Can annual legumes speed decomposition of arborist mulch?

I just laid down a 12" bed of arborist mulch on top of a grassy area for a new apple/pear guild. I intend to pull the mulch back to plant perennials into the soil itself as my understanding is that the soil/mulch zone of contact will be full of fungi/bacteria eating up all that yummy dead stuff and those microbes will compete with my plants for nitrogen. That got me thinking:

If I start annuals legumes like peas and beans in plugs, innoculated with the appropriate rhizobia, and then transplant them, not into the soil, but into the mulch layer itself, will they:

    1) Be able to survive living in mulch alone?
    2) Form nodulated roots in a "soil-less" environment?

My hope is that the legumes will continue to form noudlated roots that extend beyond the the plug, into the mulch. Then, when I cut them back before flowering, the roots will die; the nodules creating pockets of nitrogen, to feed bacteria, to speed the decomposition of the mulch.

My concerns are that the legumes won't have access to the appropriate nutriens to grow (nitrogen isn't everthing) and that the mulch may be too warm for the legumes' root zone.

Has anyone tried growing legumes in fresh arborist chips?
Is there anything I can do to ensure the success of this?
Is there some reason why I shouldn't do this?

I will undoubtedly attempt this, as I have more beans and peas than I know what to do with, but I thought someone here might have some insight.

The chips won’t compete for nitrogen. Planting stuff in them will speed breakdown of the chips by moving the mycelium around faster. But you will have to make some “fertile holes” . Search for threads by Eric Hanson. I can’t remember the thread name but he has extensive documented thread in exactly this. He will probably chime in and give you the link tho. It’s an understatement to say he loves wood chips lol. Really good info

You will have to get the legume roots in contact with the soil under the chips.  The process dose need the plant roots at the soil chip interface to feed the needed sugars into the web so it is a good plan to use plants that also feed the nitrogen fixing bacteria.  As water filters through the chips it will carry the nutrients from the living web that develops at the soil web interface to the roots.

I am going to agree with Hans. A friend of mine tried growing various beans and peas in mulch last summer, and they all showed signs of dehydration and Nitrogen deficiency. They all died before creating enough biomass for what you would want.