A controlled-release fertiliser (CRF) is a granulated fertiliser that releases nutrients gradually into the soil (i.e., with a controlled release period). The slowness of the release is determined by the low solubility of the chemical compounds in the soil moisture. Since conventional fertilisers are soluble in water, the nutrients can disperse quickly as the fertiliser dissolves. Because controlled-release fertilisers are not water-soluble, their nutrients disperse into the soil more slowly. The fertiliser granules may have an insoluble substrate or a semi-permeable jacket that prevents dissolution while allowing nutrients to flow outward.
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.
The fertiliser is administered either by topdressing the soil, or by mixing the fertiliser into the soil before sowing.
One of the advantages of CRF is reduced incidence of fertiliser burn. Other important advantages are economical benefits (labour savings) due to less applications and mostly less overall fertiliser amount. The results (yield) is in most cases improved by > 10%.
Manufacturers and distributors of slow- and controlled- release fertilizers
In North America, the leading producers and/or suppliers of slow- and controlled- release fertilizers are: Agrium Inc. (including Pursell Technologies Inc. and Nu-Gro Corp.), Georgia-Pacific, Growth Products, Helena Chemicals, Kugler Company, Lebanon Seaboard Corp., Lesco Inc, Tessenderlo Kerley and The Scotts Company.
The leading manufacturers and/or suppliers in Western Europe are: Ekompany Agro B.V. (The Netherlands), Aglukon (Germany), BASF (Germany), Compo (Germany), Scotts Europe (The Netherlands), Puccioni (Italy) and Sadepan Chimica (Italy).
In Israel the leading manufacturer and supplier is Haifa Chemicals.
The leading manufacturers and/or suppliers in Japan are: Central Union Fertilizer, Chissoasahi Fertilizer11, Co-op Chemical, Katakura Chikkarin, Mitsubishi Chemical, Sumitomo Chemical, Taki Chemical and Ube Agri-Materials.
In China, the leading manufacturers are: Hanfeng Evergreen, Shandong Kingenta Ecological Engineering and Shikefeng Chemical Industry. 
|Georgia-Pacific||Nitamin® 30L - UF Fertilizer|
|Tessenderlo Kerley||Formolene-Plus® and several Trisert® - urea-triazone formulations|
|Helena Chemicals||CoRoN® - UF Solution|
|Kugler Company||KQ XRN 28-0-0 – UF solution|
|Growth Products||Nitro-30 – UF solution 30-0-0|
|Agrium (former Nu-Gro)||Nitroform® – UF formulation
Nutralene® – methylene urea
IB Nitrogen - IBDU
|Aglukon||Plantosan® - granular
Methylene-urea - Azolon® granular and Azolon® fluid
Methylene-urea - PlantoDur® - NPK fertilizer, N based on UF
|CDU (imported from Japan) - Triabon®- NPK fertilizer based on CDU
Floranid® - N-, NK- and NPK-fertilizers, N based on IBDU
|Puccioni (Italy)||Nutritop® - Nutritop® N, Smartfert® Top - NPK and NP fertilizers, based on UF|
|Sadepan Chimica (Italy)||SirflorTM N38, based on UF
SazoleneTM - granular and liquid methylene-urea
|Chissoasahi Fertilizer||CDU nitrogen
‘UBER’ - controlled-mineralization CDU (called ‘Hyper CDU’ in Japan)
NPK fertilizer based on CDU
|Mitsubishi Chemical||IBDU nitrogen
‘Good-IB’ and ‘Super-IB’, based on IBDU
NPK fertilizer - based on IBDU
NPK fertilizer based on UF
|The Scotts Company||Agroblen® - polymer-coated N, NK and NPK fertilizers
Osmocote® - polymer-coated NPK fertilizers
|Agrium (former Pursell Technologies)||ESN®
Duration® CR - clay-coated PCU
Polyon® PCU - polymer-coated urea
Polyon® coated potassium nitrate, MAP and NPK fertilizers
|Sulphur-coated urea (SCU)|
|Agrium (Former Nu-Gro)||SCU®|
|Agrium (former Pursell Technologies)||TriKote® - several polymer, sulphur-coated fertilizer types|
|Western Europe and Israel|
|Aglucon||Plantacote® Polymer coated NPK fertilizers|
|Compo||Basacote® - polymer-coated NPK fertilizers
Basatop® - partly polymer-coated N- and NPK-fertilizers
|Ekompany Agro B.V.||Ekote® Polymer fully and partly coated NPK, Urea, Phosphat, Potash, etc. fertilizers for arable crops, open field crops and fruit trees, ornamentals, tree nurseries and turf|
|Haifa Chemicals||Multicote® - polymer-coated NPK-, NP- and NK- fertilizers
CoteNTM – polymer-coated urea
Mulitcote® Agri – coated NPK-fertilizers for open field crops and fruit trees
Multigreen® – controlled-release turf fertilizers
Multigro® – controlled-release fertilizer blends for agricul- ture and horticulture
|Shandong Kingenta Ecological Engineering||Syncote®- sulphur-coated urea and NPK-fertilizers|
|Shandong Kingenta Ecological Engineering||Syncote®- polymer/sulphur-coated urea|
|Shandong Kingenta Ecological Engineering||Syncote® - polymer-coated NPK-fertilizers and urea|
|Sun-Agro||S-Coat®- sulphur-coated NPK- fertilizers and urea|
|Chissoasahi Fertilizer||Meister®- polymer-coated urea (called ‘LP-cote’ in Japan)
Nutricote® - polymer-coated NPK fertilizer, magnesium sulphate or calcium nitrate
Pile Nutricote® - Nutricote® in paper pile
‘Naebako-makase’ - special Meister® for single basal application in nursery boxes of rice
‘Ikubyou-makase’ – special Nutricote®- for single basal application in nursery pots of horticultural crops
|Mitsubishi Chemical||M-coat® - polymer-coated urea|
|Taki Chemical||Taki-coat® - polymer-coated urea|
|MC Ferticom||U-coat® - polymer-coated urea|
|Central Union Fertilizer||Cera-Coat® Polymer-Coated Urea|
|Co-op Chemical||Co-op coat®- polymer-coated NPK fertilizers|
|Katakura Chikkarin||Sigma Coat® Polymer-Coated Urea and NPK Fertilizers|
|Sumitomo Chemical||‘SR-coat’ - polymer-coated urea|
Controlled-release fertilizer is also known as controlled-availability fertilizer, delayed-release fertilizer, metered-release fertilizer, or slow-acting fertilizer.
- C. Nitschke, G. Scherr (2005), "Urea Derivatives", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.o27_o04
- Gregorich, Edward G.; Turchenek, L. W.; Carter, M. R.; Angers, Denis A., eds. (2001). Soil and Environmental Science Dictionary. CRC Press. p. 132. ISBN 978-0-8493-3115-2. LCCN 2001025292. Retrieved 9 December 2011.
- Trenkel, M.E. (2010). Slow- and Controlled release and Stabilized Fertilizers. International Fertilizer Industry Association.
- Du, Chang-wen; Zhou, Jian-ming; Shaviv, Avi (2006). "Release Characteristics of Nutrients from Polymer-coated Compound Controlled Release Fertilizers". Journal of Polymers and the Environment. 14 (3): 223–230. doi:10.1007/s10924-006-0025-4. Retrieved 9 December 2011.
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