Mor about composting or is it mull?
There is a difference between humus and dead organic matter in the soil. Humus is a dark coloured amorphous colloidal liquidy material that leeches out of a compost heap. It seems to have a very complicated chemical make up and is formed when dead plants and animals decay. Animal excrement also seems to be important in its formation. By animals I mean all the mini beasts that live in the litter. It is a colloid and this enables it to retain water and this helps to improve the water holding capacity of the soil. A colloid is a mixture but not exactly a solution of one finely divided material suspended within another material. Humus is usually a colloidal solution. Humus also increases soil fertility and makes it more friable. Humus that is made from more acidic materials such as coniferous trees is called mor. This type of compost is made mainly by fungi decomposing the material. Humus that is more akaline is called mull and is the type that is more likely to be found in allotment soil. Mull is much more likely to encourage earthworms and other small soil organisms.
Really this is what we want to obtain from the compost heap. When the heap goes that friable black soil like material it contains a lot of humus. Putting it on the soil allows microorganisms to finish off the decomposition and turn the humus into nutrients. However, this is a very long process and some material will spend years if not centuries locked up in the soil.
