Woody and difficult to break down substances come in three general forms:
- logs and stumps
- small branches
logs and stumps
Logs have a very high carbon to nutrient ratio. This means that, no matter how they are dealt with, most of their mass will be returned to the atmosphere as CO2. All of this carbon represents a huge amount of embodied energy. This obviously makes burning an attractive possibility. Unfortunately, even with very clean burning stoves, burning significant amounts of biomass in an urban environment is not ideal due to particulate matter air pollution.
An alternative is to inoculate them with inoculated dowel or sawdust spawn. This will provide a high quality food source for many years for very little work. It will also provide an easily managed source of CO2. If you have a greenhouse, this is a match made in heaven since the logs benefit from being in a high humidity environment while the plants benefit from CO2 fertilisation. Once the logs are no longer producing, the rotted remains can be used as animals fodder.
The recalcitrance of woody substances to biodegradation makes them attractive as water saving mulch. This is indeed a good use, however because of the high carbon to nutrient ratio (the cause of their recalcitrance) they will, in the short term, rob nutrients from the soil. This means they are only appropriate for use underneath perennial vegetation. Around annual vegetables they will significantly reduce production.
To produce mulch from small branches look for a shredding mulcher. These work by crushing the sticks rather than cutting them with a blade. They are available relatively cheaply from your local big green shed (where lowest wages are just the beginning).
Ideally, woody mulch will be inoculated with an edible mushroom variety. Again, the fungi will benefit from the shade and humidity provided by the overlying vegetation while the vegetation will benefit from the (slowly) released nutrients as the mulch breaks down. Once a mushroom patch is established, new mulch can be added every year or two and you will have a never ending supply of mushrooms.
leaves and grass
Like small branches, leaves and grass can act as a beneficial mulch. However, don’t try putting them through your shredding mulcher as it will jam it. If you don’t have a leaf mulcher, you can pile them up and go over them with the mower (essentially a mulcher on wheels).
Leaf mulch can be used as a bedding for animals or. like wood mulch, can be fed to a mushroom patch. Note that different mushroom species will thrive on wood or leaves so keep your patches separate. You will also need to feed your leaf path more frequently as leaves will be digested faster than wood.