Chapter 12

Fertilizers

(book excerpts)

When the elements that are essential for plant growth are not present in sufficient quantities or in the proper balance in agricultural systems, supplemental nutrients (i.e., fertilizers) may be necessary to ensure optimal crop growth and profitability. Fertilizers are generally defined as any material, organic or inorganic, natural or synthetic, which supplies one or more of the chemical elements required for the plant growth. Industrially manufactured chemical compounds (mostly inorganic and some organic) with high nutrient contents are popularly used as fertilizers. They are called “commercial fertilizers,” “inorganic fertilizers,” “chemical fertilizers,” and “industrial fertilizers.” Commercial inorganic fertilizers are soluble, fast acting, and high analysis materials, with the concentration strictly controlled. They contain nutrients in available forms, and therefore, they are very efficient in correcting current deficiencies. On the other hand, many natural materials such as composts, manures, oil cakes, fish meal, and guano are called organic fertilizers. These fertilizers contain low concentrations of nutrients; so, they are needed in larger quantities. Moreover, their nutrient composition is not fixed; and estimating their required amounts is difficult. Most fertilizers that are commonly used in agriculture contain the three basic plant nutrients: nitrogen, phosphorus, and potassium. Some fertilizers also contain micronutrients, such as zinc, boron, and other metals, that are necessary for plant growth. Not only is it important in selecting a fertilizer that will match the nutrient needs of the crop but it is equally important to consider how a fertilizer can affect soil properties. For example, change soil pH, accelerate soil acidification, and alter the soil crust, which can lead to a decrease in organic matter load, soil biodiversity, and organic matter.

Click on the following topics for more information on fertilizers.

Topics Within This Chapter:

  • Inorganic Commercial Fertilizers
  • Fertilizer Labeling
  • Fertilizer Ratio
  • Other Nutrients
  • Regulatory Standards
  • Single- or Multiple-Nutrient Fertilizers
  • Fertilizer Forms
  • Solid Fertilizers
  • Blended Fertilizers
  • Liquid Fertilizers
  • Solution Fertilizers
  • Suspension Fertilizers
  • Gaseous Fertilizers
  • Fertilizer Salt Index
  • Fertilizer Acidity/Basicity
  • Nitrogen Fertilizers
  • Anhydrous Ammonia
  • Urea
  • Urea Ammonium Nitrate
  • Ammonium Sulfate
  • Ammonium Nitrate
  • Calcium Nitrate
  • Calcium Ammonium Nitrate
  • Nitrogen Fertilizer Volatilization
  • Factors Affecting Ammonia Volatilization
  • Enhanced Efficiency Fertilizers
  • Urease Inhibitors
  • Nitrification Inhibitors
  • Slow-Release Fertilizers
  • Phosphorus Fertilizers
  • Monoammonium Phosphate
  • Diammonium Phosphate
  • Triple Superphosphate
  • Superphosphate
  • Ammonium Polyphosphate
  • Orthophosphates versus Polyphosphates
  • Potassium Fertilizers
  • Potassium Chloride
  • Potassium Sulfate
  • Potassium Nitrate
  • Potassium Thiosulfate
  • Potassium-Magnesium Sulfate
  • Sulfur Fertilizers
  • Ammonium Sulfate
  • Ammonium Thiosulfate
  • Ammonium Phosphate Sulfate
  • Potassium Sulfate
  • Micronutrient Fertilizers
  • Chelates
  • Micronutrient versus Macronutrient Fertilizers
  • Fertilizer Application Methods
  • Broadcasting
  • Fertigation
  • Foliar Application
  • Variable-Rate Fertilizer Application
  • Types of Variable Rate Application Systems
  • Map-Based VRA
  • Sensor-Based VRA
  • Information Key to Efficient Nutrient Utilization
  • Soil Management Zones
  • Reliability of Soil Management Zones