Reference
Soil intake rates by soil type
Intake rate is how fast a soil can absorb applied water. When the zone's precipitation rate exceeds it, water ponds and then runs off, and the schedule needs cycle-soak splitting. The longest safe cycle is the intake rate divided by the precipitation rate.
| Soil texture | Commonly published range | Working value used here | Notes |
|---|---|---|---|
| Sandy | about 0.5 to 1.0 in/hr | 0.75 in/hr | Fast intake; cycles rarely limited by soil on level ground. |
| Loam | about 0.25 to 0.5 in/hr | 0.45 in/hr | The common middle case for turf areas. |
| Clay | about 0.1 to 0.25 in/hr | 0.2 in/hr | Slow intake; sprays on clay almost always need multiple short cycles. |
Slope reduces effective intake before the soil itself saturates: water begins to move downhill across the surface. On graded areas, shorten cycles below the flat-ground figure and watch the first program run for surface movement.
Worked example
A fixed spray zone measured at 1.5 in/hr on loam absorbing 0.45 in/hr saturates the surface in 0.3 hours, so cycles are capped near 18 minutes. A 40 minute daily runtime becomes three cycles of about 13 minutes with soak intervals between them. The audit tool performs this split for every schedule it recommends.
Figures on this page are ranges drawn from manufacturer catalogue data and guidance commonly cited in Irrigation Association auditor training material. They are for orientation and sanity-checking a measured result, not a specification for any particular product or site. Confirm hardware figures against the manufacturer datasheet for the installed nozzle at the operating pressure.
Frequently asked questions
How fast does clay soil absorb irrigation water?
Published basic intake figures for clay commonly fall around 0.1 to 0.25 inches per hour, far below what fixed sprays apply. That mismatch is why spray zones on clay almost always need cycle-soak programming.
Which intake value does Irrigaudit use for the cycle split?
A single working value per texture class: 0.75 in/hr for sandy soil, 0.45 for loam, and 0.2 for clay, each inside the commonly published range. On slopes, shorten cycles below what these values suggest.