Impact of Biochar, Black Liquor, and Fly Ash Application to Soil on Productivity of Wheat in Eastern Washington: Final Report

This project evaluated locally available industrial co-products as alternatives to agricultural lime for acidic wheat soils in the Inland Pacific Northwest. Researchers tested two biochars, Avista wood ash, pelletized paper mill fly ash, and flour paper mill fly ash through soil incubation, greenhouse biomass, and microplot studies. Flour fly ash raised soil pH as much as or more than agricultural lime and reacted more quickly. It also reduced soil aluminum, increased several soil nutrients, and produced similar or greater wheat biomass than lime. Neither amendment resulted in detectable cadmium, chromium, or lead in plant tissue. Pelletized fly ash and wood ash increased soil pH but were less effective. The tested biochars did not significantly affect soil pH, nutrient availability, wheat biomass, or nutrient uptake. The findings suggest flour paper mill fly ash could provide a lower-cost alternative to agricultural lime, although long-term field research is needed.