Evaluating cover crops for mature hazelnut orchards in the Willamette Valley, Oregon

Project Overview

Project Type: Professional + Producer
Funds awarded in 2016: $49,997.00
Projected End Date: 01/15/2019
Grant Recipient: Oregon State University
Region: Western
State: Oregon
Principal Investigator:
Dr. Nik Wiman
Oregon State University

Annual Reports


  • Nuts: hazelnuts


  • Crop Production: cover crops, nutrient cycling, organic fertilizers, tissue analysis
  • Education and Training: decision support system, demonstration, extension, focus group, on-farm/ranch research, participatory research
  • Pest Management: biological control, integrated pest management
  • Production Systems: agroecosystems
  • Soil Management: soil analysis, soil microbiology, organic matter, soil quality/health
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    Oregon hazelnuts are harvested from the orchard floor using a tractor to sweep nuts into a windrow that a tractor-drawn harvester collects. This requires a compact orchard floor that is relatively free of surface irregularities like erosion rills, gopher mounds, and significant ground cover. To achieve this, conventional producers commonly spray strips of herbicide on either side of the trees in the direction of harvest and sometimes over the entire orchard floor. If a strip of vegetation remains, producers repeatedly flail it almost flush with the ground until its growth slows in summer or nuts begin to drop. Producers also drag floats to compact the soil and shear off surface irregularities. Several sustainability issues have emerged from these orchard floor management practices, including diminished soil health from compaction, erosion, and depleted organic matter. In this WSARE project we plan to address a deficit of research into orchard floor management practices and provide alternative sustainable floor management options. We will examine how cover crops can be incorporated into the hazelnut production system to improve soil health. We will also document indirect costs and benefits of cover cropping (e.g. pest management) and produce an economic analysis.

    Project objectives from proposal:

    Year 1 (2016)

    1. Select candidate cover crop species using producer input (NZ clover, subterranean clover, vetch, triticale are current candidates)
    2. Lay out cover crop research plots in mature orchards (randomized complete block design).
    3. Collect historic and current baseline data on test plots for the following variables:
      • Crop yield and quality history
      • Nitrogen and humus content and amendment application history
      • Soil type, depth, and porosity
      • Evidence of erosion, current orchard floor surface irregularity, and historic orchard floor treatment
      • Canopy cover (light interception on orchard floor)
      • Amount and type of existing species of: soil microbes, veg-etation, insects, and rodents
      • Other relevant conditions, e.g., neighboring crops.

    4. Coordinate seed purchase and seed drill rental (post harvest).

    5. Seed 1 acre of each of 4 seed treatments and controls (unseeded, bare ground) into replicated test plots in randomized block design at each cooperating producer orchard (one plot already established at McAdams farm in fall 2015, 6 replications per treatment).

    Year 2 (2017)

    1. Collect data every two weeks at each site until cover crop is terminated.
      • Cover crop growth: measure height and coverage, use this data to determine phenology for the different crops.
      • Soils: organic matter, nutrient and microbe analysis.
        Foliar tissue: nutrient analysis.
      • Insect samples: sweep net samples for insects utilizing cover crops (pests, predators, pollinators), and leaf samples (aphids). As dictated by degree-day model (http://uspest.org/cgi-bin/ddmodel.us?spp=fbw&uco=1), sample filbertworm larvae hibernaculae in cover crop.
      • Rodent activity: sample each treatment in test plots for bur-rows and other signs of activity.
      • Erosion assessment.
    2. Harvest cover crop: determine optimal cover crop harvest timing.
    3. Asses harvest and potential problems from residual cover crop.
    4. Nut collections for yield estimates at nutfall.
    5. Nut crack-out to estimate quality (size) and defects (insect damage, mold, empty shells, shrivel, etc.).
    6. Assess cover crop re-establishment. Reseed as necessary.

    Year 3 (2018)

    1. Collect data every two weeks at each site (as in year 2).
    2. Harvest cover crop: potentially adjust harvest timing based on year 1 experience.
    3. Asses harvest and potential problems from residual cover crop.
    4. Nut collections for yield estimates at nutfall.
    5. Nut crack-out to estimate quality (size) and defects (insect dam-age, mold, empty shells, shrivel, etc.).
    6. Reseed if needed, leverage other resources for continued re-search.
    7. Aggregate and analyze data.
    8. Publish an Extension document detailing cover crop selection, establishment and cost/benefit analysis.
    9. Publish a peer-reviewed manuscript on study results demonstrating cover crop effects on orchard nutrient cycles, soil health, and orchard ecology.
    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.