No particular manure provides more nutrients than another, though many gardeners prefer horse and cow manure, which are easier to obtain in large quantities. It should be well rotted, at least a year, as using fresh manure creates the risk of contaminating your produce, or even ‘burning’ it. It should also kill off any disease organisms that may be present in the manure.
Be sure that chicken manure has been well-composted before adding it to your vegetable garden. Bagged chicken manure from a nursery should already be composted, but if it’s fresh, it must be composted for at least 6 months.
For any manure it is good to spread a three-inch layer over your vegetable beds in the autumn, providing a good mulch during the winter, and can be worked into the soil in the spring before planting. Horse and cow manure is good at the bottom of your potato trench as it will quickly rot in and refresh nutrients in the soil for the next crops that follow them. If you are rotating sensibly, the next crops will be things like leaf beet, spinach and other leaf crops along with the likes of broad beans and other lgeumes etc. These crops should not have manure added to the soil for that season, so the manure you put in with the potatos is ideal.