A highway expansion project provided some of the impetus for the switch from a pivot irrigation system to a sub-surface drip system on ground farmed by Derek Sawyer, McPherson. Sawyer and his wife, Katie, are being recognized by the McPherson County Soil Conservation District with the 2017 Water Conservation Award.
The Sawyers’ farm is dissected by K-61 Highway and lost 30 acres of irrigated land when the highway expanded to a four lane. The altered configuration of the field, which had been irrigated for 45-50 years with a pivot irrigation system, led to Sawyer’s interest in installing a drip system when the pivot needed replacing.
“We had already lost 20 acres of irrigation potential to the corners of the pivot system. By converting to the drip system, we were able to recover 25 acres, almost making up for what we lost to the highway,” Sawyer said.
While it is more expensive to put in a sub-surface drip system than to put up a pivot, Sawyer made up some of those costs by receiving Agricultural Water Enhancement Program (AWEP) funding. The funding, coupled with the recovered irrigated acres, made the system’s installation costs competitive with a pivot system. Sawyer also anticipates more efficient use of water and energy costs in the future.
This is the fourth sub-surface drip system Sawyer has had installed. This is the fourth year with the system on this field. While many farmers install drip systems to help extend wells with limited output, that was not Sawyer’s primary concern. The well for this particular field is in the Equus Beds and has good, consistent output. Sawyer has found the system’s primary benefit is efficiently putting water where it is needed.
Sawyer irrigates the field in six zones usually putting water on two zones, or 35 acres, at a time. The tapes which carry the water are placed 60 inches apart and 16-18 inches deep. He has the capacity to put a half- inch of water over the whole field in a 24-hour period – about what a growing corn crop requires. This allows him to delay irrigating until the crop needs it. With the pivot, it was easier to get behind with watering, he said. He applies fertilizer through the tape throughout the growing season as needed.
“(The system) is very efficient at putting water and nutrients in the root zone. I’ve been able to grow more bushels of grain per unit of water than with other systems,” Sawyer said. “It also helps conserve water because the water goes where it’s needed, there is no evaporation and the top of the ground stays dry. This is particularly helpful when we do catch a rain. When we had the surface saturated using the pivot, rainfall would run off and we’d lose it. With the drip system, rain can soak into the dry top layer and we can utilize it also.”
Sawyer has found the system requires more management, even though it cuts down on the physical labor hours of other irrigation methods. By participating in the AWEP program, he was required to go through training and use the KanSched program through Kansas State University to monitor growing conditions and soil moisture. The computer program tracks rainfall, evapotranspiration and irrigation rates to track ground saturation, and to signal when he should start irrigating. He’s found the program to be an accurate indicator of soil moisture. He’s still learning about the intricacies of the irrigation system mechanically and optimal saturation of the ground for the crop growth stage. He’s also found there are some seed varieties whose genetics respond better than others to sub-surface irrigation conditions.
Switching to the drip system has brought changes to the way Sawyer farms. Guidance systems are critical to planting in the right spot in the field in relation to the tapes. No-till and minimum tillage practices are required so tapes are not caught on deep-tillage tools. And, there’s no more planting into marginal moisture and “watering” the crop up with the pivot. Those seeds will just sit there until there is a rain.
While Sawyer has been very satisfied with the results from the drip system, there have been some unanticipated challenges. The field’s bottom 50 acres, which border the Blaze Fork drainage ditch, typically flood at least once a growing season. The weight of the water on the ground compacts it to the point that the tape has trouble expanding enough to carry the desired amount of water. The field’s heavy clay content also tends to restrict how much water the tape will carry. However, the expansion and contraction of the tape does help loosen up the ground.
“It’s definitely not fault free. The system needs maintenance,” Sawyer said. That includes flushing out the system, installing filters on some of his wells with high mineral content, running chloride through the system to keep the tapes and emitters from clogging, and repairing tapes that are damaged. Under the AWEP guidelines, the system has to be maintained for at least 15 years.
“I think water is a very important commodity and that won’t change going forward. We have to do the best we can to utilize it efficiently. Moving to systems like this can help where groundwater is depleted. But, without government assistance, such as the AWEP program, it’s very expensive to install,” Sawyer said.
This is especially concerning to him since the program is no longer offering contracts to producers. Sawyer has visited with members of Congress about the need for the program to be refunded and has hosted congressmen on his farm to show them how the system works.