Every year those of us living in temperate climates experience the Autumn fall, and it gives us a great soil improver for the garden. How can gardeners use leaves to help them enrich their soil?
Firstly, leaves decay differently from plant remains. When you compost plant debris it breaks down primarily by bacterial action; however, leaves decay more slowly and do so by by fungal action. You should therefore not include leaves and plant debris in the same composter. You want separate bins for your compost and leaf mould. Leaf mould is also slower to make than compost is. In a few weeks a hot compost heap can have provided some quite good compost, but the leaves will take a few months to decay. Some leaves take longer than others do. Certainly sycamore leaves take more time than most.
You can simply use leaves as a mulch. If you have a fruit tree, you can spread leaves around its base. Spread them in a thick layer to ensure that none of the ground is showing, but do not have them massed against the bark, as mice may hide in the leaves and nibble the bark. With a young tree a spiral guard is useful to protect the bark. Wet the leaves thoroughly after laying them down, so that they will be less prone to blow away. Eventually the leaves will break down, but they will have added some useful organic material to the soil. However, they are not a great source of plant food, but they are a good weed preventer. They do not prevent weeds indefinitely, for as they decay strong weeds will force their way through. But this does not prevent the mulch from being useful.
If you are making a leaf mould bin, you can make it in the same way as a compost bin. I made one out of canes, wire and string. I lashed it all together very firmly, and it survived some quite horrific winds one winter. It should be exposed to the elements,as water is an important factor in fungal decay. Of course, you do not need to make a bin. You can simply use black plastic bags. Fill them with leaves, tie a knot in the top, but then the knack is to press down the middle to make a dent.This allows rainwater to accumulate and drip down onto the leaves, giving them the water that the decay process needs.
It is the leaves of deciduous trees that you should use, as they are the ones that naturally drop. Green leaves are richer in nutrients than those that go brown before they drop. Ash leaves are ideal, as they drop when green. Beech leaves are brown before they drop and provide very little nourishment to the soil.
Leaf mould is a good soil improver. It is not sufficient on its own, as you need manure and compost as well. but it is a part of a gardener's arsenal