MM Question

Does Peat Moss break down?

It occured to me this morning that vermiculite is stable, we add to the compost of the mix, but not the peat? Doesn't it break down over time, causing our mix to lack something?

On thinking this through a few weeks ago I've come to the conclusion that ...Yes , it will eventually break down into humus , but because you are revitalizing each square when you harvest ready for the next crop you will replenshing the losses with your own quality compost .

Eventually all the peat will have decayed and your beds will be approx 2/3 of home made compost and 1/3 vermiculite .

The vermiculite will also eventually break down into finer particles but it will still have water retention properties along with the 2/3 compost . I suspect the bed will be slightly denser thsn when ayou first find a new bed of MM but this should not affect things too much as there will still be lots of air in the bed .

The compost will because of being put in the boxes at different times over the years also be slowly decaying just like the peat was.

Adding some worms to the beds will add extra nutrients / trace elements

All this being said, yes the sphagnum will break down into humus, continuing to add the compost will feed the plants. There will not be any need to add more sphagnum in the future.