Always use composted manure
Unless you are starting a new bed that you don’t plan to plant for some time, it’s best to use composted manure in the garden. Fresh or raw manures are more concentrated in nutrients and will burn your plants. Sheep and especially poultry manure are considered “hot” and may burn seedlings and transplants, inhibit seed germination, or make your perennials grow so fast and thin that they fall over.
Furthermore, raw manure can have an offensive odor, attract flies, and be difficult to transport. Worst of all, it contains pathogens that might make you sick and weed seeds that will spread to your garden. That last point alone sells me on composted manure since the last thing I want to do is pull more weeds.
If you do decide to apply raw manure, do not use it for surface applications or topdressing in already vegetated areas. The high nutrient content may damage your plants. Instead, dilute the manure with soil and hasten the decomposition process by incorporating the manure into the soil surface before the area is planted. Do this in early fall to give the manure time to break down before you plant in the spring. It’s also a good idea to cover the tilled area with mulch or leaves to protect the surface from erosion or throw on some winter rye seed for a cover crop.
Avoid applying manure on areas next to streams or riverbanks. It is important to keep the nutrients and pathogens in the manure away from surface waters. To protect yourself, raw manure should never be used in the vegetable garden and you should always wash your hands thoroughly after working with manure. While the chances of infection from diseases like salmonella (from poultry manure) are not huge, it’s always better to be safe than sorry.