Physical Soil Health and Water Storage Dynamics of a Novel, Perennial Cover Crop in California Almond Orchards

Commodities

• Nuts: almonds

Practices

• Crop Production: cover crops
• Education and Training: demonstration, extension, on-farm/ranch research, technical assistance
• Natural Resources/Environment: carbon sequestration, soil stabilization
• Soil Management: organic matter, soil physics, soil quality/health

Cover cropping has been demonstrated to be an effective conservation technique at combating soil degradation and restoring soil health. Unfortunately, California orchard growers have low rates of cover cropping due to management timing, costs, and concerns of competition with crops for resources, especially water. A hybridized cool season grass, Radix Poa bulbosa, commonly referred to as Oakville Bluegrass, presents a novel drought-tolerant, perennial cover crop designed for orchard systems. The project team will partner with working almond orchards in the California Central Valley to assess the impact of Oakville Bluegrass on a suite of physical and hydrologic soil properties during cover crop establishment. This research will address if the novel cover crop can bring improvements to water storage dynamics through structural changes and carbon inputs. Continuous soil moisture data will be collected in addition to water use efficiency of orchard trees to clarify perceptions of cover crop water use, addressing concerns that often lead orchard growers to maintain bare ground management. Collaborating almond growers will document operational changes linked to managing the cover crop. Field days, hosted on participating orchards, will showcase the soil health impacts of cover cropping with Oakville Bluegrass and offer technical assistance to growers. Research findings will be communicated through printed outreach materials and digital media in the form of a short video, blog, and podcast. This research aims to contribute to knowledge on soil health and water dynamics of perennial cover crops in semi arid, irrigated cropping systems of California.

Research Objectives: 

1. Evaluate the impact of perennial cover cropping on structural and hydrologic soil properties compared to bare ground management.
2. Quantify changes in soil carbon pools from cover cropping and evaluate carbon inputs from cover crop biomass, ground coverage, and plant C:N. 
3. Examine the effect of cover cropping on soil moisture and plant water response of almond trees.

Educational Objectives:

1. Create outreach materials to increase knowledge and awareness of the effect of cover cropping on soil health through:
   1) a video showcasing soil management strategies using a rainfall simulator demonstration, and 2) an illustrated fact sheet about perennial cover cropping with Oakville Bluegrass.
2. Demonstrate the soil health and management impacts of perennial cover cropping compared to bare ground management through two field days hosted at a participating producer’s orchard.
3. Communicate findings through 1) co-creating an episode for the UC ANR Water Talk podcast, 2) presenting research at extension and grower conferences, and 3) publishing research in a peer-reviewed journal.