Translations:Controlled-release fertilizer/9/en

Definitions

The Association of American Plant Food Control Officials (AAPFCO) has published the following general definitions (Official Publication 57):

• Slow- or controlled-release fertilizer: A fertilizer containing a plant nutrient in a form which delays its availability for plant uptake and use after application, or which extends its availability to the plant significantly longer than a reference ‘rapidly available nutrient fertilizer’ such as ammonium nitrate or urea, ammonium phosphate or potassium chloride. Such delay of initial availability or extended time of continued availability may occur by a variety of mechanisms. These include controlled water solubility of the material by semi-permeable coatings, occlusion, protein materials, or other chemical forms, by slow hydrolysis of water-soluble low molecular weight compounds, or by other unknown means.
• Stabilized nitrogen fertilizer: A fertilizer to which a nitrogen stabilizer has been added. A nitrogen stabilizer is a substance added to a fertilizer which extends the time the nitrogen component of the fertilizer remains in the soil in the urea-N or ammoniacal-N form.
• Nitrification inhibitor: A substance that inhibits the biological oxidation of ammoniacal-N to nitrate-N.
• Urease inhibitor: A substance that inhibits hydrolytic action on urea by the enzyme urease.