BIOS Field Day at Locke Ranch

Chris and Christy Locke share the history of Locke Ranch and their participation in the original BIOS project. (Photo by Nolan Kirby)

The Community Alliance with Family Farms (CAFF) held a Biologically Integrated Orchard System (BIOS) field day at Locke Ranch on May 23rd. Attendees were treated to a walk through the orchard with Chris and Christy Locke, who were participants in the original BIOS project over twenty years ago. 

We kicked off the event with some background on the history of the Locke Ranch, which used to be a cattle ranch before it was a walnut orchard. Chris Locke described the farm’s soil at that time as essentially a “dust bowl.” In the late 1990s, he was approached by Joe Grant, the UCCE farm advisor at the time, who wanted to apply CAFF’s BIOS program focused on almonds to walnut orchards. Through this collaboration, Chris Locke dedicated himself to cover cropping and no-till and was able to revitalize his soil’s health.

The group moved into the orchard and got to walk through the large, historic walnut trees. Chris pointed out several trees that were cut back to the trunk and then grafted with Chandler cuttings. This technique allows him to switch from heritage varieties to a more profitable variety without ripping out the already established root system of the older trees.

Old trees that were grafted with Chandler cuttings, ranging from freshly grafted to 8 years after grafting. (Photos by Nolan Kirby and Moet Takata)
Karen Lowell outlines what growers should consider when planting cover crops. (Photo by Nolan Kirby)

Between the beautiful trees was a lush cover crop stand, made up of vetch, triticale, peas, and fava beans. Tom Johnson, of Kamprath Seed, and NRCS Agronomist, Karen Lowell, spoke about the management decisions to consider when planting a cover crop. They suggested that farmers should start simple, and focus on the specific problems they want to address. Since planting a cover crop can change a lot of other management decisions, they suggested starting at a scale that works for you and that you can manage and budget for. Chris and other farmers spoke about their experience with cover crops, and how it allowed them more flexibility with getting into the orchard and with nitrogen inputs. The improved soil health also built up the tree’s resilience, since they are not as dependent on inputs and could better withstand water stress, nutrient stress, and pest pressure.

Then, Christy Locke shared a short demonstration of the pressure bomb, which applies pressure to a sample leaf to measure the tree’s water stress levels. Christy utilizes the pressure bomb once a week to make smarter irrigation management decisions. 

Jeannine Lowrimore shows prototypes of pheromone dispensers used in the early days of mating disruption. (Photo by Nolan Kirby)

Jeannine Lowrimore, PCA and entomologist with Pacific Biocontrol, spoke about pheromone mating disruption, which the Locke’s have used for codling moths since the early 2000s. Mating disruption utilizes the female moth pheromone to confuse the male moths and disrupt the chances of them finding a female to mate with. Because this mechanism relies on the moths being spread apart enough to need pheromones to find each other, mating disruption is best adopted when pest pressure is still low or has been knocked down with a spray application. Jeannine explained that mating disruption allows a measure of insurance in cases where spray applications aren’t as efficient or aren’t timed correctly. Over time, mating disruption can become a stand alone program for codling moth like it is at Locke Ranch. Chris Locke decided to move away from codling moth sprays for the safety of his downwind neighbors and his employees. For farmers who might be looking for financial assistance for adopting mating disruption, NRCS provides funds for a conservation plan that includes pheromone dispensers.

The cover crop consists of vetch, triticale, peas, and fava bean. (Photo by Nolan Kirby)

To wrap up the field day, Zahangir Kabir, NRCS Soil Health Specialist, provided demonstrations highlighting the benefits of the soil health practices discussed throughout the event. Using soil samples from conventional orchards and cover cropped, no-till orchards, he compared the water infiltration and soil aggregate stability. These factors are important to avoid standing water, soil erosion, and runoff. Then he used a rainfall simulator to compare soils from the Locke Ranch and the neighboring Plant Materials Center. This simulation showed that the cover cropped soil had better water infiltration, even within the tree row where the cover crop is not planted directly. The bare soils suffered increased runoff, highlighting the importance of having cover crops to cover the soil, as well as to catch any runoff from the tree row.

This field day was a great opportunity for attendees to hear from a farmer who has seen the long term effects of these practices, and is also still innovating in other ways to expand their toolkit. As Chris Locke aptly said at the top of the event, “You need to say yes to new ideas.”


Learn more about CAFF’s Ecological Farming Program at

Christy Locke takes a leaf sample for the pressure bomb demo.
Christy uses the pressure bomb to measure water stress.
The pressure causes a droplet of water to form at the tip of the leaf stem.
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Photos by Nolan Kirby.