How long does it take manure to decompose?
Manure, fresh out of the back of a horse, is not a lot like dirt. It is quite recognisable as mushy grass. Manure from a cow is more decomposed and largely amorphous brown. Clearly there are different types of manure and they can take different times to “decompose”. Even the definition of decompose is variable. Some people are happy to put it on their roses after a few weeks standing in the rain, others want it thoroughly composted, it won’t reach the stage of being mostly humus for many years, and even humus continues to decompose very slowly. Piled high for hot composting, any manure or even organic matter that hasn’t been through an animal, will reach a state more like soil than plants within just a few weeks. Smaller piles, or piles without the right levels of air and water, will take several months. Manure that is dried and then kept dry will last more or less indefinitely without decomposing.