Amounts to add
Fictional bed · Mehlich 3 and saturated paste examples
Fictional exampleUse your own test results
Open your Logan Labs PDFs separately below, or use a spreadsheet.
Choose the sample from each report and check the values and units.
Your files stay on your device.
About Logan Labs, testing options and prices.
Mehlich 3 PDF
Your soil mineral test.
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Saturated paste PDF
The separate soluble nutrient test, if you have one.
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You can open either PDF first.
When a report contains several samples, choose the one you want to use.
PDFs must contain selectable text, up to 10 MB each.
For scans or photos, enter the results by hand.
Spreadsheet formats: Excel (.xlsx or .xls), OpenDocument (.ods), CSV and TSV, up to 10 MB.
Recommendation targets and planned additions are not test results.
Use the original laboratory report to check any copied or calculated workbook values.
AA8.2 and water tests cannot be used as Mehlich 3 results.
View selected worksheet
Showing up to 80 rows and 20 columns.
Only the selected test result column or row is read. Other columns may contain goals, formulas or different samples.
Check the imported values
Keep reporting limits such as <0.02.
Leave results that were not reported blank.
Choose the unit shown on the source, including P₂O₅ or K₂O when applicable.
| Result | Value on source | Unit on source | Source location | Calculator value |
|---|
Soil being treated
Enter the actual soil footprint and fill depth.
Treatment depth is separate from sampling depth.
Use measured bulk density to convert the treatment volume to soil weight.
Defaults: top 6 inches for established engineered soil.
Top 4 inches for untilled native soil.
Actual incorporation depth for tilled soil.
Whole volume for a new soil mix.
Maximum per application
A cap is a ceiling, not a required dose. Mg and K need a product-specific co-element check. These references do not establish universal crop safety.
Choose Low, Middle, or High to select that point in each target range and set the application limits together. Each product shows one amount after those limits. You can adjust individual limits without changing the selected target point.
Calcium has no single application maximum that applies to every soil and amendment. The calculator currently stages calcium at 2,000 ppm per application. That setting is not a universal safety limit. The product, pH, soluble salts and accompanying nutrients still matter. University of Minnesota: liming guidance. Colorado State: calcium amendments and salinity.
How the calculation works
Target gaps and application caps
Choose your soil type. Engineered soil starts with Phase 1 targets and moves to Phase 2 when the measured M3 nutrient minimums are met. Low, Middle, or High selects one point within each target range. The table shows the amount for that choice, limited to one application. The next real test must guide later steps.
Open your test PDFs or spreadsheet above to replace the example values. Missing results stay unreported. Product choices and treatment size are yours to confirm.
Real amendment analyses
Product calculations use the linked CGG Distro descriptions and manufacturer documents. Listed co-elements count toward combined additions and caps. Unreported nutrients remain unknown, and conflicting product documents are flagged beside the analysis.
Open separate Logan Labs M3 and saturated paste PDF reports in the Calculator.
Review the extracted sample values before using them.
Complete automatic amendment selection is still in development. Read the calculation principles and sources.
Calculation basis
Treatment mass: kg. Amount in grams = elemental ppm × soil mass in kg ÷ 1,000 ÷ elemental mass fraction.
Targets are attributed Crescive practice references. Explicit numeric ranges take priority over ratio notes. Your soil-type selection sets native or engineered context. Automatic phase selection uses measured M3 nutrient minimums and never planned additions. Paste, pH, TEC, organic matter and base saturation remain separate checks.
Numeric gaps and caps do not predict a future lab result. M3 phosphorus below target with paste phosphorus above target triggers a draft review hold. This is a proposed software rule, not a new threshold from Scott and Sara.
Living Soil Supplies · October 14, 2026. Files opened here stay in your browser.