Source: Soil Multi-Parameter Sensor manual — based on 2nd national soil survey standards & sensor specifications.
Nitrogen (N) — mg/kg
| Status | Range | Notes |
|---|
| NONE | 0 | No reading / sensor off |
| LOW | < 40 | Below Level 6 standard |
| GOOD | 40 – 150 | Cultivating soil: 90–120 mg/kg optimal |
| V.HIGH | 151 – 250 | Approaching excess |
| EXTREME | > 250 | Level 1 (>150): excess causes crop overgrowth |
Phosphorus (P) — mg/kg
| Status | Range | Notes |
|---|
| NONE | 0 | No reading |
| LOW | < 20 | Below Level 6 (<3 mg/kg critical) |
| GOOD | 20 – 100 | Most crops: 10–20 mg/kg optimal |
| V.HIGH | 101 – 300 | Fast-acting phosphorus >40 = Level 1 |
| EXTREME | > 300 | Excess can inhibit microorganism activity |
Potassium (K) — mg/kg
| Status | Range | Notes |
|---|
| NONE | 0 | No reading |
| LOW | < 100 | Below Level 6 (<30 mg/kg critical) |
| GOOD | 100 – 250 | High-yield farmland: 150–200 mg/kg |
| V.HIGH | 251 – 800 | Potassium chloride >200 = Level 1 |
| EXTREME | > 800 | Excess affects absorption of other elements |
Soil pH Value (range: 3–10)
| Status | Range | Soil Type |
|---|
| ACIDIC | < 4.5 | Extremely strong acidity |
| ACIDIC | 4.5 – 5.5 | Strongly acidic soil |
| ACIDIC | 5.5 – 6.5 | Acidic soil |
| OPTIMAL | 6.5 – 7.5 | Neutral soil (ideal) |
| ALKALINE | 7.5 – 8.5 | Alkaline soil |
| HIGH | > 8.5 | Strongly / extremely alkaline |
Soil Moisture — % (m³/m³, ±2%)
| Status | Range | Notes |
|---|
| DRY | < 20% | Sandy soil optimal: 8–22% |
| GOOD | 20 – 60% | Loamy: 15–35%; Clay: 15–45% |
| WET | 61 – 80% | Approaching saturation; risk of root rot |
| SATURATED | > 80% | Max ~50% normal; 100% = pure water |
Temperature — °C (±0.3°C)
| Status | Range | Notes |
|---|
| COLD | < 15°C | Slows root activity & nutrient uptake |
| GOOD | 15 – 30°C | Optimal range for most crops |
| WARM | 31 – 35°C | Above optimal; monitor moisture |
| HOT | > 35°C | Sensor range: –40 to 80°C |
Electrical Conductivity (EC) — µS/cm (±3%)
| Status | Range | Notes |
|---|
| LOW | < 200 | Nutrient-deficient soil |
| GOOD | 200 – 800 | Ideal for plant growth; irrigation <800 |
| HIGH | 801 – 1600 | Approaching salt damage risk |
| EXTREME | > 1600 | Max plant growth ≤2500 µS/cm; can kill roots |
| Status | Range | Notes |
|---|
| LOW | < 500 | Low mineral salt concentration |
| GOOD | 500 – 2000 | Normal water-soluble salt range |
| HIGH | 2001 – 4000 | High salinity; can limit crop growth |
| EXTREME | > 4000 | Sensor range: 0–20,000 mg/L |