Nitrogen is a plant nutrient that helps with green leafy growth. In some cases, applying too much nitrogen to flowering plants can cause them to grow very large but some plants may produce fewer flowers or smaller flowers with too much nitrogen. In addition, too much nitrogen, or nitrogen applied at the wrong time, can wash off the surface of the soil and into streams and waterways. This additional nitrogen can cause systemic problems in aquatic environments. Proper use of nitrogen is very good for plants, but excessive fertilization should be avoided.
A number of organic fertilizers contain nitrogen. However, in organic fertilizers, the nitrogen is in a form that plants cannot use. The nitrogen must be converted into another form before it can be used by the plants. This conversion is done by microbes in the soil. Common organic fertilizers that have nitrogen include alfalfa and seed meals, farm animal manures, straw and corn stalks, and wood wastes such as sawdust and wood chips. Because organic fertilizers containing nitrogen must break down before they can be used, it is more difficult to over fertilize when using organic fertilizers.
Synthetic Chemical Forms
The nitrogen in chemical fertilizers is in the form closer to which most plants can use. The base forms of chemical nitrogen fertilizers are called nitrates. In these forms, nitrogen combines with other elements, usually ammonia. Ammonium nitrate fertilizer is a common synthetic nitrogen fertilizer used in small and large-scale agriculture. Another form of synthetic nitrogen fertilizer is urea. However, where fertilizers like ammonium nitrate only require two steps before being usable by plants, urea needs three steps, and thus can take longer to affect plant growth and health. These fertilizers are often the basis of the balanced fertilizers that are used in most home gardens and landscapes.
Blended Chemical Fertilizers
In most cases, the fertilizers used in home gardens and landscapes are a combination of a number of chemicals. The composition of these fertilizers is indicated by an N-P-K number on the packaging. The N-P-K number indicates the percentage of nitrogen, phosphorus and potassium, respectively. These numbers indicate the percentage of each element in the fertilizer. A 10-10-10 fertilizer contains 10 percent of each element. A 50-0-0 fertilizer, which likely contains only a single nitrogen fertilizer, contains 50 percent nitrogen by weight with none of the other fertilizers. Many turf fertilizers are higher in nitrogen than the other two elements. With chemical fertilizers, follow the directions on the package to avoid potential problems with root and plant burn caused by over fertilization.