ARS | Publication request: A Rapid Test for Prediction of Nutrient Release from Controlled Release Fertilizers

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 2009
Publication Date: November 1, 2009
Citation: Wang, S.S., Alva, A.K., Li, Y.C. 2009. A Rapid Test for Prediction of Nutrient Release from Controlled Release Fertilizers. American Society of Agronomy, Soil Science Society of America, Crop Science Society of America - Annual Meetings, Pittsburgh, PA. Nov. 1-5, 2009. Program Abstract.

Technical Abstract: Nutrient release from soluble granular fertilizers can be modified by polymer coating. The coating technology can be fine-tuned to change the duration (3 to 9 months) and rate of nutrient release, hence these products are termed as controlled release fertilizers (CRF). There is a need to develop a rapid technique to verify the release duration of the long-term release CRF. In this study, nutrient release from polymer-coated CRF products at 100° C in water was evaluated to predict nutrient release at 25° C. Polymer-coated urea (43% N) and polymer-coated N, P, K (14-14-14) fertilizer products with designated release of 3 to 6 months were used in the study. Weighed amounts of CRF products were placed in sealed mesh bags and incubated in water at 25° C and release was evaluated over 220-days period. Controlled release fertilizers constant temperature extractor was used to study the release of the above CRF products at 100° C over a 7-day period. Regression equations were developed for cumulative nutrient release rate as a function of release time separately at 25° C and 100° C. Using the above regressions, the release duration for a given percent nutrient release from each of the CRF products at each temperature were calculated to establish a relationship between the release duration at 25° C as a function of that at 100° C for a given percent release. This relationship is useful to predict the release duration at 25° C by conducting a rapid release test at 100° C. This study demonstrated that the rapid release test at 100°C successfully predicted nutrient release rate and duration at 25° C.