Controlled Release Fertilizer: how does it work?
A controlled release fertlizer is a granulated fertilizer that releases nutrients gradually into the soil within a given period, measured in months, in a controlled way. The formulations are often NPK's with - if desired - secondary nutrients like calcium and magnesium. Also trace elements can be added. To enable a controlled release effect, the granules are encapsulated with a thin layer. This layer - often called a coating - ensures a controlled release of nutrients to the plant. Ekote controlled release fertilizers have a novel coating which is based on organic materials which degrade naturally in time. The polymer coating acts as a reliable membrane which encapsulates the mineral nutrients and protects roots and grass blades from scorching. The coating prevents the nutrients from leaching or volatilisation and releases them over time and in a pattern, synchronized with the crop’s nutritional requirements.
Product longevity of a controlled release fertilizer (release time) is influenced solely by the soil temperature during the application period and not by any other factors such as rain, irrigation, soil composition, soil pH-value and bacterial life. The higher the temperature the faster the nutrient release. When the temperature is lower the release is slowed down and the nutrient release process will last longer. The thickness of the coating initially determines the longevity of the controlled release fertlizer.
After being applied, the coated granule attracts water (moisture) which passes through the coating. The dissolved nutrients are subsequently released into the soil due to osmosis and dissolving. Depending on the product design the nutrients are released over a period from 2 to 18 months. The release period is predictable, no nutrient leaching occurs and the product is safe against scorching.
All formulas are developed in the specific N (Nitrogen), P (Phosphorus) and K (Potassium) combination and release pattern to match the main nutritional needs of the plants during the growing season. The right amounts of secondary nutrients, such as Calcium (Ca) and Magnesium (Mg) are also added to address specific plant requirements or regional conditions. In addition, small but essential amounts of nutrients, such as Boron (B), Manganese (Mn) and Copper (Cu) may be added to promote optimum results and uniform development without deficiencies.