Soil Test Calculator

Estimate nutrient needs from soil test results, including nitrogen, phosphorus, potassium, lime, pH adjustment, organic matter, fertilizer cost, and amendment needs. Use this soil test calculator for crop fields, gardens, pastures, food plots, hay fields, and soil fertility planning.

Calculate Soil Test Needs

Nutrient Gap = Target Nutrient − Soil Test Nutrient.
Your result will appear here.

How the soil test calculator works

Nutrient gap:
The calculator compares soil test levels with target levels for nitrogen, phosphorus, and potassium.

Fertilizer needed:
Nutrient gaps are divided by fertilizer analysis percentages and application efficiency to estimate product needed.

Lime needed:
Current pH, target pH, buffer pH, and CEC are used to estimate lime tons per acre.

Total cost:
Fertilizer cost, lime cost, and application cost are used to estimate total project cost.

Why use a soil test calculator?

A soil test calculator helps turn soil test numbers into rough nutrient, lime, fertilizer, and amendment estimates.

It can help compare soil pH, target pH, organic matter, CEC, nutrient gaps, fertilizer product needed, lime tons, and total application cost.

What your result means

Your result shows estimated nitrogen gap, phosphorus gap, potassium gap, fertilizer pounds needed, fertilizer tons needed, lime tons needed, nutrient status, fertilizer cost, lime cost, application cost, total cost, and cost per acre. These are estimates based on the values you enter.

Soil test calculator formulas

Frequently asked questions

How do you use a soil test calculator?

Enter your soil test values, target nutrient levels, area, fertilizer analysis, and costs. The calculator estimates nutrient gaps, fertilizer needed, lime needed, and total cost.

Does this replace a soil lab recommendation?

No. This calculator gives an estimate. Soil lab recommendations, local extension guidance, crop goals, soil type, and local nutrient rules should be used for final decisions.

How do you estimate fertilizer needed from a soil test?

Subtract the soil test nutrient level from the target nutrient level, adjust for efficiency, then divide by the nutrient percentage in the fertilizer product.

Why does soil pH matter?

Soil pH affects nutrient availability, lime requirements, microbial activity, and crop growth. Low pH may reduce the effectiveness of fertilizer applications.