Exploring Low-Phosphorous Wool Pellets as Fertilizer and Soil Conditioner for Vegetables

Project Overview

Project Type: Partnership
Funds awarded in 2020: $29,329.00
Projected End Date: 05/31/2022
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Project Leader:
Dr. Terence Bradshaw
University of Vermont
Laura Johnson
UVM Center for Sustainable Agriculture

Information Products


  • Vegetables: greens (leafy), tomatoes


  • Crop Production: fertilizers, nutrient management, organic fertilizers
  • Education and Training: demonstration
  • Production Systems: organic agriculture
  • Soil Management: soil quality/health

    Proposal abstract:

    This project addresses Northeastern vegetable farmers’ needs for sufficient production and yield, careful nutrient management and climate resiliency, by using a natural and potentially locally-produced item made from a waste product from sheep farms: pelletized raw wool.  We propose a two-year study of how wool pellets affect nitrogen and phosphorus interactions with plants and soils, and how wool pellets are affecting soil moisture content.

    The experimental design will be a completely randomized design with four replications and three treatments. The trials will be conducted in two Vermont locations, one at the UVM Horticulture Research and Education Center in Burlington and the other at Cedar Circle Farm and Education Center in East Thetford. 

    Incremental and final findings will be shared through field walks, print and web-based materials, video and social media with vegetable growers, shepherds, agricultural service professionals and other colleagues throughout the region.


    Project objectives from proposal:

    This project seeks to: 

    1. Determine if by using wool pellets as fertilizer providing N and K, spinach and tomato plants will utilize existing P in the soil.
    2. Determine whether the N in the pellets releases quickly enough for plants to utilize within the growing season.
    3. Understand whether wool pellets hygroscopic property can ameliorate the fluctuating extremes of precipitation on soil moisture levels during the growing season 

    These are important questions for vegetable farmers.  If we find that by using wool pellets for N and K, plants utilize existing soil P, that means less leaching into nearby waterways – a win for producers and the community. And if we find the pellets release N slowly enough so there is minimal, if any, runoff of excess, that too, is a win for both producers and the community.  And if we find the hygroscopic properties of the pellets shows they can help absorb the moisture in excessive precipitation events, and then release in drier periods, this could help eliminate much of the need for irrigation and running electrical pumps, both promoting resilience and saving money for  producers.


    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.