I will get in spring some specialists for this situation. They would like your setting.

In my troughs I will have to adapt a bit. My rafts will have to be so thin that the substrate is always submerged in water.  Then I might have the conditions I want.  Probably I will have to add some stones to let it submerge.

One of the main advantages my system offers is the superior and greatly adjustable water reservoir. Not necessary if I live there and can control it regularly.
It does not need in case of absence some plant affine person to look after.

Nitrogen levels in the air are still very high and a thread to Sphagnum bogs and rough pasture with their rare flowers especially in Europe. From traffic it decreased since 1990
quite a bit, but agriculture is still very high. We are still far from the preindustrial level in most areas.