Fertspread Spreader Calibration

This calculator is designed to assess the performance of machines that spread fertiliser by throwing. See also our Fertiliser Placement Calibration tool for placement machines such as planters or side-dressers which lay or place bands of fertiliser on or in the ground.

This version of FertSpread does not store your data or keep any records. Leaving or refreshing this page will delete all your data, so print reports and export the data or graphs if you want to save them.

NOTE: The Application Rate calculated in the Calibration tab is most accurate for the overall field application rate. The Application Rates calculated in the Distribution tabs will be lower because trays do not catch all the fertiliser. The spread pattern will represent what happens in the field, but the rates will be lower than expected.

Beta version: See disclaimer at foot of page.

🚜 Broadcast Fertiliser Spreader Calibration Tool v1.1.0

Professional Performance Assessment & Calibration

🏡 Farm & Property Information
👨‍🔬 Consultant & Evaluation Details
🖼️ Report Branding (Optional)
Upload your company logo to appear on reports (JPG, PNG, max 500KB)
🚜 Spreader Equipment Information
Type of broadcast spreading mechanism
⚙️ Spreader Settings
For disc spreaders (if known)
Disc vane setting (if applicable)
Height above ground
🌾 Fertiliser Product Information
🔬 Product Physical Properties
Or calculate below
For bulk density calculation
For bulk density calculation
Average particle size × 100 (e.g., 350 = 3.5mm)
Ratio of small to large particles (100 = all same size)
⚡ Application Rate Calibration

Application Rate Formula:

Application Rate (kg/ha) = [Discharge Rate (kg/min) / (Bout Width (m) × Travel Speed (km/h))] × 600

📊 Discharge Rate Test
Weight of fertiliser collected during test
Minimum 30 seconds recommended
Will calculate automatically
🚜 Travel Speed & Bout Width
Distance between adjacent passes (required for uniformity results)
Or measure below
📈 Calculated Application Rate
📐 Collection Tray Test Setup

Test Method: Single Pass with Physical Overlap Simulation

This method measures the spread pattern from one pass, then adds together every overlapping pass, in BOTH same direction and reverse (alternating) direction, to predict field uniformity. Results show which travel pattern gives better uniformity for your spreader.

Side length of a square tray. Standard trays are 500mm × 500mm (0.25m²)
Equal distance between tray centres
Total width the trays cover, edge tray to edge tray. Must reach past where fertiliser stops landing. Sets the number of trays; overlap uses the bout width.
Fewest trays, with one on the centre line, whose outer edges reach the spread width
Use when you lay out more trays than the calculated number. Must be odd (one on the centre line); trays are placed at the tray spacing.
mL readings are converted to grams using the bulk density on the Product tab
⚙️ Application Conditions
Testing should be done in calm conditions
💧 Collection Tray Measurements

📄 Upload Tray Data from CSV

Upload a CSV file with tray measurements. Format:

  • 2 columns: Distance from Centre (m), Weight or Volume (g or mL)
  • Example: -12, 45.5
CSV files with or without headers are supported. The file is read in your browser and is not uploaded. If no tray fields exist yet, they are created from the CSV distances.
Generate tray input fields in the Tray Setup tab first

📊 Broadcast Fertiliser Spreader Calibration v1.1.0

Complete the tray data entry and calculate results to see analysis here.

Key Calculations:

  • Application Rate (kg/ha) based on discharge rate, bout width, and travel speed
  • Overlapped Coefficient of Variation (CV%) for spread uniformity with the optimal travel pattern
  • Overlap of all passes (same/reverse direction comparison) to determine best pattern
  • Overlapped mean application rate showing actual field conditions
  • Spread pattern visualisation showing single pass and overlapped uniformity
  • Comparison of overlapped rate vs calibrated discharge rate, with a warning if they differ by more than 15%
  • CV uses the sample standard deviation (n−1) as in ISO 5690 / ASABE S341
  • Industry standard compliance assessment

Acceptable CV Standards (Overlapped):

  • Nitrogen fertilisers: CV ≤ 15% (Excellent)
  • Other fertilisers: CV ≤ 25% (Acceptable)
  • CV ≥ 40%: Visible striping, 20% yield loss (Poor)
📋 Professional Calibration Certificate

📋 Report Features

  • Generate Report: Professional calibration certificate with all test results
  • Export Data: CSV file with all measurements and calculations
  • Export Chart: PNG images of the spread pattern and bout width charts
  • Print Report: Printer-friendly calibration certificate