Calculator inputs
Example data table
| Metric | Example Sample A | Example Sample B | Interpretation |
|---|---|---|---|
| pH | 6.40 | 7.10 | Sample B is more alkaline. |
| Moisture | 18.00% | 14.00% | Sample A retains more water. |
| Organic Matter | 3.80% | 2.90% | Sample A may support better structure and microbial activity. |
| Nitrogen | 52.00 mg/kg | 41.00 mg/kg | Sample A shows a stronger available nitrogen position. |
| Electrical Conductivity | 0.62 dS/m | 0.78 dS/m | Sample B suggests slightly greater soluble salt load. |
These values are demonstration inputs only. Replace them with laboratory or field measurements for meaningful analysis.
Formula used
- Absolute Difference = |Sample A − Sample B|
- Percent Difference = |A − B| ÷ ((|A| + |B|) ÷ 2) × 100
- Metric Similarity Score = max(0, (1 − Absolute Difference ÷ Tolerance) × 100)
- Overall Similarity = Σ(Weight × Metric Similarity) ÷ Σ(Weight)
- Difference Index = 100 − Overall Similarity
- Within Tolerance = Yes when Absolute Difference ≤ Tolerance
How to use this calculator
- Enter a comparison title, sample names, site details, date, and depth.
- Fill Sample A and Sample B values for each listed soil property.
- Set a tolerance for every metric based on acceptable laboratory or agronomic variation.
- Assign weights to emphasize metrics that matter more for your decision.
- Click Compare Soil Samples to display the result section above the form.
- Review the summary cards, detailed result table, and normalized Plotly graph.
- Use CSV for spreadsheets and PDF for printable reporting.
Frequently asked questions
1. What does the overall similarity score mean?
The overall similarity score shows how closely the two samples match after tolerance and weight settings are applied. A higher score means the samples are more alike across the selected soil properties.
2. Why does this tool use tolerances?
Soil test differences are not always equally important. Tolerances let you define what variation is acceptable for each metric before the calculator treats it as a meaningful mismatch.
3. Why are weights included?
Weights let you prioritize critical properties such as nitrogen, pH, or salinity. This helps the final score reflect your actual agronomic priorities instead of treating all metrics equally.
4. Can I compare field readings and laboratory readings together?
Yes, but the comparison is strongest when both samples come from the same testing method and unit system. Mixed methods can introduce variation unrelated to actual soil change.
5. What does percent difference show?
Percent difference expresses how far apart two values are relative to their average. It is useful for spotting stronger shifts, especially when raw units vary from one metric to another.
6. Why is the graph normalized?
Soil properties use very different units and scales. Normalizing the chart makes side by side viewing easier without letting large-unit measurements dominate the visual display.
7. Is the NPK total a complete fertility rating?
No. It is only a quick comparison of nitrogen, phosphorus, and potassium totals entered here. Real fertility interpretation should also consider crop needs, pH, salinity, and laboratory recommendations.
8. Can this replace a certified soil laboratory report?
No. This tool helps organize and compare measured data. It does not replace laboratory procedures, certified methods, calibration standards, or professional agronomic interpretation.