Reproduce a reviewed irrigation water-demand depth minus effective precipitation, apply a documented efficiency, convert signed area-depth to volume, and compare an independent volume record.
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Reproduce one reviewed irrigation water-demand depth minus effective precipitation, apply one documented efficiency and compare an independent volume without prescribing irrigation or approving a water record.
Find whether the copied depth, efficiency or volume record explains a discrepancy without receiving an unreviewed irrigation recommendation.
Name each source and common period, choose one unit system, copy the reviewed values and inspect every signed intermediate.
Can trace the arithmetic while crop, soil, weather, timing, flow and operating decisions remain with responsible records and advisers.
Keep crop-demand, effective-precipitation and efficiency definitions visible instead of hiding them behind method-wide defaults.
Use reviewed-water-budget basis, compare a separately calculated volume and investigate either positive or negative differences.
Sees an auditable unit conversion and discrepancy without a claim that the entered values, design or application are correct.
Understand effective precipitation, percent efficiency and area-depth volume while avoiding false certainty from a simple formula.
Run US and metric exercises, test zero precipitation and a precipitation value above demand, and keep the signed output.
Can reproduce the calculation and identify the agronomic, hydraulic, allocation and compliance questions the calculator cannot answer.
Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.
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NRCS distinguishes effective precipitation—the portion usable for crop evapotranspiration—from total rainfall. Copy both values from responsible records covering the same crop/area, date or period and water-balance definition; the calculator does not estimate either value.
Signed net depth = documented demand depth − documented effective-precipitation depthEfficiency must be greater than zero and no more than 100%. Its definition may cover field application, conveyance, distribution or a combined system; identify the reviewed basis instead of selecting a default from the irrigation method.
Signed gross-depth equivalent = signed net depth ÷ (documented efficiency % ÷ 100)USGS gives about 27,154 gallons per acre-inch; one hectare-millimetre is 10 cubic metres. Compare the reproduced signed volume with one independent nonnegative record. A difference is an audit prompt, not a prescription or approval.
US gallons = signed depth (in) × acres × 27,154; metric m³ = signed depth (mm) × hectares × 10Updated: August 2026
A five-acre exercise records 0.25 in demand, 0.05 in effective precipitation and 75% application efficiency for one period. The reproduced signed volume is 36,205.333 gal; versus an independent 36,000 gal record, the signed difference is +205.333 gal.
A ten-hectare record uses 6 mm demand, 2 mm effective precipitation and 80% efficiency. The 500 m³ reproduction compared with 510 m³ preserves a signed −10 m³ difference without choosing a timing or application action.
If a reviewed effective-precipitation value exceeds the reviewed demand for the same period, the signed net depth and volume remain negative. That flags a record-basis question; the calculator does not turn it into a no-irrigation recommendation.
Create a source-labelled arithmetic record from an already reviewed water budget, irrigation schedule or education exercise. Keep demand depth, effective precipitation, efficiency, area and independent volume tied to the same period and unit basis. The calculator exposes signed arithmetic and unit conversion; it does not select crop ET, rainfall treatment, efficiency, irrigation method, timing, runtime, allocation or compliance action.