Cover Crop Cocktails: Evaluating Costs and Benefits of Mixed-Species Plantings

Project Overview

Project Type: Professional + Producer
Funds awarded in 2016: $41,606.00
Projected End Date: 04/15/2019
Grant Recipient: Oahu RC&D
Region: Western
State: Hawaii
Principal Investigator:

Annual Reports


Not commodity specific


  • Crop Production: cover crops, intercropping
  • Natural Resources/Environment: biodiversity, soil stabilization
  • Pest Management: mulches - living
  • Production Systems: general crop production
  • Soil Management: green manures, organic matter, soil analysis, soil microbiology, soil quality/health


    Mixed-species cover crop plantings (aka Cover Crop Cocktails) offer multiple benefits to producers.  Through a collaboration with five Oahu-based producers, this project aimed to identify viable cover crop cocktails for producers in Hawaii.   Research and field demonstrations were used to evaluate economic costs, and to measure effects of cover crop plantings on soil health.  Information was shared with producers through on-farm field days, presentation at the Hawaii Ag Conference, and through Oahu RC&D's updated Cover Crop Handbook.

    Project objectives:

    Project Objectives and Target Dates:

    1. Identify cover crop species currently used and available in Hawaii.
      1. Conduct a survey of cover crop users, seed sales locations, and agricultural professionals to identify which cover crop species are currently in use / October 2016.
      2. Summarize information related to planting rates, costs, days to maturity, etc. / November 2016.
      3. Utilize information to determine cover crop cocktail mixes and planting rates / December 2016.
    2. Evaluate economic costs and soil health benefits of mixed-species cover crop plantings.
      1. Summarize economic costs (ie. cost of seed per acre) of cover crop cocktails / January 2017.
      2. Establish five demonstration plots in diverse geographic locations on Oahu / May – September 2017.
      3. Conduct physical, chemical, biological, and agronomic evaluations at pre-project and post-project intervals / approximate dates: March 2017, September 2018:
        1. Physical: moisture, temperature, bulk density.
        2. Chemical: pH, total nitrogen, total carbon, phosphorus, potassium.
        3. Biological: presence of earthworms, soil respiration (Solvita).
      4. Conduct agronomic evaluations of two seasons of cover crop cocktail plantings on cooperating farms:
        1. Agronomic: biomass of cover crop and, where feasible, weeds (used to determine relative weed suppression), percent soil coverage, presence of beneficial insects, estimated plant available nitrogen (tissue culture and cover crop calculator tool from the University of Hawaii CTAHR).
    3. Identify obstacles (“pain points”) and potential solutions for small farms adopting cover crop cocktails in Hawaii.
      1. Gather anecdotal feedback and observations from host farms following each planting / March 2018, December 2018, and throughout project period.
      2. Facilitate collaborative learning process through data collection, experimentation and feedback from technical advisors / throughout project period
      3. Summarize lessons learned to inform decision-making about cover crop cocktail use at the farm-level and simplify the on-boarding process for farms adopting cover crops. / December 2018
        1. Document pros and cons of different field practices and equipment used by participating farms. / December 2018
    4. Share results with producers and other agricultural professionals.
      1. Employ surveys to gauge familiarity with common cover crop species / October 2016, July 2018, March 2019.
      2. Hold two field days to demonstrate cover crop cocktails. Field days will be held at host sites, and will include presentations from the host farmer(s), 2-4 agricultural professionals on featured topic(s), and a tour or hands-on activity / September 2017, September 2018.
      3. Incorporate findings into a revised edition of the Cover Crop Handbook produced by Oahu RC&D / March – June 2019.
      4. Present findings at the 2017 Hawaii Agriculture Conference (or similar venue) / August 2017.
      5. Disseminate resources, results and related information via social media networks and producer-to-producer networks / entire project period.
    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.