Die Bodenkultur - Journal for Land Management, Food and Environment

H. Insam, I.H. Franke-Whittle, B.A. Knapp and R. Plank

Use of wood ash and anaerobic sludge for grassland fertilization: Effects on plants and microbes

Summary

The aim of this study was to investigate if the use of wood ash and sludge, or a combination of them, could change soil microbiological properties and plant growth. A second aim was to determine if high doses of these amendments could create problems in terms of nitrate leaching, and if such problems could be offset by adding a clay mineral, vermiculite. The effect of sludges and ash on soil microbial bulk parameters was found to be small, while the composition of the bacterial community was considerably changed. We were able to demonstrate that an application rate of sludge corresponding to 180 kg N ha-1 was problematic in terms of nitrate leaching and could not be offset by amending with ash or vermiculite. Germination of cress was retarded by sludge and ash addition, however, this effect was partly offset by the addition of vermiculite. Key words: Anaerobic sludge, wood ash, organic fertilizer, lysimeter, nitrate leaching.