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.