Cottonseed meal is frequently used for fertilizing acid-loving plants, such as azaleas, camellias and rhododendrons. Blood meal is dried, powdered blood collected from cattle slaughterhouses. It is a rich source of nitrogen, and it supplies some of the essential micronutrients, including iron. Fish emulsion, a well-rounded fertilizer, is a partially decomposed blend of pulverized fish. The odor is intense but it dissipates within a day or two.
Manure is a complete fertilizer, but low in the amounts of nutrients it can supply.
Manures are best used as soil conditioners instead of nutrient suppliers. Sewage sludge is a recycled product of municipal sewage treatment plants. Two forms are commonly available, activated and composted. Activated sludge has higher concentrations of nutrients than composted sludge and is usually sold in a dry, granular form for use as a general purpose, long-lasting fertilizer. There is some question about the long-term effect of using sewage sludge products in the garden, particularly around edible crops.