Effects of wood ash application on nutrient status and buffer capacity of a forest soil

Abb. 1: In small experimental plots wood ash was applied (8t/ha) to study the effects on soil biological properties. Photo: Beat Frey (WSL

With the promotion of wood energy and a concomitantly increasing use of wood as a renewable energy source, more and more wood ash will be produced. Ash from untreated wood contains a lot of nutrients and only little harmful substances. As a sustainable economic management should aim for closed material cycles, uncontaminated wood ash should be recycled. However, the application of wood ash in forests is prohibited by the law. Prior to a possible change in this code of environmental management, the scientific fundamentals of the consequences of a wood ash application should be investigated.

Aims

The goals of this study were to answer the following questions:

• What is the influence of the particular time of wood ash application in the course of the year on the soil chemical processes, with special emphasis on leaching processes?
• What is the solubility of the wood ash and how is the composition of the soil solution over time influenced by the solubility products?
• How does the wood ash change the composition of the exchange complex of the soil? Is the acid neutralizing capacity of the soil increased?
• How does the BC/Al-ratio of the soil solution change?

Methods

• Characterization of the top soil prior to and after the application of wood ash (pH-value, exchangeable cations, C-content, N-content
• Characterization of two soil profiles
• Application of wood ash, the first time in may 1998, the second time in july 1999 (4 t/ha in each case)
• Monitoring of the soil solution in 4 depth
• Measurement of soil biological properties in soils with and without wood ash application

Project partners

Maya Bundt, Peter Blaser

Publications

• Zimmermann, S.; Bundt, M., 2000: Holzasche aus Energiefeuerung: Recycling oder Dumping?. - Inf.bl. Forsch.bereich Landsch. 46: 1-4.
• Bundt, M.; Zimmermann, S.; Blaser, P.; Hagedorn, F., 2001: Sorption and transport of metals in preferential flow paths and soil matrix after the addition of wood ash. - Europ. J. Soil Sci. 52: 423-431.
• Zimmermann, S.; Frey, B., 2002: Soil respiration and microbial properties in an acidic forest soil: effects of wood ash. - Soil Biol. Biochem. 34: 1727-1737.
• Zimmermann, S.; Hallenbarter, D.; Landolt, W.; Genenger, M.; Brunner, I., 2002: Wirkung von Holzasche auf Waldboden, Baumwurzeln und Baumphysiologie. Holzasche: Zurück in den Wald? - Wald Holz 83, 11: 41-44.
• Zimmermann, S.; Frey, B., 2002: Wie reagieren Bodenmikroorganismen auf Holzasche im Wald? - Inf.bl. Forsch.bereich Wald 12: 4-5.
• Genenger, M.; Zimmermann, S.; Frossard, E.; Brunner, I., 2003: The effects of fertiliser or wood ash on the nitrate reductase activity in Norway spruce fine roots. - For. Ecol. Manage. 175: 413-423.
• Genenger, M.; Zimmermann, S.; Hallenbarter, D.; Landolt, W.; Frossard, E.; Brunner, I., 2003: Fine root growth and element concentrations of Norway spruce as affected by wood ash and liquid fertilisation. - Plant Soil 255: 253-264.
• Brunner, I.; Zimmermann, S.; Zingg, A.; Blaser, P., 2004: Wood-ash recycling affects forest soil and tree fine-root chemistry and reverses soil acidification. - Plant Soil 267: 61-71.

Contact

• Stephan Zimmermann