Journal of Polymers and the Environment

, Volume 26, Issue 12, pp 4388–4395 | Cite as

Rapid and Low-Cost Method for Evaluation of Nutrient Release from Controlled-Release Fertilizers Using Electrical Conductivity

  • Eduardo Lopes CancellierEmail author
  • Fien Degryse
  • Douglas Ramos Guelfi Silva
  • Rodrigo Coqui da Silva
  • Mike John McLaughlin
Original Paper


Methods to determine nutrient release rates of coated fertilizers usually rely on chemical analyses, which often are time-consuming and/or expensive. Our goal was to develop an innovative and rapid low-cost method to evaluate nutrient release from polymer coated MAP or urea using conductometry. The release in water is determined by measuring the electric conductivity (EC) over time, with intervals dependent on release rates. In the case of soluble salt fertilizers, EC can be immediately determined and converted to a concentration using a calibration curve. In the case of urea, an additional step is needed to convert the neutral urea into ammonium. The release rates in water were assessed for a range of commercial and laboratory-coated fertilizers. A validation test demonstrated strong agreement with the release determined using analytical techniques. The EC method hence offers an easy way to quickly evaluate the time course of release of nutrients from controlled-release fertilizers.


Urease Polymer coated fertilizers Phosphorus Nitrogen Release rate 



Electrical conductivity






Controlled release fertilizers


Polymer coated fertilizers


Total Kjeldahl nitrogen


Monoammonium phosphate


Inductively couple plasma optical emission spectroscopy



We thank Ashleigh Broadbent for technical assistance and Roslyn Baird for language review. The first author acknowledges the CAPES foundation for a scholarship, process code BEX 3904/15-6.


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Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Dep. Soil ScienceFederal University of LavrasLavrasBrazil
  2. 2.Fertiliser Technology Research Centre, Soil Science, School of Agriculture, Food and WineUniversity of AdelaideGlen OsmondAustralia

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