Another Surge Valve Experience!

This week we encountered another issue with a surge valve. After irrigating with a surge valve the producer noted that neither the 6” nor 12” sensors responded to the irrigation. When investigating the problem it appeared that the grower had done as instructed, making the proper adjustments to the advance cycle. What’s going on? Further investigation indicated that the soak cycle was not properly adjusted, therefore the water had not reached the bottom of the field. Remember the soak cycle sends a single pulse during each cycle to the tail ditch and requires fine tuning also. Under some conditions, the soak cycle may not reach the tail ditch or possibly reach the tail ditch and waste water before cycling to the 2nd set or leg.

A few weeks ago we introduced surge valves and the proper methods of setting the advanced and soak cycles. Remember there are different methods for heavy and light ground. Consider looking at https://www.mississippi-crops.com/2014/06/26/programing-a-surge-valve/ as a refresher.

Surge valves operate in two distinct cycles, an advance cycle and a soak cycle. The advance cycle sends a number of increasing pulses down the field until the tail ditch is reached. On the other hand the soak cycle sends a single pulse all the way to the tail ditch. The soak cycle only starts after the advanced cycle is complete. Both the advance  and the soak cycle will need to be manually adjusted for the desired results during the initial setup. It is important to know that just because the water has reached the end of the row in the advance cycle, the irrigation event is not complete until the soak cycle has run for the proper number of hours based on your PHAUCET recommendation.

Remember our last example where we had a sealing silt loam soil and a surge valve was used to increase infiltration. In our example, it required 25 hours last year to reach the tail ditch of the field during irrigation. This year we completed PHAUCET on the field and installed a surge valve. Following the recommended instructions we set the advance cycle of the surge valve to 13 hours (1/2 of 25+1hr) and started irrigating the field. As instructed, we checked the field in 12 hours to verify that the water had reached the tail ditch. Let’s say that the water actually reached the tail ditch in 11 hours not 13 as we had thought. We reset the surge valve advance cycle from the original 13 hours to 11. Once the soak cycle begins, we also need to verify that the single pulse is reaching the tail ditch prior to cycling to the next set or leg. Adjustment can be made to increase or decrease the soak cycle pulse. We want to reach the tail ditch without excess water leaving the field. We know our PHAUCET recommendation requires 20 hours to apply 3 acre/inches on each set or leg. Remember we have two sets or legs, so add each set or leg for the total run time. The total run time of the well and surge system from start to finish should be approximately 40 hours. Remember, a little fine tuning is required the first time you use a surge valve in a given field.