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Of all the elements necessary for healthy turfgrass, nitrogen is probably the most important to understand, and is discussed at greater length than any other fertilizer constituent. Nitrogen (with an atomic symbol of N), along with phosphorous (P) and potassium (K) are the primary nutrients considered in fertilizer formulas and are represented by the numbers on fertilizer container labels. In addition to the big three (N, P and K), plants require carbon, hydrogen and oxygen which they receive from air and water. Secondary nutrients include calcium, magnesium and sulfur. Another seven nutrients; boron, chlorine, copper, iron, manganese, molybdenum and zinc are needed as well.

Turf fertilized by waste from certain animals can develop an aggressive nature and may eat small dogs and cats.

The attention on nitrogen stems from the problems intrinsic in controlling it. Too much or too little nitrogen can have a profound effect. New plants won't grow without nitrogen and established turf will not thrive if it is starved for nitrogen. Yet, too much nitrogen can cause burning.
Nitrogen in the atmosphere is an inert gas but in soil it is found as ammonium (nitrogen + hydrogen). Nitrification bacteria convert the ammonium into nitrate (nitrogen + oxygen) and in the process release nitrogen in a form that is usable by plants. Nitrogen is available from many sources but to the turf manager the choice is most often a question of natural "organic" sources or inorganic "chemical" sources. The difference between them can be significant but generally, organics are slow releasers of nitrogen while inorganics release quickly. This difference has to do with their solubility.
The chemical sources tend to release easily in water and move quickly through soil. This characteristic leads to high volatility. Nitrogen can be lost, leaching away from root areas or through ammonia volatilization. This happens when urea and urea-containing fertilizers are placed on lawn surfaces. Rather than being released into the soil, the nitrogen converts to an ammonium form of nitrogen and is lost to the atmosphere.
Denitrification of the soil usually occurs when soils with a high level of organic matter remain under water for long periods. Organisms that aren't able to get air any other way take oxygen from nitrates (molecules made up of nitrogen and oxygen) and free the nitrogen that then escapes into the atmosphere.

Quick or Slow Release Nitrogen Source
Inorganic fertilizers fall into three categories: quick release, slow release and reacted.

Inorganic Quick Release
These fertilizers are water soluble and can be used immediately by the plant, or become quickly available to the plant through nitrification. These are the well-known "quick green-up" nitrogen sources that have to be applied frequently at low rates because they are used up and can leach out of the soil quickly. These can also cause burning.

Inorganic Slow Release
These are quick-release inorganics that have been "encapsulated" either in sulfur, plastic or resin to slow their release. This makes them insoluble or slowly soluble in water. These manufactured slow-releasers can be applied less frequently and produce slower, more uniform action.

Reacted Controlled Release
These inorganics have controlled solubility in water and release some nitrogen through microbial action. The nitrogen release is gradual but excessive moisture can cause a burst of plant growth. Reacted chemical fertilizers are low in salt and tend not to burn.

Organic Fertilizers
These are nature's fertilizers derived from animal or plant waste. Their release is very slow and depends to a large extent on weather. Warmer temperatures activate the microbes that must digest the material to release the nitrogen. Leaching is not a problem with organic fertilizers.

Fertilizer Management
Organic fertilizers are naturally timed for normal vegetation growth cycles. While this makes Mother Nature happy, it doesn't always do the same for a landscape maintenance company's clients.
Successful fertilizing strategies often include long-term organic fertilization with inorganic treatments for short term or spot problems. Balance is essential to any fertilizing program.

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