Cover Crop Systems for Almond Orchards: Exploring Benefits and Tradeoffs to Inform Management

Project Overview

GW18-142
Project Type: Graduate Student
Funds awarded in 2018: $24,852.00
Projected End Date: 03/31/2022
Grant Recipient: University of California, Davis
Region: Western
State: California
Graduate Student:
Major Professor:
William Horwath
University of California, Davis

Information Products

Commodities

  • Nuts: almonds

Practices

  • Crop Production: cover crops
  • Education and Training: on-farm/ranch research
  • Soil Management: soil quality/health

    Proposal abstract:

    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
    orchard plots
    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
    days.
    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.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.