Turfgrasses absorb nutrients in the soil through their root systems. If the soil doesn’t provide enough natural nutrients on its own, the turf will suffer.

Turfgrasses use Nitrogen in larger quantities than any other chemical element except Carbon©, Hydrogen (H) and Oxygen (O), which are supplied by air and water. Nitrogen is a vital part of every plant cell, but soils don’t naturally contain sufficient amounts of Nitrogen to sustain turfgrass needs, so fertilizers are applied to provide the necessary nutrients for green, healthy turf.

In Nitrogen-deficient soils, the Nitrogen feeds the younger shoots and leaves first. When this happens, the mature shoots and leaves lose their green color. The blades appear pale yellow to yellow-green. Nitrogen shortages can also lead to slow growth, turf thinning and increased vulnerability to weed outbreaks and certain fungal diseases.

Effective applications of Nitrogen result in the darker green color that people want to see in turfgrass. Proper Nitrogen levels also promote dense turf, stress tolerance and overall quality of the landscape.

Turfgrasses that receive the proper amount of nutrients have a tighter-knit canopy that shades out weed growth naturally. But, landscape contractors can’t rely on fertilizers exclusively to help control weeds. Proper pre-emergent herbicide application is also important.

Most traditional urea fertilizers are highly water-soluble products that release nutrients quickly. Considering the significant amounts of water used to maintain lawns, this can be problematic in the soil’s ability to retain Nitrogen. These fast-release fertilizers release Nitrogen all at once, which means nutrients may not be available to the plant later. Fast-release fertilizers show quick results with fast green-up, but there are drawbacks including propensity for grass burn and more applications needed to keep landscapes healthy. Most fast-release fertilizers are applied every two to four weeks during a growing season.

Slow- and controlled-release fertilizers deliver nutrients to the soil gradually and consistently feed the plant over a longer period of time. These granular fertilizers are manufactured in a way that prevents water from rapidly dissolving the fertilizer nutrients.

Fertilizer manufacturers accomplish this by a reaction with compounds that bind with the highly soluble nutrient sources or by encapsulation of the fertilizer source within a water-insoluble coating. The sole purpose is to prevent 100 percent release of the nutrients immediately following application.

A reaction involving a fertilizer source and an aldehyde is one way to slow the release of nutrients. An example of this is urea formaldehyde fertilizer, which provides slow-release benefits in comparison to straight urea applications.

Controlled-release is the second way coated fertilizer products release the fertilizer source. These do not contain sulfur and can last much longer. Controlled-release fertilizers rely on increases in temperature to drive nutrient release, regardless of moisture levels.

Most research indicates that urea liquid and granular formulations produce very little differences in turf growth and quality—no significant evidence shows one is better than the other.

Warm-season and cool-season grasses require different fertilization schedules. Cool-season grasses are primarily fertilized in the fall, but early spring applications are common as well. Fall feeding enables cool-season grasses to establish good roots for the spring growing season and better prepares these grasses to survive stressful summer temperatures.

Warm-season grasses should begin receiving significant feeding in late spring, with the majority of fertilization taking place during the summer months.

Most situations in turf management involve grasses going into dormancy for varying lengths of time. Nitrogen fertilizer applications should be reduced during this transition so that the plant can focus on storing carbohydrates rather than growth.

A nutrient that leaves its intended application site becomes a pollutant. Of most concern are Nitrate-Nitrogen and Phosphorus, which, through leaching or surface runoff, may move beyond the root system and become unavailable for absorption.

Slow- and controlled-release fertilizers effectively deliver more nutrients to intended plants- nutrients stay in the root zone and feed the plant at the root, which results in green, healthy turf and reduces impact on the environment.