Soil Moisture Depletion Calculator
| # | Date | Day | Net Depth (in) | Status |
|---|
What is Soil Moisture Depletion?
SMD is the difference between the soil’s water content at field capacity and its current water content — how much water the soil has lost and needs replaced to return to field capacity.
SMD Formula
SMD = (FC% − Current%) × Root Depth ÷ 100 — volumetric water percentages converted to equivalent depth in inches.
Total Available Water (TAW)
TAW = (FC% − WP%) × Root Depth ÷ 100 — maximum extractable water between field capacity and permanent wilting point.
Management Allowable Depletion (MAD)
Fraction of TAW safely depleted before crop stress. RAW = MAD × TAW. Sensitive crops: 30–40%; most crops: 50%; drought-tolerant: 60–70%.
Crop ETc
ETc = Kc × ET₀ — Kc is the crop coefficient (varies by growth stage); ET₀ is FAO-56 reference evapotranspiration.
Soil Texture Reference Table
| Soil Texture | FC (%) | WP (%) | AWC (in/in) | Ksat (in/hr) |
|---|---|---|---|---|
| Sand | 10 | 4 | 0.06 | 8.00 |
| Loamy Sand | 13 | 6 | 0.07 | 2.40 |
| Sandy Loam | 18 | 8 | 0.10 | 1.00 |
| Loam | 28 | 12 | 0.16 | 0.40 |
| Silt Loam | 32 | 12 | 0.20 | 0.25 |
| Sandy Clay Loam | 27 | 14 | 0.13 | 0.20 |
| Clay Loam | 36 | 20 | 0.16 | 0.10 |
| Silty Clay Loam | 37 | 19 | 0.18 | 0.08 |
| Sandy Clay | 38 | 24 | 0.14 | 0.06 |
| Silty Clay | 41 | 27 | 0.14 | 0.04 |
| Clay | 43 | 28 | 0.15 | 0.02 |
For Educational and General Planning Purposes Only. This calculator is a general agricultural planning aid based on FAO-56 standard formulas. Results are a starting point for irrigation decisions — not a definitive agronomic prescription.
By using this tool, you acknowledge:
- No Guarantee of Accuracy: Soil moisture varies due to local soil variability, microclimates, crop health, and other factors this calculator cannot account for.
- Field Verification Required: Always validate estimates with tensiometers, soil moisture sensors, or lab analysis before critical irrigation decisions.
- Consult a Professional: For commercial or large-scale operations, consult a qualified agronomist, soil scientist, or certified irrigation specialist.
- Input Quality Matters: Results are only as reliable as the values you enter. Incorrect soil parameters produce unreliable outputs.
- No Liability: MoralInsights.com accepts no responsibility for crop losses, irrigation failures, or any outcome from reliance on this tool’s outputs.
Always prioritize direct field observation and professional judgment over automated estimates.
- Does not replace advice from a licensed fisheries expert
- Profitability estimates depend on actual prices and operational costs
- Always test water quality before stocking any pond