By stable waste I literally mean the straw, shavings and manure from our local stable. It is pretty fresh and steaming when it first gets delivered. The stables dump it in heaps just inside our allotment site. I take it about a week after delivery. As you dig into the heaps you can see bits of ash in it in the middle. The plot holders on my site use it to build compost heaps (which I have also done), Some plot holders use it as a thin mulch on cleared beds in autumn.
After discovering your website at the beginning of the year (and then seeing you at the garden museum in March) I decided to start covering areas with your suggested thick mulch. My plot was very weedy as I had had an accident the previous April and had not been able to tend my plot for the most part of the year. My local authority usually has composted garden waste, but this year it has been scarce for some reason and I have not been able to get any.
I was worried that the stable waste would be too fresh, but in most cases it has worked well. I haven’t grown everything this year as I’ve been slowly converting my plot. I grow my plants at home in module trays/pots and have then planted into the beds once they have sat for a few weeks.
I planted my beetroots straight into the beds and they have done really well. The beans & peas (grown in root trainers and loo rolls) were planted into holes made in the stable waste which were filled with proper compost, I also used this method for courgettes, squash, sweetcorn & dahlias. I have had to weed, but not nearly as much as without the mulch. My plot was covered in couch grass and weeds. I’ve also found that the mulch means that I have not needed to water so much. I am on heavy london clay and the ground without the mulch cracks like concrete/ can dry to dust in the summer. When others have been watering, I’ve been able to plant and weed.
I plan to do some experiments next year between compost and stable waste. I will let you know how I get on. I am planning to visit the RHS London show on 1st Nov. I understand you will be there.