We are having lots of questions concerning the proper set up of surge valves. First, please consider some of the basic terminology associated with furrow irrigation.
We encourage you to visit http://www.youtube.com/watch?v=46sSLFBUrh8 and view the video before continuing.
Phases of Furrow Irrigation
1. Advance Cycle – The phase in which the dry furrow is wetted. This cycle creates multiple pluses down the field.
2. Out Time – The time required for water to reach the end of the furrow.
3. Soaking Cycle – The phase in which the required application depth is infiltrated. This is a single pulse, with each pulse reaching the tail ditch.
4. Soaking Time – The time it takes the required application depth to infiltrate.
The following are points to consider when setting up a surge valve:
If you have a silt loam or sandy soil that has a tendency to seal causing water infiltration to be an issue:
1. Determine the Out Time from past experience.
2. Set the Advance Cycle to ½ of the Out Time + one hour. For example, if you have a field that has historically required 24 hours to get the water across and you now have this same field set up with a surge valve, the Advance Cycle would be set to 13 hours.
3. It is critical that the time required for water to actually reach the tail ditch be recorded. Any adjustments to the Advance Cycle of the surge valve need to be made before the Soaking Cycle begins. You made need to add or subtract time from the original settings of the Advance Cycle. If you miss this timing, adjustments can only be made after the completion of the Soaking Cycle.
4. The Soaking Time or completion time can be found on your PHAUCET printout. If PHAUCET requires 20 hours to apply 3 acre inches on each set, then the total system run time is 40 hours before you shut the system and well off. It is equally important to adjust the Soaking Time, if the single pulse is falling short of the tail ditch, time should be added, if the single pulse is putting water in the ditch, time should be subtracted.
If you have a cracking clay soil:
1. Refer to your PHAUCET printout for the time required to apply 3 acre inches. For example, the printout may say that 22 hours are required to apply 3 acre inches.
2. Set the Advance Cycle to the recommended time on the PHAUCET printout.
3. After setting the advance cycle time producers need to adjust the total number of cycles per side for the valve to complete. Press the “custom” tab, set the number of cycles per side (#cycles/side) to a minimum of 3+1 for most situations.
4. Shut the well and system off at the recommended time.