If water pools on your lawn or runs down the driveway after irrigation starts, you have a classic problem: the precipitation rate (PR) of your sprinkler heads exceeds the soil's infiltration rate. The Cycle and Soak method solves this by splitting total run time into shorter cycles with soak pauses that let water absorb into the soil.
What Is Cycle and Soak?
Instead of running a zone for one continuous 18-minute session, you run several shorter cycles (e.g., 3 × 6 minutes) with 30–60 minute soak pauses between them. During each pause, water penetrates past the surface into the root zone rather than running off. Think of it as mimicking natural rainfall — short bursts with breaks — rather than a continuous downpour. The result: deeper moisture penetration, zero runoff, and a healthier root system.
Why It's Needed: Precipitation Rate vs. Infiltration Rate
Every sprinkler head delivers water at a specific precipitation rate (PR), measured in mm/h. At the same time, the soil can only absorb water at a limited infiltration rate that depends on soil texture, compaction, organic matter, and slope. When PR exceeds the infiltration rate, excess water cannot soak in and begins to run off. This wastes water, washes away nutrients, and can cause erosion damage to adjacent areas.
Infiltration Rates by Soil Type
| Soil Type | Infiltration Rate (mm/h) | Characteristics |
|---|---|---|
| Sand | 50+ mm/h | Water passes through quickly; cycle & soak rarely needed |
| Sandy loam | 25 mm/h | Good infiltration for most head types |
| Loam | 15 mm/h | Moderate infiltration; problems with spray heads |
| Clay loam | 8 mm/h | Slow infiltration; cycle & soak needed for most heads |
| Clay | 3–5 mm/h | Very slow infiltration; cycle & soak mandatory |
The Formula
Calculating the maximum safe cycle time is straightforward:
Max cycle time (min) = Soil infiltration rate (mm/h) ÷ Precipitation rate (mm/h) × 60
For example, clay loam (8 mm/h) with spray heads (PR = 40 mm/h):
8 ÷ 40 × 60 = 12 minutes — the longest you can run before water starts running off.
Cycle-and-Soak Requirement Matrix
Whether cycle and soak is needed depends on the combination of soil type and head type:
| Soil Type | Spray Heads (40 mm/h) | Rotors (15 mm/h) | Rotary Nozzles (10 mm/h) |
|---|---|---|---|
| Sand (50+ mm/h) | Not needed | Not needed | Not needed |
| Sandy loam (25 mm/h) | Needed | Not needed | Not needed |
| Loam (15 mm/h) | Needed | Borderline | Not needed |
| Clay loam (8 mm/h) | Needed | Needed | Needed |
| Clay (3–5 mm/h) | Needed | Needed | Needed |
Practical Example: Clay Soil + Spray Heads
Consider a common scenario: a lawn on clay soil (infiltration 3 mm/h) with fixed spray heads (rotor vs spray heads comparison) running at PR = 40 mm/h. You need to apply 10 mm of water.
Step 1. Total run time: 10 ÷ 40 × 60 = 15 minutes
Step 2. Max cycle time: 3 ÷ 40 × 60 = 4.5 minutes
Step 3. Number of cycles: 15 ÷ 4.5 = 3.3 → round up to 4 cycles
Step 4. Cycle duration: 15 ÷ 4 = 3.75 minutes (≈ 4 min)
Step 5. Soak time between cycles: 30 minutes
Schedule: 4 min ON → 30 min soak → 4 min ON → 30 min soak → 4 min ON → 30 min soak → 4 min ON
Total elapsed time with soaks: ~106 minutes instead of 15, but not a single drop is wasted to runoff.
How Smart Controllers Automate Cycle and Soak
Modern smart irrigation controllers (Hunter Hydrawise, Rain Bird ESP-ME3, Toro Evolution) have built-in cycle and soak functionality. You enter soil type and head type — the controller automatically splits run time into cycles. Some advanced controllers even learn from soil moisture sensors to fine-tune soak durations. SmartPluvia integrates with Hunter Hydrawise and OpenSprinkler via its IoT module, allowing you to configure cycle and soak from the web interface.
Key benefits of automation:
- The controller calculates optimal cycle count automatically
- Soak pauses are filled by watering other zones — time is used efficiently
- Seasonal adaptation (drier summer soil means even slower infiltration)
- No manual timer juggling — set it once and forget
Tips for Slopes
On slopes and hillsides, gravity accelerates runoff, making cycle and soak even more critical. The general rule: reduce the maximum cycle time by 50 % for slopes steeper than 15 %. In our clay example above, instead of 4.5 min max, you would use 2.25 minutes.
Additional recommendations for sloped areas: Read also: irrigation on slopes. Read also: soil moisture sensors. Read also: water conservation.
- Use low-PR heads (MP Rotator, rotary nozzles) wherever possible
- Consider drip irrigation for steep sections
- Run zone lines parallel to the slope contour, not perpendicular
- Increase soak time to 45–60 minutes
- Check for erosion channels after heavy watering sessions
Summary
Cycle and Soak is a simple but extremely effective technique that can reduce runoff losses by 50–100 %. If your soil is clay, compacted, or your property has slopes, this technique is not optional — it is essential. Use SmartPluvia to visualize coverage zones and calculate precipitation rates, then configure cycle and soak on your controller for maximum water efficiency.