4R Nutrient Stewardship Calculator

Right source, rate, time, and place optimization scoring.

N rate applied (lbs/acre)

Yield goal (bu/acre)

N factor target (lbs N/bu)

Source match (1-5)

Source-pH match (1-5)

Uses inhibitor/stabilizer (0/1)

Based on soil test (0/1)

Timing score (1-5)

Number of split apps

Placement score (1-5)

Soil texture risk (1-3)

Slope risk (1-3)

Tab to move between fields

4R Total Score (0-100)

62.9

Grade (4=A, 3=B, 2=C, 1=D)

Right Source (0-25)12

Right Rate (0-25)20.9

Right Time (0-25)15

Right Place (0-25)15

Optimal N rate (lbs/acre)220

Excess N applied (lbs/acre)0

Leaching risk (0-100)30

Volatilization risk (0-100)15

Runoff risk (0-100)12

How to Use This Calculator

Enter N Rate Applied (lbs/acre) and Yield Goal (bu/acre) to calculate rate adequacy.
Score Source Match (1–5) and Source-pH Match (1–5) for the fertilizer product you're using.
Indicate whether you Use a nitrification or urease Inhibitor/Stabilizer and whether the rate is Based on a Soil Test.
Set Timing Score (1–5) and Placement Score (1–5) for your application method.
Review the 4R Score and individual right-source, right-rate, right-time, right-place sub-scores to target improvements.

How the result changes with N rate applied (lbs/acre)

N rate applied (lbs/acre): Actual nitrogen rate applied per acre.
Yield goal (bu/acre): Realistic yield target for the field.
N factor target (lbs N/bu): University-recommended N rate per bushel of yield goal.
Source match (1-5): How well the fertilizer source matches crop/soil needs (1=poor, 5=ideal).
Source-pH match (1-5): How well the source matches soil pH (e.g., avoid urea on high-pH soils).
Uses inhibitor/stabilizer (0/1): 1 = Uses nitrification or urease inhibitor, 0 = no inhibitor.
Based on soil test (0/1): 1 = Rate calibrated from a soil test, 0 = flat rate.
Timing score (1-5): 1=fall no inhib, 2=fall+inhib, 3=early spring, 4=at planting, 5=sidedress/split.
Number of split apps: Number of separate N applications (1 = single, 2-3 = split).
Placement score (1-5): 1=surface broadcast, 2=broadcast+incorp, 3=banded, 4=2×2 starter, 5=injected/knifed.
Soil texture risk (1-3): 1 = heavy clay (low leaching), 2 = loam, 3 = sandy (high leaching).
Slope risk (1-3): 1 = flat (<2%), 2 = moderate (2-6%), 3 = steep (>6%).

4R Total Score (0-100): Overall 4R nutrient stewardship score (85+ = A, 70+ = B, 55+ = C).
Grade (4=A, 3=B, 2=C, 1=D): Letter grade equivalent for stewardship practices.
Right Source (0-25): Score for fertilizer source selection.
Right Rate (0-25): Score for application rate accuracy.
Right Time (0-25): Score for application timing.
Right Place (0-25): Score for placement method.
Optimal N rate (lbs/acre): Calculated optimal N rate from yield goal.
Excess N applied (lbs/acre): Pounds of N above the optimal rate (0 if at/below target).
Leaching risk (0-100): Estimated nitrate leaching risk score.
Volatilization risk (0-100): Estimated ammonia volatilization risk score.
Runoff risk (0-100): Estimated nutrient runoff risk score.

Identify Input Parameters
4 parameters
N rate applied (lbs/acre) = 160, Yield goal (bu/acre) = 200, N factor target (lbs N/bu) = 1.1, Source match (1-5) = 3 = 12 input(s) provided
Calculate 4R Total Score
4R Total Score = sourceScore + rateScore + timeScore + placeScore
62.9 = 62.9
Calculate Grade
2 = 2
Calculate Right Source
Right Source = min(25,
12 = 12
Calculate Right Rate
Right Rate = min(25,
20.9 = 20.9