A walnut orchard in Princeton has developed a system that demonstrates cover crop efficacy in strengthening tree health from the ground up. By reaching out to the local Natural Resources Conservation Service (NRCS) office, Daniel Unruh has been able to employ several sustainable farming tactics to help improve the health and vitality of his orchard.
“He contacted us, he wanted to know what was going on in his soil,” said NRCS District Conservationist for Colusa County Wendy Krehbiel. “I think he was on his third year of trying a new type of cover crop mix to enhance both soil biology and compaction, and hopefully to combat a phytophthora issue in his orchard.”
Unruh had originally planted mustard to help address the nematodes that were in the orchard. After performing several biological, physical, and chemical soil-health tests, a baseline could be established for the orchard. “What we found was actually very low biological activity, which correlates with growing brassica,” Krehbiel stated.
Cover crops can provide a wealth of benefits to growers, however, developing cover crops in walnut orchards can be challenging. The amount of leaf litter on the orchard floor combined with relatively low levels of light that actually reach the orchard floor can have adverse effects on the growth of cover crops. The process is also complicated by the short period of time between harvest and leaf fall.
By making changes to the cover crop mix, Unruh was able to find a balance for what worked the best in his orchard to increase his overall cover crop efficacy. “He has seen an improvement in the trees, the trees are starting to push again whereas before they were just kind of staying stagnate, basically just surviving,” said Krehbiel.
Unruh grows walnuts on nearly 200 acres in Colusa County, having moved from South Dakota to California more than ten years ago. Unruh is also well versed in soil health, plant physiology and many different types of sustainable ag practices. “He views his orchard as a lab. He takes what he’s learned and he’s applying it to the land,” Krehbiel noted.
Listen to Krehbiel’s interview below.