How common manures measure up
Manure Chicken Diary Cow Horse Steer Rabbit Sheep
N-P-K 1.1 .80 .50 .25 .15 .25 .70 .30 .60 .70 .30 .40 2.4 1.4 .60 .70 .30.90
Poultry manure (chicken in particular) is the richest animal manure in N-P-K. Chicken manure is considered "hot" and must be composted before adding it to the garden. Otherwise, it will burn any plants it comes in contact with.
Dairy (cow) manure
Dairy Manure may be the single most useful soil-builder around. Dairy manure from healthy cows is just about perfect for garden use; it can be used as a topdressing and for soil improvement. Dairy manure is preferable to steer manure, which has a higher salt and weed seed content. Though cow manure has low nutrient numbers, that's what makes ist safe to use in unlimited quantities.
Horse manure is about half as rich as chicken manure, but richer in nitrogen than cow manure. And, like chicken droppings, it's considered "hot". Horse manure often contains a lot of weed seeds, which means it's a good idea to compost it using a hot composting method.
Steer manure is one of the old standbys, but it's not the most beloved because it often contains unwanted salts and weed seeds.
cow manure organic fertilizer
Rabbit manure is even higher in nitrogen than some poultry manures and it also contains a large amount of phosphorus--important for flower and fruit formation.
Sheep manure is another "hot" manure. It is somewhat dry and very rich. Manure from sheep fed hay and grain will be more potent than manure from animals that live on pasture.
How to use manure
No matter what kind of manure you use, use it as a soil amendment, not a mulch. In other words, don't put raw manure directly on garden soils. Raw manure generally releases nitrogen compounds and ammonia which can burn plant roots, young plants and interfere with seed germination. In fact, it's recommended that all animal manure should be aged for at least 6 months. Many gardeners spread fresh manure in the fall and turn it in to the top 6 inches of soil a month before spring planting.
A better treatment is to hot-compost manure before applying it to the garden. Hot composting, where the pile reaches at least 150 degrees F) helps to reduce the probability of passing dangerous pathogens on to people who handle the manure or eat food grown with manure compost.
The bottom line
Anywhere from 75 to 90 percent of the plant nutrients fed to animals are excreted in their manure, so it should be no surprise that the stuff is an excellent fertilizer.