Enter soil nitrogen calculation inputs
Use the responsive input area below. It shows three columns on large screens, two on medium screens, and one on mobile.
Formula used
This calculator follows a Kjeldahl-style titration workflow for total nitrogen estimation in soil digests.
| Step | Formula |
|---|---|
| Nitrogen in aliquot | (Sample titration − Blank titration) × Acid normality × 14.007 |
| Total nitrogen in digest | Nitrogen in aliquot × (Digest volume ÷ Aliquot volume) × Extra dilution factor |
| Recovery-corrected nitrogen | Total nitrogen in digest ÷ (Recovery % ÷ 100) |
| Dry sample weight | Wet sample weight × (1 − Moisture % ÷ 100) |
| Dry-basis nitrogen concentration | Recovery-corrected nitrogen ÷ Dry sample weight |
| Dry-basis nitrogen percentage | Dry-basis mg/g ÷ 10 |
| Dry-basis ppm | Dry-basis mg/g × 1000 |
| Soil mass in sampled layer | Bulk density × Sampling depth × 100,000 |
| Nitrogen stock | Dry-basis ppm × Soil mass ÷ 1,000,000 |
The factor 14.007 converts one milliequivalent of acid-neutralized ammonia to milligrams of nitrogen.
How to use this calculator
- Enter a sample label so exported files are easier to track.
- Type the wet soil sample mass used for digestion.
- Enter the soil moisture percentage to convert wet results to dry basis.
- Provide sample titration volume, blank volume, and acid normality.
- Enter digest volume, aliquot volume, and any extra dilution factor used after digestion.
- Enter the recovery percentage if your method requires correction.
- Type bulk density and sampling depth to estimate field stock in kg/ha and lb/ac.
- Press Calculate nitrogen content to show results above the form, then export CSV or PDF if needed.
Example data table
The example rows below are generated with the same formulas used by the calculator.
| Sample | Weight (g) | Moisture (%) | Net titration (mL) | Dry N (%) | Dry N (ppm) | Stock (kg/ha) |
|---|---|---|---|---|---|---|
| Surface Loam | 10.00 | 12.00 | 6.200 | 0.1007 | 1,007.00 | 1,963.64 |
| Compost-Amended Bed | 12.00 | 18.00 | 10.900 | 0.3135 | 3,134.52 | 7,209.40 |
| Sandy Field | 10.00 | 5.00 | 2.900 | 0.0441 | 440.81 | 958.75 |
FAQs
1. What nitrogen measurement does this calculator estimate?
It estimates total nitrogen from titration-based digest data, then converts that result to wet basis, dry basis, ppm, and sampled-layer stock values.
2. Why do I need a blank titration value?
The blank corrects reagent and background effects. Subtracting it from the sample titration gives the net volume linked to nitrogen released from the soil sample.
3. Why is moisture content important?
Moisture changes the true dry mass of soil analyzed. Dry-basis results are usually better for comparing different soils, dates, and sampling conditions.
4. What does the extra dilution factor do?
Use it when the digest or aliquot was diluted again before titration or measurement. Enter 1 if no extra dilution step was performed.
5. What is the recovery factor?
Recovery accounts for method efficiency. If your lab recovery is 98%, the calculator slightly increases the measured nitrogen to estimate the corrected value.
6. How is kg/ha estimated?
The calculator estimates the mass of soil in one hectare for the entered depth and bulk density, then applies the dry-basis nitrogen concentration to that soil mass.
7. Can I use this for nitrate-only or ammonium-only tests?
Only if your titration workflow specifically measures that form and the assumptions match. Otherwise, treat this as a total nitrogen digest calculator.
8. Which units should I enter?
Enter mass in grams, titration and digest values in milliliters, acid strength in normality, bulk density in g/cm³, and sampling depth in centimeters.