Types

• Fertilizers provide nutrients that plants need to sustain their growth. According to the EPA's fertilizer page, the three basic plant nutrients most fertilizers supply are nitrogen, phosphorus and potassium. Nitrogen and phosphorus are needed to make nucleic acids like DNA, while potassium plays a variety of vital roles in plant biology. Pesticides are chemicals designed to kill weeds, insects or other undesirable organisms.
  
  

Features

• According to "Essential Environment," thousands of different chemical pesticides have been developed. There are several important chemical and physical properties to consider when evaluating a given pesticide. The volatility of a pesticide, its solubility in water, its half-life (the length of time it takes one-half of the original quantity to decay) and its toxicity to humans and animals are all important characteristics.
  
  

Function

• Fertilizers that supply nitrogen are generally synthesized starting with the Haber-Bosch process, which combines atmospheric nitrogen with hydrogen gas to form ammonia. Ammonia is in turn used to synthesize chemicals like ammonium nitrate that can supply nitrogen to plants. Most phosphate fertilizers are synthesized starting with rock phosphate--rocks formed from minerals high in phosphates--which are used to make phosphoric acid. Ammonia is often added to create fertilizers that supply both nitrogen and phosphorus. Potash or potassium carbonate is a common mineral often used to make potassium nitrate and other fertilizers that contain potassium.