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Calcimator

Salt Index Calculator

Look up the salt index for common fertilizers and calculate the salt effect at your application rate. Assess seedling injury risk and placement recommendations.

Inputs

lbs/acre

Results

Salt Index

75

Salt Effect at Rate

150

FertilizerUrea
Analysis (N-P-K)46-0-0
SI per Unit Nutrient163
Nutrient Applied92 lbs/acre
Seedling Injury RiskHigh Risk — Consider split application
Seed PlacementKeep 2–3 inches from seed
How to Use This Calculator
  1. Enter the fertilizer product name or select from the dropdown to load its salt index value.
  2. Input the application rate in lbs per acre.
  3. Set the placement method (broadcast, band, in-furrow) to assess seed safety.
  4. Review the Weighted Salt Index and the Relative Salt Contribution.
  5. Check the Seedling Safety Rating to ensure banded rates do not cause salt injury.

What each input means

Fertilizer Type
Select fertilizer: 1 = Urea (SI 75), 2 = MAP (SI 27), 3 = DAP (SI 34), 4 = Potash (SI 116), 5 = Ammonium Nitrate (SI 105).
Application Rate
Product application rate in pounds per acre. Higher rates increase salt concentration near seeds and roots.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Fertilizer Type = 1, Application Rate = 200 = 2 input(s) provided
  2. Calculate Salt Index
    Salt Index = 75
    75 = 75
  3. Calculate Salt Effect at Rate
    Salt Effect at Rate = round(((f.saltIndex / 100) * safeRate) * 10) / 10
    150 = 150
  4. Calculate Fertilizer
    Fertilizer = fert.name
    Urea = Urea
  5. Calculate Analysis
    46-0-0 = 46-0-0

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