Surge Valve Issues and Gleanings.

This past week we encountered the following situation. A Grower irrigated a silt loam field utilizing a surge valve. When he checked his moisture probes neither the 6” nor the 12” Watermark™ sensor had moved. What’s going on? After careful evaluation we realized that the grower had prematurely terminated the irrigation cycle.

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 ran for the proper number of hours based on your PHAUCET recommendation.

Let’s say we have a sealing silt loam soil that we have decided to utilize a surge valve to increase infiltration. Last year it required 25 hours 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. (Do not randomly set the advance cycle too long)   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. First we reset the surge valve advance cycle from the original 13 hours to 11. Secondly we refer to our PHAUCET recommendation and see that it 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. Or in this case 40 hours. The total run time of the well and surge system from start to finish should be approximately 40 hours.