Controlled Release Technologies
Controlled Release Nitrogen
Controlled release products are designed to steadily release nitrogen into the soil over a long time frame. This technology consists of urea granules coated with a thin layer polyurethane (polymer). Through osmosis, water diffuses through polymer layer and slow dissolves the core of the urea granule. Over the course of many months, urea slowly dissolves through the polymer layer providing an even, controlled distribution of nitrogen over a large portion of the growing season. Once the nutrition has been depleted, the thin polymer shell is biodegraded naturally by soil microbes, making controlled release technology extremely efficient and environmentally friendly.
TCS Product(s) Available:
Slow Release Nitrogen
Slow release products are designed to provide a slow, even distribution of nitrogen with extra longevity. They are safer to use on turfgrass than traditional fertilizers due to their limited ability to affect soil pH (i.e. lower burn potential). Slow release nitrogen can be further broken down into two technologies: “coated” and “reacted” nitrogen.
Coated Slow Release Nitrogen consists of urea granules coated first with a thin polymer layer, then a modest sulfur layer, and finally a thin wax layer. The polymer layer is designed to slow the release of dissolved urea. The sulfur layer is designed to protect the thin polymer layer. Because the sulfur layer is very brittle and subject to cracking during handling, a thin outer layer of wax is applied to protect the sulfur layer. Together, all three of these layers work to provide the slowest, most consistent release of nitrogen from any coated urea granule available in the market.
TCS Product(s) Available: XCU® (Polymer-coated Sulfur-coated Urea),
SCU (Enhanced Sulfur-coated Urea)
Reacted Slow Release Nitrogen consists of urea granules which are not coated with any polymers, sulfur, or waxes. Instead, formaldehyde is reacted with urea granules to produce both methylene urea and urea-formaldehyde molecules. These new molecules form chains of varying lengths which help prevent against volatilization and leaching. This technology works harmoniously with natural soil microbes. Over time, microbes slowly break apart these chains, resulting in continuous nitrogen availability for up to 26 weeks. Reacted slow release nitrogen is influenced by soil temperature and moisture content.
Stabilized Nitrogen Products
Stabilized Nitrogen is designed to inhibit the conversion of urea into nitrogen products which are no longer readily available for plant use. Stabilized nitrogen products reduce volatilization, nitrification/denitrification rates and leaching potential. In essence, stabilized nitrogen disrupts the nitrogen cycle. It helps urea absorb efficiently into the soil and keeps it readily available for plant use over longer time frames. Stabilized Nitrogen can be divided into two categories: “urease inhibitors” and “nitrification inhibitors.
Urease inhibitors are designed to inhibit the activity of “urease,” a key enzyme in the metabolic pathway of soil bacteria. When urea granules are deposited on the soil surface, they must be dissolved by water to be absorbed into the soil. If bacteria on the soil surface reach urea before it absorbs into the soil, the bacteria convert urea into anomia gas which immediately volatizes into the atmosphere. Urease inhibitors (such as NBPT) prevent this process from taking place.
Nitrification inhibitors are designed to prevent key soil bacteria from converting ammonium (NH4+) into nitrate (NO3). Plants can only absorb nitrogen in two forms: ammonium and nitrate. Ammonium is the preferred form of nitrogen in the root zone because it is a positively charged ion; this means it clings to soil particles until it is encountered and transported by root hairs. While plants can also absorb nitrate, this negatively charged ion makes it susceptible to denitrification (the conversion of nitrate into unusable nitrogen gases) and leaching. Nitrification inhibitors (such as DCD) prevent this process from taking place.