A soil test report tells you what your soil needs, what it already has enough of, and what you should avoid adding. The key numbers are usually pH, organic matter, phosphorus, potassium, and the fertilizer or lime recommendation for the crop you selected.
The biggest mistake is reading the numbers as if they are simple scores. Soil test values are often index values tied to a lab method, not a direct count of everything in the soil.
For testing choices, read Soil Test Kit vs Lab Test: Which Is Better?.
Last updated: June 6, 2026.
Quick Answer
Start with pH, then organic matter, then phosphorus and potassium levels, then the recommendation section. Follow the recommendation for your crop instead of adding a general fertilizer automatically. Be careful with phosphorus, compost, manure, lime, and sulfur because they can build up or change soil chemistry slowly.
The Main Parts of a Soil Report
| Report item | What it means |
|---|---|
| pH | acidity or alkalinity |
| buffer pH | lime requirement for acidic soil |
| organic matter | decomposed plant/animal material in soil |
| phosphorus | root, flowering, and fruiting nutrient |
| potassium | water regulation and plant vigor nutrient |
| calcium and magnesium | secondary nutrients and pH-related minerals |
| soluble salts | salt level that can damage roots |
| recommendation | what to add for the selected crop |
pH
Soil pH affects nutrient availability. Many vegetable crops grow best in slightly acidic to near-neutral soil, but ideal pH varies by crop.
If pH is low, the report may recommend lime. If pH is high, lowering it may be difficult, especially in calcareous soils.
Do not add lime just because it is common in gardening advice. Lime raises pH, and too much can create new problems.
Organic Matter
Organic matter helps soil structure, water holding, drainage, nutrient storage, and biological activity.
Low organic matter often means you should add compost, leaves, cover crops, or other organic materials. But more is not always better. Compost-heavy beds can build up phosphorus, potassium, calcium, salts, or alkalinity.
For raised beds, read Best Soil for Raised Garden Beds.
Phosphorus and Potassium
Phosphorus and potassium are often reported in ppm or as index values. Labs may classify them as very low, low, medium, high, or very high.
If phosphorus is high, avoid:
- bone meal
- manure
- composted manure
- complete fertilizers with phosphorus
- bloom boosters
If potassium is high, avoid extra potash unless the report recommends it.
ppm vs Pounds Per Acre
Some reports use parts per million. Others use pounds per acre. A common conversion is:
ppm x 2 = pounds per acre
This does not mean you should apply that amount. Use the recommendation section.
Fertilizer Ratios
Fertilizer labels show N-P-K. These are percentages of nitrogen, phosphate, and potash.
If your report recommends more nitrogen but little or no phosphorus, choose a nitrogen-focused product rather than a complete fertilizer. A balanced 10-10-10 fertilizer is not balanced for every soil.
For tomatoes, read Best Fertilizer for Tomatoes.
Lime and Sulfur Recommendations
Lime raises pH. Sulfur lowers pH. Both should be based on a soil test.
Important:
- texture affects amendment rate
- clay soils buffer pH more than sandy soils
- lime works slowly
- elemental sulfur works slowly
- mixing into the soil is more effective than surface spreading
- overcorrection is hard to undo
Red Flags on a Soil Test
Pay attention to:
- very high phosphorus
- high soluble salts
- very low or very high pH
- low organic matter
- excessive potassium
- lead concerns in food gardens
- recommendations that do not match your crop
If results look extreme, contact the lab or local extension office before adding amendments.
FAQ
What does high phosphorus mean?
It means your soil likely does not need more phosphorus. Avoid bone meal, manure, and fertilizers with middle-number phosphorus unless a specialist recommends otherwise.
Should I follow the fertilizer recommendation exactly?
Use it as the primary guide, then match a real fertilizer product as closely as possible without over-applying phosphorus or potassium.
Why does my report not show nitrogen?
Nitrogen changes quickly in soil, so many garden reports focus on phosphorus, potassium, pH, and organic matter, then recommend nitrogen by crop.
Related Reading
- Soil Test Kit vs Lab Test: Which Is Better?
- How to Lower Soil pH Naturally
- How to Raise Soil pH Safely
- Bone Meal vs Blood Meal