Slow Release Fertilizer
Definition - What does Slow Release Fertilizer mean?
Many fertilizers on the market are marketed as "slow-release" or "controlled release" formulas. This term refers to how fast the fertilizer ingredients are taken up by the plants. Slow-release fertilizer is slightly different than controlled-release fertilizer, but they share many of the same qualities and provide many of the same benefits to growers.
Many gardeners choose to use slow-release or controlled-release fertilizer products because they are easy to use and provide long-lasting results. These slower-acting products are an alternative to quick-boost liquids.
A slow-release fertilizer releases nutrients to plants slowly over some time. Slow-release fertilizers are usually dry blends or granular formulas; they are easy to spread and are suitable for covering broad areas.
Slow-release fertilizers release their nutrients slowly after each irrigation. The benefits to the farmer are that the plants don't receive toxic amounts of fertilizers all at once. The rate of release is determined by how soluble the ingredients of the fertilizer are, among other things like existing soil and weather conditions.
MaximumYield explains Slow Release Fertilizer
Releasing nutrients at a slow pace, slow-release liquid or granular fertilizers relinquish their nutrients at a less predictable rate than quick-boost formulas. The rate at which the fertilizers work depends mainly on the activity of organisms that are present in the soil.
However, the controlled-release fertilizers (also known as coated fertilizers) release their nutrients at a specific rate over a specific period of time as they are controlled.
Slow-release fertilizers are less expensive than controlled-release kinds. They are best used when the precision and higher cost of controlled-release is not required, and where natural organics are not desired. When researching fertilizers, be sure to research how each type interacts with your chosen grow medium. For example, coco coir, rockwool, and clay pebbles might be better suited to quick-release formulas, where long-term soil health is not a concern.
Some downsides to controlled-release fertilizers are that they are often made of synthetic nutrients (not-organic) and do not improve the soil over time. In order to keep the soil healthy, natural organic matter needs to be added on a regular basis.