Effects of wood ash application on tree nutrition and soil dynamics in a Pinus taeda system

Authors: QUADROS, LEONARDO - Universidade Federal Do Parana; DUCHEIKO, HENRIQUE - Universidade Federal Do Parana; MAEDA, SHIZUO - Brazilian Agricultural Research Corporation (EMBRAPA); Prior, Stephen - Steve; ARAUJO, ELOA - Universidade Federal Do Parana; GOMES, JOAO - Brazilian Agricultural Research Corporation (EMBRAPA); BOGNOLLA, ITAMAR - Brazilian Agricultural Research Corporation (EMBRAPA); SOARES, MARCIA - Brazilian Agricultural Research Corporation (EMBRAPA); MAGRI, EDERLAN - Universidade Federal Do Parana; FRIGO, CLEITON - Universidade Federal Do Parana; KAWASAKI, ALBERTO - Universidade Federal Do Parana; MOTTA, ANTONIO - Universidade Federal Do Parana

Submitted to: Forest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2021
Publication Date: 8/4/2021
Citation: Quadros, L.P., Ducheiko, H.A., Maeda, S., Prior, S.A., Araujo, E.M., Gomes, J.B., Bognolla, I.A., Soares, M.T., Magri, E., Frigo, C., Kawasaki, A., Motta, A.C. 2021. Effects of wood ash application on tree nutrition and soil dynamics in a Pinus taeda system. Forest Science. 67(5):618-628. https://doi.org/10.1093/forsci/fxab030.
DOI: https://doi.org/10.1093/forsci/fxab030

Interpretive Summary: This work investigated application of a wood ash by-product to a Pinus taeda forest system. Wood ash application increased nutrient availability (primarily Ca and K) and reduced soil acidity. These effects could extend into deeper soil layers (down to 60 cm) and remain over time. However, increased soil fertility did not affect wood yield (remained around 0.56 m3 plant-1) nor litter build-up. The initial nutrient status of soil was likely sufficient to sustain productivity, explaining the ineffectiveness of wood ash application. We observed that 161 m3 ha-1 of soil were mobilized due to bioturbation in areas receiving 80 T ha-1 of wood ash, indicating resilient biological activity of macrorganisms. Since wood ash did not hinder forest productivity, its use in planted forests can be an ecologically sound alternative for disposal of this industrial by-product.

Technical Abstract: Many forest industries in Brazil use wood biomass as a sustainable energy source that generates a wood ash by-product. Many of these industries have used nearby planted forests as a venue for receiving this ash residue. To evaluate the effects of wood ash rates on Pinus taeda growth, a study was established on a high clay soil in 2006. Five rates of wood ash (0, 10, 20, 40, and 80 T ha-1) were broadcasted onto the forest floor surface when trees were three years old. Soil chemical properties were evaluated three times at different depths. Tree growth (i.e., height, diameter at breast height, and commercial volume) and nutrition (needle elemental composition) were determined. After 11 years, litter accumulation and soil mobilization (bioturbation) were also evaluated. There was no effect of ash application on tree growth/yield or litter accumulation. Two years after ash application, a small reduction in soil acidity and increased bases concentrated in the upper soil layer (0-10 cm) were observed. These changes increased after six years to deeper soil depths, but retreated to shallow depths at 11 years. Potassium displayed faster release and higher mobility within the soil profile compared to Ca and Mg. Despite these soil changes, only Mn concentration was reduced in needle tissue. A soil amount of 14.6 m3 ha-1 year-1 was relocated closer to the soil surface due to bioturbation by macrorganisms. The application of wood ash to forest soils appears to be an ecologically sound alternative for disposal of this industrial by-product.