Estimate N release over time from polymer-coated urea using historical climate normals.
Monthly release (through 80% cumulative)
How this works. ZIP code is geocoded to lat/lon (Zippopotam.us), then 0–7 cm
soil temperature normals are computed from the past 5 years of Open-Meteo / ERA5 hourly reanalysis
data, averaged hourly→daily and then by calendar day-of-year, walking forward from the
application date.
Two release models available: Sigmoidal (Weibull) — each day contributes
Q10(T−20)/10 of accumulated “biological time,” fit so the
cumulative release curve matches the days-to-80% values at 59/72/86°F published for each product.
Linear — a simpler planning model that releases N evenly across a
temperature-adjusted window. Both models are calibrated to the same days-to-80% reference table; they
diverge mainly in the shape of the within-window release (sigmoidal has a peak, linear is flat).
This is a planning estimate, not a guarantee — field release depends on soil moisture, depth of
incorporation, and lot-to-lot coating variability.