Soil-less Mix Interpretation
Interpretation of Bark Soil-less Mixes
| Mineral Analysis | Insufficient | Sufficient | Supraoptimal |
| Nitrate-Nitrogen (NO3-N), ppm | <50 | 50-200 | >200 |
| Phosphorus (P), ppm | <10 | 10-30 | >30 |
| Potassium (K), ppm | <25 | 25-50 | >50 |
| Magnesium (Mg), ppm | <10 | 10-50 | >50 |
| Calcium (Ca), ppm | <10 | 10-50 | >50 |
| Soluble Salts | Optimum | ||
| Electrical Conductivity, mmhos /cm | 0.7 – 3.0 | ||
| Total Dissolved Solids, ppm | 448 - 1920 | ||
| pH | 5.0 - 6.5 |
Interpretation of Peat Based Soil-less Mixes
| Mineral Analysis | Insufficient | Sufficient | Supraoptimal |
| Nitrate-Nitrogen (NO3-N), ppm | <40 | 40-300 | >300 |
| Phosphorus (P), ppm | <3 | 3-18 | >18 |
| Potassium (K), ppm | <60 | 60-350 | >350 |
| Magnesium (Mg), ppm | <30 | 30-140 | >140 |
| Calcium (Ca), ppm | <80 | 80-400 | >400 |
| Soluble Salts | Optimum | ||
| Electrical Conductivity, mmhos /cm | 0.8 - 5.0 | ||
| Total Dissolved Solids, ppm | 512 - 3200 | ||
| pH | 5.3 - 6.5 |
Important Concerns
- Plants of the Ericaceae family, e.g., azaleas and salt sensitive plants, require only one half the level of mineral nutrients and can tolerate only one half the soluble salts shown on the table above.
- Plant growth will be enhanced if additional nutrients are added in cases where the mineral analysis is low.
- Plant growth may be enhanced if nutrients at the lower end of the sufficient range are increased in the media.
- Plant growth will not be enhanced by the additional rates of nutrients, which are already in the supraoptimal range.
- Lab results for nitrate-nitrogen may be artificially high if a slow-release fertilizer is present in the mix.
- Soluble salt values exceeding the optimum range indicate the potential for excess salt accumulation, which may be toxic to plants.