Chemical vs. Organic Fertilizers

• Chemical fertilizers are composed of raw chemicals, in powder or liquid form, manufactured and combined in specific well-characterized formulations. Organic fertilizers are derived from unprocessed or minimally processed natural materials, and are often less uniform in composition, less concentrated, and slower and longer acting.
  
  

Complete Fertilizers

• A chemical fertilizer is complete if it contains each of the three major macronutrients: nitrogen, phosphorus, and potassium (N-P-K). Fertilizers provide these elements as inorganic salts, such as ammonium nitrate, ammonium phosphate and potassium sulfate.
  
  

Incomplete Fertilizers

• Some soils contain ample amounts of one of the three major macronutrients. In these cases, an incomplete chemical fertilizer can be used, which does not contain all three (e.g., N-P or N-K).
  
  

Secondary Macronutrients

• Few chemical fertilizers contain all 13 of the elements needed by all plants. If soil or tissue testing indicates a deficiency of one or more secondary macronutrient elements (magnesium, calcium, sulfur), a separate application of a compound containing the desired element can be provided.
  
  

Micronutrient Fertilizers

• A micronutrient fertilizer contains one, a few, or all of the essential elements that plants need in much smaller quantities than the macronutrients. The micronutrient elements include chlorine, iron, manganese, boron, zinc, copper and molybdenum. They can be provided as salts or, in the case of boron, as an acid.