| Soil | Slope (%) | Precip (mm/hr) | Target depth (mm) | Cycles | Run/cycle (min) | Soak (min) |
|---|---|---|---|---|---|---|
| Sandy | 2 | 30 | 10 | 1–2 | 12–18 | 5–8 |
| Loam | 6 | 35 | 12 | 2–3 | 10–14 | 8–15 |
| Clay | 10 | 40 | 10 | 3–5 | 6–10 | 12–20 |
- Application rate per minute: mm_per_min = precip_rate / 60
- Total runtime from target depth: runtime = target_depth / (mm_per_min × efficiency)
- Allowable depth per cycle: base by soil, reduced by slope.
- Cycle minutes: cycle_min ≈ allowable_cycle_depth / mm_per_min (then clamped to practical limits).
- Number of cycles: cycles = ceil(runtime / run_each)
- Soak minutes: soak = max(min_soak, run_each × soak_multiplier) (then capped).
- Pick your soil texture, then enter slope and precipitation rate.
- Enter a target watering depth, or enter total runtime.
- Keep efficiency realistic; 0.70–0.85 is common outdoors.
- Optionally override soil intake and max cycle depth if measured.
- Click Calculate, then program the run and soak sequence.
- Observe the zone; shorten cycles if runoff appears.
Why cycle‑soak improves infiltration
Spray zones often apply water faster than soil can absorb it, so water runs sideways before it moves down. Typical spray precipitation runs 30–60 mm/hr, while intake ranges about 15–30 for sand, 5–15 for loam, and 2–6 for clay. Splitting runtime into short cycles limits surface sealing, keeps pores open, and reduces runoff near hardscape edges. This approach also improves uniformity on compacted beds and new turf.
Interpreting precipitation rate and efficiency
The effective application rate equals precipitation rate multiplied by efficiency. A well‑matched nozzle set and correct pressure may deliver 0.75–0.85 efficiency, while windy conditions or mixed radii can fall near 0.60–0.70. If your planned weekly depth is 25 mm and efficiency is 0.70, you must apply about 36 mm to net the target in the root zone.
Setting cycle length from soil intake and slope
Cycle minutes are driven by allowable depth per cycle divided by the effective mm per minute. On slopes, reduce allowable depth 20–50% because runoff starts sooner and infiltration is uneven. Stream rotators often apply 10–20 mm/hr, so they tolerate longer cycles than fixed sprays. For clay on a slope, start small, then lengthen only after observation.
Choosing soak time for redistribution
Soak time lets water redistribute through capillary movement before the next burst. Many gardens perform well with 10–30 minutes on loam, and 20–45 minutes on clay where infiltration is slow. In sand, shorter soaks can work because intake is high but drainage is fast. Use longer soaks when you see puddling disappear between cycles.
Field checks and seasonal adjustments
After programming, watch the zone during the first cycle and use a simple catch‑can test to verify precipitation. If water sheets, shorten cycles and increase the number of cycles; if soil stays dry at 75–100 mm depth, increase total runtime. In peak heat, raise weekly depth or frequency; during cool seasons, reduce depth and keep cycles minimal to prevent disease and algae. Start conservative; fine-tune after two irrigation cycles.
What is cycle‑soak irrigation?
Cycle‑soak splits one long watering into several short runs with pauses. The pauses let water infiltrate, reducing runoff and improving wetting depth, especially on clay soils, slopes, and compacted lawns.
How do I estimate precipitation rate for my zone?
Use the nozzle chart, or run a 10‑minute catch‑can test. Measure average collected depth in millimeters, then convert to mm/hr by multiplying by 6.
What efficiency value should I use?
Start with 0.75 for well‑matched heads in calm conditions. Use 0.65–0.70 if wind, overspray, or uneven coverage is common, and improve hardware if readings stay low.
How many cycles are practical?
Two to five cycles work for most gardens. More cycles can be useful on steep slopes, but too many cycles may stretch schedules and reduce deep percolation time overnight.
Should soak time be longer for clay soils?
Usually, yes. Clay benefits from longer pauses so surface water can move down between runs. Try 20–45 minutes, then adjust based on whether puddles disappear before the next cycle.
Can I use this for drip irrigation?
Yes, but drip rarely needs cycle‑soak because application is slow. Enter the dripline precipitation rate, use a high efficiency, and expect fewer cycles with shorter soak times.