Soil Test Report Reference.
Soil Test Report Reference
Read your soil report like an agronomist. pH, CEC, base saturation, P/K, micronutrients, organic matter — what each number means and what to do.
How to take a representative soil sample
- Identify management zones. Don't lump distinctly different areas (e.g., a wet bottom with a sandy ridge). Sample each zone separately.
- Take 15-20 cores per zone. Random walk through the zone. Single cores are not representative.
- Sample to the right depth: 0-6" for vegetable beds; 0-8" for tilled annual crops; deeper (12-24") for perennials, fruit trees, mineral profiling.
- Avoid recently-fertilized strips, fence rows, gates, and animal-rest areas.
- Combine in clean bucket; mix; air-dry; submit ~2 cups of mix.
- Same time of year, same lab, every time. Comparable trends matter more than absolute numbers.
Lab choice and methodology
| Region | Common lab method | What's reported |
|---|---|---|
| Midwest (acid Mollisols) | Bray-1 P + ammonium acetate K | pH, OM, P, K, Ca, Mg, micros |
| Northeast / Mid-Atlantic | Mehlich-3 | Most ag/garden — universal extractant |
| Southeast | Mehlich-3 or Mehlich-1 | |
| Western / alkaline soils | Olsen P, ammonium acetate K | Bray gives false-low on alkaline soils; Olsen designed for high pH |
| Coastal / high-OM | Modified Morgan | Mild extractant; better for organic soils |
Ranges in this widget are approximate guides. Pick a lab and stick with it — different extractants give different numerical ranges for the same actual soil.
The "Albrecht / base saturation" approach (controversial)
Some soil consultants (Albrecht / Reams / Beddoe schools) prescribe specific base saturation ratios — typically 65% Ca, 15% Mg, 5% K, 5-15% H+. The mainstream agronomic view is that sufficient absolute amounts matter more than ratios, and that pursuing precise base saturation targets can be expensive without yield benefit.
Reality: both views have evidence. For most growers:
- Hit pH and OM targets first (largest yield impact)
- Get major elements in the "sufficient" range (P, K, Ca, Mg)
- Don't chase decimal-point base saturation if soil already tests sufficient
- Pay attention if a single ratio is extreme (e.g., Mg > 30% of CEC = compaction/water issues)
Free under CC BY 4.0. Cite as "OAT Soil Test Report Reference (openagriculturetechnology.com)". Sufficiency thresholds approximate; consult your lab's specific guidance for crop-specific recommendations.