Answer: Manure is best used if composted first. When used fresh it tends to be "hot" and can burn plantings. Horse and cow manure also contain a lot of weed seeds which actually grow better in your garden after having been digested! Composting the manure heats up the seeds and "kills" them. As far as fertilizer quality goes, chicken is the best manure. However, any of the manures (horse, cow, chicken, goat) can be used and they can be combined also. The best way to use the manure is to compost it first. Create a 3' x 3' x 3' pile mixing 1/2 manure and 1/2 brown organic matter such as leaves, hay or straw. Keep it moist and covered with plastic. Then let it cook. (I fully realize how unsavory this sounds...sorry). It should get really hot for about two weeks. After that turn the pile and let it cook again. After about 1-2 months the fertilizer should be ready enough to use in the garden. Another method would be to spread the manure (horse, chicken, goat, cow, etc.) directly on the garden in fall, till it in and let it over winter. You may lose some of the fertilizer benefits, but manure will be well broken down by then. As I mention earlier, spreading fresh manure on young plants can cause them to die from over exposure to ammonia nitrogen.
Once you've composted your manure, you can incorporate it into the soil prior to planting by spreading a 3"-4" layer over the surface of the soil and digging it in to a depth of about 8".
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