- Nuts: almonds
- Crop Production: cover crops
- Education and Training: on-farm/ranch research
- Soil Management: soil quality/health
With a total crop value of $5 billion, almond (Prunus dulcis) is one of California’s most important
crops. Almond production is faced with multiple challenges, many of which are related to soil
degradation. Based on the recent Almond Board of California Sustainability Survey, there has been
a shift in growers’ soil management practices away from the conventional bare soil management,
and towards maintaining a resident vegetation soil cover throughout most of the year. This change
was in response to increasing concerns regarding orchard soil health, and the increased interest to
reduce the environmental footprint of almond production. Despite the need for soil health
improvement strategies, there is currently no scientific assessment of the impact of different soil
management practices on soil health of almond orchards. Short-term studies conducted in the
1990s showed that cover cropping was compatible with these production systems. However, this
practice was never widely implemented due to remaining concerns regarding possible tradeoffs,
particularly relating to water usage. To address these uncertainties, my project is first conducting
a state-wide survey to identify barriers, which have hampered cover crop adoption in California,
and to understand the motivators, which could shift growers’ decisions. Three replicated,
randomized experiments have been established in 2017 in growers’ orchards across California’s
soil-climate gradient to assess the impact of two cover crop mixes on soil health. The two multispecies
cover crop mixes were designed to address key grower objectives (pollinator health and
soil health). The project is integrated within a larger system-wide analysis in collaboration with
other UC Davis research teams evaluating multiple co-benefits of cover cropping on ecosystem
services (pollinator health, soil food web support, weed management, parasitic nematode
suppression and water balance). This will provide growers with a comprehensive opportunity cost
assessment and support the adoption of sustainable soil management practices.
Project objectives from proposal:
Objective 1 – Compile knowledge on the use, management and barriers for the adoption of cover
crops in irrigated almond orchards.
Objective 2 – Provide an overall soil health analysis of cover cropped versus non-cover cropped
Objective 3 – Determine how cover cropping management can be integrated in almond orchards
to address specific soil-related issues.
a. Orchard trial 1: Compaction study: Determine the capacity of cover cropping to restore
and maintain soil quality and structure at a compacted site compared to deep ripping.
b. Orchard trial 2: Termination study: Determine how cover crop termination timing
affects nitrogen fixation, and C: N dynamics in orchard soils.
c. Orchard trial 3: Nitrogen study: Determine the effect of cover cropping on nitrogen
cycling in orchard systems.
Objective 4 – Evaluate the performance of each cover crop species mixture through an ecosystem
service assessment to weigh the benefits to tradeoffs of cover cropping.
Objective 5 – Extend information and communicate results to growers on the potential of cover
cropping to augment ecosystem services in almond orchards, through workshops and grower field
Objective 6 – Contribute to the scientific body of knowledge related to sustainable agriculture by
publishing the outcomes of objectives 1-5 in peer-reviewed journals.