Examples of Fast Release Fertilizers

Slow-Release Vs. Fast-Release

• Fast-release fertilizers are not preferable in all situations because their nutrients are highly soluble. This means that the nutrients readily dissolve into the water in the soil. Dissolved nutrients can be immediately absorbed by plant roots, but they can also be leached away by rainwater or irrigation; this is especially true for nitrogen fertilizers. Fast-release fertilizers are beneficial for crops that grow rapidly and for crops that need a boost during the growing season. Slow-release fertilizers are a better choice when you need sustained release of nutrients over the course of several weeks or months.

Synthetic Nitrogen Fertilizers

• Nitrogen is one of the three major plant nutrients. Plants need it in large amounts, yet the supply is often inadequate because nitrogen is not stable in the soil -- it is easily leached beyond the root zone or lost to the atmosphere. This is why many fertilizers supply significant quantities of nitrogen. Most synthetic sources of nitrogen -- such as ammonium sulfate, ammonium nitrate and potassium nitrate -- provide fast release of nutrients, but the nutrients will only remain available for four to six weeks. A few synthetic nitrogen products are slow-release because they are specially manufactured to inhibit solubility; these include resin-coated urea and methylene urea.

Other Synthetic Fertilizers

• Numerous mineral nutrients are needed for optimal plant growth, but most fertilizers supply phosphorus and potassium because these are likely to limit plant growth. In general, synthetic phosphorus sources -- such as superphosphate, monoammonium phosphate and diammonium phosphate -- release their nutrients quickly because they contain a large percentage of soluble phosphate. The same is true for most commercial potassium fertilizers. Muriate of potash, also known as potassium chloride, is a common potassium source that is highly water soluble.

Organic Fertilizers

• Most organic fertilizers release their nutrients somewhat slowly because the nutrients are bound up into larger compounds and cannot be used by plants until these compounds are broken down by chemical or biological processes. Nevertheless, some organic fertilizers do provide relatively fast release of nutrients. These include alfalfa meal and blood meal for nitrogen, bone meal for phosphorus, and sul-po-mag and wood ash for potassium.