Slow-Release Nitrogen Calculator

Release curve and timing from product and temperature.

Coating / product type

Total N applied (lbs/acre)

Avg soil temperature (°F)

Days after application

Product rate (lbs/acre)

Product N content (%)

Tab to move between fields

Cumulative N released (%)

25.9%

N available (lbs/acre)

25.9

N still coated (lbs/acre)74.1

Current daily release (lbs/acre/day)0.37

Released at 14 days (%)6.8%

Released at 30 days (%)13.9%

Released at 60 days (%)25.9%

Released at 90 days (%)36.2%

Days to 50% release138.6

Days to 80% release321.9

How to Use This Calculator

Select Coating/Product Type: PCU (polymer-coated), SCU (sulfur-coated), Methylene Urea, IBDU, or Uncoated Urea.
Enter Total N Applied (lbs/acre), Product Rate (lbs/acre), and Product N Content (%).
Set Average Soil Temperature (°F) — higher temperatures accelerate release for PCU and SCU products.
Enter Days After Application to calculate cumulative release at a specific point in the season.
Review Cumulative N Released (%), N Available (lbs/acre), N Still Coated, and Daily Release Rate to match release curve to crop uptake.

How the result changes with Avg soil temperature (°F)

Coating / product type: 1 = Polymer-coated (PCU), 2 = Sulfur-coated (SCU), 3 = Methylene urea, 4 = IBDU, 5 = Uncoated urea.
Total N applied (lbs/acre): Pounds of nitrogen per acre applied.
Avg soil temperature (°F): Average soil temperature at 4-inch depth during the period.
Days after application: Number of days since fertilizer was applied.
Product rate (lbs/acre): Pounds of fertilizer product applied per acre.
Product N content (%): Nitrogen percentage of the product (e.g., ESN = 44%).

Cumulative N released (%): Percentage of total N released by the specified day.
N available (lbs/acre): Pounds of plant-available N released so far.
N still coated (lbs/acre): Nitrogen remaining inside coating, not yet plant-available.
Current daily release (lbs/acre/day): Instantaneous release rate at the specified day.
Released at 14 days (%): Cumulative release by 2 weeks.
Released at 30 days (%): Cumulative release by 1 month.
Released at 60 days (%): Cumulative release by 2 months.
Released at 90 days (%): Cumulative release by 3 months.
Days to 50% release: Estimated days until half the N has been released.
Days to 80% release: Estimated days until 80% of N has been released.

Identify Input Parameters
4 parameters
Coating / product type = 1, Total N applied (lbs/acre) = 100, Avg soil temperature (°F) = 70, Days after application = 60 = 6 input(s) provided
Calculate Cumulative N released
25.9 = 25.9%
Calculate N available
N available = totalNApplied * (cumulativeReleasePct / 100)
25.9 = 25.9
Calculate N still coated
N still coated = totalNApplied - nAvailableAtDay
74.1 = 74.1
Calculate Current daily release
Current daily release = totalNApplied * dailyReleasePct / 100
0.37 = 0.37