How the calculation works
The calculator combines three equations: the base UAN-32 mass from target nitrogen rate, refill logistics from tank capacity, and spraying time from sprayer productivity. Mass formula: area × N rate / 32% / 1000. Working solution volume = mass (kg) / UAN-32 density 1.32 kg/L. Sprayer productivity is boom width × speed / 10 = ha/h, with 15 minutes per refill added. The temperature safety window is based on ammonia volatilization research: above 22°C, nitrogen losses exceed 10%.
- 1
Enter area and rate
Field area (ha) and target nitrogen rate (kg N/ha).
- 2
Enter sprayer parameters
Boom width, forward speed, and tank capacity.
- 3
Enter air temperature
Current or forecasted temperature at application time.
- 4
Read the result
Physical mass, volume, refills, spraying time, and safety status.
When to use this tool
- Planning fieldwork for the front edge of the season based on weather forecast
- Calculating UAN-32 tanker procurement for the full season
- Scheduling sprayer utilization to avoid idle time
- Validating nozzle and pressure choice before heading to the field
Limitations
The calculator computes physical mass and time without accounting for volatilization losses, wind drift, or refill spillage. Add 3–5% buffer for procurement planning. YMYL warning: exceeding the safe temperature window can cause leaf burn and 5–15% nitrogen losses.
Frequently asked questions
Why is temperature above 22°C unsafe for UAN-32?
Above 22°C the amide fraction of UAN-32 (50% of the mix) volatilizes faster. Ammonia losses reach 10–15% within 24 hours. The sprayer's fine droplet spectrum also concentrates salts on leaves, causing burn.
How do I reduce refill time?
Use a 4,000–5,000 L tank, a fill station with a 600–800 L/min pump (cuts refill from 15 to 5 min), or a mobile tanker delivering direct to the field.
What if rain is forecast 4 hours after application?
Light rain (up to 4 mm/h, 3+ hours after application) helps by washing UAN into the soil and cutting volatilization. Heavy rain within 1 hour washes fertilizer off. Reschedule if heavy rain is forecast.
