Water-soluble chemical fertilizers will injure plants if not washed or brushed off the foliage. Slow-release fertilizers are less susceptible to leaching and are preferred on sandy soil types, which tend to leach. Various salts and minerals can serve as fertilizer materials. Examples are ammonium sulfate, potassium nitrate, super- phosphate, potassium chloride and potassium sulfate. Examples are urea and ureaform.
Cottonseed meal is a by-product of cotton manufacturing.
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.