Use of Wood Ash as Soil Amendment on Annual Rangelands

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2011: $28,995.00
Projected End Date: 12/31/2013
Region: Western
State: California
Principal Investigator:
Mel Thompson
Sierra Farms
Glenn Nader
University of California Cooperative Extension

Annual Reports


  • Additional Plants: native plants
  • Animals: bovine, sheep


  • Animal Production: grazing management, pasture fertility, range improvement, grazing - rotational
  • Crop Production: organic fertilizers, tissue analysis
  • Education and Training: demonstration, extension, farmer to farmer, mentoring, networking, on-farm/ranch research, participatory research, workshop
  • Energy: energy use
  • Farm Business Management: budgets/cost and returns, marketing management, value added
  • Natural Resources/Environment: carbon sequestration, biodiversity, habitat enhancement
  • Production Systems: agroecosystems
  • Soil Management: organic matter, soil analysis, nutrient mineralization, soil chemistry, soil quality/health
  • Sustainable Communities: new business opportunities, employment opportunities, sustainability measures

    Proposal summary:

    This project will address the rangeland use of wood ash from co-generation energy plants where biomass is used as feedstock for electricity production. Increased interest in biomass energy conversion is leading to increased wood ash production and concern for its management. Alternative uses of ash are being explored, including rangeland where it has potential as a low cost fertilizer and liming agent over large landscapes and where commercial amendments are not economically feasible.

    The local co-generation plant produces over 10,000 tons of ash each year and currently is land-filling all of it, with considerable environmental and transportation costs. In recent years most of the output was land-applied, but ash handling concerns ended that practice and resulted in ash production being temporarily halted. Since re-starting, plant owners are reluctant to resume land applications without application protocol and assurances.

    Because ash is considered a toxic substance when accumulated and subject to air and water quality regulations, successful ash management is vital to the continuing operation of this plant as a central hub of the local biomass industry. Forestry, municipal and agriculture contribute over 120,000 tons of chipped green waste per year to this plant. Local employment, tax revenue and alternative grid energy rely on its continued function. The nearest similar plant is beyond feasible limits for transporting local feedstock.

    This project will expand on experiments with ash on our sheep-utilized rangeland conducted in 2007-2008 and use more scientific methods to produce photo and analytical data. Other Butte County ranchers will be included to test results on a wider array of soil types and grazing conditions, as well as a University of California, Davis research team that will determine soil carbon baseline and carbon sequestration potential data not currently available.

    The rangeland industry will benefit from specific research in ash application on sustainable grasslands. Several thousand acres of rangeland lay in a 15-mile radius of the plant. In addition, cost savings from local ash dissemination may encourage reallocation of revenue by plant owners into equipment needed to conduct ash application on rangeland. Demonstration of safe and efficient ash usage is a major goal of this project.

    Other goals include best application methods, rates and timing; more complete soil and vegetation analysis; soil moisture retention; forage production and species shift data; dust control; ash migration due to air and water flows; effective setback distances; and grazing differences between cattle and sheep. Annual rangelands begin growth following October-November rains, with forages reaching maturity in late April and May. Grazing typically follows grass growth, lasting about six months; November until May. Earlier ash experiments, using exclosures, recorded favorable changes in grass and forb production and significant shifting toward annual legumes, with no re-seeding.

    Seed banks exist for Medicago, Trifolium and Vicia, which in places showed five-fold or more growth compared to untreated plots, and in the case of the true clover, (T. variegatum), appeared without recorded precedent. High Potassium and moderate Phosphorous, Sulfur and Nitrogen levels in ash favor legume growth. Ash treated forage production averaged 2.1 tons/acre more than untreated areas. Because forage quality improved, residual dry matter (RDM) also improved in quality. Ewes and lambs grazed an extra 60 days in mature feed with no appreciable negative impact on lamb growth. Early-gestation ewes were able to graze all summer with minimal supplementation.

    This project will have a selective objective of showing more comprehensively ash benefit to rangeland forages, wildlife and the economies that rely upon production. Ancillary objectives will include creating a collaboration between rangeland users and the biomass energy industry to help sustain the local facility and surrounding communities. Carbon testing will establish baseline data and sequestration potential, and inclusion of a wide rangeland interest constituency will insure project results will be widely disseminated.

    Project objectives from proposal:

    *Determine best means and rate of ash application, considering area coverage, labor requirements, vegetation response and impact on RDM.

    *Analyze soil and vegetation differences between ash treated and untreated areas.

    *Determine forage production changes.

    *Record changes in plant diversity and density.

    *Observe changes to soil texture, porosity and infiltration rates.

    *Determine if grazing season has lengthened.

    *Provide outreach to other ranchers and interest groups as to findings, benefits and unforeseen problems.

    *Provide outreach to cogeneration plant owners on ash usage, application requirements, time of use and other issues specific to rangeland application.

    *Determine carbon baseline data and determine sequestration potential for ash-treated annual rangeland.

    *Publish findings and post on website.

    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.