Soil and Beds
Drainage Test Rate Calculator
Drainage Test Rate requires one defined scenario. Calculate a soil drainage-test rate from water-level change. Use water-level drop and observation time from the Drainage Test Rate record.
Enter values for drainage rate
Water-level drop and the other Drainage Test Rate fields share one scenario.
What Drainage Test Rate answers
The planning question for Drainage Test Rate is whether you can calculate a soil drainage-test rate from water-level change. Drainage Test Rate measures this portion as Drainage rate. Compare this result with Soil Percolation Time Calculator when drain time is also needed.
Record adjustments outside Drainage rate separately.
Worked drainage rate example
The drainage rate ratio uses Water-level drop and Observation time in the order shown.
Water-level drop at 4.5 in, observation time at 3 hr produces 1.50 in/hr in the demonstration case.
Reading drainage rate
Read Drainage rate as the answer to “Calculate a soil drainage-test rate from water-level change.” Keep the Drainage Test Rate units attached.
Water-level drop and the other inputs
Drainage rate is calculated from Water-level drop and Observation time. Check the Drainage Test Rate units before editing.
Water-level drop. Default in Drainage Test Rate: 4.5 in.
Observation time. Default in Drainage Test Rate: 3 hr.
Drainage rate: condition to verify
Repeat the test after pre-soaking when the procedure requires it.
A zero Observation time leaves drainage rate undefined in Drainage Test Rate.
Saving the Drainage Test Rate case
The calculation log for Drainage Test Rate needs Water-level drop and Observation time plus Drainage rate.
Attach the date and source of water-level drop; those details matter when the case is repeated.
Keep the measured outcome next to the drainage rate estimate so future planning can use both. Continue with Available Soil Water Calculator to find the water fraction held between field capacity and wilting point.
Checking the saved Drainage Test Rate case
Recalculate Drainage Test Rate from the saved water-level drop and observation time. The result should reproduce drainage rate.
If water-level drop changes, preserve the earlier case and label the revision.
Drainage Test Rate low-and-high comparison
A ten-percent test change in Water-level drop replaces 4.5 in with 4.95 in. Under the remaining sample values, drainage rate changes from 1.50 in/hr to 1.65 in/hr.
Only water-level drop changes in this Drainage Test Rate example, making its numerical effect visible.
Keep the original drainage rate and the test result as separate scenarios. Keep lime product needed in a separate Lime Application Amount Calculator case.
Before relying on drainage rate
How does “Repeat the test after pre-soaking when the procedure requires it.” affect drainage rate?
Drainage Test Rate uses the entered numbers only. Let water-level drop reflect that condition before calculating.
Can Observation time be zero in Drainage Test Rate?
In Drainage Test Rate, zero observation time makes drainage rate undefined.