leaf breakdown

[vicmel]

Can someone tell me why it is OK to pile leaves to make leaf mould but not Ok to leave them in beds. Why does disease allegedly thrive in the beds but not in a larger pile?

[Coobeastie]

I'm no expert but think its something to do with the heat generated as the pile mulches down that kills off any nasties.

[rosyrussell]

As leaves break down, the bacteria breaking them down use nitrogen from the soil, thus depleting the nutrient value. That is why you should also not mulch borders with fresh grass cuttings. Once the leaves have broken down, they are fine to use as a mulch, they tend to have a more acidic pH and work well as a soil conditioner.