COMMON HOUSEHOLD AND LAWN PRODUCTS:FERTILIZER.

FERTILIZER

Plants require a number of different chemical elements to grow. The elements carbon, hydrogen, and oxygen are readily available from water and air and are required for plants to thrive. Other essential elements required by the plant are called macronutrients and include nitrogen, phosphorus, and potassium. These elements are basic building blocks for the amino acids that make up proteins and ultimately plant cells. These elements are the key to healthy plants. Molecules that make up the membranes of cells all contain phosphorus (phospholipids), nitrogen is important for the synthesis of amino acids, which all contain nitrogen, and potassium is essential to the metabolism of plant cells. If these macronutrients are absent, it severely limits the growth rate of the plant. The decay of dead plants in the soil is a source of these essential elements. Nature recycles the elements from dead plants to produce healthy growing plants. The purpose of fertilizers is to provide the elements that the plant needs to grow in easily available forms. Many fertilizers supply nitrogen, phosphorus, and potassium. The availability of these macronutrients seems to be the major limiting factor in plant growth. Carefully reading a bag of fertilizer, one will notice a series of three numbers on the bag. These numbers tell you the available percentage of nitrogen, phosphorus, and potassium found in the fertilizer. Although fertilizers mainly provide these macro- nutrients, a number of other elements, called micronutrients, are required in much lesser amounts to help plants grow. When looking at the periodic table, it is interesting to observe that only twenty-five of these elements are considered to be essential for plants and animals. Trace elements required for normal plant growth include boron, copper, iron, manganese, zinc, and molybdenum. Copper is important in the reproductive stage of the plants. Deficiencies in copper limit the yield and quality of the fruits and seeds, the products of reproduction humans typically con- sume. Manganese and molybdenum are essential for nitrogen metabo- lism and fixation. Iron is critical for photosynthesis and respiration. Zinc is essential for sugar regulation and enzymes that control plant growth. One danger of fertilizers is inherent to the available nitrogen source. Nitrogen in the form ammonium nitrate is the most widely used and can make up 10 to 40 percent by weight of a bag of fertilizer. Unfortunately, ammonium nitrate is a powerful explosive, and fertilizers can be misused with disastrous results, as in the Oklahoma City bombing.