Evaluating the impact of aeration and over-seeding on soil health, forage quality and forage quantity in perennial hay pastures in Western Washington

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2018: $19,948.00
Projected End Date: 03/31/2022
Grant Recipient: Oak Knoll Farm
Region: Western
State: Washington
Principal Investigator:
Adam Greene
Oak Knoll Farm


Not commodity specific


  • Animal Production: rangeland/pasture management
  • Education and Training: demonstration, on-farm/ranch research
  • Farm Business Management: budgets/cost and returns
  • Soil Management: soil quality/health

    Proposal summary:

    Many pasturelands in western Washington are not actively managed or renovated after
    the initial pasture seeding. Compaction, depletion of soil nutrients, and domination by
    aggressive and unpalatable grass species lead to poor forage quality and reduced forage
    quantity. Livestock producers recognize the need to improve pastures, but lack specific
    information necessary to evaluate the risk and benefits of different pasture renovation
    techniques. Conventional tillage and re-seeding is a lengthy, costly process that disrupts
    soil structure and function and may favor invasive weeds, increase soil erosion, and
    exacerbate loss of organic matter. A few producers practice annual aeration as a
    management technique to oxygenate the soil, increase water infiltration, and improve a
    seed bed. Research results on the effects of aeration vary widely. Variation in soil types,
    climates, and vegetation also makes extrapolating data problematic. This leaves
    producers with little data to assess the long-term impact on soil health or forage quality
    and quantity, so the expense and risk of implementing this technique remain a barrier to
    adoption. Sheep ranchers Adam Greene and Sarah Pope will perform field trials,
    collecting data and demonstrating practices. Trials will focus on aerator use versus no use
    (control) and compare over-seeding with and without aeration to unseeded areas.
    Research design, data collection and analysis, and outreach support will be provided by
    Dr. Brook Brouwer and Angie Freeman Shephard, MS of Washington State University
    Extension San Juan County. This study will increase awareness of pasture renovation and
    management best practices with a well-placed demonstration to other farmers/ranchers.
    Information and results will be shared widely through field days, fact sheets, articles, and
    on the extension website.

    Project objectives from proposal:

    1. Measure how aeration and over-seeding impacts soil health for three years (Years 1-3)
    2. Measure how aeration and over-seeding impacts forage quality/quantity (Years 1-3)
    3. Measure establishment of over-seeded legumes in aerated vs. non-aerated (Years 1-3)
    4. Quantify economics of aeration and over-seeding: cost to implement and estimated
    value of benefits or negative impacts (Years 2-3, results published in Year 3)
    5. Encourage pasture renovation by illuminating risks and benefits (Years 2 and 3)
    6. Quantify adoption impacts using before-and-after questionnaires (Years 1-3)

    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.