I have a large composter that is easy to turn and all my non meat food scraps and some garden scraps go into that. I sieve my Sycamore leaves and add them. When it is ready I sieve it again and save it until needed.
Makes good compost.

Two hills of 2 year old Sycamore leaves, with wheelbarrow and sieve

I also make soil.

After about 3 years in a pile the Sycamore leaves are crushed down. Again I sieve them into a wheelbarrow. (At this point they make a mulch to keep moisture in flower beds) I add an equal amount of sieved soil from under our trees which include the needles from the Junipers. And I add a small amount of nitrogen. Mix it all together and shovel it into used plastic bags from commercial products. Add water and leave sit in the sun about 2 months, turning several times. Beautiful, enriched soil is the result. I have leaves t