Simulation of Crop Response to Polyolefin-Coated Urea: I. Field Dissolution
1991
Gandeza, A. T. | Shoji, S. | Yamada, I.
Polyolefin-coated urea (POCU) is a controlled-release granular fertilizer whose dissolution is primarily temperature-dependent. The coating is made of ethylene vinyl acetate, polyolefin, and talc to control N release. Dissolution doubles for every 10 °C rise in temperature, a Q₁₀ matching that of plants. This study was conducted to understand its N release under Andisol field conditions and show its temperature dependency. Cumulative N release (CNR) with time between 10 and 30 °C is described by a quadratic equation in the general form CNR = a + b(day) + c(day)². The equation corresponding to the mean daily soil or air temperature was used to calculate CNR. The CNR gradually increased with time and reached about 80% of the total N content at about 126 d after application. Two-year experiments showed that observed CNR and predicted CNR determined using either soil or air temperature expressed as functions of time were closely correlated. Using cumulative temperature (CT) as the variable, CNR is given by the relation CNR = a + b(CT) + c(CT)². This means that N dissolution from POCU can be predicted. Such behavior of N dissolution has significant implications on N supply to plants, fertilizer efficiency, and efforts to minimize environmental pollution.
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