At nine years old, Liam Taylor was easily the youngest member of a panel of growers who talked about the virtues and challenges of pivot irrigation systems for California crops during a field day at Five Points, Calif.
His dad, Will Taylor of King City, Calif., south of Salinas, saw to it that Liam was there to describe the ease of managing the system Taylor uses to grow potatoes that go to buyers, including In-N-Out Burger.
“It’s easy,” Liam affirmed when pressed by participants in the field day.
But not all is easy when it comes to overhead irrigation and use of conservation tillage and cover crops. Participants in the field day at the West Side Research and Extension Center got an earful about the challenges of those systems and the potential rewards for adopting them.
Jeff Mitchell, cropping systems specialist with the University of California’s Kearney Agricultural Center, described the experimental acreage as “the most visited field in California.” That’s because of what’s been going on there for 10 years: research into growing crops using conservation tillage and cover crops, and – more recently – overhead irrigation coupled with those two practices.
Among successes Mitchell cited was a crop of 52 tons per acre of processing tomatoes on land in conservation tillage.
Will Horwath, professor of soil biogeochemistry and soil biogeochemist at UC Davis, cited another positive development: Carbon was increased on the experimental plots “up to 5 tons per hectare,” about 2.5 acres, by combining reduced tillage with cover crops.
Each step, he said, combined to result in doubling of carbon content in 10 years.
A hands-on experiment later in the field day showed the importance of added carbon.
Volunteers did a soil infiltration test and collected handfuls of soil from plots in which a cover crop and conservation tillage was used and from sites where no cover crop and standard tillage was used.
Genett Carstensen, a soil conservationist with the Natural Resources Conservation Service, cited differences in slaking in the soil clumps after they were immersed in water. “Carbon acts as a glue,” she said, pointing out that the soil from the cover crop/conservation tillage plot remained bound together. By comparison, soil from the non-cover crop/conventional tillage plot crumbled quickly.
Mitchell talked of the use of overhead irrigation on crops that included wheat, corn, tomatoes, onions, cotton and broccoli. He said one of the characteristics of the overhead systems was “uniform water applications.” He emphasized that water evaporates from bare soil more quickly than from soil with cover crop residues. Moreover, he said, reducing tillage has been shown in studies in Nebraska to save nearly 1 inch of water in a growing season.