Nutrient (ppm) | Very Low | Low | Medium | High | Very High | Best Use of Test | |
Phosphorus P | |||||||
Olsen Bicarbonate | 0-3 | 4-9 | 10-16 | 17-30 | 30+ | neutral, alkaline, calcareous | |
Bray-1 | 0-5 | 6-12 | 13-25 | 26-50 | 51+ | neutral, acidic | |
Bray-2 | * | * | * | * | * | pH dependent | |
Mehlich-2 | 0-5 | 6-12 | 13-25 | 26-50 | 51+ | wide range of soils | |
Mehlich-3 | 0-5 | 6-12 | 13-25 | 26-50 | 51+ | wide range of soils | |
Potassium K | 0-40 | 41-80 | 81-120 | 121-200 | 201+ | ||
Sulfate | 0-4 | 5-7 | 8-11 | 12-15 | 16+ | low organic matter | |
Magnesium Mg | 0-10 | 11-20 | 21-35 | 36-50 | 51+ | ||
Zinc Zn | 0-0.25 | 0.26-0.50 | 0.51-0.75 | 0.76-1.00 | 1.01+ | alkaline soils | |
Iron Fe | 0-1.0 | 1.1-2.0 | 2.1-4.5 | 4.6-10.0 | 10.1+ | alkaline soils | |
Copper Cu | 0-0.10 | 0.11-0.20 | 0.21-0.30 | 0.31-0.60 | 0.61+ | ||
Manganese Mn | 0-0.5 | 0.6-1.0 | 1.1-1.5 | 1.6-4.0 | 4.1+ | alkaline soils | |
Boron B | 0-0.10 | 0.11-0.25 | 0.26-0.50 | 0.51-2.00 | 2.1+ | ||
Aluminum | |||||||
KCI xchangeable |
0-1 | 2-5 | 6-20 | 21-40 | 40+ | for acid soils | |
*Predicts amount of insoluble tricalcium phosphate | |||||||
CEC ranges for different soil textures, pH<7.0 | |||||||
Sand | <6 | ||||||
Sandy Loam | 5-10 | ||||||
Loam | 9-18 | ||||||
Clay Loam | 15-25 | ||||||
Clay | >22 | ||||||
1:1 pH | pH Rating | ||||||
<5.4 | Strongly acidic | ||||||
5.4-5.7 | Moderately acidic | ||||||
5.8-6.2 | Slightly acidic | ||||||
6.3-7.3 | Neutral | ||||||
>7.3 | Alkaline | ||||||
Soluble Salts | mmho/cm | ||||||
No crop hazard | 0-1.5 | ||||||
Yield reduction on sensitive crops | 1.6-3.0 | ||||||
Moderate yield reduction | 3.1-5.5 | ||||||
Severe yield reduction | 5.6+ | ||||||