The gardener must be careful not to use more than the amount recommended on the label. Fish emulsion is a partially decomposed blend of finely pulverized fish. The odor is intense, but dissipates within a day or two. Fish emulsion contains up to 5 percent readily available nitrogen and is a source of several trace elements. Contrary to popular belief, too strong a solution of fish emulsion can burn plants, particularly those in containers.
Animal manure is also a complete fertilizer but is low in nutrients.
Manures vary in nutrient content according to the animal source and what the animal has been eating. Commonly available manures include horse, cow, chicken, and sometimes sheep. As it is aged, leached, or composted, nutrient content is reduced. However, the subsequent reduction in salts will reduce the chances of burning plants. Fresh manure should not be used where it will contact tender plant roots.